GB2622080A

GB2622080A - Plate heat exchanger

Info

Publication number: GB2622080A
Application number: GB2212768.2A
Authority: GB
Inventors: Philip Duffy James
Original assignee: Individual
Current assignee: Individual
Priority date: 2022-09-02
Filing date: 2022-09-02
Publication date: 2024-03-06
Also published as: GB202212768D0

Abstract

A plate heat exchanger 1 comprising heat exchange modules M1, M2, M3, each heat exchange module comprising a first plate 20 and a second plate 30 and a thermoelectric module 40 located therebetween. The first plate provides a relatively hot heat exchange surface and the second plate provides a relatively cold heat exchange surface. Each heat exchange module has a first flow path (FP1, Fig.1) and a second flow path (FP2, Fig.1) therethrough. The first plate of a first of the heat exchange modules faces the first plate of a second of the heat exchange modules. The second plate of the second of the heat exchange modules faces a plate of a further module. The heat exchanger may comprise gaskets 60 located between the facing first plates and the facing second plates. The thermoelectric module 40 may comprise a holder plate (40A, Fig.6) and a thermoelectric device (40B, Fig.6). By providing electrical power to the thermoelectric devices, the plate heat exchanger 1 may be used as a heat pump, for example as a thermo-electric ground source heat pump (TGSHP) or a thermo-electric air source heat pump (TASHP).

Description

PLATE HEAT EXCHANGER

This invention relates generally to a plate heat exchanger. More specifically, although not exclusively, this invention relates to a plate heat exchanger for use in heating, cooling or energy reclaim modes of operation.

In heat pumps, such as ground source heat pumps (GSHP) or air source heat pumps (ASHP), a relatively cold fluid circuit passes through a heat source, for example through the ground in a GSHP, which increases the temperature of the relatively cold fluid. Typically, the relatively cold fluid then increases the temperature of a separate heat transfer fluid in an evaporator, which then passes through a compressor to heat up a separate, relatively hot fluid in a condenser. The relatively hot fluid then provides heat, for example to a building to provide heating for rooms or heating for providing hot water. Typically, the heat transfer fluid then passes through an expansion valve to cool it further, and the cycle continues.

Such heat pumps typically are bulky and complex, and the components are often costly, meaning that construction, installation and maintenance is often expensive.

Also, whilst the principles behind the operation of a heat pump, as described above, are similar to those of a refrigeration cycle, for example for air conditioning, the actual construction of a cooling system might be different to that of a heat pump and so the two are not interchangeable. This is because in order to provide a high level of cooling, similar to that of an air conditioning system for example, it is necessary for the flow through the compressor and expansion valve to be reversed. Therefore, it is often necessary to provide separate heating and cooling systems.

It is known to overcome the issue of bulkiness and complexity in some cooling systems by using thermoelectric, or Peltier, cooling. Such systems might, for example, have multiple thermoelectric devices which are spaced apart, for fluid to flow therebetween. However, it is often difficult to provide efficient heat transfer in such systems. This is because the pipework required to provide fluid flow between adjacent thermoelectric devices usually necessitates that the distance between adjacent thermoelectric devices is large, resulting in a large flow thickness and thus inefficient heat transfer between the thermoelectric devices and the fluid. Furthermore, as the pipework might be complex, and the efficiency might be suboptimal in comparison to a normal refrigeration cycle, there may be no significant cost benefit to using a Peltier cooling system. In fact, the cost of a Peltier cooling system is generally higher than a convention refrigeration system using a condenser and evaporator.

It would therefore be advantageous to overcome at least some of the aforementioned limitations.

Accordingly, a first aspect of the invention provides a plate heat exchanger, the plate heat exchanger comprising plural heat exchange modules, each heat exchange module comprising a first plate and a second plate and a thermoelectric device located therebetween, the first plate providing a relatively hot heat exchange surface and the second plate providing a relatively cold heat exchange surface, and each heat exchange module having a first and second flow path therethrough, the first plate of a first of said plural heat exchange modules facing a first plate of a second of said plural heat exchange modules, the second plate of said second of said plural heat exchange modules facing a plate of a further module.

Advantageously, the plate heat exchanger is more compact and less complex than known heat exchangers, because the first and second flow paths extend through the heat exchange modules, rather than the flow paths going around the heat exchange modules, externally.

The further module may be a third of said plural heat exchange modules. The plate of the further module may be the second plate of said third of said plural heat exchange modules which faces the second plate of said second of said plural heat exchange modules. The second plate of the first of said plural heat exchange modules may face a plate of a second further module. The first plate of the third of said plural heat exchange modules may face a plate of a third further module. The second further module may comprise a first end plate. The third further module may comprise a second end plate. Alternatively, the third further module may comprise a fourth of said plural heat exchange modules. The first plate of the fourth of said plural heat exchange modules may face the first plate of the third of said plural heat exchange modules. The second plate of the fourth of said plural heat exchange modules may face a fourth further module. The fourth further module may comprise a second end plate.

The thermoelectric devices may be connectable or connected to a power supply. The thermoelectric devices may be connectable or connected to an energy storage system.

The first flow path may comprise first and second fluid flow paths which are fluidly connected. The second flow path may comprise third and fourth fluid flow paths which are fluidly connected.

Each of the first and second flow paths may comprise an inlet conduit and an outlet conduit, the inlet conduit of each flow path being in fluid communication with the outlet conduit of io the respective flow path. The inlet conduit and the outlet conduit of the first flow path may be in fluid communication between the facing second plates of the second and third of the plural heat exchange modules. The inlet conduit and the outlet conduit of the second flow path may be in fluid communication between the facing first plates of the first and second of the plural heat exchange modules. The inlet conduit of the first flow path may provide the first fluid flow path and the outlet conduit of the first flow path may provide the second fluid flow path. The inlet conduit of the second flow path may provide the third fluid flow path and the outlet conduit of the second flow path may provide the fourth fluid flow path.

The plate heat exchanger may comprise plural gaskets. A first of said plural gaskets may be located between the facing first plates of said first and second heat exchange modules.

A second of said gaskets may be located between the facing second plates of said second and third heat exchange modules. The gaskets may provide fluid communication in the first flow path of successive heat exchange modules. The gaskets may provide fluid communication in the second flow path of successive heat exchange modules. The gaskets may provide fluid communication between the first and second fluid flow paths of successive heat exchange modules. The gaskets may provide fluid communication between the third and fourth fluid flow paths of successive heat exchange modules.

Fluid flow, through the gaskets, may be in substantially the same direction between the first and second fluid flow paths as between the third and fourth fluid flow paths. Alternatively, fluid flow, through the gaskets, may be in substantially the opposite direction between the first and second fluid flow paths as between the third and fourth fluid flow paths.

Advantageously, the provision of gaskets to provide fluid communication between flow paths means that the thickness of the flow path between the facing plates may be small, and so heat transfer between the fluid and the facing plates has a high efficiency.

The gaskets may have a thickness of between 0.5 mm and 10 mm. The gasket thickness may be dependent upon any number of gasket size, gasket material, operating pressures of the heat exchanger and compression ratios of the heat exchanger.

Each gasket of said plural gaskets may comprise two bypass apertures, an inlet aperture, io and an outlet aperture. The first gasket may be orientated such that the bypass apertures thereof are in the first flow path and the heat transfer aperture is in the second flow path. The second gasket may be orientated such that the bypass apertures thereof are in the second flow path and the heat transfer aperture is in the first flow path.

Each one of the gaskets may have a substantially rectangular in-plane shape. Each one of the bypass apertures of each gasket may be located proximal a respective first and second corner of the gasket. Each inlet aperture of each gasket may be located proximal a third corner. Each outlet aperture of each gasket may be located proximal a fourth corner. The first and second corners may be diagonally opposite to one another. The third and fourth corners may be diagonally opposite to one another.

The first plates, second plates and gaskets may all have substantially identical perimeters. The heat transfer aperture may have two opposing angled sides which are spaced from the bypass apertures. The heat transfer aperture may have two opposing sides which are substantially parallel to sides of the respective gasket. The heat transfer aperture may have a substantially parallelogram shape. Advantageously, this provides the maximum flow area in the heat transfer aperture.

Each first plate of each of said plural heat exchange modules may have two bypass apertures, an inlet aperture, and an outlet aperture. The bypass apertures may be in fluid communication with the first flow path. The inlet and outlet apertures may be in fluid communication with the second flow path. Each second plate of each of said plural heat exchange modules may have two bypass apertures, an inlet aperture, and an outlet aperture. The bypass apertures may be in fluid communication with the second flow path.

The inlet and outlet apertures may be in fluid communication with the first flow path.

The bypass apertures of the first plates of the first and second heat transfer modules may be substantially aligned, e.g., coaxial with the bypass apertures of the first gasket. The inlet and outlet apertures of the first plates of the first and second heat transfer modules may be substantially aligned, e.g., coaxial with the inlet and outlet apertures, respectively, of the first gasket. The bypass apertures of the second plates of the second and third heat transfer modules may be substantially aligned, e.g., coaxial with the bypass apertures of the second gasket. The inlet and outlet apertures of the second plates of the second and third heat transfer modules may be substantially aligned, e.g., coaxial with the inlet and outlet apertures, respectively, of the second gasket.

