Rongjia TAO, et al.
Electric Fuel Treatment
ScienceDaily, 27 February 2015
Saving energy: Increasing oil flow in
the Keystone pipeline with electric fields
Suppressing turbulence and enhancing liquid
suspension flow in pipelines with electrorheology.
R. Tao, G. Q. Gu.
Summary:
A strong electric field applied to a section of the Keystone
pipeline can smooth oil flow and yield significant pump energy
savings. Once aligned with an electric field, oil retained its
low viscosity and turbulence for more than 11 hours before
returning to its original viscosity. The process is repeatable
and the researchers envision placing aligning stations spaced
along a pipeline, significantly reducing the energy necessary to
transport oil.
Researchers have shown that a strong electric field applied to a
section of the Keystone pipeline can smooth oil flow and yield
significant pump energy savings.
Traditionally, pipeline oil is heated over several miles in
order to reduce the oil's thickness (which is also known as
viscosity), but this requires a large amount of energy and
counter-productively increases turbulence within the flow. In
2006 Rongjia Tao of Temple University in Pennsylvania proposed a
more efficient way of improving flow rates by applying an
electric field to the oil. The idea is to electrically align
particles within the crude oil, which reduces viscosity and
turbulence.
To test this, Tao collaborated with energy company Save The
World Air, Inc. to develop an Applied Oil Technology (AOT)
device that links to oil pipelines and produces an electric
field along the direction of the oil flow. Recent trials on oil
pipelines in Wyoming and China verified that crude oil particles
form short chains in an electric field. These chains reduce
viscosity in the direction of flow to a minimum. At the same
time the viscosity perpendicular to the flow increases, which
helps suppress turbulence in the overall flow.
This past summer Tao and his colleagues also successfully tested
the AOT device on a section of the Keystone pipeline near
Wichita, Kansas.
"People were amazed at the energy savings when we first tested
this device. They didn't initially understand the physics," said
Tao. "A second test with an independent company was arranged and
found the same thing." Tests on a section of the Keystone
pipeline found that the same flow rate could be achieved with a
75 percent reduction of pump power from 2.8 megawatts to 0.7
megawatts, thanks to the AOT device. The device itself uses 720
watts.
Once aligned, the oil retained its low viscosity and turbulence
for more than 11 hours before returning to its original
viscosity. But the process is repeatable and Tao and his
colleagues envision AOT stations spaced along a pipeline,
significantly reducing the energy necessary to transport oil.
This work was published in January 2015 in Physical Review E and
Tao will present the additional Keystone pipeline test results
at the American Physical Society March Meeting 2015 in San
Antonio (March 2-6).
Previously Tao has also shown that the same technique applied
with a magnetic field can reduce blood viscosity by 20 to 30
percent, published in 2011 in Physical Review E. With clinical
trials, Tao says this could represent a future treatment for
heart disease.
Researchers have shown that a strong electric field
applied to a section of the Keystone pipeline can smooth oil
flow and yield significant pump energy savings.
Traditionally, pipeline oil is heated over several miles in
order to reduce the oil's thickness (which is also known as
viscosity), but this requires a large amount of energy and
counter-productively increases turbulence within the flow. In
2006 Rongjia Tao of Temple University in Pennsylvania proposed a
more efficient way of improving flow rates by applying an
electric field to the oil. The idea is to electrically align
particles within the crude oil, which reduces viscosity and
turbulence.
To test this, Tao collaborated with energy company Save The
World Air, Inc. to develop an Applied Oil Technology (AOT)
device that links to oil pipelines and produces an electric
field along the direction of the oil flow. Recent trials on oil
pipelines in Wyoming and China verified that crude oil particles
form short chains in an electric field. These chains reduce
viscosity in the direction of flow to a minimum. At the same
time the viscosity perpendicular to the flow increases, which
helps suppress turbulence in the overall flow.
This past summer Tao and his colleagues also successfully tested
the AOT device on a section of the Keystone pipeline near
Wichita, Kansas.
"People were amazed at the energy savings when we first tested
this device. They didn't initially understand the physics," said
Tao. "A second test with an independent company was arranged and
found the same thing." Tests on a section of the Keystone
pipeline found that the same flow rate could be achieved with a
75 percent reduction of pump power from 2.8 megawatts to 0.7
megawatts, thanks to the AOT device. The device itself uses 720
watts.
Once aligned, the oil retained its low viscosity and turbulence
for more than 11 hours before returning to its original
viscosity. But the process is repeatable and Tao and his
colleagues envision AOT stations spaced along a pipeline,
significantly reducing the energy necessary to transport oil.
This work was published in January 2015 in Physical Review E and
Tao will present the additional Keystone pipeline test results
at the American Physical Society March Meeting 2015 in San
Antonio (March 2-6).
Previously Tao has also shown that the same technique applied
with a magnetic field can reduce blood viscosity by 20 to 30
percent, published in 2011 in Physical Review E. With clinical
trials, Tao says this could represent a future treatment for
heart disease.
http://journals.aps.org/pre/abstract/10.1103/PhysRevE.91.012304
Phys. Rev. E 91, 012304
13 January 2015
Physical Review E, 2015; 91 (1)
DOI: 10.1103/PhysRevE.91.012304
R. Tao and G. Q. Gu
Abstract
Flows through pipes, such as crude oil through pipelines,
are the most common and important method of transportation of
fluids. To enhance the flow output along the pipeline requires
reducing viscosity and suppressing turbulence simultaneously and
effectively. Unfortunately, no method is currently available to
accomplish both goals simultaneously. Here we show that
electrorheology provides an efficient solution. When a strong
electric field is applied along the flow direction in a small
section of pipeline, the field polarizes and aggregates the
particles suspended inside the base liquid into short chains
along the flow direction. Such aggregation breaks the rotational
symmetry and makes the fluid viscosity anisotropic. In the
directions perpendicular to the flow, the viscosity is
substantially increased, effectively suppressing the turbulence.
Along the flow direction, the viscosity is significantly
reduced; thus the flow along the pipeline is enhanced. Recent
field tests with a crude oil pipeline fully confirm the
theoretical results.
Figure 1
As the liquid suspension flow passes a strong local electric
field, the suspended particles are aggregated into short
chains along the field direction.
Figure 2
Small-angle neutron scattering has confirmed the aggregation.
With no electric field, the scattering is isotropic and
sparse, indicating the particles are randomly distributed in
the oil (left). Under an electric field of 250V/mm (middle),
the scattering reveals short chains of particles aggregated
along the field direction. When E=400V/mm, the short chain has
a prolate spheroid shape (right).
Figure 3
The electric field makes the viscosity along the flow
direction much lower than the original viscosity, while it
raises the viscosity perpendicular to the flow much higher
than the original viscosity.
Figure 4
The AOT device is placed downstream next to the pump.
Figure 5
After the AOT device was turned on, there was less pressure
loss. When the loop was filled with all treated crude oil, the
pressure loss was down 40%. After the device was turned off,
the pressure loss returned to the original value as the
untreated crude oil pushed the treated crude oil away.
Figure 6
The electric-field-treated oil flow has pump pressure linearly
proportional to the flow rate, indicating the flow remains
laminar as the Reynolds number reaches 6348. The untreated oil
has pump pressure increasing much faster than the linear
relation with the flow rate, indicting the flow becomes
turbulent when the Reynolds number >2300.
Figure 7
Outside the electric field, the viscosity of treated crude oil
goes up slowly after the treatment.
Figure 8
During the test, the treated crude oil kept its reduced
viscosity for 11 h after the AOT device was shut off.
http://www.sciencedaily.com/releases/2008/09/080925111836.htm
Want Better Mileage? Simple Device Which Uses Electrical Field Could Boost Gas Efficiency Up To 20%
ScienceDaily (Sep. 26, 2008) — With the high cost of gasoline and diesel fuel impacting costs for automobiles, trucks, buses and the overall economy, a Temple University physics professor has developed a simple device which could dramatically improve fuel efficiency as much as 20 percent.
According to Rongjia Tao, Chair of Temple's Physics Department, the small device consists of an electrically charged tube that can be attached to the fuel line of a car's engine near the fuel injector. With the use of a power supply from the vehicle's battery, the device creates an electric field that thins fuel, or reduces its viscosity, so that smaller droplets are injected into the engine. That leads to more efficient and cleaner combustion than a standard fuel injector, he says.
Six months of road testing in a diesel-powered Mercedes-Benz automobile showed that the device increased highway fuel from 32 miles per gallon to 38 mpg, a 20 percent boost, and a 12-15 percent gain in city driving.
The results of the laboratory and road tests verifying that this simple device can boost gas mileage.
"We expect the device will have wide applications on all types of internal combustion engines, present ones and future ones," Tao wrote in the study published in Energy & Fuels.
Further improvements in the device could lead to even better mileage, he suggests, and cited engines powered by gasoline, biodiesel, and kerosene as having potential use of the device.
Temple has applied for a patent on this technology, which has been licensed to California-based Save The World Air, Inc., an environmentally conscientious enterprise focused on the design, development, and commercialization of revolutionary technologies targeted at reducing emissions from internal combustion engines.
According to Joe Dell, Vice President of Marketing for STWA, the company is currently working with a trucking company near Reading, Pa., to test the device on diesel-powered trucks, where he estimates it could increase fuel efficiency as much as 6-12 percent.
Dell predicts this type of increased fuel efficiency could save tens of billions of dollars in the trucking industry and have a major impact on the economy through the lowering of costs to deliver goods and services.
"Temple University is very excited about the translation of this new important technology from the research laboratory to the marketplace," said Larry F. Lemanski, Senior Vice President for Research and Strategic Initiatives at Temple. "This discovery promises to significantly improve fuel efficiency in all types of internal combustion engine powered vehicles and at the same time will have far-reaching effects in reducing pollution of our environment."
Journal reference:
1 . Tao, et al. Electrorheology Leads to Efficient
Combustion. Energy & Fuels, 2008; DOI: 10.1021/ef8004898
Adapted from materials provided by Temple University.
Electric-Field Assisted Fuel Atomization [ PDF ]
by
R. Tao
http://media.cleantech.com/3573/electric-device-promises-better-gas-efficiency
September 25, 2008
Electric Device Promises Better Gas Efficiency
Researchers say they’ve produced an electric device that can boost fuel efficiency in cars and trucks and by as much as 20 percent
Researchers at Temple University today said today they had developed a simple electrically charged tube, which when attached to a car’s fuel line can boost energy efficiency by as much as 20 percent.
Temple University physics professor Rongjia Tao said the charged tube is powered by the vehicle’s battery. In essence, the electrical field powered by the battery thins the fuel and reduces its viscosity (see Nano-ceramic boosts fuel efficiency).
That means smaller droplets can be injected into the engine. This process of generating small droplets leads to more efficient and cleaner combustion than a standard fuel injector, according to the researcher.
Temple University said the device has undergone six months of road testing in a diesel-powered Mercedes-Benz automobile. Results from the testing revealed the device boosted highway fuel mileage by 20 percent, from 32 miles-per-gallon to 38 mpg. On city streets, the device only provided a 12 to 15 percent gain.
Further improvements in the device could lead to even better mileage (see Driving team takes on Guinness efficiency record). What's more, the device can work in other types of internal combustion engines powered by gasoline, biodiesel and kerosene.
Researchers said there is more work to be done on the prototype device to further improve mileage yields. Temple University said it has applied for a patent on the technology. The university said Calif.-based Save The World Air has licensed the technology.
The research results were published in Energy & Fuels, a bi-monthly journal published by the American Chemical Society.
