THERMOELECTRIC CONVERSION UNIT

A thermoelectric conversion unit includes a pair of low-temperature fluid flow path sections arranged to face each other, a high-temperature fluid flow path section arranged between the pair of low-temperature fluid flow path sections, a pair of thermoelectric modules each arranged between the high-temperature fluid flow path section and one of the pair of low-temperature fluid flow path sections in a one-to-one relation, and flat heat transfer plates arranged in the high-temperature fluid flow path section to face each other. Each of the flat heat transfer plates includes an opening and a baffle projecting from a peripheral edge of the opening and baffling a high-temperature fluid passing through the opening to flow in a direction toward one of the pair of thermoelectric modules or the other.

BACKGROUND

1. Technical Field

The present disclosure relates to a thermoelectric conversion unit converting thermal energy to electrical energy.

2. Description of the Related Art

There is known a thermoelectric conversion unit converting thermal energy to electrical energy (see, for example, Japanese Unexamined Patent Application Publication No. 2005-83251). The related-art thermoelectric conversion unit includes a low-temperature fluid flow path section through which a low-temperature fluid flows, a high-temperature fluid flow path section through which a high-temperature fluid flows, and a thermoelectric module disposed between the low-temperature fluid flow path section and the high-temperature fluid flow path section. The thermoelectric module converts thermal energy, given as a temperature difference between the high-temperature fluid flowing through the high-temperature fluid flow path section and the low-temperature fluid flowing through the low-temperature fluid flow path section, to electrical energy by utilizing the Seebeck effect.

The above-described related-art thermoelectric conversion unit further includes corrugated plate fins that are disposed in the high-temperature fluid flow path section and that are stacked in a predetermined direction. Heat of the high-temperature fluid flowing through the high-temperature fluid flow path section is transferred to each of a pair of thermoelectric modules through the plate fins.

SUMMARY

In the related-art thermoelectric conversion unit described above, the high-temperature fluid flow path section is partitioned by the plate fins into flow paths arrayed in the predetermined direction. A flow velocity of the high-temperature fluid flowing through one of the flow paths, the one being close to the thermoelectric module, is lower than that of the high-temperature fluid flowing through the flow path farther away from the thermoelectric module. Therefore, the efficiency of heat transfer to the thermoelectric module from the high-temperature fluid flowing through the flow path away from the thermoelectric module is reduced.

Because the heat of the high-temperature fluid flowing through the flow path away from the thermoelectric module is difficult to transfer to the thermoelectric module, a contribution rate of that heat to power generation through the thermoelectric module is reduced. As a result, the efficiency of heat transfer to the thermoelectric module from the high-temperature fluid flowing through the flow path away from the thermoelectric module is reduced.

One non-limiting and exemplary embodiment provides a thermoelectric conversion unit capable of increasing the efficiency of heat transfer from a second fluid (high-temperature fluid) to a thermoelectric module.

In one general aspect, the techniques disclosed here feature a thermoelectric conversion unit generating electricity based on a temperature difference between a first fluid and a second fluid at higher temperature than the first fluid, the thermoelectric conversion unit including a pair of first fluid flow path sections through each of which the first fluid flows, the first fluid flow path sections being arranged to face each other, a second fluid flow path section through which the second fluid flows, the second fluid flow path section being arranged between the pair of first fluid flow path sections, a pair of thermoelectric modules each arranged between the second fluid flow path section and one of the pair of first fluid flow path sections in a one-to-one relation, the thermoelectric modules converting thermal energy given by the temperature difference between the first fluid and the second fluid to electrical energy, and heat transfer plates arranged in the second fluid flow path section to face each other along a predetermined direction from one of the pair of thermoelectric modules toward the other, wherein at least one of the heat transfer plates includes an opening and a baffle projecting from a peripheral edge of the opening and baffling the second fluid passing through the opening to flow in a direction toward the one of the pair of thermoelectric modules or the other.

With the thermoelectric conversion unit according to the one general aspect of the present disclosure, the efficiency of heat transfer from the second fluid to the thermoelectric module can be increased.

It should be noted that the above-described generic or specific embodiment may be implemented in the form of a device or a method or may be implemented in a selective combination of a device and a method.

DETAILED DESCRIPTIONS

A thermoelectric conversion unit according to one aspect of the present disclosure generates electricity based on a temperature difference between a first fluid and a second fluid at higher temperature than the first fluid, the thermoelectric conversion unit including a pair of first fluid flow path sections through each of which the first fluid flows, the first fluid flow path sections being arranged to face each other, a second fluid flow path section through which the second fluid flows, the second fluid flow path section being arranged between the pair of first fluid flow path sections, a pair of thermoelectric modules each arranged between the second fluid flow path section and one of the pair of first fluid flow path sections in a one-to-one relation, the thermoelectric modules converting thermal energy given by the temperature difference between the first fluid and the second fluid to electrical energy, and heat transfer plates arranged in the second fluid flow path section to face each other along a predetermined direction from one of the pair of thermoelectric modules toward the other, wherein at least one of the heat transfer plates includes an opening and a baffle projecting from a peripheral edge of the opening and baffling the second fluid passing through the opening to flow in a direction toward the one of the pair of thermoelectric modules or the other.

With the feature described above, part of the second fluid flowing through a region of the second fluid flow path section away from the thermoelectric module is baffled by the baffle of the heat transfer plate to flow in a direction toward the thermoelectric module, whereby the part of the second fluid flows into a region of the second fluid flow path section closer to the thermoelectric module. Accordingly, a flow velocity of the second fluid flowing through the region of the second fluid flow path section closer to the thermoelectric module can be increased, and heat of the second fluid flowing through the region of the second fluid flow path section away from the thermoelectric module can be utilized to contribute to the power generation by the thermoelectric module. As a result, the efficiency of heat transfer from the second fluid to the thermoelectric module can be increased.