Each one of the first plates and the second plates may have a substantially rectangular in-plane shape. Each one of the first plates and the second plates may be of substantially the same in-plane size. Each one of the bypass apertures of each first and second plate may be located proximal a respective first and second corner of the plate. Each inlet aperture of each first and second plate may be located proximal a third corner. Each outlet aperture of each first and second plate may be located proximal a fourth corner. The first and second corners may be diagonally opposite to one another. The third and fourth corners may be diagonally opposite to one another.

The plate heat exchanger may further comprise a plurality of bypass tubes. A first and second of said bypass tubes may extend through respective ones of the bypass apertures of the first plates of the first and second heat exchange modules. The first and second bypass tubes may abut an abutment surface of, and may surround respective inlet and outlet apertures of, the second plates of the first and second heat exchange modules. A third and fourth of said bypass tubes may extend through respective ones of the bypass apertures of the second plates of the second and third heat exchange modules. The third and fourth of said bypass tubes may abut an abutment surface of, and may surround respective inlet and outlet apertures of, the first plates of the second and third heat exchange modules.

The abutment of the bypass tubes against abutment surfaces of the first and second plates may provide a sealed abutment. For example resilient means such as 0-rings may be located between the ends of the bypass tubes and the respective first and second plates.

The plate heat exchanger may further comprise a plurality of holder plates. Each holder plate may be located in each heat exchange module. Each holder plate may be configured to hold the respective thermoelectric device between the first and second plates of the respective heat exchange module.

Each holder plate may comprise four bypass apertures. Two of the bypass apertures may be in the first flows path. The other two of the bypass apertures may be in the second flow path.

to The first and second bypass tubes may pass through first and second bypass apertures of the holder plates of the first and second heat exchange modules. The third and fourth bypass tubes may pass through third and fourth bypass apertures of the holder plates of the second and third heat exchange modules.

The plate heat exchanger may further comprise a first end plate and a second end plate The first end plate may comprise a first inlet aperture and a first outlet aperture in the first flow path. The first end plate may comprise a second inlet aperture and a second outlet aperture in the second flow path.

Alternatively, the first end plate may comprise a first inlet aperture in the first flow path, and a first outlet aperture in the second flow path. The second end plate may comprise a second inlet aperture in the second flow path and a second outlet aperture in the first flow path. The plate heat exchanger, for example the gaskets, may be arranged such that fluid flows in a first direction along two consecutive gaskets which are in the first flow path, and fluid flows in a second direction along successive two consecutive gaskets which are in the first flow path, the second direction being opposite to the first direction. The plate heat exchanger, for example the gaskets, may be arranged such that fluid flows in a third direction along two consecutive gaskets which are in the second flow path, and fluid flows in a fourth direction along successive two consecutive gaskets which are in the second flow path, the third direction being opposite to the fourth direction. The successive two gaskets may be immediately successive or may be separated said two consecutive gaskets by one or more intervening gaskets.

The first end plate and the second end plate may be rectangular in in-plane shape. The first end plate and the second end plate may have a substantially identical perimeter as the first and second plates. The first end plate and the second end plate may have a substantially identical perimeter as the gaskets.

The plate heat exchanger may further comprise a third gasket located between the second further module, for example the first end plate, and the second plate of the first heat transfer module. The plate heat exchanger may comprise a fourth gasket located between the third further module, for example the second end plate and the first plate of the third heat transfer module. The third and/or fourth gaskets may be the same as the first and second gaskets. The third gasket may provide fluid communication in the first flow path. The fourth gasket io may provide fluid communication in the second flow path.

The plate heat exchanger may further comprise a plurality of end bypass tubes. A first and second of the end bypass tubes may extend through respective bypass apertures of the first gasket and of the second plate of the first heat exchange module. The first and second of the end bypass tubes may abut an abutment surface of, and surround the respective inlet and outlet apertures of, the first end plate and the first plate of the first heat exchange module. A third and fourth of the end bypass tubes may extend through respective bypass apertures of the fourth gasket and the first plate of the third heat exchange module. The third and fourth of the end bypass tubes may abut an abutment surface of the second end plate, and may abut an abutment surface of, and surround respective inlet and outlet apertures of, the second plate of the third heat exchange module.

The abutment of the end bypass tubes against first and second plates may provide a sealed abutment. For example resilient means such as 0-rings may be located between the ends of the end bypass tubes and the respective one of the first plate, second plate, and second end plate The first and second end bypass tubes may pass through third and fourth bypass apertures of the holder plate of the first exchange module. The third and fourth end bypass tubes may pass through first and second bypass apertures of the holder plate of the third heat exchange module.

The plate heat exchanger may further comprise fixing means which urge the first and second plates towards one another.

Securing of the fixing means may be configured to compress the gaskets. Securing of the fixing means may be configured to compress the resilient means, e.g., to compress the 0-rings. The fixing means may be bolts or threaded bars, which are configured to threadedly engage with nuts.

Each of the first and second plates of each heat exchange module may have a flow surface configured to receive fluid flow thereover. The flow surface may comprise a plurality of lateral channels. Each lateral channel may be orientated at an oblique angle relative to a flow direction of the fluid over the flow surface, in use. The heat exchange surface of each io of the first and second plates may provide the respective flow surface, The flow direction may be an average flow direction, i.e. of fluid flowing over the respective flow surface.

Advantageously, the lateral channels create turbulence and so increase the heat transfer between the fluid and the respective first or second plate.

The flow surface of each plate may further comprise a plurality of flow channels substantially aligned with a flow direction of the fluid over the flow surface, in use. The flow channels may substantially guide fluid from the inlet aperture to lateral channels and then may substantially guide fluid from the lateral channels to the outlet aperture, of the respective first or second plate. This advantageously distributes the fluid across the respective flow surface.

The plate heat exchanger may further comprise a plurality of thermoelectric devices located between first and second plates of each heat exchange module.

The thermoelectric devices may comprise positive and negative semiconductors which are in direct contact with the respective first and second plates. The thermoelectric devices may comprise positive and negative semiconductors which are sandwiched between the respective first and second plates, with conductive sheets, for example thin conductive sheets, located between the semiconductors and each of the respective first and second plates.

According to a second aspect of the invention there is provided a heat exchange system comprising the aforementioned plate heat exchanger, and a controller, the controller being configured to independently control the electrical power which is provided to each thermoelectric device.

According to a third aspect of the invention there is provided a heat pump comprising the aforementioned plate heat exchanger or the aforementioned heat exchange system.

According to a fourth aspect of the invention there is provided a heating system, for example io for heating rooms in a building, or for heating a water supply, comprising the aforementioned plate heat exchanger or the aforementioned heat exchange system.

The heating system may further comprise a power supply for supplying power to the thermoelectric devices.

According to a fifth aspect of the invention there is provided a cooling system, for example a cooling system for cooling rooms in a building, or for cooling a water supply, comprising the aforementioned plate heat exchanger or the aforementioned heat exchange system.

The cooling system may further comprise a power supply for supplying power to the thermoelectric devices.

According to a sixth aspect of the invention there is provided an energy reclaim system comprising the aforementioned plate heat exchanger.

The energy reclaim system may comprise an energy storage system for storing energy generated by the thermoelectric devices.

According to a seventh aspect of the invention there is provided a gasket for use in a plate heat exchanger, the gasket comprising two bypass apertures, an inlet aperture, and an outlet aperture. Each one of the gaskets may have a substantially rectangular in-plane shape. Each one of the bypass apertures of each gasket may be located proximal a respective first and second corner of the gasket. Each inlet aperture of each gasket may be located proximal a third corner. Each outlet aperture of each gasket may be located proximal a fourth corner. The first and second corners may be diagonally opposite to one another. The third and fourth corners may be diagonally opposite to one another. The heat transfer aperture may have opposing angled sides which are spaced from the bypass apertures. The heat transfer aperture may have opposing parallel sides which are substantially parallel with sides of the gasket. The heat transfer aperture may have a substantially parallelogram shape. Advantageously, this provides the maximum flow area in the heat transfer aperture.

According to an eighth aspect of the invention there is provided a plate for use in a plate heat exchanger, the plate comprising a flow surface configured to receive fluid flow thereover, the flow surface comprising a plurality of lateral channels, each lateral channel being orientated at an oblique angle relative to a flow direction of the fluid over the flow surface, in use.

The flow direction may be an average flow direction, i.e. of fluid flowing over the respective is flow surface.

The plate may comprise an inlet aperture, and an outlet aperture. The flow surface of each plate may further comprise a plurality of flow channels substantially aligned with a flow direction of the fluid over the flow surface, in use. The flow channels may substantially guide fluid from inlet aperture to lateral channels and then may substantially guide fluid from the lateral channels to the outlet aperture. The plate may comprise two bypass apertures.

This advantageously distributes the fluid across the respective flow surface.

According to a ninth aspect of the invention there is provided a method of exchanging heat between a first and a second fluid, the method comprising pumping the first fluid along a first flow path of a plate heat exchanger, by passing the first fluid passing through a plurality of heat exchange modules, the method further comprising pumping the second fluid along a second fluid flow path of the plate heat exchanger, by passing the second fluid through the plurality of heat exchange modules, the second fluid flowing between facing first plates of first and second heat exchange modules of said plurality of heat exchange modules, the first fluid flowing between the second plate of the second of said plurality of heat exchange modules and a plate of a further module, wherein one of the thermoelectric devices is located between the first and second plates of each heat exchange module such that heat is transferred between the first fluid and each thermoelectric device, through the respective one of the second plates, and heat is transferred between the second fluid and each thermoelectric device, through the respective one of the first plates.

