rexresearch.com
Georgios VATISTAS
Vortex Cooling
http://www.physorg.com/news/2012-02-hot-cools-environment-environmentally-friendly-exchanger.html
Hot invention cools down environment :
Environmentally-friendly heat exchanger produced
February 15, 2012


The current global energy crisis means that sustainability now supplants necessity as the mother of all invention. Concordia University's Georgios Vatistas, professor in the Department of Mechanical and Industrial Engineering, has taken this adage to heart with his reinvention of an industrial staple: the heat exchanger.

Used in large-scale commercial settings such as refrigeration systems, power plants and petroleum refineries, heat exchangers are massive machines that transfer heat from one medium to another in order to regulate the temperature of industrial processes. Because of the massive scale, this heat transfer results in enormous energy demands and huge drains on environmental resources.

With the research portion of the project now complete, Vatistas has high hopes that his design will be met with enthusiastic industrial development. "Ultimately," he says, "this heat exchanger will have broad use across countless sectors. By responding to industrial needs with a more sustainable solution, we're showing that the future of engineering can be a green one."

The innovation behind Vatistas's unique design comes from over two decades of research into vortex flows. "Growing up in southern costal Greece," recalls Vatistas, "I became familiar with the concept of vortices at an early age when my elders would warn me of the dangers of swimming near whirlpools!" Youthful fascination evolved into research passion as Vatistas performed advanced theoretical work into how vortices alter the flow of fluid substances like air or water. He later went on to gain international renown for proving Nobel Prize winner J.J. Thomson's 125-year-old theorem on the stability of vortex rings.

But it is on the practical side of things where Vatistas's work resonates loudest. When Vatistas realized that swirling flow could dramatically increase heat transfer exchange, the commercial application of his research quickly became evident. He then partnered with Gestion Valéo to investigate new designs of heat exchangers and received a prestigious "Idea to Innovation" grant from the Natural Sciences and Engineering Research Council in support of the work.

With the collaboration of PhD student and doctoral fellow Mohammed Fayed, Vatistas reengineered this widely used device to produce a prototype that is 40 times more efficient than the traditional model. This reinvention represents enormous energy savings, lower operating costs and far-reaching industrial implications.

HEAT-EXCHANGER CONFIGURATION
WO2010148515

Inventor(s): VATISTAS GEORGIOS H [CA]; FAYED MOHAMED
Applicant(s): VALORBEC SOC EN COMMANDITE REPRESENTEE PAR GESTION VALEO S E C [CA]; VATISTAS GEORGIOS H [CA]; FAYED MOHAMED [CA] + (VALORBEC SOCIETE EN COMMANDITE, REPRESENTEE PAR GESTION VALEO S.E.C, ; VATISTAS, GEORGIOS H, ; FAYED, MOHAMED)
Classification: - international: F28D1/03; F28D7/10; F28D9/00; F28F13/06; F28F3/04; F28F3/08
- European: F28D9/00D; F28D9/00P; F28F13/12; F28F9/02K4B

Abstract -- A heat exchanger comprises a first plate. A second plate is spaced apart from the first plate and defines a first gap between inner surfaces of the first plate and the second plate in which a first fluid circulates. A major portion of the first gap is free of obstructions. A second fluid contacts an outer surface of the first or second plate for heat exchange with the first fluid. A first peripheral wall on the periphery of the first gap has a curved profile inside the first gap. At least one inlet is radially positioned with respect to the first gap and injects the first fluid in the gap. At least one outlet is centrally positioned in one of the first and the second plate to enable the first fluid to exit the first gap. The first fluid circulates in a swirling flow in the major portion of the first gap.

FIELD OF THE APPLICATION

The present application pertains to heat exchangers and, more particularly, to a heat-exchanger design for reducing the pressure drop of fluids across the heat exchanger.