Zapped Crude Oil Flows Faster Through Pipes
by
Kurt Kleiner
Zapping thick crude oil with a magnetic or electric field could make it flow more smoothly through pipes. The technique, which reduces the viscosity of the liquid, could make transporting crude through cold underwater pipes easier and cheaper, researchers claim.
The cost of transporting oil is a major factor in the energy economy, although the type of oil being moved is changing. "More heavy oil is being pumped. Lighter crude is being found less and less," says Rongjia Tao, a physicist at Temple University in Philadelphia, US.
Since heavy crude is more viscous, it flows more slowly through the pipes, reducing the volume of oil that can be pumped. If it flows too slowly, oil companies try diluting it with gasoline or other solvents, or sometimes heating the oil. But those techniques can be expensive and hard to implement on ocean-based oil rigs.
Tao says the viscosity of a suspension is partly the result of the size of the suspended particles. Smaller particles create a fluid that is more viscous than large particles.
The two researchers reasoned that if they could get the small particles to clump together, or aggregate, viscosity would go down. First they tested the theory with a suspension of iron nanoparticles in silicon oil. They applied a magnetic field to the suspension, and did indeed observe a reduction in viscosity.
Ongoing effect
Tao says that the magnetic field apparently caused the iron particles to stick together into larger clumps. Once the field was turned off they continued to stick together for several hours, only gradually breaking apart.
Tao and his colleague Xiaojun Xu then decided to see what affect magnetic and electric fields would have on the viscosity of crude oil.
Crude oil can contain either paraffin, asphalt, or both. The researchers found that a magnetic field reduced the viscosity of paraffin-based crude oil by about 15% when applied at 1.33 Tesla for 50 seconds. The reduction in viscosity lasted for several hours, gradually returning to normal. Tao says the magnetic field seems to have polarised the paraffin particles, causing them to clump together in the same way as the iron particles.
The magnetic field did not work on asphalt-based crude oil,
however. So Tao and Xu decided to try applying an electric field
to this mixture. They applied a powerful electric field to the
oil and again saw a reduction in viscosity. Tao believes the
particles were similarly polarised. Whatever the process, the
particles clumped together before gradually breaking apart over
several hours.
Cost sensitive
Tao says that the technique could eventually be useful in oil pipelines. Powerful magnets could be positioned at regular intervals along the pipeline, or electrified grids could run on the inside.
But Ross Chow of the Alberta Research Council in Edmonton, Canada, says that the researchers had to apply large amounts of electrical energy for fairly small decreases in viscosity. He also says it is not clear whether Tao and Xu's theoretical explanation of what is happening is correct.
On the other hand, Chow says the effect seems to be real, and agrees that further research might lead to an economic way of using magnetic and electric fields in pipelines.
Journal reference: Energy Fuels (DOI: 10.1021/ef060072x)
http://www.geotimes.org/nov06/resources.html
Easing Oil’s Flow
by
Megan Sever
Researchers have figured out a new way to make crude oil flow faster using electric and magnetic pulses. They hope such technologies will help harvest crude oil buried in fields deep below the seafloor.
Cold temperatures can make it nearly impossible for thick asphalt-based crude oil to flow through a pipeline, such as the TransCanada Mainline in western Canada. New research suggests electric pulses could ease the oil flow. Photograph is copyright TransCanada Pipelines Limited.
Low temperatures in offshore pipelines decrease oil’s ability to flow, so that it is much more difficult to move through the pipelines. But the seemingly simplest solution — heating those pipelines — has proven difficult and expensive, says Rongjia Tao, a physicist at Temple University in Philadelphia, Pa.
While some companies still use heat, perhaps the most common way energy companies currently reduce oil viscosity is through the use of chemical additives, which modify the internal structure of the oil and allow it to flow more easily, says Ken Barker, a chemist with Baker Petrolite in St. Louis. Companies, however, are always trying new options to improve the efficiency of the process.
In China and Russia, for example, companies frequently dilute the crude oil with gasoline, Tao says. And the Department of Energy has looked at adding bacteria or other biological agents to improve flow rates. People also have tried using magnets since at least the 1970s, Barker says, but until now, such experiments have lacked a solid foundation.
The new method, described by Tao and colleague Xiaojun Xu in the Sept. 20 Energy & Fuels is based on a simple concept, Tao says: Send a magnetic or electric pulse through the pipeline and into the oil. That pulse causes the wax-like molecules in the crude oil to cluster together into a smaller number of large particles, which makes it flow more easily. The trick, he says, is not to overdo it or you can have the opposite effect; too much clumping will increase the viscosity of the oil.
So Tao and Xu ran a series of experiments to see exactly what level of pulses was needed to maximize the flow rate of both paraffin-based oil and asphalt-based oil. Paraffin-based crude is common in Asia and the Middle East, and asphalt-based oil is most common in North America.
They found that 1- to 3-second-long magnetic pulses were best for increasing the flow rate of paraffin oil, while seconds-long electric pulses worked best on asphalt-based oil. The pulses could keep the oil flowing easily for up to 12 hours. Once the oil started to thicken again, the pulses could be reapplied to thin the oil for another few hours, Tao says. In a pipeline, the magnetic or electric pulse machines could be separated several kilometers apart to apply the pulses as soon as the oil viscosity starts to increase, he says.
Barker says that it is probably accurate that applying a pulse will affect the oil’s viscosity, but to what degree, he does not know. “This research is good and offers an explanation for why these [electric and magnetic] fields will work, but how significant it will be remains to be seen,” he says. Every crude oil has slightly different properties, he says, and Tao and Xu only looked at several samples, so more research is necessary.
Tao agrees that they need to further experiment with flow rates in the field and with different types of oil, including heavy oil and oil sands. But meanwhile, he and Xu have sought a patent on their technology, and a California company is planning to develop it.
http://pubs.acs.org/journals/enfuem/promo/inthenews/index.html
The Philadelphia Inquirer ( Sept. 20, 2006 )
Energy & Fuels; (Article); 2006; 20(5); 2046-2051.
DOI: 10.1021/ef060072x
Reducing the Viscosity of Crude Oil by
Pulsed Electric or Magnetic Field
Tao, R.; Xu, X.
Temple physics prof. says he can speed crude oil's flow through pipelines
The thin glass tube was held upright with a clamp, but the thick, dark oil inside didn't budge - much like ketchup stuck in an overturned bottle. No problem. Rongjia Tao brushed the outside of the tube a few times with a small magnet, and the oil began to flow slowly downward. Tao, a physics professor at Temple University, wants to take his technique from glass tubes to pipelines, improving the flow of tarlike crude oil in oil fields worldwide - especially in cold, deepwater environments where it takes more energy to pump the thick stuff. In today's edition of the journal Energy & Fuels, Tao reports that he and colleagues were able to reduce the viscosity of crude with magnetic or electrical pulses. A patent is pending, and a California company has been licensed to develop the technology.
http://esciencenews.com/articles/2008/09/25/simple.device.which.uses.electrical.field.could.boost.gas.efficiency
25 September2008
Simple Device which uses Electrical Field could Boost Gas Efficiency
With the high cost of gasoline and diesel fuel impacting costs for automobiles, trucks, buses and the overall economy, a Temple University physics professor has developed a simple device which could dramatically improve fuel efficiency as much as 20 percent. According to Rongjia Tao, Chair of Temple's Physics Department, the small device consists of an electrically charged tube that can be attached to the fuel line of a car's engine near the fuel injector. With the use of a power supply from the vehicle's battery, the device creates an electric field that thins fuel, or reduces its viscosity, so that smaller droplets are injected into the engine. That leads to more efficient and cleaner combustion than a standard fuel injector, he says.
Six months of road testing in a diesel-powered Mercedes-Benz automobile showed that the device increased highway fuel from 32 miles per gallon to 38 mpg, a 20 percent boost, and a 12-15 percent gain in city driving.
The results of the laboratory and road tests verifying that this simple device can boost gas mileage was published in Energy & Fuels, a bi-monthly journal published by the American Chemical Society.
"We expect the device will have wide applications on all types of internal combustion engines, present ones and future ones," Tao wrote in the published study, "Electrorheology Leads to Efficient Combustion."
Further improvements in the device could lead to even better mileage, he suggests, and cited engines powered by gasoline, biodiesel, and kerosene as having potential use of the device.
Temple has applied for a patent on this technology, which has been licensed to California-based Save The World Air, Inc., an environmentally conscientious enterprise focused on the design, development, and commercialization of revolutionary technologies targeted at reducing emissions from internal combustion engines.
According to Joe Dell, Vice President of Marketing for STWA, the company is currently working with a trucking company near Reading, Pa., to test the device on diesel-powered trucks, where he estimates it could increase fuel efficiency as much as 6-12 percent.
Dell predicts this type of increased fuel efficiency could save tens of billions of dollars in the trucking industry and have a major impact on the economy through the lowering of costs to deliver goods and services.
"Temple University is very excited about the translation of this new important technology from the research laboratory to the marketplace," said Larry F. Lemanski, Senior Vice President for Research and Strategic Initiatives at Temple. "This discovery promises to significantly improve fuel efficiency in all types of internal combustion engine powered vehicles and at the same time will have far-reaching effects in reducing pollution of our environment."
http://temple-news.com/2008/10/06/new-device-boosts-gas-efficiency/
6 October 2008
New Device Boosts Gas Efficiency
by
Greg Adomaitis
( greg.adomaitis@temple.edu )
Presidential candidates have suggested inflating your tires, mechanics instruct motorists to keep their cars in shape and everyday drivers are cutting their travels when possible. But the physics department at Temple has developed a part for vehicles that may impact drivers’ wallets.
Rongjia Tao, chair of the physics department, has developed a small device that when connected to the fuel line in diesel engines can improve gas efficiency by 20 percent.
The small device Rongjia Tao invented can increase gas efficiency by up to 20 percent. It was tested on a Mercedes-Benz 300D (Ana Zhilkova/TTN).
The device receives power from a vehicle’s battery to create an electric field that thins fuel, resulting in smaller amounts of fuel being injected into the engine.
Development of the device began in 2006 with Tao and five other researchers, two of whom were Temple students.
“The major difficulty was that there was a shortage of good technicians in our machine shop to manufacture the device,” Tao said.
After testing the device on a Mercedes-Benz 300D, there was an increase in highway miles per gallon from 32 to 38. City driving tests resulted in a 15 percent gain.
The group intended to improve fuel efficiency and decrease pollutant emissions according to the study published in Energy & Fuels.
Diesel-powered vehicles gain more mpg, along with less black plumes of exhaust. The use of biodiesel, an alternative diesel fuel made from renewable resources, has lower emissions compared to petroleum diesel.
The device was selected by Save The World Air, Inc. According to its Web site, STWA seeks “to provide a comprehensive range of cost-effective and value-added products to the worldwide combustion engine market” that are deemed clean technology resources.
STWA became aware of Tao’s product through a client who provided research grants. The corporation purchased licenses to Tao’s patents. STWA has a contract with AWI Truck Company of Reading, Pa., to install the device on its trucks.
Eddie Casanova, an employee of Temple’s grounds department, drives a diesel truck for the university. Temple pays for the fuel in the truck Casanova drives.
“We should have gotten the first choice,” Casanova said about the device being used in Reading rather than being implemented on campus first.
Expanding the research to gasoline engines is under way, as testing is scheduled to be performed soon, Tao said.
“I feel that basic science research can be very useful in solving some big technology issues.”
