Heat Exchanger and Refrigeration Cycle Apparatus

This is a continuation application of International Patent Application No. PCT/JP2023/035444, filed Sep. 28, 2023, and claims priority to Japanese Patent Application No. 2023-001787, filed Jan. 10, 2023. The contents of these priority applications are incorporated herein by reference.

The present disclosure relates to a heat exchanger and a refrigeration cycle apparatus.

Conventionally, there has been known a plate-type heat exchanger formed by stacking and bonding a plurality of heat transfer plates to each other. This heat exchanger exchanges heat between a first fluid and a second fluid by alternately stacking a space that is sandwiched between heat transfer plates and through which the first fluid flows and a space that is sandwiched between heat transfer plates and through which the second fluid flows.

In such a plate-type heat exchanger, for example, some adopt double-wall type heat transfer plates, each of which includes two partition walls, as described in PTL 1 (Japanese Unexamined Patent Application Publication No. 2002-107089). The double-wall type heat transfer plate has a structure in which a gap is interposed between two partition walls that overlap each other. According to this heat exchanger, even in a case where either of the partition walls of the heat transfer plate is cracked due to a factor, such as corrosion, since the heat transfer plate has a double-wall structure, a fluid leaked from the crack can be guided to the gap, and the fluids to be heat-exchanged are prevented from mixing.

A heat exchanger according to a first aspect is a heat exchanger that exchanges heat between a first fluid and a second fluid, including a first flow path, a second flow path, a first wall portion, and a second wall portion. The first fluid flows through the first flow path. The second fluid flows through the second flow path. The first wall portion is located between the first flow path and the second flow path. The second wall portion is located between the first wall portion and the second flow path. The first fluid flows through the first flow path in a direction intersecting a stacking direction that is a direction in which the first wall portion and the second wall portion are stacked. The second fluid flows through the second flow path in a direction intersecting the stacking direction. In the heat exchanger, at least either the first wall portion including a first flat portion and a plurality of first protrusions protruding in the stacking direction, and distal ends of the first protrusions being in contact with the second wall portion, or the second wall portion including a second flat portion and a plurality of second protrusions protruding in the stacking direction, and distal ends of the second protrusions being in contact with the first wall portion.

Hereinafter, a heat exchanger and a heat pump system as a refrigeration cycle apparatus including the heat exchanger will be described with reference to the drawings.

is a schematic configuration diagram of a plate heat exchangeras a heat exchanger according to one or more embodiments of the present disclosure and a heat pump systemas a refrigeration cycle apparatus including the plate heat exchanger.

The heat pump systemmainly includes a first circuitand a second circuit. The first circuitis a refrigerant circuit through which a refrigerant as a first fluid serving as a heat exchange medium circulates. The second circuitis a water circuit through which water as a second fluid serving as a heating target fluid circulates. The heat pump systemis an apparatus that heats water by utilizing a refrigerant compression-type heat pump cycle in the first circuit, and processes a use-side load such as heating an inside of a room with the heated water.

Note that the refrigerant that circulates through the first circuitis not limited, and for example, a refrigerant with flammability can be used. Note that, as the refrigerant with flammability, highly flammable refrigerants of classes A3 and B3, flammable refrigerants of classes A2 and B2, low-flammable refrigerants of classes A2L and B2L, and the like in ASHRAE Safety Group can be named. For example, especially, the refrigerant with flammability may be one or two or more kinds selected from the group consisting of R290, R600, and R600a. Note that the first circuitis filled with refrigerating machine oil together with the above-described refrigerant.

The first circuitmainly includes a compressor, the plate heat exchanger, an expansion mechanism, and a first heat exchanger. In addition, the first circuitis filled with a refrigerant. The refrigerant is not limited, and for example, an HFC-based refrigerant, an HFO-based refrigerant, a natural refrigerant, or the like can be used.

The compressoris a device that compresses a refrigerant. The compressoris, for example, a compressor in which a refrigerant compression element of a rotary type, a scroll type, or the like is driven by a drive mechanism such as a motor.