Plural sets each including the heat transfer plates and the pair of thermoelectric modules may be stacked in the predetermined direction.

With the feature described above, the thermoelectric conversion unit can be made compact.

The opening and the baffle: may be formed respectively as plural openings and plural baffles, the openings may include a first opening arranged in an upstream region of the second fluid flow path section, a second opening arranged in a midstream region of the second fluid flow path section on a downstream side of the upstream region, and a third opening arranged in a downstream region of the second fluid flow path section on a downstream side of the midstream region, and the baffles may include a first baffle projecting from a peripheral edge of the first opening and baffling the second fluid passing through the first opening to flow in the direction toward the one of the pair of thermoelectric modules, a second baffle projecting from a peripheral edge of the second opening and baffling the second fluid passing through the second opening to flow in the direction toward the other of the pair of thermoelectric modules, and a third baffle projecting from a peripheral edge of the third opening and baffling the second fluid passing through the third opening to flow in the direction toward the one of the pair of thermoelectric modules.

With the feature described above, since a baffle direction for the second fluid baffled by the second baffle disposed in the midstream region of the second fluid flow path section is revered to that of the second fluid baffled by the first baffle disposed in the upstream region of the second fluid flow path section, a flow velocity distribution and a temperature distribution of the second fluid in the midstream region of the second fluid flow path section can be made uniform once. As a result, it is possible to maintain the effect of baffling the second fluid by the third baffle disposed in the downstream region of the second fluid flow path section and to increase the efficiency of heat transfer from the second fluid flowing in the downstream region of the second fluid flow path section to the thermoelectric module.

The baffle may project from the peripheral edge of the opening in a direction opposite to a direction in which the second fluid passes through the opening.

With the feature described above, the second fluid passing through the opening can be efficiently baffled by the baffle.

The heat transfer plates may be composed of flat heat transfer plates and corrugated heat transfer plates that are alternately stacked.

With the feature described above, the heat of the second fluid can be efficiently transferred to the thermoelectric module through the flat heat transfer plates and the corrugated heat transfer plates.

A pair of adjacent ones of the heat transfer plates may be connected to each other with a rod-shaped fin interposed therebetween.

With the feature described above, the heat of the second fluid can be efficiently transferred to the thermoelectric module through the pair of heat transfer plates and the rod-shaped fin therebetween.

An interior and a surface of each of the heat transfer plates may be made of different materials.

The interior of each of the heat transfer plates may be made of copper, a copper alloy, aluminum, an aluminum alloy, stainless, or ceramic.

With the feature described above, the interior of each heat transfer plate can be made of a material with high thermal conductivity.

The surface of each of the heat transfer plates may be made of nickel, a nickel alloy, chromium, or a chromium alloy.

With the feature described above, the surface of each heat transfer plate can be coated with a material with high corrosion resistance. As a result, the interior of each heat transfer plate can be suppressed from being oxidized and corroded in the atmosphere at high temperature.

Those generic or specific embodiments may be implemented in the form of a device or a method or may be implemented in a selective combination of a device and a method.

The embodiments will be described below with reference to the drawings.

It is to be noted that the following embodiments represent generic or specific examples. Numerical values, shapes, materials, constituent elements, layout positions and connection forms of the constituent elements, steps, order of the steps, etc., which are described in the following embodiments, are merely illustrative, and they are not purported to limit the scope of Claims. Ones of the constituent elements in the following embodiments, those ones being not stated in independent claims representing the most significant concept, are explained as optional constituent elements. The drawings are not always exactly drawn in a strict sense. In the drawings, substantially the same constituent elements are denoted by the same reference sings, and duplicate description of those constituent elements is omitted or simplified in some cases.

1-1. Overall Structure of Thermoelectric Conversion Unit

First, an overall structure of a thermoelectric conversion unit2according to Embodiment 1 will be described below with reference toFIGS.1to4.FIG.1is a perspective view of the thermoelectric conversion unit2according to Embodiment 1.FIG.2is an exploded perspective view of the thermoelectric conversion unit2according to Embodiment 1.FIG.3is a sectional view, taken along a line III-III inFIG.2, of principal part of the thermoelectric conversion unit2according to Embodiment 1.FIG.4is a sectional view, taken along a line IV-IV inFIG.3, of principal part of the thermoelectric conversion unit2according to Embodiment 1. InFIGS.1to4, a front-rear direction of the thermoelectric conversion unit2is referred to as an X-axis direction, a left-right direction of the thermoelectric conversion unit2is referred to as a Y-axis direction, and an up-down direction of the thermoelectric conversion unit2is referred to as a Z-axis direction.

The thermoelectric conversion unit2is a thermoelectric conversion unit for generating electricity by utilizing thermal energy of, for example, exhaust gas discharged from an on-vehicle engine.

As illustrated inFIGS.1to4, the thermoelectric conversion unit2includes a pair of low-temperature fluid flow path sections4and6(an example of a pair of first fluid flow path sections), a pair of side restriction member8and10, a high-temperature fluid flow path section12(an example of a second fluid flow path section), a high-temperature fluid introduction member14, a high-temperature fluid discharge member16, a pair of thermoelectric modules18and20, and a fin structure22.

As illustrated inFIGS.2to4, the pair of low-temperature fluid flow path sections4and6are arranged to face each other with a spacing therebetween in the up-down direction (Z-axis direction).