Patents & Applications
Method for Reduction of Crude Oil
Viscosity
Inventor: RONGJIA TAO (US); XIAOJUN XU
CN101084397
2007-12-05
Also published as: WO2006065775 (A3) WO2006065775 (A2) GB2434800
(A) CA2591579 (A1)
Abstract --The present invention relates to a method for
reducing the viscosity and facilitating the flow of
petroleum-based fluids. The method includes the step of applying
an electric field of sufficient strength and for a sufficient
time to the petroleum-based fluid to cause a reduction in
viscosity of the fluid.
METHOD FOR REDUCTION OF CRUDE OIL VISCOSITY
US2008257414 (A1)TAO RONGJIA; XU XIAOJUN; HUANG KE
Applicant(s): UNIV TEMPLE [US]
Classification: - international: F17D1/16; F17D1/00 - European: F17D1/16
Also publishewd as : NO20073617 (B) // GB2434800 (A)Abstract -- The present invention relates to a method for reducing the viscosity and facilitating the flow of petroleum-based fluids. The method includes the step of applying an electric field of sufficient strength and for a sufficient time to the petroleum-based fluid to cause a reduction in viscosity of the fluid.
FIELD OF THE INVENTION
[0002]The present invention relates to petroleum-based fluids. More specifically, it relates to a method for reducing the viscosity and facilitating the flow of petroleum-based fluids.
BACKGROUND OF THE INVENTION
[0003]It is well known in the art that petroleum-based fluids, such as crude oil, have viscosity characteristics of liquid suspensions or emulsions. As a result, the three basic types of crude oil--paraffin-based, asphalt-based, and mixed-base (paraffin-based and asphalt-based mixed)--all exhibit the characteristic of increased viscosity corresponding to decreased fluid temperatures. In paraffin-based crude oil, as the temperature of the fluid decreases, especially when the temperature falls just below the temperature at which wax begins to precipitate (called the wax-appearance temperature), paraffin in the fluid crystallizes into many nanometer-sized particles which suspend in the solvent and increase the apparent viscosity of the fluid. In asphalt-based crude oil, asphalt in the fluid solidifies into an increasing number of asphaltene particles as the temperature decreases, resulting in a continuous increase in apparent viscosity. Mixed-based crude oil likewise demonstrates an inverse viscosity/temperature relationship similar to characteristics of both paraffin-based and asphalt-based crude oils. This inverse viscosity/temperature relationship is particularly problematic when the increase in viscosity fouls pipelines in which crude oil is transported.
[0004]In addition to the viscosity increase at lower temperatures, crude oil precipitates wax or asphaltene particles at lower temperatures, which is particularly problematic because of its detrimental effect on the transportation of crude oil via pipeline. As a result of crude oil wax or asphaltene precipitation, pipelines must be frequently shut down and cleaned to scrape out wax or asphaltene buildup in the piping to prevent obstruction of crude oil flow.
[0005]With increasing demands on world oil supplies and the low temperature climates, for example offshore oil wells and the Artic and sub-Arctic environs, in which oil is extracted or through which it is transported, it is increasingly important to develop methods for improving the flow of crude oil in pipelines at lower temperatures.
[0006]For the reasons described above, a method for decreasing viscosity and facilitating fluid flow of petroleum-based fluids, such as crude oil, is desirable.
SUMMARY OF THE INVENTION
[0007]According to the method of the present invention, there is provided a method for reducing the viscosity of petroleum based fluids. The method comprises applying to the fluid an electric field of sufficient strength and of a sufficient period of time to reduce viscosity of the fluid and applying that field for a time sufficient to facilitate improved flow of the fluid. The selection of an appropriate strength electric field and an appropriate time period for application of the field is necessary to produce a desired reduction in viscosity of the petroleum-based fluid and improvement in the flow thereof. The present invention is particularly useful in the transportation of crude oil through pipelines where improved fluid flow is desirable, and more specifically where cooler fluid temperatures cause increased fluid viscosity, and raising the fluid's temperature in order to reduce the viscosity is difficult to achieve.
BRIEF DESCRIPTION OF THE DRAWINGS
[0008]The invention is best understood from the following detailed description when read in connection with the accompanying drawing. It is emphasized that, according to common practice, the various features of the drawing are not rendered to scale. On the contrary, the dimensions of the various features are arbitrarily expanded or reduced for clarity. Included in the drawing are the following figures:
FIG. 1 is an illustration of a capacitor for applying an electric field in accordance with an embodiment of the invention.
FIG. 2 is a graph of viscosity versus time for an oil sample in accordance with Example 1.
FIG. 3 is a graph of viscosity versus time for an oil sample in accordance to Example 2.
FIG. 4 is a graph of the lowest viscosity versus duration or an applied DC electric field strength of 600 V/mm for an oil sample in accordance with Example 3.
FIG. 5 is a graph of the lowest viscosity versus duration of an applied DC electric field strength of 600 V/mm for an oil sample in accordance with Example 4.
FIG. 6 is a graph of viscosity versus time for an oil sample in accordance with Example 5.
FIG. 7 is a graph of kinetic viscosity versus time for an oil sample in accordance with Example 7.
DETAILED DESCRIPTION OF THE INVENTION
[0016]The present invention provides a method for reducing viscosity and improving the flow of petroleum-based fluids, by applying to the fluid an electric field of sufficient strength and for a period of time sufficient to reduce viscosity of the fluid.
[0017]The method is directed to petroleum-based fluids, such as crude oil, but is not limited to this particular petroleum-based fluid. Thus the method is applicable, for example, to crude oil, including but not limited to paraffin based crude oil, asphalt based crude oil, mixed based crude oil (a combination of both paraffin-based and asphalt-based), and mixtures thereof. More particularly the present invention is directed to fluids which are too viscous, due at least in part to temperature considerations, to be easily transported or piped from one location to another.
[0018]It has been discovered that by applying an electric field to the fluid, viscosity of the fluid can be reduced to facilitate flow of the fluid and/or prevent precipitation of solids which might cause blockage or reduced flow through pipes or vessels through which the fluid must pass. In order to obtain a desired reduction in viscosity, the applied electric field must be of a strength of at least about 10 V/mm in order to produce a reduction in viscosity of the fluid. For example, the field strength may suitably be in the range of about 10 V/mm up to about 2000 V/mm, for example in the range of about 400 V/mm to about 1500 V/mm. The selection of a particular value within this range is expected to depend on the composition of the fluid, the desired degree of reduction in viscosity, the temperature of the fluid, and the period during which the field is to be applied. It will be appreciated that if the field strength is too low or the application period too short no significant change in viscosity will result. Conversely if the strength of the electric field is too high or the period of application too long, the viscosity of the fluid may actually increase.
[0019]As indicated above, the duration of exposure of the fluid to the electric field is also important in order to reduce the viscosity. The exposure period is suitably in the range of about 1 second to about 300 seconds, for example, about 1 second to about 100 seconds.
[0020]As the fluid continues its flow over extended periods of time, the viscosity following application of the field as described above will tend to increase slowly back toward its original value. It may therefore be necessary, in order to maintain a desired viscosity range, to reapply the electric field periodically at a point or multiple points downstream from the point at which the initial electric field was applied. For example, it may be desirable to reapply the electric field at intervals ranging, for example, from about 15 minutes to about 60 minutes as the fluid progresses along its path of travel to ensure that viscosity is always below a predetermined level. In crude oil applications, it may thus be desirable to locate electric fields at a series of points downstream from the initial point to the destination point. Since crude oil in a pipeline flows several miles per hour, applying an electric field at intervals every couple of miles would allow viscosity to be maintained below the predetermined value. The viscosity would continually be driven to the lower values by counteracting the rebounding that occurs as the crude oil flows through areas of the pipe not exposed to the electric fields.
[0021]By applying the electric field within these ranges of strength and period, nearby paraffin particles or asphaltene particles are forced to aggregate into larger particles that are limited to micrometer size, while not permitting enough time or strength to let these particles form macroscopic clusters. As the average particle size increases, the viscosity is reduced. Once the electric field is removed, the rate that the viscosity returns to its original value decreases over time as the aggregated particles gradually disassemble. It may take as long as about 8-10 hours for the viscosity to return to its initial value.
[0022]The electric field used may be a direct current (DC) or an alternating current (AC) electric field. When applying an AC electric field, the frequency of the applied field is in the range of about 1 to about 3000 Hz, for example from about 25 Hz to about 1500 Hz. This field can be applied in a direction parallel to the direction of the flow of the fluid or it can be applied in a direction other than the direction of the flow of the fluid.
[0023]The strength of the field and duration of the period of time the fluid is exposed to the field varies depending on the type of crude oil involved, such as paraffin-based crude oil, asphalt-based crude oil, mixed-based crude oil, or a mixture thereof. It has been determined that the higher the initial viscosity of the fluid before being subjected to the electric field, the greater the reduction in viscosity after being subjected to the electric field.
[0024]In one embodiment, the electric field is applied using a capacitor 10 wherein the crude oil flows through the capacitor 10, experiencing a short pulse electric field as a constant voltage is applied to the capacitor. The capacitor may be of the type which includes at least two metallic meshes 20 connected to a large tube 30, as illustrated in FIG. 1, wherein the crude oil passes through the mesh.
[0025]It will be appreciated by those skilled in the art that other types of capacitors may also be used. In this embodiment, the electric field is applied in a direction parallel to the direction of fluid flow. These types of capacitors can be used to generate pulse electric fields that can be applied to crude oil in pipelines.
[0026]In another embodiment, the electric field is generated by a capacitor across which the electric field is applied in a direction other than the direction of the flow of the fluid. It is contemplated that the electric field can be applied in almost any feasible direction across the fluid and still achieve a reduction in viscosity.
[0027]The following are examples that are illustrative of the invention:
EXAMPLE 1
[0028]A DC electric field of 600 V/mm was applied to a paraffin-based crude oil sample for 60 seconds, which had an initial viscosity of 44.02 cp at 10.degree. C. After exposure to the electric field, the viscosity dropped to 35.21 cp, or about 20% of its initial value. After the electric field was removed, the viscosity, as shown in FIG. 2, gradually increased. After about 30 minutes, the viscosity had climbed to 41 cp, still 7% below the original viscosity. The rate of viscosity increase after the first 30-minute period dropped considerably.
EXAMPLE 2
[0029]A paraffin-based crude oil sample with an initial viscosity of 33.05 cp at 10.degree. C., was exposed to a 50-Hz AC electric field of 600V/mm for 30 seconds. The viscosity of the fluid dropped to about 26.81 cp, or 19% of the initial value. After 30 minutes, the viscosity climbed to only about 30 cp, still about 10% below the original value, as shown in FIG. 3.
[0030]The results as shown in Examples 1 and 2 indicate that both DC electric fields and low-frequency AC fields are effective in reducing the apparent viscosity of the crude oil samples tested. Experiments also revealed that it takes approximately 10 hours for the viscosity which has been reduced by the applied electric field to return to its original value.
EXAMPLE 3
[0031]The duration of the applied electric field to the sample was determined for the optimal duration of the electric field. For the paraffin-based crude oil sample tested, the optimal duration was determined to be 15 seconds for an applied DC electric field strength of 600 V/mm. The lowest viscosity immediately after the electric field was applied was 19.44 cp, 17.1% down from the original viscosity value of 23.45 cp, before the electric field was applied, as shown in FIG. 4.
EXAMPLE 4
[0032]For a crude oil sample having a viscosity of about 44.02 cp at 10.degree. C. before the electric field was applied, the optimal duration was found to be about 60 seconds using an electric field of 600 V/mm. The sample's viscosity dropped to about 35.21 cp, or 20%, for this time period, as is illustrated in FIG. 5. This result shows that the effect of the electric field gets stronger as the viscosity of crude oil gets higher.