BACKGROUND OF THE ART

Heat exchangers are commonly used in order to transfer energy from one fluid to another through a solid surface. Typical heat exchangers feature tubes, ducts or paths (hereinafter tubes) in which a first fluid circulates as a result of action from a pump, pressure source or the like. A second fluid is in contact with an exterior surface of the tube so as to exchange energy with the first fluid circulating in the tubes. The tube may be shaped in a coil, provided with fins or the like, depending on the heat-exchanger configuration (e.g., shell and tube, heat-exchanger coil, radiator, etc.)

One of the issues with such heat exchangers is that the tubes are costly in terms of material and space. Moreover, because of the friction of the first fluid against the surface of the tube, there is a substantial fluid pressure drop in the heat exchanger. Accordingly, a substantial amount of energy is required to maintain a suitable flow of the first fluid in heat exchangers .

SUMMARY OF THE APPLICATION

It is therefore an aim of the present application to provide a heat exchanger that addresses issues associated with the prior art. Therefore, in accordance with a first embodiment, there is provided a heat exchanger comprising: at least a first plate and a second plate spaced apart from the first plate to define a first gap between inner surfaces of the first plate and of the second plate in which at least a first fluid circulates, with a major portion of the first gap being free of obstructions, with at least a second fluid contacting an outer surface of at least one of the first plate and of the second plate for heat exchange with the first fluid; a first peripheral wall on the periphery of the first gap, the first peripheral wall having a curved profile inside the first gap; at least one inlet radially positioned with respect to the first gap to inject the first fluid in the gap; and at least one outlet centrally positioned in one of the first plate and the second plate, for the first fluid to exit the first gap,- whereby the first fluid circulates in a swirling flow in the major portion of the first gap.

Further in accordance with the first embodiment, the first plate is a first disk and the second plate is a second disk having a peripheral outline similar to that of the first disk.

Still further in accordance with the first embodiment, the heat exchanger further comprises at least a third plate spaced apart from the outer surface of any one of the first plate and the second plate to define a second gap with a major portion of the second gap being free of obstructions, a second peripheral wall on the periphery of the second gap having a curved profile inside the second gap, at least one said inlet and at least one said outlet being in fluid communication with the second gap to cause a swirling flow of the second fluid in the second gap.

Still further in accordance with the first embodiment, the first plate forms the first gap with the second plate, and the first plate forms the second gap with the third plate, with a first one of said outlet being a first pipe centrally positioned in the second plate for the first fluid to exit the first gap, and with a second one of said outlet being a second pipe centrally positioned in the third plate for the second fluid to exit the second gap, whereby the first pipe and the second pipe are concentric .

Still further in accordance with the first embodiment, the heat exchanger further comprises at least a fourth plate spaced apart from the second plate to define a third gap with a major portion of the third gap being free of obstructions, a third peripheral wall on the periphery of the third gap having a curved profile inside the third gap, at least one said inlet and at least one said outlet being in fluid communication with the third gap to cause a swirling flow of a fluid in the third gap, with a third one of said outlet being a third pipe centrally positioned in the fourth plate and having a diameter greater than the first pipe to form an annular passage about the first pipe for fluid to exit the third gap, whereby the first pipe and the third pipe are concentric .

Still further in accordance with the first embodiment, the first plate forms the first gap with the second plate, and the second plate forms the second gap with the third plate, with a first one of said outlet being a first pipe centrally positioned in the second plate and passing through the third plate for the first fluid to exit the first gap, and with a second one of said outlet being a second pipe having a diameter greater than the first pipe and being centrally
- 5 -positioned in the third plate to form an annular passage about the first pipe for fluid to exit the second gap, whereby the first pipe and the second pipe are concentric . Still further in accordance with the firsu embodiment, at least one radial outlet pipe is connected to any one of the pipes of the outlets centrally positioned in the plates, for exit of fluids therethrough . Still further in accordance with the first embodiment, vanes extend between surfaces of the spaced apart plates in at least one of the gaps to guide fluids in the swirling flow.

Still further in accordance with the first embodiment, a first set of the vanes are radially distributed and equidistantly spaced from one another and from a center of a respective one of the gaps.