The low-temperature fluid flow path section4on an upper side is composed of a flat and hollow rectangular parallelepiped housing24, a tubular low-temperature fluid introduction member26, and a tubular low-temperature fluid discharge member28, those members26and28projecting to the outside from a side surface of the housing24. As illustrated inFIG.3, a low-temperature fluid flow path30through which a low-temperature fluid (an example of a first fluid) flows is formed inside the housing24. The low-temperature fluid is, for example, cold water or cold air at lower temperature than a high-temperature fluid (described later). The low-temperature fluid introduction member26and the low-temperature fluid discharge member28are arranged with a spacing therebetween in the front-rear direction (X-axis direction) and are in communication with the low-temperature fluid flow path30inside the housing24. The low-temperature fluid flows into the low-temperature fluid flow path30inside the housing24through the low-temperature fluid introduction member26and is discharged to the outside through the low-temperature fluid discharge member28after flowing through the low-temperature fluid flow path30.

The low-temperature fluid flow path section6on a lower side is composed of a flat and hollow rectangular parallelepiped housing31, a tubular low-temperature fluid introduction member33, and a tubular low-temperature fluid discharge member35, those members33and35projecting to the outside from a side surface of the housing31. As illustrated inFIG.3, a low-temperature fluid flow path37through which the low-temperature fluid flows is formed inside the housing31. The low-temperature fluid introduction member33and the low-temperature fluid discharge member35are arranged with a spacing therebetween in the front-rear direction and are in communication with the low-temperature fluid flow path37inside the housing31. The low-temperature fluid flows into the low-temperature fluid flow path37inside the housing31through the low-temperature fluid introduction member33and is discharged to the outside through the low-temperature fluid discharge member35after flowing through the low-temperature fluid flow path37.

As illustrated inFIGS.1and2, the pair of side restriction members8and10are arranged to face each other with a spacing therebetween in the left-right direction (Y-axis direction). In more detail, the pair of side restriction members8and10are arranged to cover the high-temperature fluid flow path section12(described later) arranged between the pair of low-temperature fluid flow path sections4and6from sides in the left-right direction. The pair of side restriction members8and10are each formed in a rectangular flat plate shape.

As illustrated inFIGS.2to4, the high-temperature fluid flow path section12is arranged between the pair of low-temperature fluid flow path sections4and6. More specifically, the high-temperature fluid flow path section12is defined by a space surrounded by the pair of low-temperature fluid flow path sections4and6and the pair of side restriction members8and10. The high-temperature fluid flow path section12functions as a high-temperature fluid flow path through which the high-temperature fluid (an example of the second fluid) flows. The high-temperature fluid is a fluid at higher temperature than the low-temperature fluid and is, for example, the exhaust gas discharged from the on-vehicle engine.

The high-temperature fluid introduction member14and the high-temperature fluid discharge member16are arranged to face each other with a spacing therebetween in the front-rear direction. In more detail, the high-temperature fluid introduction member14and the high-temperature fluid discharge member16are arranged to cover the high-temperature fluid flow path section12arranged between the pair of low-temperature fluid flow path sections4and6from sides in the front-rear direction. The high-temperature fluid introduction member14and the high-temperature fluid discharge member16are formed in a tubular shape and are in communication with the high-temperature fluid flow path section12. The high-temperature fluid flows into the high-temperature fluid flow path section12through the high-temperature fluid introduction member14and is discharged to the outside through the high-temperature fluid discharge member16after flowing through the high-temperature fluid flow path section12in the front-rear direction (from a minus side toward a plus side of an X axis).

As illustrated inFIGS.2to4, the pair of thermoelectric modules18and20are each arranged between the high-temperature fluid flow path section12and one of the pair of low-temperature fluid flow path sections4and6in a one-to-one relation. Thus, the pair of thermoelectric modules18and20are arranged to face each other with a spacing therebetween in the up-down direction.

The thermoelectric module18on an upper side is formed in a rectangular flat plate shape and is fixed to a lower surface (a surface on a side closer to the high-temperature fluid flow path section12) of the housing24of the low-temperature fluid flog path section4on the upper side. In other words, the thermoelectric module18on the upper side is arranged such that it is sandwiched between the high-temperature fluid flow path section12and the low-temperature fluid flow path section4on the upper side from below and above, respectively. The thermoelectric module18on the upper side includes a thermoelectric generator that converts thermal energy, given as a temperature difference between the high-temperature fluid flowing through the high-temperature fluid flow path section12and the low-temperature fluid flowing through the low-temperature fluid flow path section4on the upper side, to electrical energy based on the Seebeck effect.

The thermoelectric module20on a lower side is formed in a rectangular flat plate shape and is fixed to an upper surface (a surface on a side closer to the high-temperature fluid flow path section12) of the housing31of the low-temperature fluid flow path section6on the lower side. In other words, the thermoelectric module20on the lower side is arranged such that it is sandwiched between the high-temperature fluid flow path section12and the low-temperature fluid flow path section6on the lower side from above and below, respectively. The thermoelectric module20on the lower side includes a thermoelectric generator that converts thermal energy, given as a temperature difference between the high-temperature fluid flowing through the high-temperature fluid flow path section12and the low-temperature fluid flowing through the low-temperature fluid flow path section6on the lower side, to electrical energy based on the Seebeck effect.

An example of each of the thermoelectric module18and the thermoelectric module20may be a TEG module102disclosed in U.S. Patent Application Publication No. 2013/0340801. U.S. Patent Application Publication No. 2013/0340801 indicates that the TEG module102includes p-type thermoelectric material legs105A and n-type thermoelectric material legs105B.