The first fluid may be a relatively cold fluid. The second fluid may be a relatively hot fluid.

The further module may comprise a third of said plural heat exchange modules. The plate io of the further module may be the second plate of the third of said plural heat exchange modules. The method may comprise the first fluid flowing between the facing second plates of the second and third of said plural heat exchange modules. The method may comprise the first fluid flowing between the second plate of the first of said plural heat exchange modules and a plate of a second further module. The method may comprise the second fluid flowing between the first plate of the third of said plural heat exchange modules and a plate of a third further module. The second further module may comprise a first end plate. The third further module may comprise a second end plate. Alternatively, the third further module may comprise a fourth of said plural heat exchange modules. The method may comprise the second fluid flowing between the facing first plates of the third and fourth of said plural heat exchange modules. The method may comprise the first fluid flowing between the second plate of the fourth of said plural heat exchange modules and a fourth further module. The fourth further module may comprise a second end plate.

The method may further comprise pumping the first fluid between one of two end plates of the plate heat exchanger, and the second plate of the first heat exchange module and pumping the second fluid between the other of the two end plates of the plate heat exchanger, and the first plate of the third heat exchange module.

The method may further comprise providing electrical power to the thermoelectric devices such that each thermoelectric device has a relatively cold surface and a relatively hot surface, wherein heat is transferred from the first fluid to the relatively cold surface of each thermoelectric device, and wherein heat is transferred from the relatively hot surface of each thermoelectric device to the second fluid.

The method may further comprise individually controlling the electrical power which is provided to each thermoelectric device.

For the avoidance of doubt, any of the features described herein apply equally to any aspect of the invention.

Within the scope of this application it is expressly intended that the various aspects, embodiments, examples and alternatives set out in the preceding paragraphs, in the claims and/or in the following description and drawings, and in particular the individual features thereof, may be taken independently or in any combination. That is, all embodiments and/or features of any embodiment can be combined in any way and/or combination, unless such features are incompatible. For the avoidance of doubt, the terms "may", "and/or", "e.g.", "for example" and any similar term as used herein should be interpreted as non-limiting such that any feature so-described need not be present. Indeed, any combination of optional features is expressly envisaged without departing from the scope of the invention, whether or not these are expressly claimed. The applicant reserves the right to change any originally filed claim or file any new claim accordingly, including the right to amend any originally filed claim to depend from and/or incorporate any feature of any other claim although not originally claimed in that manner.

Embodiments of the invention will now be described by way of example only with reference to the accompanying drawings in which: Figure 1 is a plate heat exchanger according to the invention; Figure 2 is a cross-sectional view of the plate heat exchanger of Figure 1; Figure 3 is a gasket of the plate heat exchanger of Figure 1; Figure 4 is a holder plate of the plate heat exchanger of Figure 1; Figure 5A is a holder plate of the plate heat exchanger of Figure 1; Figure 5B is a thermoelectric device of the plate heat exchanger of Figure 1; Figure 6 is an exploded view of the plate heat exchanger of Figure 1; Figure 7 is a schematic showing the flow paths through the plate heat exchanger of Figure 1; Figure 8 is an alternative example of the holder plate; Figure 9 is an alternative embodiment of the plate heat exchanger in a first counter-flow configuration; Figure 10 is an alternative embodiment of the plate heat exchanger in a second counter-flow configuration; Figure 11 is an alternative embodiment of the plate heat exchanger, with multi-stage flow paths; Figure 12 is a graph of the measured coefficient of performance over time, for a prototype of the plate heat exchanger; and Figure 13 is a graph of the measured temperature differential over the thermoelectric devices of the prototype from which the graph of Figure 10 was produced.

to Referring to Figure 1, there is shown a plate heat exchanger 1. The plate heat exchanger 1 is formed of a plurality of stacked rectangular plates, which are described in more detail subsequently, and which include a first end plate 10 and a second end plate 70. The plates are stacked and secured together using bolts (not shown) which are inserted through bolt holes located around the periphery of the stacked plates, bolt holes 11 of the first end plate 10 being visible in Figure 1. The plate heat exchanger 1 has four flow conduits, each flow conduit passing through a respective corner of the rectangular stacked plates. These four flow conduits are partially provided by flow apertures 12a-d through the first end plate 10. The flow apertures 12a-d are circular in shape. Of these flow apertures 12a-d there is a first inlet aperture 12a, a first outlet aperture12b, a second inlet aperture 12c and a second outlet aperture 12d. The first inlet aperture 12a and the first outlet aperture 12b are a part of a first flow path FP1 through the plate heat exchanger 1. The second inlet aperture 12c and the second outlet aperture 12d are a part of a second flow path FP2 through the plate heat exchanger 1. The first inlet aperture 12a and corresponding apertures in the other plates of the plate heat exchanger 1, in the first flow path FP1, may be collectively referred to as a "first fluid flow path", which is shown with "FPI-1 in Figure 1. The first outlet aperture 12b and corresponding apertures in the other plates of the plate heat exchanger 1, in the first flow path FP1, may be collectively referred to as a "second fluid flow path", which is shown with "FP1-2 in Figure 1. The second inlet aperture 12c and corresponding apertures in the other plates of the plate heat exchanger 1, in the second flow path FP2, may be collectively referred to as a "third fluid flow path", which is shown with "FP2-3 in Figure 1.

The second outlet aperture 12d and corresponding apertures in the other plates of the plate heat exchanger 1, in the second flow path FP2, may be collectively referred to as a "fourth fluid flow path", which is shown with "FP2-4 in Figure 1. The second end plate 70 is the same as the first end plate 10 except that the second end plate 70 does not have flow apertures. In this example, each end plate 10, 70 is manufactured from aluminium, for example aluminium alloy, and is 6 mm in thickness. However, it will be appreciated that any suitable material or any suitable thickness may be used for the end plates 10, 70, for example steel (e.g., mild steel or stainless steel) may be used which is, for example, 3 mm thick.

The plate heat exchanger 1 has four tubular connectors 15, each connector 15 being located partially in a respective flow conduit. Each connector 15 is located in a respective aperture 12a-d of the first end plate 10 and protrudes from the first end plate 10. The plate heat exchanger 1 has electrical wires W extending from a side thereof, the electrical wires W being connected to thermoelectric modules 40, which are visible in Figure 2, located in the plate heat exchanger 1.

Referring now to Figure 2 an section view, taken along line A-A in Figure 1, of the plate heat exchanger 1 is shown, where the stacked plates are visible. The plate heat exchanger 1 has three heat exchange modules Ml, M2, M3. Each heat exchange module Ml, M2, M3 has a first plate 20 and a second plate 30. Each heat exchange module Ml, M2, M3 also has a thermoelectric module 40 located between the first and second plates 20, 30. The plate heat exchanger 1 also has a plurality of gaskets 60. One of the gaskets 60 is located between facing first plates 20 of the first and second modules Ml, M2. One of the gaskets 60 is located between facing second plates 30 of the second and third modules M2, M3. One of the gaskets 60 is also located between the second plate 30 of the first heat exchange module M1 and the first end plate 70. One of the gaskets 60 is also located between the first plate 20 of the third heat exchange module M3 and the first end plate 10.

Referring now to Figure 3, one of the second plates 30 is shown. The second plate 30 has bolt holes 31 located around the periphery thereof. The second plate 30 also has four flow apertures 32a, 32b, 32c, 32d, each of the flow apertures 32a-d being located proximal a respective corner of the second plate 30. Each flow aperture 32a-d is circular in shape. The centre of each flow aperture 32a-d is in substantially the same position relative to edges of the second plate 30 as the centre of the flow apertures 12a-d of the first end plate 10 are relative to the edges of the first end plate 10. Of the four flow apertures 32a-d there is an inlet aperture 32a, an outlet aperture 32b, a first bypass aperture 32c and a second bypass aperture 32d. The first bypass aperture 32c and the second bypass aperture 32d have substantially the same diameter than the flow apertures 12a-d of the first end plate 10. The inlet aperture 32a and the outlet aperture 32b are of a smaller diameter than the flow apertures 12a-d of the first end plate 10. The inlet aperture 32a is located diagonally opposite to the outlet aperture 32b. The first bypass aperture 32c is located diagonally opposite to the second bypass aperture 32d. The second plate 30 has a plurality of lateral channels 33 in a flow surface thereof, the flow surface being configured to receive fluid flow thereover, in use. Each lateral channel 33 has a substantially square or rectangular cross-section and has a chevron shape across the width of the second plate 20. In other words, each lateral channel 33 is formed of two side portions which meet in the centre of the second plate 30, the side portions being at an oblique angle to one another. The oblique angle is shallow, for example less than 100. The lateral channels 33 extend in a width to direction of the rectangular shape of the second plate 30 with the chevron shape pointing towards one of the shorter sides of the rectangular shape of the second plate 30. The lateral channels 33 are all of substantially the same width, and each end of each lateral channel 33 is spaced from the respective long edge of the second plate 30 such that bolt holes 31 are between ends of the lateral channels 33 and the edge of the second plate 30. The second plate 30 also has flow channels 34 in the flow surface. Some of the flow channels 34 of the second plate 30 extend between the inlet aperture 32a and the lateral channels 33. The remainder of the flow channels 34 extend between the outlet aperture 32b and the lateral channels 33. Each flow channel 34 has a square or rectangular cross section which increases in width between the respective one of the inlet aperture 32a or outlet aperture 32b and the lateral channels 33. In this way, the flow channels 34 all adjoin the respective one of the inlet aperture 32a or outlet aperture 32b and all adjoin the one of the lateral channels 34 which is closest to the respective one of the inlet aperture 32a or outlet aperture 32b. The second plate 30 has a substantially flat abutment surface which is on the opposite side of the second plate 30 to the flow surface. The flow surface may otherwise be called a heat transfer surface, as heat is transferred between this surface and the fluid, in use.