Still further in accordance with the first embodiment, the first set of vanes is adjacent to the at least one peripheral wall .

Still further in accordance with the first embodiment, the heat exchanger further comprises a second set of the vanes, the second set of the vanes being radially distributed and equidistantly spaced from one another and from a center of a respective one of the gaps, the second set being positioned between the first set of the vanes and a center of a respective one of the gaps .

Still further in accordance with the first embodiment, the at least one set of the vanes comprises at least one annular plate integral with the vanes, the annular plate being coplanar with a respective one of the plates when the sets of vanes are in the respective gap. Still further in accordance with the first embodiment, vanes are at an 80 degree angle from a radius of the gap.

Still further in accordance with the first embodiment, the curved profile of the at least one peripheral wall is substantially circular.

Still further in accordance with the first embodiment, the at least one inlet is tangentially oriented with respect to the curved profile of the at least one gap.

Still further in accordance with the first embodiment, the heat exchanger comprises at least two of the inlet for at least one of the gaps .

BRIEF DESCRIPTION OF DRAWINGS

Fig. 1 is a schematic perspective view of a heat exchanger in accordance with the embodiment of the present application;



Fig. 2 is a sectional schematic view of the heat exchanger of Fig. 1, with two stages;


Fig. 3 is a schematic sectional view of the heat exchanger of Fig. 1 with five stages;


Fig. 4 is a sectional view of a portion of the heat exchanger of Fig. 3;


Fig. 5 is a side elevation view of the heat exchanger of Fig. 1 with three stages,- and


Fig. 6 is a plan view of an interior of the heat exchanger of Fig. 1 m accordance with another embodiment of the present application.


DESCRIPTION OF PREFERRED EMBODIMENTS

Referring to the drawings and, more particularly to Fig. 1, a heat exchanger in accordance with the present disclosure is generally shown at 10. The heat exchanger 10 of Fig. 1 is a disk-type heat exchanger in which circulates a fluid or combination of fluids, fluid and solid (i.e., liquid and/or gas, with solids m suspension) . Another fluid, combination of fluid/solid or fluids is m contact with an exterior surface of the heat exchanger 10. For simplicity purposes, reference will be made to fluids hereinafter. The heat exchanger 10 of Fig. 1 is therefore said to have a single stage 11.

The heat exchanger 10 of Fig. 1 has a pair of disks 12. Typically, the disks 12 are circular m shape, although other shapes are considered, preferably with rounded or arcuate peripheries. The disks 12 are spaced apart, so as to define a gap therebetween, m which the fluid will flow. A peripheral wall bounds the gap between the disks 12, and inlets 13 (i.e., one or more) are provided m this peripheral wall or m the disks 12, for the injection of fluid into the gap. The peripheral wall 13 has a curved inner profile to def me the curved inner periphery of the gap In an embodiment, the curved inner profile of the peripheral wall 13 is circular. As a radial periphery of the gap m which the fluid circulates is defined by the pe[pi]pneral wall 13, the disks may be replaced by plates or walls of different shapes, etc.

A central outlet 14 projects upwardly from one of the disks 12, although both disks 12 may be provided with a central outlet 14. As the inlet (s) 13 are provided on the periphery of the heat exchanger 10, and the outlet 14 is centrally positioned, the fluid injected into the gap exits centrally. However, it is desired to have the fluid flow m a swirling pattern Therefore, when fluid is injected into the inlets 13, the inlets 13 may be oriented so as to give a generally tangential direction, to cause a swirling pattern of the fluid m the gap. Due to the area reduction, the fluid is accelerated (i.e., accelerating flow or m-sirik flow) Accordingly, the fluid m the heat exchanger 10 adopts the swirling pattern and remains between the disks 12 until it exits through the central outlet 14. It is observed that the gap between the disks 12 is generally free of obstructions. While the fluid swirls to the central outlet 14, the fluid contacts the inner surfaces of the disks 12 in the gap, thereby exchanging heat with fluid on the outside of the disks 12. The residence time of the fluid in the stage 11 may be controlled by adjusting the flow of the fluid in the stage 11, for instance by adjusting the intensity of the pump(s) whether upstream or downstream of the heat exchanger 10.