The thermoelectric generator has, for example, a it-structure. In the thermoelectric generator of the π-structure, a p-type thermoelectric material and an n-type thermoelectric material are electrically connected in series through an electrode mounted on a ceramic substrate. One end of each of the thermoelectric materials is arranged on a high temperature side, and the other end is arranged on a low temperature side. Thus, a temperature difference is produced between both the ends of each thermoelectric material and a voltage difference is generated between both ends of the thermoelectric generator, whereby electricity is generated.

As illustrated inFIGS.2to4, the fin structure22is arranged in the high-temperature fluid flow path section12. The fin structure22has a role of transferring heat of the high-temperature fluid flowing through the high-temperature fluid flow path section12to each of the pair of thermoelectric modules18and20. A configuration of the fin structure22will be described in detail below.

1-2. Configuration of Fin Structure

The configuration of the fin structure22is described with reference toFIGS.2to6.FIG.5is a perspective view of a flat heat transfer plate34according to Embodiment 1.FIG.6is an enlarged perspective view illustrating a baffle structure40of the flat heat transfer plate34inFIG.5.

As illustrated inFIGS.2and3, the fin structure22includes corrugated heat transfer plates32(32a,32band32c) and the flat heat transfer plates34(34aand34b). The corrugated heat transfer plates32and the flat heat transfer plates34are alternately stacked in the up-down direction to face each other. In more detail, the corrugated heat transfer plate32a, the flat heat transfer plate34a, the corrugated heat transfer plate32b, the flat heat transfer plate34b, and the corrugated heat transfer plate32care successively stacked in order along a predetermined direction from the thermoelectric module18on the upper side toward the thermoelectric module20on the lower side.

As illustrated inFIG.3, the corrugated heat transfer plate32is formed by mountain portions36curved in a convex shape toward the thermoelectric module18on the upper side and valley portions38curved in a convex shape toward the thermoelectric module20on the lower side, the mountain and valley portions being alternately interconnected in the left-right direction. The flat heat transfer plate34is formed in a flat plate (thin plate) shape.

As illustrated inFIG.3, the mountain portions36of the corrugated heat transfer plate32aon an upper side are each in contact with a lower surface (a surface on a side closer to the high-temperature fluid flow path section12) of the thermoelectric module18on the upper side. The valley portions38of the corrugated heat transfer plate32aon the upper side are each in contact with an upper surface (a surface on a side closer to the corrugated heat transfer plate32a) of the flat heat transfer plate34aon the upper side. The mountain portions36of the corrugated heat transfer plate32bat a center are each in contact with a lower surface (a surface on a side closer to the corrugated heat transfer plate32b) of the flat heat transfer plate34aon the upper side. The valley portions38of the corrugated heat transfer plate32bat the center are each in contact with an upper surface (a surface on a side closer to the corrugated heat transfer plate32b) of the flat heat transfer plate34bon the lower side. The mountain portions36of the corrugated heat transfer plate32con a lower side are each in contact with a lower surface (a surface on a side closer to the corrugated heat transfer plate32c) of the flat heat transfer plate34bon the lower side. The valley portions38of the corrugated heat transfer plate32con the lower side are each in contact with an upper surface (a surface on a side closer to the high-temperature fluid flow path section12) of the thermoelectric module20on the lower side.

An interior and a surface of each of the corrugated heat transfer plate32and the flat heat transfer plate34are made of different materials. The interior of each of the corrugated heat transfer plate32and the flat heat transfer plate34is made of a material with high thermal conductivity, such as copper, a copper alloy, aluminum, an aluminum alloy, stainless, or ceramic. The surface of each of the corrugated heat transfer plate32and the flat heat transfer plate34is coated with a metal with high corrosion resistance, such as nickel, a nickel alloy, chromium, or a chromium alloy. For example, electrolytic plating, non-electrolytic plating, or thermal spraying can be used to coat the surface of each of the corrugated heat transfer plate32and the flat heat transfer plate34.

Furthermore, as illustrated inFIG.5, the flat heat transfer plate34includes the baffle structures40arranged in a lattice pattern. As illustrated inFIG.6, each of the baffle structures40includes an opening42formed in the flat heat transfer plate34and a baffle44projecting from a peripheral edge of the opening42. The opening42is formed in, for example, a triangular shape. The baffle44is a projected piece to baffle the high-temperature fluid after passing through the opening42in a direction toward the thermoelectric module18on the upper side or the thermoelectric module20on the lower side. The baffle44is formed in, for example, a semi-conical shape. A base portion44aand both side portions44band44cof the baffle44are connected to the peripheral edge of the opening42. The baffle44is formed by, for example, press working such as cutting and bending on a metal plate. Alternately, the baffle44may be formed by welding, for example, without being limited the pressworking.

As illustrated inFIG.4, openings46are formed in the valley portions38of the corrugated heat transfer plate32aon the upper side corresponding to the baffle structures40of the flat heat transfer plate34aon the upper side in a one-to-one relation. The openings46of the corrugated heat transfer plate32aon the upper side are in communication with the openings42of the baffle structures40of the flat heat transfer plate34aon the upper side.

Although not illustrated, openings46are formed in the mountain portions36of the corrugated heat transfer plate32bat the center corresponding to the baffle structures40of the flat heat transfer plate34aon the upper side in a one-to-one relation. The openings46of the corrugated heat transfer plate32bat the center are in communication with the openings42of the baffle structures40of the flat heat transfer plate34aon the upper side.

The baffles44of the baffle structures40of the flat heat transfer plate34aon the upper side each project from the peripheral edge of the opening42in a direction opposite to the direction in which the high-temperature fluid passes through the opening42(namely, toward the thermoelectric module20on the lower side) and in an obliquely downward direction relative to the flat heat transfer plate34a.