EXAMPLE 5
[0033]The graph shown in FIG. 6 is a plot of the results for the sample in Example 2 at its optimal duration. The crude oil originally had viscosity 23.45 cp. After application of a DC field of 600V/mm for 15 seconds, the viscosity dropped to 19.44 cp, down 4.01 cp, a 17.10% reduction. On the other hand, as shown in Example 1, the viscosity was down 8.81 cp, a 20% reduction.
EXAMPLE 6
[0034]Further experimentation in which samples of crude oil were tested at 10.degree. and 20.degree. revealed that the electric field's effect is stronger when the temperature of the fluid is lower. As the temperature is decreased, the volume fraction of paraffin particles gets higher; therefore, the apparent viscosity gets higher and the effect of the electric field on the fluid viscosity also becomes more pronounced. In Example 6, the paraffin-based crude oil was tested at both 20.degree. C. and 10.degree. C. and the results indicated that the electric field effect at 10.degree. C. is stronger than that at 20.degree. C. For example, at 20.degree. C. the largest viscosity drop was less than 10%, while at 10.degree. C. it was significantly higher than 10%.
EXAMPLE 7
[0035]An asphalt-based crude oil sample at 23.5.degree. C., having a kinetic viscosity 773.8 cSt, required about 8 seconds of exposure to an applied electric field of 1000 V/mm for viscosity reduction. In the sample, the kinetic viscosity immediately dropped to 669.5 cSt, down 104.3 cSt or approximately 13.5% After about 90 minutes, the kinetic viscosity was at 706.8 cSt, still 67 cSt below the original value. During the experiment, the temperature was maintained at 23.5.degree. C. The results are shown in FIG. 7.
[0036]In comparing the effects of applying a magnetic field with the effects of applying an electric field to the asphalt-based crude oil, it was determined that the magnetic field had only a minimal effect on the viscosity of the sample, however, application of the electric field to the same sample reduced the viscosity of the asphalt-based crude oil significantly.
[0037]Another feature of the present invention is that it also slows the precipitation of wax from crude oil. As the nanoscale paraffin particles aggregate to micrometer-sized particles, the available surface area for crystallization is dramatically reduced. Thus, the precipitation of wax from crude oil is significantly decreased.
[0038]Although the invention is illustrated and described herein with reference to specific embodiments, the invention is not intended to be limited to the details shown. Rather, various modifications may be made in the details within the scope and range of equivalents of the claims and without departing from the invention. It is contemplated that the invention, while described with respect to crude oil, may be useful in other applications where increased petroleum-based fluid viscosity is problematic and inhibits flow of the fluid.
2008-08-14 Method and Apparatus for Treatment of a Fluid
US2008190771 (A1)
Classification: - international: C10G32/02; F02M27/04; G05D24/00; C10G32/00; F02M27/00; G05D24/00- European: C10G32/02; F02M27/04M
Also published as: WO2005111756 (A1) // WO2005111756 (A8) // NO20065632 (A) // GB2432193 (A) // GB2432193 (B)Abstract -- An apparatus for the magnetic treatment of a fluid which produces at least one magnetic field for a period of time, Tc at or above a critical magnetic field strength, Hc, the period Tc and the field strength Hc determined relative to one another and dependant upon the properties of the fluid.
FIELD OF THE INVENTION
[0001]The present invention relates to the treatment of fluids, particularly hydrocarbons, fuels and oils and in particular to methods and devices for affecting the physical properties of the hydrocarbons using a magnetic field.
BACKGROUND ART
[0002]The use of magnetic devices and methods for the treatment of hydrocarbons is known in the prior art. However, the mechanisms and effects of such treatment are not well known and difficult to predict.
[0003]A sample of prior art in the general field of magnetic treatment of fuels is as follows: [0004]U.S. Pat. No. 3,830,621--Process and Apparatus for Effecting Efficient Combustion. [0005]U.S. Pat. No. 4,188,296--Fuel Combustion and Magnetizing Apparatus used therefor. [0006]U.S. Pat. No. 4,461,262--Fuel Treating Device. [0007]U.S. Pat. No. 4,572,145--Magnetic Fuel Line Device. [0008]U.S. Pat. No. 5,124,045--Permanent Magnetic Power Cell System for Treating Fuel Lines for More Efficient Combustion and Less Pollution. [0009]U.S. Pat. No. 5,331,807--Air Fuel Magnetizer. [0010]U.S. Pat. No. 5,664,546--Fuel Saving Device. [0011]U.S. Pat. No. 5,671,719--Fuel Activation Apparatus using Magnetic Body. [0012]U.S. Pat. No. 5,829,420--Electromagnetic Device for the Magnetic Treatment of Fuel.
[0013]The prior art documents, of which the above represent only a small proportion, are specifically directed towards the treatment of a fuel stream for the purpose of either the prevention of scaling, corrosion or biological growth in pipes or alternatively, to increase the combustion efficiency of the fuel when burnt in an engine.
[0014]However, there are also a number of documents which propose devices for the "conditioning of a fluid or fuel" with the application of the device being left vague. An outline of some of these documents is below: [0015]WO 99/23381--Apparatus for Conditioning a Fluid
[0016]This document teaches an apparatus for conditioning a fluid flowing in a pipe by means of a magnetic field. The fluid may be "fuel" and the magnet may be neodymium iron boron particles which are centred and compressed to provide a particularly strong permanent magnet. The document teaches the conditioning of a liquid using permanent magnets. [0017]U.S. Pat. No. 6,056,872--Magnetic device for the treatment of fluids
[0018]This document discloses a device for the magnetic treatment of fluids such as gases or liquids. The device includes a plurality of sets of magnets (permanent or electromagnets) for imparting a magnetic field to a fluid. The magnets are arranged peripherally about a pipe or other fluid conduit within which is a flowing fluid, and the device utilises magnets having different magnetic field strengths for varying the field flux along the length of the pipe or fluid conduit. It is to be noted that in the background of the invention portion of the specification, the problems discussed relate to the prevention of scaling, corrosion or algae growth in pipes. Magnetic devices are also discussed in the context of improving the fuel consumption of, and reducing the undesirable omissions of engines.
[0019]Paraffins are a major problem in the production of some crude oils. Although paraffins usually remain in solution in the formation, as the oil is produced some of the light ends are lost which can alter the crystalline pattern of the paraffin allowing it to precipitate and/or create a paraffin wax due to temperature changes. Approximately 40% of the cost to bring useable petroleum to the market is in the control of paraffin.
[0020]It is known to use chemicals, usually acids and expensive biocides, to prevent, dissolve or remove these materials from the pipes. However, these are not always effective. The chemicals may be toxic or expensive and frequently these chemicals provide a long term operating expense as they must be continuously added to the fluid.
[0021]It will be clearly understood that, if a prior art publication is referred to herein, this reference does not constitute an admission that the publication forms part of the common general knowledge in the art in Australia or in any other country.
SUMMARY OF THE INVENTION
[0022]The present invention is directed to an apparatus for the magnetic treatment of fluids which may at least partially overcome at least one of the abovementioned disadvantages or provide the consumer with a useful or commercial choice.
[0023]In one form, the invention resides in an apparatus for the magnetic treatment of fluids which produces a change in at least one physical or rheological characteristic of the fluid treated, the apparatus including at least one magnetic means for applying a magnetic field to a fluid.
[0024]In a more particular form, the invention resides in an apparatus for the magnetic treatment of fluids which produces at least one magnetic field for a period of time, T.sub.c at or above a critical magnetic field strength, H.sub.c, the period T.sub.c and the field strength H.sub.c determined relative to one another and dependant upon the properties of the fluid.
[0025]In another form, the invention may reside in a method for the magnetic treatment of fluids, the method including the step of applying at least one magnetic field to a fluid to be treated.
[0026]In a more particular form, the invention resides in a method for the magnetic treatment of fluids the method including the step of applying at least one magnetic field for a period of time, T.sub.c at or above a critical magnetic field strength, H.sub.c, the period T.sub.c and the field strength H.sub.c determined relative to one another and dependant upon the properties of the fluid.
[0027]The method and apparatus according to the present invention find particular application when applied to fluids with hydrocarbons whether they be liquids or gaseous. It is to be appreciated that while particularly applicable to hydrocarbon fluids or those containing hydrocarbons (whether a mixture or not), the apparatus and method of the present invention may be used with other fluids. Generally, a simple way of applying the magnetic field to the fluid may be as the fluid is flowing and as such, the field may be applied to a fluid flowing through a pipe or conduit.
[0028]While not wishing to be bound by theory, it appears a hydrocarbon fluid may be notionally divided into "particles", which can be defined as large molecules, suspended in a base fluid made up of smaller molecules which are usually in the majority and thus form the base liquid. The viscosity of the hydrocarbon fluid may therefore be approximated as the viscosity of a liquid suspension, which is very different to single-molecule liquid, such as water and liquid nitrogen. For the same volume fraction, .PHI., the apparent viscosity depends on the particle size. As the particles get smaller, the apparent viscosity gets higher. This can be seen from the Mooney equation [4),
/.eta..sub.0=exp [2.5.PHI./(1-k .PHI.)], (1)
where the crowding factor k increases as the particle size decreases. Some prior art experiments estimated k=1.079+exp(0.01008/D)+exp(0.00290/D.sup.2) for micrometer-size particles, where D is the particle diameter in unit of micrometers.
[0029]Each of the large molecules or "particles" has a magnetic susceptibility .mu..sub.p which is different from the magnetic susceptibility of the base fluid .mu..sub.f. In a magnetic field, the particles are thus polarised along the field direction. If the particles are uniform spheres of radius a, in a magnetic field the dipole moment may be estimated by the formula:
m=H a.sup.3(.mu..sub.p-.mu..sub.f)/(.mu..sub.p-2 .mu..sub.f) (2)
where H is the local magnetic field, which should be close to the external field in dilute cases. The dipolar interaction between these to dipoles induces magnetic dipoles, the strength of which is given by:
U=.mu..sub.fm.sup.2(1-3 cos.sup.2.theta.)/r.sup.3 (3)
where r is the distance between these two dipoles and .theta. is the angle between the straight line between the dipoles and the magnetic field. If this interaction is stronger than the normal Brownian motion, these two dipoles will aggregate together to align in the field direction. If the dipole interaction is very strong and the duration of magnetic field is long enough, the particles will aggregate into macroscopic chains or columns, which will jam the liquid flow and increase the apparent viscosity, a well known phenomenon in magnetorheological (MR) fluids.
[0030]It has been surprisingly found that if the applied magnetic field is a short pulse, the induced dipolar interaction does not have enough time to affect particles at macroscopic distances apart, but forces nearby ones into small clusters. The assembled clusters are thus of limited size, for example of micrometer size. While the particle volume fraction remains the same, the average size of the "new particles" is increased. This may lead to the reduction in apparent viscosity because the value of the crowding factor k, is reduced.
[0031]Preferably, the correlation between the strength of the magnetic field H.sub.c and the period of application of the field, T.sub.c may be calculated according to the following
[0032]Once the magnetic field applied to the fluid for T.sub.c ceases, the induced dipolar interaction will generally disappear. However, typically, the aggregated clusters of particles could sustain for a period of time due to hysteresis. After a time, the Brownian motion and other variable disturbances will typically act to break the assemble particles down. After the assembled particles are completely broken down (which could take approximately 8 to 10 hours, breakdown time T.sub.b), the rheological properties of the liquid suspension generally return to the state of prior to the magnetic treatment. Therefore, it would be preferable for applications in long distance or extended transport time fluid transport, for example fuel oil pipelines, that the magnetic field be applied to the fluid at periods determined according to the breakdown time, T.sub.b.