Referring to Fig. 2, a configuration similar to that of the heat exchanger 10 of Fig. 1 is illustrated, but with two stages 11. Accordingly, a first fluid circulates in stage HA, whereas a second fluid circulates in stage HB. For clarity purposes, the components of the stage HA have been affixed with the letter A, whereas the components of stage HB have been affixed with the letter B. Therefore, in the case of Fig. 2, two fluids are in heat exchange using the heat-exchanger configuration 10 of Fig. 1, through common disk 12A/B. One of the fluid absorbs heat released by the other fluid. The disk 12A/B is made of a material preferably having high heat conductivity, such as metal (e.g., aluminum) . Throughout the description, the nomenclature using affixed letters separated by a slash (e.g., 12A/B) will refer to a disk separating two stages (A and B) . Coatings may be added to the surfaces of the disks to minimize the friction of fluids against the surfaces of the disks.

Referring to Fig. 3, the heat exchanger 10 is shown having a multi-disk configuration having five different stages, namely stages HA, HB, HC, HD and HE. Accordingly, five different fluids may flow in the separate stages of the heat exchanger 10. Alternatively, some of the stages are combined as different passes for a same fluid, or parallel stages for a same fluid. As an example, a first fluid may circulate in stages HA, HC and HE, while a second fluid circulates in stages HB and HC. As another example, the fluid collected at the outlets 14A may be subsequently circulated in stages HC and HE, amongst other possibilities. It is observed that stage HA may have a pair of central outlets 14A, as illustrated. Moreover, the outlets of stages HB, HC, HD and HE are concentrically positioned with respect to the central outlet 14A, with the outlets 14 of stages HB- HD forming annular geometries.

Referring to Fig. 4, a sectional view of the heat exchanger 10 of Fig. 3 is illustrated, showing that the outlets 14B and 14C may comprise outlet pipes projecting radially from the annular central outlets 14B and 14C, although various other configurations may be used as well. Referring concurrently to Figs. 5 and 6, another embodiment of the heat exchanger 10 is illustrated, with vanes 15 provided in the gap between disks 12 (i.e., vanes 15A-15C for stages HA-HC in Fig. 5) . More specifically, the vanes 15 are provided adjacent to the peripheral wall and thus adjacent to the inlets 13. The vanes 15 are narrow rigid plates used to guide the flow of fluid in adopting a swirling pattern in the gap. A leading edge of each vane 15 is closer to the periphery than the trailing edge of the adjacent vane 15. Other devices or deflectors may be used to guide the flow of fluid into the swirling pattern. According to an embodiment, the vanes 15 are radially arranged, and may be equidistantly spaced from a center of the gap and from one another. In an embodiment, the vanes 15 are provided on a ring plate (i.e., annular plate) coplanar disposed on one of the disks, as shown in Figs. 5 and 6. Accordingly, all vanes 15 are installed/removed by the simple manipulation of the ring plate (e.g., plexiglass) . Another similar ring plate with vanes 15 may be provided with a smaller diameter and hence be closer to the center of the heat exchanger 10. In an example, the vanes are at an 80 degree angle from a radius of the gap between the disks 12. Other materials may be used as well (e.g., mesh) . Despite the presence of vanes 15, a major portion of the gap is free of obstructions, whereby the fluid adopts a swirling pattern without a spiral-type conduit in the gaps, resulting in relatively low friction. The heat exchanger 10 of Figs. 1 to 6 is also relatively simple to maintain, as the disks 12 may readily be separated from one another for maintenance. As is shown in Figs. 4 and 5, the inlets 13 and peripheral wall may be one integral piece interconnecting the disks 12. The applications using the heat exchanger 10 may range from domestic heating systems, to steam power plants, to refineries, amongst numerous possibilities.