As illustrated inFIG.4, openings48are formed in the valley portions38of the corrugated heat transfer plate32bat the center corresponding to the baffle structures40of the flat heat transfer plate34bon the lower side in a one-to-one relation. The openings48of the corrugated heat transfer plate32bat the center are in communication with the openings42of the baffle structures40of the flat heat transfer plate34bon the lower side.

Although not illustrated, openings46are formed in the mountain portions36of the corrugated heat transfer plate32con the lower side corresponding to the baffle structures40of the flat heat transfer plate34bon the lower side in a one-to-one relation. The openings46of the corrugated heat transfer plate32con the lower side are in communication with the openings42of the baffle structures40of the flat heat transfer plate34bon the lower side.

The baffles44of the baffle structures40of the flat heat transfer plate34bon the lower side each project from the peripheral edge of the opening42in the direction opposite to the direction in which the high-temperature fluid passes through the opening42(namely, toward the thermoelectric module18on the upper side) and in an Obliquely upward direction relative to the flat heat transfer plate34b.

While, in this embodiment, the baffle structures40are formed in the flat heat transfer plate34, the present disclosure is not limited to the illustrated embodiment, and baffle structures may be formed in the corrugated heat transfer plate32. In that case, openings are formed in the flat heat transfer plate34corresponding to the baffle structures of the corrugated heat transfer plate32in a one-to-one relation.

1-3. Operation of Thermoelectric Conversion Unit

Operation of the thermoelectric conversion unit2according to Embodiment 1 will be described below with reference toFIGS.1,3and4.

As illustrated inFIGS.1,3and4, the low-temperature fluid flows into the low-temperature fluid flow path30inside the housing24of the low-temperature fluid flow path section4on the upper side through the low-temperature fluid introduction member26and, after flowing through the low-temperature fluid flow path30, it is discharged to the outside through the low-temperature fluid discharge member28. Heat of the low-temperature fluid flowing through the low-temperature fluid flow path section4on the upper side is transferred to an upper surface (a surface on a side closer to the low-temperature fluid flow path section4) of the thermoelectric module18on the upper side, whereby the upper surface of the thermoelectric module1S on the upper side is cooled.

The low-temperature fluid flows into the low-temperature fluid flow path37inside the housing31of the low-temperature fluid flow path section6on the lower side through the low-temperature fluid introduction member33and, after flowing through the low-temperature fluid flow path37, it is discharged to the outside through the low-temperature fluid discharge member35. Heat of the low-temperature fluid flowing through the low-temperature fluid flow path section6on the lower side is transferred to a lower surface (a surface on a side closer to the low-temperature fluid flow path section6) of the thermoelectric module20on the lower side, whereby the lower surface of the thermoelectric module20on the lower side is cooled.

As illustrated inFIGS.1and4, the high-temperature fluid flows into the high-temperature fluid flow path section12through the high-temperature fluid introduction member14and, after flowing through the high-temperature fluid flow path section12in the front-rear direction, it is discharged to the outside through the high-temperature fluid discharge member16.

As illustrated inFIG.4, the high-temperature fluid flowing through a flow path12aof the high-temperature fluid flow path section12between the thermoelectric module18on the upper side and the flat heat transfer plate34aon the upper side heats the lower surface of the thermoelectric module18on the upper side while flowing through the flow path12ain the front-rear direction. The high-temperature fluid flowing through a flow path12bof the high-temperature fluid flow path section12between the flat heat transfer plate34aon the upper side and the flat heat transfer plate34bon the lower side flows through the flow path12bin the front-rear direction, while part of the above-mentioned high-temperature fluid is baffled by the baffles44of the flat heat transfer plate34aon the upper side to flow in the direction toward the thermoelectric module18on the upper side. Hence the part of the above-mentioned high-temperature fluid flows into the flow path12athrough the openings42of the flat heat transfer plate34aon the upper side and the openings46of the corrugated heat transfer plate32aon the upper side.

Thus, the high-temperature fluid flowing through the flow path12ain the front-rear direction as described above joins with the high-temperature fluid flowing into the flow path12afrom the flow path12band heats the lower surface of the thermoelectric module18on the upper side while increasing its flow velocity. With such a flow of the high-temperature fluid, the heat of the high-temperature fluid flowing through the high-temperature fluid flow path section12is transferred to the lower surface of the thermoelectric module18on the upper side through the corrugated heat transfer plate32bat the center, the flat heat transfer plate34aon the upper side, and the corrugated heat transfer plate32aon the upper side. The lower surface of the thermoelectric module18on the upper side is heated as described above.

As illustrated inFIG.4, the high-temperature fluid flowing through a flow path12cof the high-temperature fluid flow path section12between the thermoelectric module20on the lower side and the flat heat transfer plate34bon the lower side heats the upper surface of the thermoelectric module20on the lower side while flowing through the flow path12cin the front-rear direction. The high-temperature fluid flowing through the flow path12bof the high-temperature fluid flow path section12between the flat heat transfer plate34aon the upper side and the flat heat transfer plate34bon the lower side flows through the flow path12bin the front-rear direction, while part of the above-mentioned high-temperature fluid is baffled by the baffles44of the flat heat transfer plate34hon the lower side to flow in the direction toward the thermoelectric module20on the lower side. Hence the part of the above-mentioned high-temperature fluid flows into the flow path12cthrough the openings42of the flat heat transfer plate34bon the lower side and the openings48of the corrugated heat transfer plate32con the lower side.