[0033]Suitably, there may be a plurality of apparatus applying the magnetic field spaced along a conduit or pipe transporting the fluid. The separation distance of the apparatus may be determined according to the velocity of the fluid flow through the conduit and the breakdown time, T.sub.b. The application of the field and the spacing of the magnetic assemblies on a pipe with respect to the flow rate through the pipe may be adjusted or adjustable in order to maintain a lowered viscosity in the fluid.
[0034]If the particle number density is n, two neighbouring particles are typically separated about n.sup.-1/3. Using Equation (2), the dipolar interaction between two neighbouring particles is about m.sup.2n.mu..sub.f. In order for particles to cluster together, this interaction will preferably be stronger than the thermal Brownian motion which acts to pull neighbouring particles together. Suitably, the following parameter, .alpha. which may specify the competition between the dipolar interaction and the thermal motion may then be arrived at
=.mu..sub.fm.sup.2n/(k.sub.BT).gtoreq.1 (4)
where k.sub.B is the Boltzmann constant and T is the absolute temperature.
[0035]With Equation (2), the critical field to be applied in order to realise the invention may then be calculated as
H.sub.c=[k.sub.BT/(n.mu..sub.f)].sup.1/2(.mu..sub.p+2.mu..sub.f)/[.alpha..- sup.3(.mu..sub.p-.mu..sub.f)] (5)
[0036]If the applied magnetic field is weaker than H.sub.c, the thermal Brownian motion may prevent particles from aggregating together. In order to change the apparent viscosity of the liquid suspension, the applied magnetic field applied according to the invention, is suitably not lower than H.sub.c
[0037]From the dipolar interaction, the force between two neighbouring particles is generally about 6.mu..sub.fm.sup.2n.sup.4/3. Using the relation for Stoke's drag force on a particle 6.alpha..pi..eta..sub.a.nu., the particle's average velocity is suitably about v=.mu..sub.fm.sup.2n.sup.4/3/(.pi..eta..sub.aa).
[0038]The time required for two neighbouring particles to get together may then be approximately about
=n.sup.-1/3/v=.pi..eta..sub.0(.mu..sub.p+2.mu..sub.f).sup.2/[.mu..sub.fn.s- up.5/3a.sup.5(.mu..sub.p+.mu..sub.f).sup.2H.sup.2]=.pi..eta..sub.0a/(n.sup- .2/3k.sub.BT.alpha.). (6)
[0039]If the duration of magnetic field is too much shorter than .tau., the particles may not have enough time to aggregate together. On the other hand, if the duration of magnetic field is much longer than .tau., macroscopic chains may be formed and the apparent viscosity of the fluid could be increased instead of reduced.
[0040]Therefore, according to a preferred embodiment of the invention, a suitable duration of the magnetic field should be in the order of .tau.. From Equation (6), it is clear that if the applied magnetic field is getting stronger, the pulse duration should get shorter. Therefore, the strength of the applied magnetic field, H.sub.c may be determined relative to the period of application of the field, T.sub.c.
[0041]In MR fluids (.alpha..gtoreq.100), the dipolar interaction may be too strong and force the particles into chains along the field direction in milliseconds. In petroleum oils, the induced magnetic dipolar interaction may suitably be much weaker than that in MR fluids. Therefore, according to a particularly preferred embodiment of the present invention, in which the fluid treated has an .alpha.-value between 1 and 10, the apparent viscosity of a liquid suspension may be effectively reduced by selecting a suitable duration of application of a magnetic field.
[0042]The aggregated particles by the magnetic field which generally result from use of the invention, may not be spherical. They may be elongated along the field direction and may rotate under the influence of magnetic field, which may further help the reduction of the apparent viscosity,
[0043]An apparatus may be provided embodying the invention. Generally, the apparatus for applying the magnetic field will be magnets. The magnets may be constructed of any appropriate material and may, for example, be permanent magnets or electromagnets as known to the art or which may hereinafter be developed. When the magnets are permanent magnets, especially suitable magnetic materials include ceramics, and rare earth materials, which particularly include neodymium-iron-boron magnets as well as samarium-cobalt type magnets.
[0044]With the case of electromagnets, it will be apparent that these should be attached to an appropriate electrical source so that their electromagnetic properties are maintained. The physical form of the magnets may be of any appropriate form and it is only preferred in the arrangements of the apparatus described herein.
[0045]The magnets should have a Curie temperature sufficiently high that they retain their magnetic characteristics at the operating temperatures to which they are exposed. For example, in an automobile engine, the fuel line magnets will lie above the engine block where relative heating will greatly increase their temperature. Some magnets lose much of their magnetic field strength as their temperature rise. The Curie temperature of Alnico magnets are 760.degree. C. to 890.degree. C., of Ceramic magnets (ferrite magnets) 450.degree. C., of Neodymium 310.degree. C. to 360.degree. C. and of Samarium 720.degree. C. to 825.degree. C.
[0046]It is also to be understood that magnets which have been described above with reference to the invention may be magnets, as well as any combination of a magnet and one or more elements which may act to improve the penetration of the magnetic field into the conduit, or which condenses the field strength of the magnet. These include the use of one or more pole pieces formed of iron or steel, especially low carbon content cold rolled steel. Such a pole piece is preferably positioned intermediate one face or one pole of a magnet, and the exterior wall of a conduit. Desirably, the portion of the pole piece in contact with the exterior wall of the conduit has a profile which approximates the profile of the exterior wall of the conduit so that the pole piece may be mounted onto the conduit. Typically, the portion of the pole piece in contact with the exterior wall has an arcuate profile which corresponds to the exterior radius of a conduit, especially a pipe. Where the conduit has a flat surface (such as for conduit having a square, triangular or rectangular shaped cross section) the portion of the pole piece in contact with the exterior wall may be a flat profile. The pieces may be arranged on any side of any of the magnets, such as intermediate the magnet and the outer wall of the conduit, in contact with at least a part of a magnet and at the same time perpendicular to exterior wall of the conduit. The pole piece may also be tapered such that the face of the pole piece which is in contact with the magnet is equal to or greater than the surface area of the side of the magnet which it contacts, but on its opposite face, the pole piece has a lesser surface area. In such an arrangement the pole piece is provided with a tapered configuration which acts to concentrate the magnetic field at the interface of the magnet with pole piece, to the smaller area at the opposite face of the pole piece which is at or near the exterior wall of the pipe.
[0047]With regard to the construction of the apparatus according to the present invention, any means which are suited for peripherally arranging each of the sets of magnets with respect to a conduit as described above may be used. The magnets need not physically contact the conduit, but this may be desirable with a ferromagnetic conduit such as an iron or steel pipe. These means may include appropriate mechanical means such as clamps, brackets, bands, straps, housing devices having spaces for retaining the magnets therein, as well as chemical means such as adhering the magnets to the exterior wall of the conduit.
[0048]Any suitable means including any of the means or devices which may have been described in any of the patents mentioned above, may be used. In further embodiments, it is also contemplated that the sets of magnets could be an integral part of the conduit such as being included in the construction of the wall of the conduit as well. The sets of magnets may also be placed on the interior wall of the conduit. It is also contemplated that the sets of magnets used to practise the invention may form an integral part of the wall of a conduit. In such an arrangement, there may be provided a conduit section with flanges, threads or other means of attachment which may be used to insert said conduit section in-line with the conduit within which flows a fluid. Such a conduit section would include magnets in an arrangement in accordance with the present inventive concepts taught herein, included in or as part of the wall of the conduit section.
[0049]The method and apparatus of the present invention may also be applied to atomisation of hydrocarbon fluids. Atomisation generally occurs as a result of interaction between a liquid and the surrounding air, and the overall atomisation process involves several interacting mechanisms, among which is the splitting up of the larger drops during the final stages of disintegration. In equilibrium, a droplet's radius is determined by the liquid's surface tension and the pressure difference,
r=2.gamma./.DELTA.p (7)
where .gamma. is the surface tension and .DELTA.p=p.sub.i-p.sub.a is the pressure difference between pressure inside the droplet, p.sub.i, and the air pressure near the droplet surface, p.sub.a. The size r in Equation (7) is usually noted as the critical size. In the spray process, drops may be initially much larger than r. They then may break again and again into small droplets. The influence of liquid's viscosity, by opposing deformation of the drop, may increase the break-up time. Therefore, low liquid viscosity favours quick breaking of drops and leads to smaller size of droplets.
[0050]In addition, in many complex fluids, if a fluid's viscosity is reduced, its surface tension also goes down. It is anticipated that a pulsed magnetic field applied according to the method of the invention may also reduce the surface tension of these petroleum fuels as well as their apparent viscosity.
BRIEF DESCRIPTION OF THE DRAWINGS
[0051]Various embodiments of the invention will be described with reference to the following drawings, in which:
FIG. 1 is a graph illustrating the viscosity of gasoline with 20% ethanol at 10.degree. C. and 95 rpm after application of a magnetic field of 1.3 T for 5 seconds.
FIG. 2 is a graph illustrating the viscosity of gasoline with 10% MTBE at 10.degree. C. and 95 rpm after application of a magnetic field of 1.3 T for 1 second.
FIG. 3 is a graph illustrating the viscosity of diesel at 10.degree. C. and 35 rpm after application of a magnetic field of 1.1 T for 8 seconds.
FIG. 4 is a graph illustrating the viscosity of Sunoco crude oil at 10.degree. C. and 10 rpm after application of a magnetic field of 1.3 T for 4 seconds.
DETAILED DESCRIPTION OF THE INVENTION
[0056]According to an aspect of the invention, a method for treating hydrocarbons and particularly fuels, fuel oils and crude oils is provided.
[0057]A number of examples applications were undertaken wherein a magnetic field was applied to a hydrocarbon fluid for a period of time, T.sub.c at or above a critical magnetic field strength, H.sub.c. The period T.sub.c and the field strength H.sub.c were determined relative to one another and were dependant upon the properties of the fluid. The imposition of the magnetic field in this manner was found to reduce the apparent viscosity of the fluid.
[0058]In the examples, the method and apparatus were used to treat pure gasoline, pure diesel and pure kerosene without any additives. However, since the bulk of the hydrocarbon fluids produced contains additives of some kind, the examples described herein were conducted on hydrocarbon fluids having composition which approximate the major types of fuels used for automobiles and trucks and also on crude oil.
[0059]The examples were conducted using a Brookfield.RTM. digital viscometer LVDV-II+ equipped with a UL adapter. The Brookfield LVDV-II+ viscometer measures fluid viscosity at a given shear rate. The principal of operation is to drive a spindle immersed in the test fluid through a calibrated spring. The viscous drag of the fluid against the spindle is measured by the spring deflection and measured with a rotary transducer. The LVDV-II+ has a measurement range of 15-2,000,000 cP.
[0060]The UL adaptor consists of a precision cylindrical spindle rotating inside an accurately machined tube to measure the viscosity of low viscosity fluids with a high accuracy. With the UL adaptor and spindle, viscosities in the range of 1-2,000 cP are measurable.
[0061]In the following description and the accompanying figures, the magnetic field was imposed at time zero (T=0).
EXAMPLE 1
Gasoline with 20% Ethanol
[0062]Ethanol is an important additive in gasoline sold in some markets. This example was conducted on gasoline with 20% ethanol. It is interesting to note that pure gasoline has very low viscosity, about 0.8 cP at 10.degree. C. However, ethanol has quite high viscosity, about 1.7 cP at 10.degree. C. Therefore, a mixture of gasoline with 20% ethanol has viscosity of about 0.95 cP.