Each first plate 20 has the features of the second plate 30 mirrored about one of the longer edges of the second plate 30. Examples of the first plates 20 are shown in Figure 6. The lateral channels 23 of the first plates 20 are the same as the lateral channels 33 of second plates 30. The flow channels 24 in the first plate 20 extend between the inlet aperture 22a and the lateral channels 23, and between the outlet aperture 22b and the lateral channels 23. The inlet aperture 22a and the outlet aperture 22b of each first plate 20 are of substantially the same diameter as the inlet aperture 32a and the outlet aperture 32b of each second plate 30. The first bypass aperture 22c and the second bypass aperture 22d are of substantially the same diameter as the first bypass aperture 32c and the second bypass aperture 32d of the second plate 30.

In this example the first and second plates 20, 30 are manufactured using an aluminium material. The lateral channels 23, 33 and flow channels 24, 34 are machined into the aluminium using any suitable manufacturing process, for example milling. In this example the inlet and outlet apertures 22a, 32a, 22b, 32b have a diameter of 20 mm.

Referring now to Figure 4, one of the gaskets 60 is shown. The gasket 60 has bolt holes 61 io located around the periphery thereof. The gasket 60 also has four flow apertures 62a, 62b, 62c, 62d, each of the flow apertures 62a-d being located proximal a respective corner of the gasket 60. Of the four flow apertures 62a-d there is an inlet aperture 62a and an outlet aperture 62b, first bypass aperture 62c and a second bypass aperture 62d. The first bypass aperture 62c is located diagonally opposite to the second bypass aperture 62d. The first and second bypass apertures 62c, 62d are substantially circular in shape and of substantially the same diameter as the bypass apertures 22c, 32c, 22d, 32d of the first and second plates 20, 30. The inlet aperture 62a is located diagonally opposite to the outlet aperture 62b. The gasket 60 also has a heat transfer aperture 63. The heat transfer aperture has substantially parallel longer edges 63a which are substantially parallel with the longer sides of the rectangular gasket 60. Each longer edge 63a of the heat transfer aperture 63 is spaced from the respective longer side of the gasket 60 such that bolt holes 61 are located between the longer edge 63a of the heat transfer aperture 63 and the longer side of the gasket 60. The gasket 60 has in-plane dimensions which are substantially the same as the first and second plates 20, 30. That is, the perimeter of the gasket 60 is substantially identical to the perimeter of the first and second plates 20, 30. The longer edges 63a of the heat transfer aperture 63 of the gasket 60 are closer to the respective longer side of the gasket 60 than the edges of the lateral channels 23, 33 of the first and second plates 20, 30 are to the respective longer sides of the first and second plates 20, 30. The heat transfer aperture 63 is connected to the inlet aperture 62a and to the outlet aperture 62b, such that the inlet aperture 62a and the outlet aperture 62b are partially circular in shape and are of substantially the same diameter as the inlet aperture 22a, 32a and the outlet aperture 22b, 32b of the first and second plates 20, 30. The centres of each of the inlet aperture 62a, outlet aperture 62b, first bypass aperture 62c and second bypass aperture 62d is in substantially the same position relative to edges of the gasket 60 as the centres of the corresponding flow apertures 12a-d of the first end plate 10 are relative to the edges of the first end plate 10. Shorter edges 63b of the heat transfer aperture 63 extend from the respective one of the inlet aperture 62a or outlet aperture 62b to both of the longer edges 63a of the heat transfer aperture 63, whilst being spaced from the respective one of the first bypass aperture 62c or second bypass aperture 62d. In this way, the gasket 60 is usable to direct fluid from the inlet aperture 62a to the outlet aperture 62b without the fluid entering into either of the first or second bypass aperture 62c, 62d. Advantageously, the geometry of the gasket 60 means that the gasket 60 can be placed in either orientation about a long edge thereof, for the bypass apertures 62c, 62d to be in different corners. This means that the gasket 60 can be mounted against one of the second plates 30 with the inlet aperture 62a and the outlet aperture 62b in the first flow path FP1 to provide communication, in the first flow path FP1, between the inlet aperture 62a and the outlet aperture 62b. Contrarily, the gasket 60 can be turned over and mounted against one of the first plates 20 with the inlet aperture 62a and the outlet aperture 62b in the second flow path FP2 to provide communication, in the second flow path FP2, between the inlet aperture 62a and the outlet aperture 62b. Therefore, only one design of gasket 60 needs be produced for the plate heat exchanger 1.

In this example the gaskets 60 are manufactured using cork. However, it will be appreciated that other gasket materials may be used.

Referring now to Figures 5A and 5B, Figure 5A shows a holder plate 40A of the thermoelectric module 40. Figure 5B shows a thermoelectric device 403 of the thermoelectric module 40. The holder plate 40A has bolt holes 41 located around the periphery thereof. The holder plate 40A is rectangular in shape and has outer in-plane dimensions which are substantially the same as the first and second plates 20, 30 and of the gaskets 60. The holder plate 40A also has four flow apertures 42, each of the flow apertures 42 being located proximal a respective corner of the holder plate 40A. Each flow aperture 42 is circular in shape and of substantially the same diameter as the bypass apertures 22c, 32c, 22d, 32d of the first and second plates 20, 30. The centre of each flow aperture 42 is in substantially the same position relative to edges of the holder plate 40A as the centre of the flow apertures 12a-d of the first end plate 10 are relative to the edges of the first end plate 10. The holder plate 40A has a central aperture 43 which has an in-plane size and shape which is substantially the same as that of the thermoelectric device 40B. In this example the thermoelectric device 40B is rectangular in shape, and so the central aperture 43 of the holder plate 40A is also rectangular in shape. The central aperture 43 is located such that some of the bolt holes 41 are located between each longer edge of the central aperture 43 and the respective longer edge of the holder plate 40A. The central aperture 43 is also located such that some of the bolt holes 41 and the flow apertures 42a-d are located between each shorter edge of the central aperture 43 and the respective shorter edge of the holder plate 40A. Located along one longer edge of the holder plate 40A are wire channels 44. The wire channels 44 are located such that a bolt hole 41 is located between each of two adjacent channels 44. Located along the longer edge of the central aperture 43 which is closest to the wire channels 44 is a relief portion 45. The relief portion 44 is an area of reduced thickness on the same surface upon which is located the to wire channels 44. The relief portion 45 is of the same depth as the wire channels 44.

In this example the holder plates 40A are manufactured using Polylactic acid (PLA) plastic, using an additive manufacture, or 3D printing, technique. However, it will be appreciated that any suitable material, and any suitable manufacturing method, may be used.

In this example the thermoelectric device 40B has single large element face on either side, providing the major surfaces of the thermoelectric device 40B. Also, in this example, the thermoelectric device 40B is produced using a plurality of individual thermoelectric modules therein, provided with a plurality of electrical connections to the wires W. In this example the thermoelectric modules are TEC1-12710 thermoelectric modules. However, it will be appreciated that other thermoelectric modules are suitable.

With reference now to Figure 6, the assembly of the plate heat exchanger 1 is now described. It will be appreciated that the plate heat exchanger 1 may be assembled by starting at either the first end plate 10 or the second end plate. Assembly starting with the second end plate 70 is described here.

Bolts, rods or threaded bars (not shown), which will hereinafter be referred to generally as bolts, are inserted through bolt holes 71 of the second end plate 70. The bolts extend from the second end plate 70 to a length sufficient to stack all of the plates thereupon.

A first one of the gaskets 60 is assembled onto a surface of the second end plate 70 with the bolts passing through the bolt holes 61. The gasket 60 is orientated such that the inlet and outlet apertures 62a, 62b are located in the second flow path FP2.

A first one of the first plates 20 is assembled onto the first one of the gaskets 60 such that the gasket 60 abuts the flow surface of the first plate 20. The bolts pass through the bolt holes 21 of the first plate 20. This orientation leads to the inlet and outlet apertures 22a, 22b of the first one of the first plates 20 being in the second flow path FP2.

A first one of the holder plates 40A is assembled onto the first one of the first plates 20 such that the bolts pass through the bolt holes 41 of the holder plate 40A and such that the holder plate 40A abuts the abutment surface of the first one of the first plates 20. A first one of the thermoelectric devices 40B is inserted into the central aperture 43 of the holder plate 40A io such that a major surface of the thermoelectric device 40B abuts the abutment surface of the first one of the first plates 20. The wires W of the thermoelectric device 40B are guided through the wire channels 44, and, if necessary, along the relief portion 45, of the holder plate 40A.