Thus, the high-temperature fluid flowing through the flow path12cin the front-rear direction as described above joins with the high-temperature fluid flowing into the flow path12cfrom the flow path12band heats the upper surface of the thermoelectric module20on the lower side while increasing its flow velocity. With such a flow of the high-temperature fluid, the heat of the high-temperature fluid flowing through the high-temperature fluid flow path section12is transferred to the upper surface of the thermoelectric modules20on the lower side through the corrugated heat transfer plate32bat the center, the flat heat transfer plate34bon the lower side, and the corrugated heat transfer plate32con the lower side. The upper surface of the thermoelectric module20on the lower side is heated as described above.

In such a manner, a temperature difference (temperature gradient) is given to the thermoelectric module18on the upper side in its thickness direction (Z-axis direction) such that a lower surface side is held at high temperature and an upper surface side is held at low temperature. Therefore, the thermoelectric module18on the upper side generates electricity based on the temperature difference between the lower surface side and the upper surface side (i.e., the temperature difference between the high-temperature fluid and the low-temperature fluid).

A temperature difference (temperature gradient) is given to the thermoelectric module20on the lower side in its thickness direction (Z-axis direction) such that an upper surface side is held at high temperature and a lower surface side is held at low temperature. Therefore, the thermoelectric module20on the lower side generates electricity based on the temperature difference between the upper surface side and the lower surface side (i.e., the temperature difference between the high-temperature fluid and the low-temperature fluid).

According to this embodiment, as described above, the part of the high-temperature fluid flowing through the flow path12bis baffled by the baffles44of the flat heat transfer plate34aon the upper side in the direction toward the thermoelectric module18on the upper side and hence flows into the flow path12athrough the openings42of the flat heat transfer plate34aon the upper side and the openings46of the corrugated heat transfer plate32aon the upper side. Thus, the high-temperature fluid flowing through the flow path12ain the front-rear direction joins with the high-temperature fluid flowing into the flow path12afrom the flow path12band heats the lower surface of the thermoelectric module18on the upper side while increasing its flow velocity.

The part of the high-temperature fluid flowing through the flow path12his baffled by the baffles44of the flat heat transfer plate34bon the lower side in the direction toward the thermoelectric module20on the lower side and hence flows into the flow path12cthrough the openings42of the flat heat transfer plate34bon the lower side and the openings48of the corrugated heat transfer plate32con the lower side. Thus, the high-temperature fluid flowing through the flow path12cin the front-rear direction joins with the high-temperature fluid flowing into the flow path12cfrom the flow path12band heats the upper surface of the thermoelectric module20on the lower side while increasing its flow velocity.

Accordingly, it is possible to increase the flow velocity of each of the high-temperature fluid flowing through the flow path12aclose to the thermoelectric module18on the upper side and the high-temperature fluid flowing through the flow path12cclose to the thermoelectric module20on the lower side. The heat of the high-temperature fluid flowing through the flow path12bcan be utilized to contribute to the power generation by the thermoelectric module18on the upper side and the thermoelectric module20on the lower side by introducing the parts of the high-temperature fluid flowing through the flow path12baway from the thermoelectric module18on the upper side and the thermoelectric module20on the lower side to the flow paths12aand12c. As a result, the efficiency of heat transfer from the high-temperature fluid to each of the thermoelectric module18on the upper side and the thermoelectric module20on the lower side can be increased.

1-5, Modification of Baffle Structure

A configuration of a baffle structure40A of a flat heat transfer plate34A according to a modification of Embodiment 1 will be described below with reference toFIG.7.FIG.7is a perspective view illustrating the baffle structure40A of the flat heat transfer plate34A according to the modification of Embodiment 1.

As illustrated inFIG.7, in the baffle structure40A of the flat heat transfer plate34A according to the modification, an opening42A is formed in a rectangular shape, and a baffle44A is formed in a rectangular flat plate shape. A base portion44Aa of the baffle44A is connected to a peripheral edge of the opening42A, but both side portions44Ab and44Ac of the baffle44A are not connected to the peripheral edge of the opening42. The baffle44A is formed by, for example, press working such as cutting and bending on a metal plate. The baffle structure40A with the above-described configuration can also provide similar advantageous effects to those described above.

1-6. Modification of Corrugated Heat Transfer Plate

A configuration of a corrugated heat transfer plate32B according to a modification of Embodiment 1 will be described below with reference toFIG.8.FIG.8is a perspective view illustrating the corrugated heat transfer plate32B according to the modification of Embodiment 1.

As illustrated inFIG.8, the corrugated heat transfer plate32B according to the modification has the so-called split fin structure. More specifically, in the corrugated heat transfer plate32B, concave-convex portion rows50each including mountain portions36B and valley portions38B arranged alternately are arranged side by side in the front-rear direction of the corrugated heat transfer plate32B (i.e., in the X-axis direction) and are offset-arrayed such that positions of the mountain portions36B and the valley portions38B are shifted in the left-right direction of the corrugated heat transfer plate32B (i.e., in the Y-axis direction).

The above-described configuration of the corrugated heat transfer plate32B enables flows of the high-temperature fluid to merge (mix) not only in the up-down direction (Z-axis direction) of the corrugated heat transfer plate32B, but also in the left-right direction. As a result, it is possible to smooth position dependency of temperature of the high-temperature fluid caused by the difference in heat exchange state, and to increase overall heat transfer performance and thermoelectric conversion performance of the thermoelectric conversion unit.

A configuration of a thermoelectric conversion unit2C according to Embodiment 2 will be described below with reference toFIG.9.FIG.9is a sectional view of principal part of the thermoelectric conversion unit2C according to Embodiment 2. In the following embodiments, the same constituent elements as those in the above-described Embodiment 1 are denoted by the same reference sings, and duplicate description of those constituent elements is omitted.