[0063]A strong magnetic field of 1.3 T was applied to the sample for 5 seconds. The apparent viscosity dropped to 0.81 cP, but soon climbed to about 0.865 cP, fluctuating there and gradually increasing, as seen in FIG. 1. However, after 3 hours, the apparent viscosity remained at 0.88 cp, 8% below the original value. The apparent viscosity remained substantially below the original value 200 minutes after the application of magnetic field. We expect that the viscosity would return to 0.95 cp in about 10 hours.
EXAMPLE 2
Gasoline with 10% MTBE
[0064]MTBE (methyl tertiary butyl ether) is still widely used as gasoline additive. This example was conducted on gasoline with 10% MTBE. Different from ethanol, MTBE has quite low viscosity. Therefore, a mixture of gasoline with 10% MTBE at 10.degree. C. has a viscosity of 0.84 cP, slightly higher than that of pure gasoline.
[0065]A magnetic field of 1.3 T was applied to the sample for about 1 second. The apparent viscosity immediately dropped to 0.77 cP. Then it was fluctuating around 0.78 cP for several hours and gradually increasing, as can be seen from FIG. 2.
[0066]However, as shown in FIG. 2, after more than 2 hours, the viscosity remained about 7% below 0.84 cP, the previous value. The apparent viscosity remained substantially below the original value 150 minutes after the application of magnetic field. This behaviour is quite similar to that of gasoline with ethanol in a pulse magnetic field, but we also noted that for gasoline with 10% MTBE the magnetic pulse duration should be shorter than that for gasoline with 10% ethanol.
EXAMPLE 3
Diesel Fuel
[0067]Diesel has much higher viscosity than that of gasoline. Example 3 was conducted on pure diesel and diesel with 0.5% of ethylhexyl nitrate (EHN) as additive. The behaviour for both samples is quite similar because the volume fraction of the additive is very small.
[0068]As shown in FIG. 3, diesel has a viscosity of 5.80 cP at 10.degree. C. which is considerably higher than that of gasoline. After application of a magnetic field of 1.1 T for 8 seconds, the apparent viscosity dropped to 5.64 cP, then remained at 5.70 cP for several hours. The apparent viscosity remained below the original value 160 minutes after the application of magnetic field.
[0069]Further testing may be required to determine the optimal duration of magnetic pulse. On one hand, since diesel is more close to crude oil, it is expected that the magnetic field induced dipolar interaction should be stronger than that in gasoline. On the other hand, since the diesel's original viscosity is higher than that of gasoline, it is expected the magnetic pulse should have a slightly long duration. The results in FIG. 3 indicate that a pulse magnetic field can reduce the apparent viscosity of diesel.
EXAMPLE 4
Crude Oil
[0070]Example 4 was conducted with Sunoco crude oil. Since Sunoco crude oil is light crude oil and has low wax-appearance temperature, the example was performed at 10.degree. C. As shown in FIG. 4, at that temperature Sunoco crude oil has a viscosity about 26.2 cp. After application of a magnetic field of 1.3 T for 4 seconds, the apparent viscosity dropped to 22.2 cp, which was 16% lower than the original value. After the magnetic field was turned off, the viscosity remained low, but was gradually increasing.
[0071]After 200 minutes, it reached 25.0 cp, but still 5% below the original value. From extrapolation of this curve, it is expected that the viscosity will return to the original value after about 10 hours.
[0072]In the present specification and claims (if any), the word "comprising" and its derivatives including "comprises" and "comprise" include each of the stated integers but does not exclude the inclusion of one or more further integers.
[0073]Reference throughout this specification to "one embodiment" or "an embodiment" means that a particular feature, structure, or characteristic described in connection with the embodiment is included in at least one embodiment of the present invention. Thus, the appearance of the phrases "in one embodiment" or "in an embodiment" in various places throughout this specification are not necessarily all referring to the same embodiment. Furthermore, the particular features, structures, or characteristics may be combined in any suitable manner in one or more combinations.
Method and Apparatus for Increasing and Modulating the Yield Shear Stress of Electrorheological Fluids
US68278222003-05-15
Inventor(s): TAO RONGJIA [US]; LAN YUCHENG [US]; XU XIAOJUN [US]; KACZANOWICZ EDWARD [US]
Classification: - international: F16F13/30; C10M171/00; F15B21/06; F16D35/00; F16F9/53; F16F15/03; F16F13/04; C10M171/00; F15B21/00; F16D35/00; F16F9/53; F16F15/03; (IPC1-7): B01J19/08 - European: C10M171/00B; F15B21/06B; F16F9/53L
Also published as: (B2) // WO03042765 (A2) // WO03042765 (A3) // JP2005509815 (T) // EP1450945 (A2)Abstract -- A method for increasing and/or modulating the yield shear stress of an electrorheological fluid includes applying a sufficient electric field to the fluid to cause the formation of chains of particles, and then applying a sufficient pressure to the fluid to cause thickening or aggregation of the chains. An apparatus for increasing and/or modulating the transfer or force or torque between two working structures includes an electrorheological fluid and electrodes through which an electric field is applied to the fluid such that particles chains of particles are formed in the fluid and, upon application of pressure to the fluid, the chains thicken or aggregate and improve the force or torque transmission.
References Cited
U.S. Patent Documents5507967 April 1996 Fujita et al.
5558803 September 1996 Okada et al.
RE35773 April 1998 Okada et al.
5843331 December 1998 Schober et al.
5891356 April 1999 Inoue et al.
6027429 February 2000 Daniels
6096235 August 2000 Asako et al.
6116257 September 2000 Yokota et al.
6149166 November 2000 Struss et al.
6159396 December 2000 Fujita et al.
RE37015 January 2001 Rensel et al.
6231427 May 2001 Talieh et al.
6251785 June 2001 Wright
6297159 October 2001 PatonOther References
R Tao et al., "Three-Dimensional Structure of Induced Electrorheological Solid", Phys. Rev. Lett., vol. 67, No. 3, Jul 15, 1991, pps. 398-401. .
Chen et al., "Laser Diffraction Determination of the Crystalline Structure of an Electrorheological Fluid", Phys. Rev. Lett., vol. 68, No. 16, Apr. 20, 1992, pps. 2555-2558. .
G.L. Gulley et al., "Static Shear Stress of Electrorheological Fluids", Phys. Rev. E, vol. 48, No. 4 Oct. 1993, pps. 2744-2751. .
X. Tang et al., "Structure-enhanced Yield Stress of Magnetorheological Fluids", J. of Applied Physics, vol. 87, No. 5, Mar. 1, 2000, pps. 2634-2638. .
R. Tao et al., "Electrorheological Fluids Under Shear", International J. of Modern Physics B, vol. 15, 2001..Description
FIELD OF THE INVENTION
The present invention relates to electrorheological fluids. More specifically, it relates to a method for increasing and/or modulating the yield shear stress of electrorheological fluids and to an apparatus employing such method.
BACKGROUND OF THE INVENTION
Electrorheological (ER) fluids and ER effects are well known in the art. Since the discovery of ER fluids around 1947, many efforts have been made to increase the yield shear stress of ER fluids to a level at which they can advantageously be used for various industrial applications, such as actuators for torque transmission (such as clutch, brake, and power transmission), vibration absorption (such as shock absorber, engine mount, and damper), fluid control (such as servo valve and pressure valve) and many other industrial applications. ER fluids are generally more energy efficient than hydraulic, mechanical or electromechanical devices which serve the same function. However, the strength of ER fluids has not been generally high enough in the past. The search for strong ER fluids has produced limited results. ER fluids currently have yield shear stress up to about 5 kPa in the presence of an applied electric field, not generally sufficient for major industrial applications, most of which therefore do not utilize ER fluids. The present invention achieves increased yield shear stress through a novel use of the microstructure properties of ER fluids.
The flow characteristics of an ER fluid change when an electric field is applied through it. The ER fluid responds to the applied electric field by what can be described as progressively gelling. More specifically, the ER fluid is generally comprised of a carrier fluid, such as pump oil, silicone oil, mineral oil, or chlorinated paraffin. Fine particles, such as polymers, minerals, or ceramics, are suspended in the carrier fluid. When an electric field is applied through the ER fluid, positive and negative charges on the particles separate, thus giving each particle a positive end and a negative end. The suspended particles are then attracted to each other and form chains leading from one electrode to the other. These chains of particles cause the ER fluid to "gel" in the electric field between the electrodes in proportion to the magnitude of the applied electric field. Thus, the prior art provides a means to increase the yield shear stress ("effective viscosity") of an ER fluid by application of an electrical field, but the maximum yield shear stress thus attained (up to about 5 kPa) is still not sufficient for use in most industrial applications.
For the reasons described above, a method for increasing and/or modulating the yield shear stress of ER fluids by a simple process would be desirable. In addition an apparatus employing such method of increasing and/or modulating the yield shear stress of ER fluids would further be desirable.
SUMMARY OF THE INVENTION
The present invention is directed to a method for increasing and/or modulating the yield shear stress of ER fluids and to an apparatus employing such method.
According to the method of the present invention, a sufficient electric field is first applied to the ER fluid to cause particles within the ER fluid to form into chains of particles and to cause the ER fluid to "gel" in the electric field applied between the electrodes. Then, a sufficient pressure is applied to the ER fluid between the electrodes, while the electric field applied in the previous step is substantially maintained. This causes the chains of particles to thicken and thus increases the yield shear stress. The pressure and the shear stress may be applied in any direction, relative to that of the applied electric field, which causes the chains of particles to thicken. When the increased shear stress is no longer needed or needs to be modulated upwardly or downwardly, the pressure and, optionally, the electric field are adjusted upwardly or downwardly as required.
In a first embodiment of the method of the invention, the pressure is applied in a direction substantially perpendicular to that of the electric field, in which case the chains aggregate and thus become thicker. In a second embodiment, the pressure is applied in a direction substantially parallel to that of the electric field, in which case the chains become shorter and thus become thicker. However, as contemplated in the present invention, the pressure may be applied in any direction with respect to that of the applied electric field which results in thickening of the chains through a combination of shortening and aggregation of the chains.
According to the apparatus of the present invention, the ER fluid is placed between and in communication with two working structures, between which a force or a torque is to be transmitted (through the ER fluid). The ER fluid is also in communication with at least two electrodes having different electric potentials, which serve to apply an electric field through the ER fluid when an increase in the yield shear stress is desired. The electrodes may be on the same or different working structures, or be separate from them. A sufficient electric potential is first applied to the electrodes to cause particles within the ER fluid between the electrodes to form into chains of particles and to cause the ER fluid to gel. Then, a sufficient pressure is applied to the ER fluid, suitably by bringing the two working structures closer together, while the electric potential applied in the previous step is substantially maintained, to cause the chains of particles to become thicker and thus to increase the yield shear stress. The increase in the yield shear stress resulting from the applied pressure causes any force or torque which is provided by one working structure to be transmitted more efficiently to the other working structure. When the more effective force or torque transmission is no longer needed, the pressure and, optionally, the electric field may be removed. If an intermediately effective force or torque transmission is needed, the applied pressure may be decreased while the applied electric field remains applied at the same, a higher, or a lower level. Thus, once a higher yield shear stress has been established, it may be modulated upwardly or downwardly as required by increasing or decreasing the strength of the electric field, the applied pressure, or both.