The assembly so far leads to the bypass aperture 62c, 62d of the first one of the gaskets being substantially aligned with the bypass apertures 22c, 22d of the first one of the first plates 20, and with two diagonally opposite flow apertures 42 of the first one of the holder plates 40A. A short bypass tube 92 with an 0-ring 91 at either end is inserted into the substantially aligned: * each one of the two diagonally opposite flow apertures 42, which are in the first flow path FP1, of the first one of the holder plates 40A; * each corresponding bypass aperture 22c, 22d of the first one of the first plates 20; * each corresponding bypass aperture 62c, 62d of the first one of the gaskets 60; such that one of the 0-rings 91 on a first end of each shorter bypass tube 92 abut the second end plate 70. In this example the short bypass tubes 92 have an outer diameter of mm.

A first one of the second plates 30 is assembled such that the bolts pass through the bolt holes 31 thereof. The abutment surface of the first one of the second plates 30 abuts the first one of the holder plates 40A and the first one of the thermoelectric devices 40B. The abutment surface of the first one of the second plates 30 also abuts the 0-Rings 91 at a second end of the shorter bypass tubes 92. This orientation leads to the inlet and outlet apertures 32a, 32b of the first one of the second plates 30 being in the first flow path FP1.

The first ones of the first plates 20, second plates 20, holder plates 40A and thermoelectric device 403 together provide the third heat exchanged module M3.

A second one of the gaskets 60 is assembled onto the bolts such that the gasket 60 abuts the flow surface of the first one of the second plates 30. The second one of the gaskets 60 is orientated such that the inlet and outlet apertures 62a, 62b are in the first flow path FP1.

A second one of the second plates 30 is assembled onto the bolts such that the flow surface of the second plate 30 abuts the second one of the gaskets 60. This orientation leads to the io inlet and outlet apertures 32a, 32b of the second one of the second plates 30 being in the first flow path FP1.

A second one of the holder plates 40A is assembled onto the bolts such that the holder plate 408 abuts the abutment surface of the second one of the second plates 30. A second one of the thermoelectric devices 40B is inserted into the central aperture 43 of the second one of the holder plates 40A such that the thermoelectric device 40B abuts the abutment surface of the second one of the second plates 30. The wires W of the thermoelectric device 403 are guided through the wire channels 44, and, if necessary, along the relief portion 45, of the holder plate 40A.

A first set of long bypass tubes 93 with an 0-ring 91 at either end is inserted into the substantially aligned: * each one of two diagonally opposite flow apertures 42, which are in the second flow path FP2, of the second one of the holder plates 40A; * each corresponding bypass aperture 22c, 22d of the second one of the second plates 30; * each corresponding bypass aperture 62c, 62d of the second one of the gaskets 60; * each corresponding bypass aperture 22c, 22d of the first one of the second plates 30; * each corresponding one of two diagonally opposite flow apertures 42, which are in the second flow path FPI, of the first one of the holder plates 40A; such that one of the 0-rings 91 on a first end of each long bypass tube 92 abut the abutment surface of the first one of the first plates 20. In this example the long bypass tubes 93 have an outer diameter of 25 mm.

A second one of the first plates 20 is assembled onto the bolts such that the abutment surface of the first plate 20 abuts the 0-rings 91 at a second end of the long bypass tubes 93 of the first set of bypass tubes 93. The abutment surface of the second one of the first plates 20 abuts the second one of the holder plates 40A and the second one of the thermoelectric devices 40B. This orientation leads to the inlet and outlet apertures 22a, 22b of the second one of the first plates 20 being in the second flow path FP2.

The second one of the second plates 30, the second one of the holder plates 40A, the second one of the thermoelectric devices 40B and the second one of the first plates 20 io together provide the second heat transfer module M2.

A third one of the gaskets 60 is assembled onto the bolts such that the gasket 60 abuts the flow surface of the second one of the first plates 20. The third one of the gaskets 60 is orientated such that the inlet and outlet apertures 62a, 62b are in the second flow path FP2.

A third one of the first plates 20 is assembled onto the bolts such that the flow surface of the first plate 20 abuts the third one of the gaskets 60. This orientation leads to the inlet and outlet apertures 22a, 22b of the third one of the first plates 20 being in the second flow path FP2 A third one of the holder plates 40A is assembled onto the bolts such that the holder plate 40A abuts the abutment surface of the third one of the first plates 20. A third one of the thermoelectric devices 40B is inserted into the central aperture 43 of the third one of the holder plates 40A, such that the thermoelectric device 40B abuts the abutment surface of the third one of the first plates 20. The wires W of the thermoelectric device 40B are guided through the wire channels 44, and, if necessary, along the relief portion 45, of the holder plate 40A.

A second set of long bypass tubes 93 with an 0-ring 91 at either end are inserted into the substantially aligned: * each one of two diagonally opposite flow apertures 42, which are in the first flow path FP1, of the third one of the holder plates 40A; * each corresponding bypass aperture 22c, 22d of the third one of the first plates 20; * each corresponding bypass aperture 62c, 62d of the third one of the gaskets 60; * each corresponding bypass aperture 22c, 22d of the second one of the first plates 20; * each corresponding one of two diagonally opposite flow apertures 42, which are in the first flow path FP1, of the second one of the holder plates 40A; such that one of the 0-rings 91 on a first end of each long bypass tube 93 abuts the abutment surface of the second one of the second plates 30.

A third one of the second plates 30 is assembled onto the bolts such that the abutment surface of the second plate 30 abuts the 0-rings 91 at a second end of the long bypass tubes 93 of the second set of bypass tubes 93. The abutment surface of the third one of the second plates 30 abuts the third one of the holder plates 40A and the third one of the thermoelectric devices 40B. This orientation leads to the inlet and outlet apertures 32a, 32b of the third one of the second plates 30 being in the first flow path FP1.

The third one of the first plates 20, the third one of the holder plates 40A, the third one of the thermoelectric devices 40B and the third one of the second plates 30 together provide is the first heat transfer module Ml.

A fourth one of the gaskets 60 is assembled onto the bolts such that the gasket 60 abuts the flow surface of the third one of the second plates 30. The fourth one of the gaskets 60 is orientated such that the inlet and outlet apertures 62a, 62b are in the first flow path FP1.

A second set of short bypass tubes 92 with 0-rings 91 at either end are inserted into the substantially aligned: * each bypass aperture 62c, 62d of the fourth one of the gaskets 60; * each corresponding bypass aperture 32c, 32d of the third one of the second plates 30; * each corresponding one of two diagonally opposite flow apertures 42, which are in the second flow path FP2, of the third one of the holder plates 40A; such that one of the 0-rings 91 on a first end of each short bypass tube 92 abuts the abutment surface of the third one of the first plates 20.

The tubular connectors 15 are inserted into the flow apertures 12a-d of the first end plate and are attached thereto, for example via welding or soldering. The tubular connectors 15 are substantially flush with an abutting surface of the first end plate 10 and protrude from the opposite surface of the first end plate 10.

The first end plate 10, with the tubular connectors 15 attached thereto, is assembled onto the bolts such that the abutting surface of the first end plate 10 abuts the fourth one of the gaskets 60. The 0-rings 91 of the second set of short bypass tubes 92 abut ends of the tubular connectors 15 such that the 0-rings 91 surround the internal bores of the tubular connectors 15.

The first and second end plates 10, 70 are then compressed together to seal gaskets 60 against the corresponding abutting surfaces, and to seal the 0-rings 91 against the corresponding abutting surfaces. For example, if the bolts are threaded bars then nuts are lc) applied to either end to seal the plate heat exchanger 1.

In use, a flow pipe or tube (not shown) is connected to each of the tubular connectors 15 and the wires W are connected to a power supply. A first, relatively cold fluid is circulated through one of the first flow path FP1 or the second flow path FP2, and a second, relatively hot fluid is circulated the other of the first flow path FP1 or the second flow path FP2. Which of the flow paths FP1, FP2 receive the relatively hot or cold fluid depends upon the polarity of the thermoelectric devices 40B. In this example the first flow path FP1 contains the relatively cold fluid and the second flow path FP2 contains the relatively hot fluid.

The relatively cold fluid flows along the first flow path FP1 through the first inlet aperture 12a of the first end plate 10. When the relatively cold fluid arrives at the inlet aperture 62a of the fourth one of the gaskets 60 some of the relatively cold fluid flows along the heat transfer aperture 63 to the outlet 62b of the fourth one of the gaskets 60. This relatively cold fluid flows along the flow surface of the third one of the second plates 30. The flow of the relatively cold fluid along the heat transfer aperture 63 is distributed across the width of the third one of the second plates 30 by flowing along the flow channels 34 which are close to the inlet aperture 32a of the second plate 30. The relatively cold fluid then flows along the length (the long direction of the rectangular second plate 30) in a turbulent manner due to the flow being distributed by the lateral channels 33. The relatively cold fluid then flows towards the outlet aperture 32b of the second plate 30 and the outlet aperture 62b of the gasket 60, along the flow channels 34 which are proximal the outlet aperture 32b of the second plate 30. The aforementioned turbulence increases heat transfer between the second plate 30 and the relatively cold fluid.