As illustrated inFIG.9, the thermoelectric conversion unit2C according to Embodiment 2 is different from Embodiment 1 in configuration of a fin structure22C. More specifically, the fin structure22C includes flat heat transfer plates34C (34Ca,34Cb,34Cc and34Cd) and rod-shaped fins52. The tin structure22C does not include the corrugated heat transfer plate32described in Embodiment 1.

The flat heat transfer plates34C are arranged with a spacing therebetween in the up-down direction. In more detail, the flat heat transfer plates34Ca,34Cb,34Cc and34Cd are successively arranged in order along the predetermined direction from the thermoelectric module18on the upper side toward the thermoelectric module20on the lower side. The flat heat transfer plate34Ca at an uppermost position is fixed to the lower surface of the thermoelectric module18on the upper side. The flat heat transfer plate34Cd at a lowermost position is fixed to the upper surface of the thermoelectric module20on the lower side. The baffle structures40are formed in each of the flat heat transfer plate34Cb at a second uppermost position and the flat heat transfer plate34Cc at a second lowest position as in Embodiment 1.

Each of the rod-shaped fins52is formed in a cylindrical rod (pin) shape and is arranged between adjacent pairs34Ca and34Cb ((34Cb and34Cc) or (34Cc and34Cd)) of the flat heat transfer plates34C in a one-to-one relation. Both ends of each of the rod-shaped fins52are fixed to the adjacent pairs of flat heat transfer plates34Ca and34Cb ((34Cb and34Cc) or (34Cc and34Cd)). Thus, the adjacent pairs of flat heat transfer plates34Ca and34Cb ((34Cb and34Cc) or (34Cc and34Cd)) are connected to each other through the rod-shaped fins52.

The heat of the high-temperature fluid flowing through the high-temperature fluid flow path section12is transferred to the pair of thermoelectric modules18and20through the rod-shaped fins52and the flat heat transfer plates34C. Accordingly, this embodiment can also provide similar advantageous effects to those obtained in Embodiment 1.

A configuration of a thermoelectric conversion unit2D according to Embodiment 3 will be described below with reference toFIG.10,FIG.10is a sectional view of principal part of the thermoelectric conversion unit21) according to Embodiment 3.

As illustrated inFIG.10, the thermoelectric conversion unit2D according to Embodiment 3 is different from Embodiment 1 in configuration of a fin structure22D. More specifically, a baffle direction for the high-temperature fluid baffled by baffle structures40formed in an upstream region54and a downstream region58of the high-temperature fluid flow path section12is reversal in the up-down direction to a baffle direction for the high-temperature fluid baffled by a baffle structure40D formed in a midstream region56of the high-temperature fluid flow path section12. The midstream region56of the high-temperature fluid flow path section12is a region that is positioned on a downstream side (plus side of the X-axis) of the upstream region54, and the downstream region58of the high-temperature fluid flow path section12is a region that is positioned on a downstream side of the midstream region56.

A baffle44(an example of a first baffle) of each baffle structure40of the flat heat transfer plate34aon the upper side arranged in the upstream region54of the high-temperature fluid flow path section12projects from the peripheral edge of the opening42(an example of a first opening) in the direction opposite to the direction in which the high-temperature fluid passes through the opening42(namely, toward the thermoelectric module20on the lower side) and in an obliquely downward direction relative to the flat heat transfer plate34a. In other words, the baffle direction for the high-temperature fluid baffled by the baffle structure40of the flat heat transfer plate34aon the upper side arranged in the upstream region54of the high-temperature fluid flow path section12is a direction toward the thermoelectric module18on the upper side.

A baffle44D (an example of a second baffle) of each baffle structure40D of the flat heat transfer plate34aon the upper side arranged in the midstream region56of the high-temperature fluid flow path section12projects from the peripheral edge of the opening42(an example of a second opening) in the direction opposite to the direction in which the high-temperature fluid passes through the opening42(namely, toward the thermoelectric module18on the upper side) and in an obliquely upward direction relative to the flat heat transfer plate34a. In other words, the baffle direction for the high-temperature fluid baffled by the baffle structure40D of the flat heat transfer plate34aon the upper side arranged in the midstream region56of the high-temperature fluid flow path section12is a direction toward the thermoelectric module20on the lower side.

A baffle44(an example of a third baffle) of each baffle structure40of the flat heat transfer plate34aon the upper side arranged in the downstream region58of the high-temperature fluid flow path section12projects from the peripheral edge of the opening42(an example of a third opening) in the direction opposite to the direction in which the high-temperature fluid passes through the opening42(namely, toward the thermoelectric module20on the lower side) and in an obliquely downward direction relative to the flat heat transfer plate34a. In other words, the baffle direction for the high-temperature fluid baffled by the baffle44of the baffle structure40of the flat heat transfer plate34aon the upper side arranged in the downstream region58of the high-temperature fluid flow path section12is the direction toward the thermoelectric module18on the upper side.

A baffle44(an example of the first baffle) of each baffle structure40of the flat heat transfer plate34bon the lower side arranged in the upstream region54of the high-temperature fluid flow path section12projects from the peripheral edge of the opening42(an example of the first opening) in the direction opposite to the direction in which the high-temperature fluid passes through the opening42(namely, toward the thermoelectric module18on the upper side) and in an obliquely upward direction relative to the flat heat transfer plate34b. In other words, the baffle direction for the high-temperature fluid baffled by the baffle structure40of the flat heat transfer plate34bon the lower side arranged in the upstream region54of the high-temperature fluid flow path section12is direction toward the thermoelectric module20on the lower side.