In a first embodiment of the apparatus of the invention, the first working structure is preferably electrically insulating, but may also be grounded electrically, and the electrodes are all on the second working structure, the working surface of which is parallel to the working surface of the first working structure. In this embodiment, the chains of particles form in the vicinity of the second working structure, between electrodes through the ER fluid. Pressure is applied in a direction perpendicular to that of the electric field by bringing the two working surfaces closer together, which causes aggregation of the chains into thicker chains, providing an increase in the yield shear stress. In one variation of this embodiment, the electrodes have an alternating arrangement on the second working structure, separated by insulating zones, so that neighboring (adjacent) electrodes have different electric potentials. However, other electrode arrangements are possible with similar results. In addition, other variations of this embodiment are possible in which the two working structures are not parallel and/or not planar.
In a second embodiment of the apparatus of the invention, the two working structures are parallel and each one serves as an electrode. In this embodiment, the chains of particles form between the two working structures, through the ER fluid. Pressure is applied in a direction parallel to that of the electric field by bringing the two working surfaces closer together, which causes the chains to become shorter and thus thicker, again providing an increase in the yield shear stress. Variations of this embodiment are also possible in which the two working structures are not parallel and/or not planar.
It is to be understood that both the foregoing general description and the following detailed description are exemplary, but not restrictive, of the invention.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 illustrates the first embodiment of an apparatus according to the present invention, with multiple electrodes on one of the working structures, the applied pressure being perpendicular to the electric field and the shear stress being applied parallel to the electric field.
FIG. 2 illustrates the first embodiment of an apparatus according to the present invention, with multiple electrodes on one of the working structures, the applied pressure being perpendicular to the electric field and the shear stress being applied perpendicular to the electric field.
FIG. 3 illustrates a variation of the apparatus of FIG. 2.
FIG. 4 illustrates the second embodiment of an apparatus according to the present invention, with one electrode in each working structure, the applied pressure being parallel to the electric field and the shear stress being applied perpendicular to the electric field, the apparatus being connected to a system used in measuring the yield shear stress of the electrorheological fluid, under compression.
FIG. 5 is a graph showing the results of a yield shear stress measurement in which pressures, under different constant electric fields, having different values and having been applied to the electrorheological fluid according to the apparatus of FIG. 1.
FIG. 6 is a graph showing the results of a yield shear stress measurement in which pressures, under different constant electric fields, having different values and having been applied to the electrorheological fluid according to the apparatus of FIG. 2.
FIG. 7 is a graph showing the results of a yield shear stress measurement in which electric fields, under different constant pressures, having different values and having been applied to the electrorheological fluid according to the apparatus of FIG. 1.
FIG. 8 is a graph showing the results of a yield shear stress measurement in which electric fields, under different constant pressures, having different values and having been applied to the electrorheological fluid according to the apparatus of FIG. 2.
FIG. 9 is a graph showing the results of a yield shear stress measurement in which pressures, under different constant electric fields, having different values and having been applied to the electrorheological fluid according to the apparatus of FIG. 4.
FIG. 10 is a graph showing the results of a yield shear stress measurement in which electric fields, under constant pressures, having different values and having been applied to the electrorheological fluid according to the apparatus of FIG. 4.
Like reference numbers denote like elements throughout the drawings.
DETAILED DESCRIPTION OF THE INVENTION
The present invention increases the yield shear stress of electrorheological (ER) fluids, by producing a change in their microstructure through the application of pressure. Referring to FIGS. 1-10, the present invention is directed to a method for increasing and/or modulating the yield shear stress of ER fluids and to an apparatus employing such method.
The method for increasing the yield shear stress of an ER fluid 10 according to the present invention comprises the steps of:
a) applying a sufficient electric field to the ER fluid 10 to cause particles within the ER fluid 10 to form into chains of particles within the electric field; and
b) applying a sufficient pressure to the ER fluid 10, after step a) and while substantially maintaining the electric field applied in step a), to cause the chains of particles to thicken or aggregate and thus impart to the ER fluid 10 an increase in the yield shear stress.
Further, following increasing the yield shear stress of the ER fluid 10 according to steps a) and b) above, the yield shear stress can be modulated by one of the following additional steps:
c) decreasing or increasing the applied pressure, after step b), to modulate the yield shear stress downwardly or upwardly as required to adjust the force or torque being transmitted from one working structure to another working structure;
d) decreasing or increasing the applied electric field, after step b) to modulate the yield shear stress downwardly or upwardly as required to adjust the force or torque being transmitted from one working structure to another working structure; or
e) combining steps c) and d) to modulate the yield shear stress downwardly or upwardly as required.
An example of the method above described for increasing and/or modulating the yield shear stress of an ER fluid 10 according to the present invention comprises the steps of:
a) applying a sufficient electric field to the ER fluid 10 to cause particles within the ER fluid 10 to form into chains of particles within the electric field;
b) applying a sufficient pressure to the ER fluid 10, after step a) and while substantially maintaining the electric field applied in step a), to cause the chains of particles to thicken or aggregate and thus impart to the ER fluid 10 an increase in the yield shear stress;
c) decreasing or removing the applied pressure, after step b) and while substantially maintaining the electric field applied in step a), to cause the thickness of the chains of particles to decrease and thus impart to the ER fluid 10 a decrease in the yield shear stress; and
d) repeating steps b) and c) as needed.
In this example of the method of the invention, because the electric field remains, the yield shear stress that remains after step c) is not zero, as it would be if the electric field were also removed. It may be noted that the maximum yield shear stress which can be obtained with most ER fluids in the absence of applied pressure is so low (typically 5 kPa or less) that removal of the electric field will not be necessary in some applications, for which this example of the method of the invention will thus be adequate.
In each of the embodiments and examples described herein, it is preferred that the ER fluid 10 has a volume fraction not too low or too high and comprises dielectric particles in a non-conducting liquid, such as oil, like (but not limited to) pump oil, transformer oil, silicon oil, etc. The term "volume fraction", as used in the present application, refers to the volume of net dielectric particles relative to the volume of the ER fluid, and its useful range of values is well known in the prior art pertaining to ER fluids. The tests of the present invention with a volume fraction of 35% give an excellent result, but tests with other volume fractions work well too, for example, a volume fraction of about 10% to about 60%, more specifically about 20% to about 50%.
For the methods of the present invention being described, each of the steps may be carried out at varying parameters and conditions. The parameters and conditions which are disclosed allow one of skill in the art to carry out the particular described method(s), but are not intended to imply that the particular described method(s) cannot be effectively or efficiently carried out at other parameters and/or conditions. The specific parameters and conditions chosen may vary due to many factors, such as the particular ER fluid being used, the desired increase in or level of yield shear stress of the ER fluid, the specific apparatus or device required to carry out these methods, etc.
The step of applying an electric field, or step a), of the embodiments described in the present application causes the particles within the ER fluid 10 to form into chains of particles when a sufficient electric field is applied to the ER fluid 10, via electrodes, by direct application to the ER fluid 10, or by any other known suitable method. For example, the electrodes may be separated from the ER fluid 10 by an electrically insulating layer and still apply a sufficient electric field (albeit more or less attenuated) to the ER fluid 10. There is no hard limit as to the strength of the electric field being applied in this step, but the useful range of values is well known in the prior art pertaining to ER fluids. The electric field should be sufficiently high such that an adequate number of chains of particles are formed in the ER fluid 10. The electric field applied may, for example, be in the range of about 500 V/mm to about 3000 V/mm, more specifically about 1000 V/mm to about 2000 V/mm. The electric field may be DC or AC.
The step of applying pressure, or step b), of the embodiments described in the present application causes the chains of particles that are formed in step a) to thicken when a sufficient pressure is applied to the ER fluid 10 while the electric field is being maintained. The thickening of the chains provides the ER fluid 10 with an increase in yield shear stress. The step of applying pressure is required to occur after step a) and while the electric field applied in step a) is substantially maintained. The pressure applied may be in the range about 50 kPa to about 850 kPa, but can be lower or higher, depending on the magnitude of the increase in yield shear stress which is required. The pressure may be applied in any direction relative to that of the applied electric field, including in particular, in a parallel direction (in which case the chains shorten and thus become thicker) or in a perpendicular direction (in which case chains aggregate and thus become thicker).
An apparatus employing the method for increasing and/or modulating the yield shear stress of an ER fluid 10 according to the present invention comprises two working structures, between which a force or a torque needs to be transmitted and an ER fluid 10 between them and in communication with them. The ER fluid 10 between the two working structures is also in communication with at least two electrodes having different electric potentials, which serve to apply an electric field through the ER fluid 10 when an increase in the yield shear stress is desired for the purpose of better transferring a force or torque between the two working structures. The electrodes may be part of one or both working structures, or may be separate from both of them, provided that they are within, or near the boundary of, the region between the two working structures. According to the method of the present invention, a sufficient electric field is first applied to the ER fluid 10, between the working structures, to form chains of particles and to cause the ER fluid 10 to "gel". The electric field is generated by applying an electric potential difference between the electrodes. Then, a sufficient pressure is applied to the ER fluid 10, suitably by bringing the two working structures closer together, while the electric potential difference applied in the previous step is substantially maintained, to cause the chains of particles to become thicker and thus to increase the yield shear stress. The increase in the yield shear stress resulting from the applied pressure improves the transmission of any force or torque between the working structures. When the improved force or torque transmission is no longer needed, the pressure and, optionally, the electric field are removed or modulated upwardly or downwardly as required for a particular application.
In a first embodiment of the apparatus of the invention, the first working structure is preferably electrically insulating, but may also be grounded electrically, and all electrodes are on the second working structure as shown in greater detail in FIGS. 1-3. In this embodiment, the chains of particles form in the vicinity of the second working structure, going between electrodes through the ER fluid 10. Application of pressure is made by bringing the working structures closer together, and causes aggregation of the chains into thicker chains, thus leading to a higher yield shear stress and improved force or torque transmission. In this embodiment, the applied pressure and the electric field are perpendicular. In one variation of this embodiment, shown in FIGS. 1 and 2, linear parallel electrodes 25, 27 have an alternating arrangement on the second working structure 22, separated by insulating zones, so that neighboring electrodes 25, 27 have different electric potentials. In a variation of this embodiment, shown in FIG. 3, the apparatus 12 have electrodes 15, 17 that are circular and concentric. Many other variations are possible which maintain the essential features required to apply the method of the invention including, for example: (1) working surfaces that are not parallel to each other or are not planar (for example, concentric spherical sections), (2) electrodes which are part of a grid (open or not) which is not attached to either of the working structures but is between them, or (3) electrodes which are separated from the ER fluid 10 by an electrically insulating layer or membrane.
Referring to FIGS. 1 and 2, apparatus 20 according to the first embodiment of the apparatus of the present invention comprises a first working structure 18, a second working structure 22, metallic strips which serve as electrodes 25, 27, insulating barriers 24, 26, and an ER fluid 10. The first working structure 18 has an inner (bottom, in the figures) insulating surface 28 (which is in contact with the ER fluid 10), an outer surface 30, and a plurality of sides 32. The electrodes 25, 27 of this embodiment are embedded in the inner (top, in the figures) surface 29 (which is in contact with the ER fluid 10) of the second working structure 22 and are separated by insulating barriers 24, 26. The electrodes 25, 27 are positioned in an alternating arrangement such that each positive electrode 25 is positioned next to at least one negative electrode 27. The terms "positive" and "negative" in respect to the electrodes are not meant to convey any relationship to electric ground but, rather, to indicate that one electrode (positive) is at higher electric potential than the other (negative). Furthermore, the polarities (positive and negative) of the electrodes may be reversed without affecting the operation of the apparatus. This arrangement generates a sufficient electric field to align the particles of the ER fluid 10 into chains of particles which align in the ER fluid in the direction of the applied electric field. As illustrated in FIGS. 1 and 2, the top surface of the electrodes 25, 27 and the top surface of the barriers 24, 26, defining a working surface, are leveled, flat, smooth, and parallel to the inner surface 28 of the first working structure 18. This minimizes the viscous friction between this working surface and the ER fluid 10 when the electric field is not applied. The ER fluid 10 is positioned between the working structures 18, 22. When the apparatus 20 is in use, the working structures 18, 22 can be moved toward and away from each other. The first apparatus 20 and its variations, such as that illustrated in FIG. 3, are believed suitable for many industrial applications such as automobile clutch, torque transmission, etc. FIGS. 1-3 assign to the first working structure 18 all movement producing the applied pressure. In practice, movement of either or both working structures 18, 22 may contribute to the applied pressure.