The remainder of the relatively cold fluid, which did not enter the heat transfer aperture 63 of the fourth one of the gaskets 60, flows through one of the long bypass tubes 93 of the second set of long bypass tubes 93 to bypass the second and third ones of the holder plates 40A, the second and third ones of the first plates 20, and the third one of the gaskets 60.

The 0-rings 91 at either end of the long bypass tube 93 prevent any leakage of the relatively cold fluid away from the aforementioned bypassing flow path.

The relatively cold fluid then passes through the inlet aperture 32a of the second one of the second plates 30 and into the inlet aperture 62a of the second one of the gaskets 60. Some to of the relatively cold fluid then flows along the heat transfer aperture 63 to the outlet 62b of the third one of the gaskets 60. This relatively cold fluid flows along the flow surfaces of the first and second ones of the second plates 30. The flow of the relatively cold fluid along the heat transfer aperture 63 is distributed across the widths of the first and second ones of the second plates 30 by flowing along the flow channels 34 which are close to the inlet apertures 32a of the second plates 30. The relatively cold fluid then flows along the length of the second plates 30 in a turbulent manner due to the flow being distributed by the lateral channels 33. The relatively cold fluid then flows towards the outlet apertures 32b of the second plates 30 and the outlet aperture 62b of the gasket 60, along the flow channels 34 which are proximal the outlet apertures 32b of the second plates 30. Again, this turbulence increases heat transfer between the second plates 30 and the relatively cold fluid.

The remainder of the relatively cold fluid, which did not enter the heat transfer aperture 63 of the second one of the gaskets 60, flows through one of the short bypass tubes 92 of the first set of short bypass tubes 92 to bypass the first one of the holder plates 40A, the first one of the first plates 20, and the first one of the gaskets 60. The 0-rings 91 at either end of the short bypass tubes 92 prevent any leakage of the relatively cold fluid away from the aforementioned bypassing flow path. The relatively cold fluid flow is stopped by the second end plate 70.

Relatively cold fluid exits the second one of the gaskets 60 through the outlet aperture 62b thereof and flows one way into the other one of the short bypass tubes 92 of the first set of short bypass tubes 92 to bypass the first one of the holder plates 40A, the first one of the first plates 20, and the first one of the gaskets 60. The 0-rings 91 at either end of the long bypass tubes 93 prevent any leakage of the relatively cold fluid away from the aforementioned bypassing flow path. The relatively cold fluid flow is stopped by the second end plate 70. Relatively cold fluid exits the second one of the gaskets 60 through the outlet aperture 62b thereof and flows in the opposite direction into the other bypass tube 93 of the second set of bypass tubes 93 to bypass the third one of the gaskets 60, the second and third ones of the first plates 20 and the second and third ones of the holder plates 40A.

Again, the 0-rings 91 at either end of the long bypass tube 93 prevent any leakage of the relatively cold fluid away from the aforementioned bypassing flow path. This relatively cold fluid then joins with relatively cold fluid which exits the heat transfer aperture 63 of the fourth one of the gaskets 60 through the outlet aperture 63b. The joined relatively cold fluid then enters into the tubular connector 15 in the first outlet aperture 12b of the first end plate 10 to to exit the plate heat exchanger 1.

The relatively hot fluid flows along the second flow path FP2 through the second inlet aperture 12c of the first end plate 10. The relatively hot fluid enters one of the short bypass tubes 92 of the second set of bypass tubes to bypass the fourth one of the gaskets 60, the third one of the second plates 30 and the third one of the holder plates 40A. The 0-rings 91 at either end of the short bypass tube 92 prevent any leakage of the relatively hot fluid away from the aforementioned bypassing flow path.

The relatively hot fluid flows through the inlet aperture 22a of the third one of the first plates 20 and arrives at the inlet aperture 62 of the third one of the gaskets 60. Some of the relatively hot fluid then flows along the heat transfer aperture 63 to the outlet aperture 62b of the third one of the gaskets 60. This relatively hot fluid flows along the flow surfaces of the second and third ones of the first plates 20. The flow of the relatively hot fluid along the heat transfer aperture 63 is distributed across the width of the second and third ones of the first plates 20 by flowing along the flow channels 24 which are close to the inlet apertures 22a of the first plates 20. The relatively hot fluid then flows along the length direction (the long direction of the rectangular first plates 20) in a turbulent manner due to the flow being distributed by the lateral channels 23. The relatively hot fluid then flows towards the outlet apertures 22b of the first plates 20 and the outlet aperture 62b of the gasket 60, along the flow channels 24 which are proximal the outlet apertures 22b of the first plates 20. This turbulence increases heat transfer between the first plates 20 and the relatively hot fluid.

The remainder of the relatively hot fluid, which did not enter the heat transfer aperture 63 of the third one of the gaskets 60, flows through one of the long bypass tubes 93 of the first set of long bypass tubes 93 to bypass the first and second ones of the holder plates 40A, the first and second ones of the second plates 30 and the second one of the gaskets 60. The 0-rings 91 at either end of the long bypass tube 93 prevent any leakage of the relatively hot fluid away from the aforementioned bypassing flow path.

The relatively hot fluid then passes through the inlet aperture 22a of the first one of the first plates 20 and into the inlet aperture 62a of the first one of the gaskets 60. The relatively hot fluid is prevented from travelling further by the second end plate 70. The relatively hot fluid therefore flows along the heat transfer aperture 63 to the outlet aperture 62b of the first one of the gaskets 60. This relatively hot fluid flows along the flow surface of the first one of the o first plates 20. The flow of the relatively hot fluid along the heat transfer temperature 63 is distributed across the width of the first one of the first plates 20 by flowing along the flow channels 34 which are close to the inlet aperture 22a of the first plate 20. The relatively hot fluid then flows along the length of the first plate 20 in a turbulent manner due to the flow being distributed by the lateral channels 23. The relatively hot fluid then flows towards the outlet aperture 22b of the first plates 20 and the outlet aperture 62b of the gasket 60, along the flow channels 24 which are proximal the outlet aperture 22b of the first plate 20. Again, this turbulence increases heat transfer between the first plate 30 and the relatively hot fluid.

Relatively hot fluid exits the first one of the gaskets 60 through the outlet aperture 62b thereof, and flows into the other bypass tube 93 of the first set of long bypass tubes 93 to bypass the second one of the gaskets 60, the first and second ones of the second plates 30 and the first and second ones of the holder plates 40A. Again, the 0-rings 91 at either end of the long bypass tube 93 prevent any leakage of the relatively cold fluid away from the aforementioned bypassing flow path. This relatively hot fluid then joins with relatively hot fluid which exits the heat transfer aperture 63 of the third one of the gaskets 60 through the outlet aperture 63b. The joined relatively hot fluid then enters into the other short bypass tube 92 of the second set of short bypass tubes 92 and bypasses the third one of the holder plates 40A, the third one of the second plates 30 and the fourth one of the gaskets 60. The relatively hot fluid then enters the tubular connector 15 in the second outlet aperture 12b of the first end plate 10 to exit the plate heat exchanger 1.

A schematic of the first and second flow paths FP1, FP2 through the heat exchanger 1, is shown in Figure 7. In Figure 7, the first flow path FP1 is shown with dashed arrows and the second flow path FP2 is shown with solid arrows.

The polarity of the three thermoelectric devices 40B is such that the major surface of the first one of the thermoelectric devices 40B, which is part of the first heat exchange module Ml, which faces the third one of the second plates 30, is colder than the major surface which faces the third one of the first plates 20. Therefore, when the relatively cold fluid flows over the flow surface of the third one of the second plates 30, heat is transferred from the relatively cold fluid, through the third one of the second plates 30, to heat the relatively cold major surface of the thermoelectric device 40B. In other words, the thermoelectric device 40B cools the relatively cold fluid. Heat is then transferred from the relatively hot major surface of the thermoelectric device 40B, through the third one of the first plates 20, to the io relatively hot fluid.

Similarly, in the second heat exchange module M2, heat is transferred from the relatively cold fluid flowing over the flow surface of the second one of the second plates 30, to be transferred to the relatively cold major surface of the second one of the thermoelectric devices 40B. Heat is transferred form the relatively hot major surface of the second one of the thermoelectric devices 40B, through the second one of the first plates 20, to the relatively hot fluid flowing over the flow surface thereof.

Similarly, heat is transferred from the relatively cold fluid flowing over the flow surface of the first one of the second plates 30, to be transferred to the relatively cold major surface of the first one of the thermoelectric devices 40B. Heat is transferred from the relatively hot major surface of the first one of the thermoelectric devices 40B, through the first one of the first plates 20, to the relatively hot fluid flowing over the flow surface thereof.

In this way, relatively cold and relatively hot fluids flow in a parallel manner through the plate heat exchanger, and heat is transferred from the relatively cold fluid to the relatively hot fluid. This allows the plate heat exchanger to be used in various modes of operation, as described here: Heating system By providing electrical power to the thermoelectric devices 40A, the plate heat exchanger 1 is usable as a heat pump, for example as a thermo-electric ground source heat pump (TGSHP) or a thermo-electric air source heat pump (TASHP). The relatively cold fluid circulates through a heat source, for example through underground tubing, which increases the temperature of the relatively cold fluid. This increase in temperature is then transferred to the thermoelectric devices 40A in the plate heat exchanger 1, and then to the relatively hot fluid. The relatively hot fluid is then used in another heat exchanger to provide heat energy, for example to heat air which is circulated into a building or to heat water for a hot water system. This reduces the temperature of the relatively hot fluid, to then have the temperature increased again in the plate heat exchanger 1.