A baffle44D (an example of the second baffle) of each baffle structure40D of the flat heat transfer plate34bon the lower side arranged in the midstream region56of the high-temperature fluid flow path section12projects from the peripheral edge of the opening42(an example of the second opening) in the direction opposite to the direction in which the high-temperature fluid passes through the opening42(namely, toward the thermoelectric module20on the lower side) and in an obliquely downward direction relative to the flat heat transfer plate34b. In other words, the baffle direction for the high-temperature fluid baffled by the baffle structure40D of the flat heat transfer plate34bon the lower side arranged in the midstream region56of the high-temperature fluid flow path section12is the direction toward the thermoelectric module18on the upper side.

A baffle44(an example of the third baffle) of each baffle structure40of the flat heat transfer plate34bon the lower side arranged in the downstream region58of the high-temperature fluid flow path section12projects from the peripheral edge of the opening42(an example of the third opening) in the direction opposite to the direction in which the high-temperature fluid passes through the opening42(namely, toward the thermoelectric module18on the upper side) and in an obliquely upward direction relative to the flat heat transfer plate34b. In other words, the baffle direction for the high-temperature fluid baffled by the baffle44of the baffle structure40of the flat heat transfer plate34bon the lower side arranged in the downstream region58of the high-temperature fluid flow path section12is the direction toward the thermoelectric module20on the lower side.

The advantageous effects obtained with the thermoelectric conversion unit2D according to Embodiment 3 will be described below. Part of the high-temperature fluid flowing through the flow path12bof the high-temperature fluid flow path section12is baffled by the baffles44of the flat heat transfer plate34aon the upper side in the direction toward the thermoelectric module18on the upper side, those baffles44being arranged in the upstream region54of the high-temperature fluid flow path section12, and hence flows into the flow path12athrough the openings42of the flat heat transfer plate34aon the upper side and the openings46of the corrugated heat transfer plate32aon the upper side. Part of the high-temperature fluid flowing through the flow path12bof the high-temperature fluid flow path section12is baffled by the baffles44of the flat heat transfer plate34bon the lower side in the direction toward the thermoelectric module20on the lower side, those baffles44being arranged in the upstream region54of the high-temperature fluid flow path section12, and hence flows into the flow path12cthrough the openings48of the corrugated heat transfer plate32bat the center and the openings42of the flat heat transfer plate34bon the lower side. On that occasion, when a pressure difference between the flow path12aand the flow path12band a pressure difference between the flow path12bthe flow path12creach a certain value, a further baffle effect is lost.

According to this embodiment, taking into account the above-mentioned point, in the midstream region56of the high-temperature fluid flow path section12, part of the high-temperature fluid flowing through the flow path12aof the high-temperature fluid flow path section12is baffled by the baffles44of the flat heat, transfer plate34aon the upper side to flow in the direction toward the thermoelectric module20on the lower side, whereby the part of the high-temperature fluid flows into the flow path12bthrough the openings46of the corrugated heat transfer plate32aon the upper side and the openings42of the flat heat transfer plate34aon the upper side. Furthermore, in the midstream region56of the high-temperature fluid flow path section12, part of the high-temperature fluid flowing through the flow path12cof the high-temperature fluid flow path section12is baffled by the baffles44of the flat heat transfer plate34bon the lower side to flow in the direction toward the thermoelectric module18on the upper side, whereby the part of the high-temperature fluid flows into the flow path12bthrough the openings42of the flat heat transfer plate34bon the lower side and the openings48of the corrugated heat transfer plate32bat the center.

Accordingly, a flow velocity distribution and a temperature distribution of the high-temperature fluid in the midstream region56of the high-temperature fluid flow path section12can be made uniform once. As a result, it is possible to maintain the effect of baffling the high-temperature fluid by the baffles44disposed in the downstream region58of the high-temperature fluid flow path section12and to increase the efficiency of heat transfer from the high-temperature fluid flowing in the downstream region58of the high-temperature fluid flow path section12to each of the pair of thermoelectric modules18and20.

A configuration of a thermoelectric conversion unit2E according to Embodiment 4 will be described below with reference toFIG.11.FIG.11is a sectional view of principal part of the thermoelectric conversion unit2E according to Embodiment 4.

As illustrated inFIG.11, in the thermoelectric conversion unit2E according to Embodiment 4, two sets of units each including the pair of thermoelectric modules18and20and the fin structure22between both the thermoelectric modules are stacked (arranged one on the other) in the up-down direction with a low-temperature fluid flow path section60at a center interposed between those two sets of units. The low-temperature fluid flow path section60has the same structure as the above-described pair of low-temperature fluid flow path sections4and6. The above-mentioned stack structure enables the thermoelectric conversion unit2E to be made compact.

While, in this embodiment, the two sets of units each including the pair of thermoelectric modules18and20and the fin structure22between both the thermoelectric modules are stacked in the up-down direction, the present disclosure is not limited to that case, and three or more sets may be stacked.

OTHER EMBODIMENTS

The thermoelectric conversion unit according to one or more aspects of the present disclosure has been described in connection with the embodiments, but the present disclosure is not limited to those embodiments, Various modifications conceivable by those skilled in the art from the above-described embodiments may also fall within the scope of the one or more aspects of the present disclosure insofar as not departing from the gist of the present disclosure.

While the above-described embodiments employ the exhaust gas as the high-temperature fluid and cold water or cold air as the low-temperature fluid, the present disclosure is not limited to that case, and each of the high-temperature fluid and the low-temperature fluid may be any suitable liquid or gas (gaseous medium).

The thermoelectric conversion unit according to the present disclosure can be used as, for example, a power generator generating electricity by utilizing thermal energy of exhaust gas discharged from an automobile, a factory, and so on, or as a small-sized portable power generator and so on.