In a variation (not illustrated) of the embodiments shown in FIGS. 1 and 2, all the electrode strips 25, 27 at the same electric potential may be combined into a single comb-shaped electrode having teeth so that the teeth of the positive comb-shaped electrode are intercalated between the teeth of the negative comb-shaped electrode. Each one of these two comb-shaped electrodes may be constructed by tying together all of the individual electrode strips 25, 27, shown in FIGS. 1 and 2, at the same electric potential through an electrically conducting cross-bar (either under the plane of the individual electrode strips or in the same plane as the individual electrode strips), or it may be manufactured as a single piece of the same comb-shaped electrode. A similar variation may be applied to the embodiment shown in FIG. 3.
In a further variation (not illustrated) of the first embodiment of the apparatus of the present invention, the electrodes are arranged in a two-dimensional array of alternating electrodes at different electric potentials, i.e., the two-dimensional equivalent of the one-dimensional arrays shown in FIGS. 1 and 2. Alternatively, the entire working surface, may serve as the single electrode at one electric potential, incorporating a two-dimensional array of holes permitting insertion of the electrodes at the other electric potential (and any insulating spacers). In either case, individual electrodes may be tied together, under the plane of the individual electrodes, into the two-dimensional equivalents of the comb-shaped electrodes described in the preceeding paragraph.
In a second embodiment of the apparatus of the invention, each working structure serves as an electrode to which a different electric potential is applied. In this embodiment, the chains of particles form between the two working structures, through the ER fluid. Application of pressure causes shortening of the chains, which become thicker, leading to a higher yield shear stress. In this embodiment, the applied pressure and the electric field are parallel. This embodiment has two principal disadvantages over the first embodiment, which may or may not be important in particular applications: (1) both working structures (which are rotating or moving in some other way relative to each other), rather than only one, require electrical connections; and (2) the distance between the electrodes changes when the working structures are brought closer together to apply the pressure, making control of the electric field (which, at constant applied electric potential, is inversely proportional to the distance between the electrodes) more difficult and introducing the possibility of electrical breakdown between the working structures. Variations of this embodiment are possible which maintain the essential features required to apply the method of the invention including, for example: (1) working surfaces that are not parallel to each other or are not planar (for example, concentric spherical sections), (2) multiple electrodes at the same electric potential on each working structure, (3) one or more electrodes which are not attached to either of the working structures but are between them, or (4) electrodes which are separated from the ER fluid 10 by an electrically insulating layer or membrane.
Referring to FIG. 4, the apparatus 40 according to the second embodiment of the apparatus of the present invention comprises two working structures 42, 43, two electrodes 44, 46, and an ER fluid 10 positioned between the working structures 42, 43. The first working structure 42 has an inner surface 48 (which is in contact with the ER fluid 10), an outer surface 50, and a plurality of sides 52. The second working structure 43 has an inner surface 54 (which is in contact with the ER fluid 10), an outer surface 56, and a plurality of sides 58. The negative electrode 46 is positioned on the inner surface 54 of the second working structure 43. The positive electrode 44 is positioned on the inner surface 48 of the first working structure 42, and can be moved toward and away from the negative electrode 46 when apparatus 40 is in use. Again, the terms "positive" and "negative" in respect to the electrodes are not meant to convey any relationship to electric ground but, rather, to indicate that one electrode (positive) is at higher electric potential than the other (negative). Furthermore, the polarities (positive and negative) of the electrodes may be reversed without affecting the operation of the apparatus. FIG. 4 assigns to the first working structure 42 all movement producing the applied pressure. In practice, movement of either or both working structures 42, 43 may contribute to the applied pressure.
A third embodiment (not illustrated) of the apparatus of the invention combines the first and second embodiments. In this embodiment, both working structures incorporate multiple electrodes at different electric potentials, as described in the first embodiment for only one working structure, so that the applied electric field has components which are parallel and components which are perpendicular to the direction of the applied pressure. Application of the electric field leads to the formation, within the ER fluid 10, of chains of particles which go from electrode to electrode on the same working structure, as well as chains of particles which go from electrodes on one working structure to electrodes on the other working structure. In one variation of this embodiment, the electrode arrangement is the same on both working structures, except that their polarities are reversed, so that each positive electrode on one working structure is closest to: (1) at least one negative electrode on the same working structure and (2) at least one negative electrode on the other working structure. As illustrated in FIG. 4, the apparatus 40 is connected to the system 60 used in measuring the yield shear stress of the ER fluid 10. The system 60 used in measuring the yield shear stress includes a linear table 62, a first force sensor 64, a second force sensor 66, and a lead screw 68. The second force sensor 66 measures the normal pressure. Then, shear force is applied to the first force sensor 64 to determine the yield shear stress. A system similar to system 60 is used in measuring the yield shear stress of the ER fluid 10 in apparatus 20. Also, it is obvious to one of skill in the art that other systems can be used to measure the yield shear stress of the ER fluid 10.
In reference to the first apparatus 20, FIGS. 5-8 are graphs showing the results of a yield shear stress measurement in which electric fields, under different pressures and constant pressure, respectively, having different values and having been applied to the ER fluid 10, according to the present invention. In FIG. 5, when the shear force SF.sub.1 that is applied is parallel to the electric field, as in the apparatus of FIG. 1, the yield shear stress of the ER fluid 10 increases almost linearly with the different pressures applied at electric fields of 500 V/mm, 1000 V/mm, and 2000 V/mm. In FIG. 6, when the shear force SF.sub.2 that is applied is perpendicular to the electric field, as in the apparatus of FIG. 2, the yield shear stress of the ER fluid 10 increases almost linearly with the different pressures applied at electric fields of 500 V/mm and 1000 V/mm. As the applied electric field increases, the slope k increases slightly but measurably. In FIG. 7, when the shear force SF.sub.1 that is applied is parallel to the electric field, the yield shear stress of the ER fluid 10 increases with the applied electric field at constant pressures of 50 kPa, 100 kPa, 200 kPa, and 400 kPa. In FIG. 8, when the shear force SF.sub.2 that is applied is perpendicular to the electric field, the yield shear stress of the ER fluid 10 increases with the applied electric field at constant pressures of 100 kPa, 200 kPa, and 400 kPa. As the pressure increases, the yield shear stress also increases more dramatically with the applied electric field. With the technology of the present invention, the ER fluid 10 has a yield shear stress value of about 110 kPa at 2000 V/mm and 400 kPa pressure (FIG. 5), about 95 kPa at 1000 V/mm and 400 kPa pressure (FIG. 6), more than sufficient for many major industrial applications. If the shear force is in an arbitrary direction in the plane perpendicular to the direction of the applied force, it can be decomposed into two components, one parallel to the electric field and the other perpendicular to the electric field. FIGS. 5-8 can then be used to find the yield shear stress in any arbitrary direction perpendicular to the applied pressure. FIGS. 5-8 show that, in both cases, the yield shear stress is greatly raised, and that apparatus 20 and its variations work for a shear force in any arbitrary direction perpendicular to the applied force.
In reference to the second apparatus 40, FIGS. 9 and 10 are graphs, similar to the graphs for the first apparatus 20, showing the results of a yield shear stress measurement in which electric fields, under different pressures and constant pressure, respectively, having different values and having been applied to the ER fluid 10, according to the present invention. FIG. 9 shows the yield shear stress of the ER fluid 10 increasing almost linearly with the different pressures applied at electric fields of 1000 V/mm, 2000 V/mm, and 3000 V/mm. As the applied electric field increases, the slope k increases. FIG. 10 shows the yield shear stress of the ER fluid 10 increasing with the applied electric field at constant pressures of 50 kPa, 210 kPa, and 500 kPa. As the pressure increases, the yield shear stress also increases more dramatically with the electric field. With the technology of the present invention, the ER fluid 10 has a yield shear stress value of about 200 kPa at 3000 V/mm and 800 kPa pressure, roughly a 40-fold improvement due to the application of pressure, and more than sufficient for most major industrial applications.
FIGS. 9 and 10, when combined with FIGS. 5-8, can be used to find the increase in yield shear stress with the applied pressure in any arbitrary direction with respect to the applied electric field. This shows that the yield shear stress is greatly raised in all cases and that a combination of apparatus 20 and of apparatus 40 (the third embodiment of the apparatus of the invention) works for a shear force in any arbitrary direction with respect to the applied force and to the applied electric field.
The present invention increases the strength, or yield shear stress, of ER fluids 10 by a factor that, depending on the applied pressure, can be as high as 40 or more. With this new technology, ER fluids will have many major industrial applications. For example, ER fluids can be used for an automobile clutch made of two discs and filled with ER fluid between them (FIG. 3). One disc is connected to the engine and the other is connected to the driving wheels. If there is no electric potential difference or pressure applied between the two discs, the ER fluid has practically zero yield shear stress and the clutch is unengaged. When an electric field is applied, followed by an increase in pressure in accordance with the present invention, the ER fluid may reach a yield shear stress of about 200 kPa in milliseconds. Thus, the clutch is engaged. It is clear that such a new automobile clutch will be much more efficient and agile than existing ones and, since it has no wearing parts, it will be more reliable and have a much longer working life.
There is no prior art technology that can produce a yield shear much above 5 kPa. The method of the present invention provides a means for increasing the yield shear stress of ER fluids to over 100 kPa and up to as much as 200 kPa or more, which exceeds the requirement of most major industrial applications. In addition, the methods of the present invention can be applied to many, or all, of the existing ER fluids since they are general and effective.
It is to be understood that the present invention is not limited to the preferred or other embodiments described herein, but encompasses all embodiments within the scope of the following claims.
ELECTRIC-FIELD ASSISTED FUEL ATOMIZATION SYSTEM AND METHODS OF USE
WO2008054753 (A2)2008-05-08
Inventor(s): HUANG KE [US]; KHILNANEY-CHHABRIA DEEPIKA [US]; KACZANOWICZ EDWARD [US]; TAO RONGJIA [US]
Classification: international: F02M27/04; F02M27/00- European: F02M27/04
Also published as: WO2008054753 (A3)
Abstract -- An apparatus (100) for reducing the size of fuel particles injected into a combustion chamber is disclosed. The apparatus includes fuel line (110), a first metallic mesh (114) disposed within the fuel line (110), and a second metallic mesh(112) disposed within the fuel line (110), upstream of the first metallic mesh (114). An electrical supply (130) is electrically coupled to the first metallic mesh (114) and the second metallic mesh (112). Operation of the electrical supply (130) generates an electrical field between the first metallic mesh (114) and the second metallic mesh (112). A fuel injector (120) is disposed at an end of the fuel line (110), downstream from the first metallic mesh (114). Methods of reducing the size of fuel particles, improving gas mileage in a vehicle, increasing power output from a combustion engine, and improving emissions for a combustion engine are also provided.