Cooling system By providing electrical power to the thermoelasfic devices 40A, the plate heat exchanger 1 is usable in cooling applications. The relatively hot fluid is circulated through a heat sink, or io another heat exchanger, which reduces the temperature of the relatively hot fluid. The relatively cold fluid is circulated in a cooling system, for example in an air conditioning system, which increases the temperature of the relatively cold fluid. This additional heat energy in the relatively cold fluid is then transferred to the thermoelectric devices 40B in the plate heat exchanger 1, to be transferred to the relatively hot fluid, which, again, disperses the heat. The cooling system has another heat exchanger to cool a fluid for the cooling system, for example to cool air for air conditioning.

Energy recovery When the plate heat exchanger 1 is used in an energy recovery system, heated fluid, for example solar heated water, is circulated over the relatively hot side of the thermoelectric devices 40B to transfer heat thereto. The relatively cold fluid is used to cool the relatively cold side of each thermoelectric module 40B. Heat transferred to the relatively cold fluid is then dissipated in a heat sink. This produces a temperature differential across the thermoelectric device 40B, and thus generates electricity therein. This electricity may then be used, or stored, by another suitable device.

Referring now to Figure 8, an alternative design of a holder plate 140A is shown. The holder plate 140A of this example is the same as the holder plate 40A described with reference to Figure 5A (like features are provided with the same reference numerals with a preceding '1'), with the exception that the holder plate 140A of this example is designed to hold 12 smaller thermoelectric devices (not shown), each thermoelectric device being insertable into a device aperture 143. Each device aperture 143 has chamfered edges 146, which aid in maintaining the correct position of each thermoelectric device in the corresponding device aperture 143. The wire channels 144 extend across a width of the holder plate 140A such that wires from each thermoelectric device can be guided along one of the wire channels 144. The wire channels 144 have spaced cover portions 144a extending across the width thereof, which hold the wires in the wire channels 144. The wire channels 144 have side apertures (not shown) connected to each device aperture 143. In use, one of the thermoelectric devices is inserted into one of the device apertures 143, with the wires are guided through the side aperture of the respective wire channel 144 and guided under the cover portions 144a along the respective wire channel 144.

In this example the holder plate 140A is manufactured from Polylacfic acid (PLA) plastic, using an additive manufacture, or 3D printing, technique. However, it will be appreciated io that any suitable material, and any suitable manufacturing method, may be used.

In this example the thermoelectric devices are TEC1-12710 thermoelectric modules. However, it will be appreciated that other thermoelectric modules are suitable.

In the assembly of the plate heat exchanger the holder plate 140A and thermoelectric devices of this example directly replace the holder plates 40A and thermoelectric devices 40B of the previous examples. The operation of the plate heat exchanger is as described previously, where relatively cold and relative hot fluid flows over first and second plates 20, 30, respectively, which abut either side of the thermoelectric devices, transferring heat to and from, respectively, the thermoelectric devices.

In further embodiment the thermoelectric devices comprise positive and negative semiconductors sandwiched between the first and second plates 20, 30. The semiconductors are either in direct contact with the first and second plates 20, 30, or thin conductive sheets are located between the semiconductors and the respective first and second plates 20, 30.

Referring now to Figure 9 there is shown an alternative embodiment of the plate heat exchanger 21. In this example the same reference numerals are provided for similar components to those described with reference to Figures 1 to 7, with a preceding '2'.

In this embodiment the plate heat exchanger 21 is a counter-flow heat exchanger, in that the flow paths FP21, FP22 flow in substantially opposite directions through the gaskets 260. More specifically, where in the plate heat exchanger 1 of the previous embodiment, the flow paths FP1, FP2 extends from the top of the gaskets 60 to the bottom of the gaskets 60, in the plate heat exchanger 21 of this embodiment the first flow path FP21 flows from the top of the gaskets 260 to the bottom of the gaskets 260, and the second flow path FP22 flows from the bottom of the gaskets 260 to the top of the gaskets 260. Otherwise, the first flow path FP21 may flow from the bottom of the gaskets 260 to the top of the gaskets 260, and the second flow path FP22 may flow from the top of the gaskets 260 to the bottom of the gaskets 260 As with the previous embodiment, the number of heat exchange modules may vary depending upon the heat exchange requirements.

Referring now to Figure 10, there is shown an alternative embodiment of the counter-flow plate heat exchanger 21 of Figure 9. Similar features between this embodiment and the previous embodiment are denoted with a '3' instead of a '2'. In this plate heat exchanger 31 the inlets to the first and second flow paths FP31, FP32 are through the first end plate 310 and the outlets are through the second end plate 370. There are also more heat exchange modules illustrated in this embodiment, but as stated previously, the number of heat exchange modules may vary depending upon the specific heat exchange requirements.

As with the embodiment of Figure 9, fluid flow through the gaskets 360 of this embodiment are in opposite directions to one another, in each of the two flow paths FP31, FP32. More specifically, the first flow path FP31 flows from the top of the gaskets 360 to the bottom of the gaskets 360, and the second flow path FP32 flows from the bottom of the gaskets 360 to the top of the gaskets 360. Otherwise, the first flow path FP31 may flow from the bottom of the gaskets 360 to the top of the gaskets 360, and the second flow path FP32 may flow from the top of the gaskets 360 to the bottom of the gaskets 360 Referring now to Figure 11 there is shown an alternative embodiment of the plate heat exchanger 41, In this example the same reference numerals are provided for similar components to those described with reference to Figures 1 to 7, with a preceding '4'.

The plate heat exchanger 41 of this example is a multi-stage plate heat exchanger 41. This plate heat exchanger 41 differs from the previously described plate heat exchanger 1 in that the second end plate 470 has an outlet aperture for the first flow path FP41, and an inlet aperture for the second flow path FP42, and the first end plate 410 only has an inlet aperture for the first flow path FP41 and an outlet aperture for the second flow path FP42.

This plate heat exchanger 41 also differs from the previously described plate heat exchanger 1 in that there are more heat exchange modules. However, as explained previously, any number of heat exchange module may be provided, and the Figures merely provide an arbitrary illustration of the number of modules The plate heat exchanger 41 of this example differs from the previous plate heat exchanger 1 in that the first flow path FP21 enters the plate heat exchanger 41 through the first end plate 410 and exits through the second end plate 470. Also, the second flow path FP42 enters through the second end plate 470 and exits through the first end plate 410. The io gaskets 460 and first and second plates 420, 430 are arranged such that fluid flows in a first direction along two consecutive gaskets 460 which are in the first flow path FP41, and fluid flows in a second direction along the next two consecutive gaskets 460 which are in the first flow path FP41, the second direction being opposite to the first direction. The gaskets 460 and first and second plates 420, 430 are arranged such that fluid flows in a third direction along two consecutive gaskets 460 which are in the second flow path FP42, and fluid flows in a fourth direction along the next two consecutive gaskets 460 which are in the second flow path FP42, the third direction being opposite to the fourth direction. This provides a multi-stage flow path through the plate heat exchanger 41.

Another embodiment of the invention is a counter-flow, multi-stage heat exchanger, which is the same as that shown in Figure 11 except that the second flow paths are in substantially the opposite direction through the gaskets than the first flow paths. More specifically, in the first flow path fluid flows from the top of the gaskets to the bottom of the gaskets, and the second flow path flows from the bottom of the gaskets to the top of the gaskets.

As exemplified by the different stacking configurations shown in Figures 6 and in Figure 9, it will be appreciated by those skilled in the art that the plates of the plate heat exchanger may be stacked in numerous ways to achieve different flow path configurations. For example, the flow direction through two consecutive gaskets in the same flow path in any of the configurations, may be in substantially the same or substantially opposite directions.

Also, any number of heat transfer modules may be provided. Furthermore, the stacked plates may not be rectangular in shape, but can be of any in-plane shape.

With all examples of the plate heat exchanger, the first and second plate, holder plate, thermoelectric devices and gaskets, are substantially the same as those described in the first example. The assembly of the plate heat exchanger is also similar, using fixing means to secure the stacked plates together, and long and short bypass tubes and 0-rings to provide the sealed fluid flow.

It will be appreciated by those skilled in the art that several variations to the aforementioned embodiments are envisaged without departing from the scope of the invention. For example, the plate heat exchanger might be of a different in-plane shape, for example a square. Furthermore, it will be appreciated that more heat exchange modules may be provided, with gaskets 60 provided therebetween. By way of another example, the first and io second plates may be provided without either of both of the flow channels and lateral channels. By way of another example, further heat exchange modules may be provided, in the same fashion as that described above. For example, a fourth hat exchange module may be provided which has a first plate which faces the first plate 20 of the third heat exchange module M3, such that the first plate of the fourth heat exchange module abuts the first gasket 60. It will be appreciated that any number of heat exchange modules may be provided. It will therefore be appreciated that, when referring to any number of heat exchange modules, another heat exchange module at the end of those of reference may be referred to as a "further module". Otherwise, end plates may be referred to as "further modules".