The plate heat exchangeris a device that exchanges heat between the refrigerant circulating through the first circuit and water circulating through the second circuit. In the present embodiments, the plate heat exchangercools the refrigerant compressed in the compressorwith the water circulating through the second circuit. Note that details of the plate heat exchangerwill be described later. Furthermore, a discharge port of the compressorand a refrigerant inlet, which is an inlet on the refrigerant side of the plate heat exchanger, are connected by a first refrigerant pipe.

The expansion mechanismis a device that decompresses the refrigerant cooled in the plate heat exchanger. The expansion mechanismis, for example, an expansion valve or a capillary tube. Furthermore, a refrigerant outlet, which is an outlet on the refrigerant side of the plate heat exchanger, and the expansion mechanismare connected by a second refrigerant pipe.

The first heat exchangeris a device that exchanges heat between the refrigerant flowing inside the first heat exchangerand a fluid, such as air, passing around the first heat exchanger. In the present embodiments, the first heat exchangerevaporates the refrigerant decompressed in the expansion mechanismby exchanging heat with the air supplied by a blower fan. The blower fangenerates a flow of air that serves as a heating source for the refrigerant. As such a first heat exchanger, for example, a fin-and-tube heat exchanger that heats the refrigerant with air can be used. The blower fanis a fan that drives a blower element of a propeller type or the like by a drive mechanism such as a motor. Furthermore, the expansion mechanismand a refrigerant inlet of the first heat exchangerare connected by a third refrigerant pipe. A refrigerant outlet of the first heat exchangerand a suction port of the compressorare connected by a fourth refrigerant pipe.

The second circuitmainly includes the plate heat exchanger, a pump, and a second heat exchanger. In addition, the second circuitis filled with water.

As described above, the plate heat exchangeris a device that cools the refrigerant compressed in the compressorwith water circulating through the second circuit. Furthermore, the plate heat exchangeris a device that heats water with the refrigerant circulating through the first circuit. Note that details of the plate heat exchangerwill be described later.

The pumpis a device that generates a flow of water in the second circuit, and boosts water in the present embodiments. The pumpis, for example, a pump that drives a centrifugal or positive displacement pump element by a drive mechanism such as a motor. Here, a water outlet, which is an outlet on the water side of the plate heat exchanger, and a suction port of the pumpare connected by a second water pipe.

The second heat exchangeris a device that heats, or the like, an inside of a room with the water heated by the plate heat exchanger. The second heat exchangeris, for example, a radiator or a floor heater. Furthermore, a discharge port of the pumpand a water inlet of the second heat exchangerare connected by a third water pipe. A water outlet of the second heat exchangerand a water inlet, which is an inlet on the water side of the plate heat exchanger, are connected by a first water pipe.

The devices forming the heat pump systemare controlled by a control apparatus. The control apparatusincludes a control board, or the like, on which a processor such as a central processing unit (CPU), memories such as a ROM and a RAM, and the like are mounted.

Next, an example of the operation of the heat pump systemwill be described with reference to.

As described above, the heat pump systemcan perform a heating operation, or the like, in which water is heated by utilizing the refrigerant compression-type heat pump cycle in the first circuit, and an inside of a room is heated with the heated water. Note that the heating operation is controlled by the control apparatus.

In the first circuit, the refrigerant compressed in the compressorand discharged is sent to the plate heat exchanger. The refrigerant sent to the plate heat exchangeris cooled and condensed through heat exchange with the water circulating through the second circuit. The refrigerant, the heat of which has been radiated in the plate heat exchanger, is decompressed by the expansion mechanismand then sent to the first heat exchanger. The refrigerant sent to the first heat exchangeris evaporated by being heated through heat exchange with the air passing through the first heat exchangerby the blower fan. The refrigerant evaporated in the first heat exchangeris sucked into the compressor, compressed again in the compressor, and discharged.

On the other hand, in the second circuit, water is heated by the heat radiated from the refrigerant in the plate heat exchanger. The water heated in the plate heat exchangeris boosted and discharged by the pump. The water discharged from the pumpis sent to the second heat exchanger. The water sent to the second heat exchangeris cooled by heating the inside of the room. The water cooled in the second heat exchangeris sent to the plate heat exchanger, and heated again in the plate heat exchanger.

Next, details of the plate heat exchangeras a water heat exchanger will be described with reference to.