It will also be appreciated by those skilled in the art that any number of combinations of the aforementioned features and/or those shown in the appended drawings provide clear advantages over the prior art and are therefore within the scope of the invention described herein.

Example

In the following example the plate heat exchanger was provided according to Figure 6, but with the thermoelectric module of Figure 8. The thermoelectric devices 140B were each 30 powered with 3V DC.

Figure 12 shows the measured coefficient of performance (COP) with time for the plate heat exchanger, and Figure 13 shows the difference in temperature (Delta T) between the relatively hot side and the relatively cold side of the thermoelectric devices 140B. As can be seen, the plate heat exchanger has a COP of between 1.3 and 1.4 when the temperature difference is between 11°C and 13°C.

This data shows that a positive COP is achievable with thermoelectric materials. The data also shows a drop in COP as the Delta T across the plates increase, and this trend is also evident in conventional heat pumps.

Claims

CLAIMS1 A plate heat exchanger, the plate heat exchanger comprising plural heat exchange modules, each heat exchange module comprising a first plate and a second plate and a thermoelectric device located therebetween, the first plate providing a relatively hot heat exchange surface and the second plate providing a relatively cold heat exchange surface, and each heat exchange module having a first and second flow path therethrough, the first plate of a first of said plural heat exchange modules facing a first plate of a second of said plural heat exchange modules, the second io plate of said second of said plural heat exchange modules facing a plate of a further module.
2 A plate heat exchanger according to claim 1, wherein the further module is a third of said plural heat exchange modules, and the plate of the further module is the second plate of said third of said plural heat exchange modules which faces the second plate of said second of said plural heat exchange modules.
3 A plate heat exchanger according to claim 1 or claim 2, wherein the first flow path comprises first and second fluid flow paths which are fluidly connected, and the second flow path comprises third and fourth fluid flow paths which are fluidly connected.
4 A plate heat exchanger according to any preceding claim, further comprising plural gaskets, a first of said plural gaskets being located between the facing first plates of said first and second heat exchange modules and a second of said gaskets being located between the facing second plates of said second and third heat exchange modules, the gaskets providing fluid communication in the first flow path of successive heat exchange modules and fluid communication in the second flow path of successive heat exchange modules.
A plate heat exchanger according to claim 4, wherein each gasket of said plural gaskets comprises two bypass apertures, an inlet aperture, and an outlet aperture, wherein the first gasket is orientated such that the bypass apertures thereof are in the first flow path and the heat transfer aperture is in the second flow path, and wherein the second gasket is orientated such that the bypass apertures thereof are in the second flow path and the heat transfer aperture is in the first flow path.
6 A plate heat exchanger according to claim 5, wherein each gasket has a substantially rectangular in-plane shape, and each bypass aperture of each gasket is located proximal a respective first and second corner of the gasket, each inlet aperture of each gasket is located proximal a third corner, and each outlet aperture of each gasket is located proximal a fourth corner, wherein the first and second corners are diagonally opposite to one another, and the third and fourth corners are io diagonally opposite to one another.
7 A plate heat exchanger according to any preceding claim, wherein each first plate of each of said plural heat exchange modules has two bypass apertures, an inlet aperture, and an outlet aperture, the bypass apertures being in fluid communication with the first flow path and the inlet and outlet apertures being in fluid communication with the second flow path, and wherein each second plate of each of said plural heat exchange modules has two bypass apertures, an inlet aperture, and an outlet aperture, the bypass apertures being in fluid communication with the second flow path and the inlet and outlet apertures being in fluid communication with the first flow path.
8 A plate heat exchanger according to claim 7, wherein the bypass apertures of the first plates of the first and second heat transfer modules are substantially aligned with the or a bypass apertures of the first gasket, the inlet and outlet apertures of the first plates of the first and second heat transfer modules are substantially aligned with the or a inlet and outlet apertures, respectively, of the first gasket, and wherein the bypass apertures of the second plates of the second and third heat transfer modules are substantially aligned with the or a bypass apertures of the second gasket, and the inlet and outlet apertures of the second plates of the second and third heat transfer modules are substantially aligned with the or a inlet and outlet apertures, respectively, of the second gasket.
9 A plate heat exchanger according to either claim 7 or claim 8, wherein each one of the first plates and the second plates has a substantially rectangular in-plane shape of substantially the same in-plane size, wherein each one of the bypass apertures of each first and second plate is located proximal a respective first and second corner of the plate, each inlet aperture of each first and second plate is located proximal a third corner, and each outlet aperture of each first and second plate is located proximal a fourth corner, wherein the first and second corners are diagonally opposite to one another, and the third and fourth corners are diagonally opposite to one another.
A plate heat exchanger according to any of claims 7 to 9, further comprising a plurality of bypass tubes, wherein a first and second of said bypass tubes extend io through respective ones of the bypass apertures of the first plates of the first and second heat exchange modules, the first and second bypass tubes abutting an abutment surface of, and surrounding respective inlet and outlet apertures of, the second plates of the first and second heat exchange modules, and wherein a third and fourth of said bypass tubes extend through respective ones of the bypass apertures of the second plates of the second and third heat exchange modules, the third and fourth bypass tubes abutting an abutment surface of, and surrounding respective inlet and outlet apertures of, the first plates of the second and third heat exchange modules.
11. A plate heat exchanger according to claim 10, wherein the abutment of the bypass tubes against abutment surfaces of the first and second plates provides a sealed abutment.
12. A plate heat exchanger according to any preceding claim, further comprising one or more holder plates, a holder plate being located in one or more of the heat exchange modules, each holder plate being configured to hold the respective thermoelectric device between the first and second plates of the respective heat exchange module.
13. A plate heat exchanger according to claim 12, wherein each holder plate comprises four bypass apertures, two of the bypass apertures being in the first flows path and the other two of the bypass apertures being in the second flow path.
14. A plate heat exchanger according to claim 13, wherein the first and second bypass tubes pass through first and second bypass apertures of the holder plates of the first and second heat exchange modules, and wherein the third and fourth bypass tubes pass through third and fourth bypass apertures of the holder plates of the second and third heat exchange modules.
15. A plate heat exchanger according to any preceding claim, further comprising a first end plate and a second end plate wherein the first end plate comprises a first inlet aperture and a first outlet aperture in the first flow path, and a second inlet aperture and a second outlet aperture in the second flow path.
16 A plate heat exchanger according to claim 15, further comprising a third gasket to located between the first end plate and the second plate of the first heat transfer module, and wherein the second cold plate is the second plate of a third of said plural heat exchange modules, the plate heat exchanger further comprising a fourth gasket located between the second end plate and the first plate of the third heat transfer module, the third gasket providing fluid communication between first flow path and the fourth gasket providing fluid communication between the second flow path.
17 A plate heat exchanger according to claim 16, further comprising a plurality of end bypass tubes, wherein a first and second of the end bypass tubes extends through respective bypass apertures of the first gasket and of the second plate of the first heat exchange module, and abut an abutment surface of, and surround the respective inlet and outlet apertures of, the first end plate and the first plate of the first heat exchange module, and wherein a third and fourth of the end bypass tubes extend through respective bypass apertures of the fourth gasket and the first plate of the third heat exchange module, and abut an abutment surface of the second end plate, and abut an abutment surface of, and surround respective inlet and outlet apertures of, the second plate of the third heat exchange module.
18. A plate heat exchanger according to claim 17, wherein the abutment of the end bypass tubes against first and second plates provides a sealed abutment.
19. A plate heat exchanger according to any of claim 15 to 18, further comprising fixing means which urge the first and second plates towards one another.
A plate heat exchanger according to any preceding claim, wherein each of the first and second plates of each heat exchange module have a flow surface configured to receive fluid flow thereover, the flow surface comprising a plurality of lateral channels, each lateral channel being orientated at an oblique angle relative to a flow direction of the fluid over the flow surface, in use.
21. A plate heat exchanger according to any preceding claim, further comprising a plurality of thermoelectric devices located between first and second plates of each heat exchange module.
22. A heat exchange system comprising a plate heat exchanger according to any preceding claim, and a controller, the controller being configured to independently control the electrical power which is provided to each thermoelectric device.
23. A heat pump comprising a plate heat exchanger according to any of claims 1 to 21 or a heat exchange system according to claim 22.
24 A method of exchanging heat between a first fluid and a second fluid, the method comprising pumping the first fluid along a first flow path of a plate heat exchanger, by passing the first fluid through a plurality of heat exchange modules, the method further comprising pumping the second fluid along a second flow path of the plate heat exchanger, by passing the second fluid through the plurality of heat exchange modules, the second fluid flowing between facing first plates of first and second heat exchange modules of said plurality of heat exchange modules, the first fluid flowing between the second plate of the second of said plurality of heat exchange modules and a plate of a further module, wherein one of the thermoelectric devices is located between the first and second plates of each heat exchange module such that heat is transferred between the first fluid and each thermoelectric device, through the respective one of the second plates, and heat is transferred between the second fluid and each thermoelectric device, through the respective one of the first plates.
25. A method according to claim 24, further comprising providing electrical power to the thermoelectric devices such that each thermoelectric device has a relatively cold surface and a relatively hot surface, wherein heat is transferred from the first fluid to the relatively cold surface of each thermoelectric device, and wherein heat is transferred from the relatively hot surface of each thermoelectric device to the second fluid.