Here,is a schematic perspective view of an external appearance of the plate heat exchanger.is an explanatory view illustrating an arrangement of first flow pathsin a case where the plate heat exchangeris viewed from the front direction.is an explanatory view illustrating an arrangement of second flow pathsin a case where the plate heat exchangeris viewed from the front direction.is a partially exploded perspective view illustrating a main part of a heat exchange unit.is an explanatory view illustrating an arrangement in the vicinity of inlets and outlets of the first flow pathsin a case where the main part of the heat exchange unitis viewed from the left.is an explanatory view illustrating an arrangement in the vicinity of inlets of the second flow pathsin a case where the main part of the heat exchange unitis viewed from below.

Furthermore, in the following description, in order to describe directions and positional relationships, expressions such as “up”, “down”, “left”, “right”, “front”, and “rear” are used in some cases. The directions indicated by these expressions follow the directions of arrows illustrated in the drawings unless otherwise specified. Note that, in the present embodiments, an example of a posture of the plate heat exchangeris illustrated. The plate heat exchangermay be used by changing each direction of up and down, left and right, and front and rear.

The plate heat exchangermainly includes a casingand the heat exchange unitthat is disposed inside the casingand exchanges heat between water and a refrigerant as a heat exchange medium.

The casingaccommodates the heat exchange unittherein.

In the present embodiments, the casinghas a substantially rectangular parallelepiped shape.

Each surface portion of the casingof the present embodiments may be made of, for example, metal, and for example, stainless steel, an aluminum alloy, a copper alloy, or the like can be used. Note that the casingand the heat exchange unit, described later, may be made of the same material.

The water inletserving as an inlet of water is formed in a lower surface portion of the casing, and communicates with a water inlet headerincluded in the heat exchange unitdescribed later. The first water pipeis connected to the water inlet.

The water outletserving as an outlet of water is formed in an upper surface portion of the casing, and communicates with a water outlet headerincluded in the heat exchange unitdescribed later. The second water pipeis connected to the water outlet.

The refrigerant inletserving as an inlet of refrigerant is formed in an upper portion of a left side surface portion of the casing, and communicates with a refrigerant inlet headerincluded in the heat exchange unitdescribed later. The first refrigerant pipeis connected to the refrigerant inlet.

The refrigerant outletserving as an outlet of refrigerant is formed in a lower portion of the left side surface portion of the casing, and communicates with a refrigerant outlet headerincluded in the heat exchange unitdescribed later. The second refrigerant pipeis connected to the refrigerant outlet.

Each surface portion of the casingis disposed so as to cover each surface of the heat exchange unit, and is bonded to the heat exchange unit. The heat exchange unitand the casingare bonded in a state where an object obtained by repeatedly stacking a predetermined number of a first water partition wall, a second plate-shaped member, a second water partition wall, a first refrigerant partition wall, a first plate-shaped member, and a second refrigerant partition wall, described later, is covered with each surface portion of the casing. This bonding method is not limited, and diffusion bonding and the like can be named, for example. Note that, from the viewpoint of obtaining a favorable bonded state, the heat exchange unitand the casingmay be bonded in a state of being pressurized in a plate thickness direction that is a stacking direction of the plate-shaped members and the partition walls forming the heat exchange unit. Note that, after the heat exchange unitis formed by bonding the plate-shaped members and the partition walls of the heat exchange unitto each other, the casingmay be further bonded to the heat exchange unit.

In the plate heat exchanger, when the heat pump systemis in operation, water flows from the water inletinto the water inlet headerof the heat exchange unitdescribed later. The water that has flowed into the water inlet headeris branched into inlet portions of the plurality of second flow paths, and flows upward from below in each of the second flow paths. The water is heated through heat exchange with the refrigerant as the water flows through the plurality of second flow paths, and merges in the water outlet headerof the heat exchange unit, described later, via outlet portions of the plurality of second flow paths. The water that has merged in the water outlet headerflows out from the water outlet.

In the plate heat exchanger, when the heat pump systemis in operation, a refrigerant flows from the refrigerant inletinto the refrigerant inlet headerof the heat exchange unitdescribed later. The refrigerant that has flowed into the refrigerant inlet headeris branched into inlet portions of the plurality of first flow paths, and flows downward from above while alternately flowing between left and right in the first flow paths. The refrigerant radiates heat through heat exchange with water as the water flows through the plurality of first flow paths, and merges in the refrigerant outlet headerof the heat exchange unit, described later, via outlet portions of the plurality of first flow paths. The refrigerant that has merged in the refrigerant outlet headerflows out from the refrigerant outlet.

The heat exchange unitis formed by stacking the plurality of first plate-shaped members, the plurality of second plate-shaped members, the plurality of first refrigerant partition walls, the plurality of second refrigerant partition walls, the plurality of first water partition walls, and the plurality of second water partition wallson each other in the plate thickness direction. Members forming the heat exchange unitmay be made of, for example, metal, and for example, stainless steel, an aluminum alloy, a copper alloy, or the like can be used.

Note that the direction in which the first plate-shaped members, the second plate-shaped members, the first refrigerant partition walls, the second refrigerant partition walls, the first water partition walls, and the second water partition wallsare stacked is defined as the stacking direction, and corresponds to the front-rear direction in the present embodiments.

In the heat exchange unit, the front side of one first plate-shaped memberand the rear side of one first refrigerant partition wallare partially in surface contact with each other. The rear side of one first plate-shaped memberand the front side of one second refrigerant partition wallare partially in surface contact with each other. The front side of one second plate-shaped memberand the rear side of one first water partition wallare partially in surface contact with each other. The rear side of one second plate-shaped memberand the front side of one second water partition wallare partially in surface contact with each other. The front side of one first refrigerant partition walland the rear side of one second water partition wallare partially in surface contact with each other. The rear side of one second refrigerant partition walland the front side of one first water partition wallare partially in surface contact with each other. In this manner, from the front side toward the rear side, plate-shaped members and partition walls are stacked in the plate thickness direction so as to be repeatedly arranged in order of the first refrigerant partition wall, the first plate-shaped member, the second refrigerant partition wall, the first water partition wall, the second plate-shaped member, the second water partition wall, the first refrigerant partition wall, the first plate-shaped member, and so on.

In the heat exchange unit, these pluralities of first plate-shaped members, second plate-shaped members, first refrigerant partition walls, second refrigerant partition walls, first water partition walls, and second water partition wallsare bonded to each other in a state of being stacked in the plate thickness direction. Here, the bonding method is not limited, and vacuum brazing, diffusion bonding, and the like can be named, for example. Note that, from the viewpoint of obtaining a favorable bonded state, the plate-shaped members and the partition walls may be bonded in a state of being pressurized in the plate thickness direction.

One first plate-shaped memberincludes a plurality of first flow pathsthat allow the refrigerant to flow within a range of the plate thickness. The first flow pathis a flow path provided so as to penetrate the first plate-shaped memberin the plate thickness direction and formed by being sandwiched between the first refrigerant partition walland the second refrigerant partition wall, which are adjacent to the first plate-shaped member, in the front-rear direction. In the present embodiments, the plurality of first flow pathsare arranged in the vertical direction in one first plate-shaped member. The direction in which the plurality of first flow pathsare arranged is defined as an arrangement direction of the first flow paths. Furthermore, each first flow pathextends in the left-right direction. In this manner, when the first plate-shaped memberis viewed along the front-rear direction that is the stacking direction of the second plate-shaped memberand the first plate-shaped member, the first flow pathsextend in the left-right direction in the first plate-shaped memberalong a direction intersecting the arrangement direction in which the plurality of first flow pathsare arranged.

Note that, in the present embodiments, the plurality of first flow pathsare divided into a plurality of flow path groups arranged in the vertical direction, and are configured to allow the refrigerant to flow as described below. Specifically, the refrigerant that has flowed into the refrigerant inlet headerflows toward the right in a flow path group including a plurality of first flow paths, and flows toward a first return header. The refrigerant that has reached the first return headerflows so as to return toward the left in a flow path group that is located one stage below the above flow path group and includes a plurality of first flow paths, and flows toward a second return header. The refrigerant that has reached the second return headerflows so as to return toward the right in a flow path group that is located one stage further below the above flow path group and includes a plurality of first flow paths, and flows toward a third return header. The refrigerant that has reached the third return headerflows so as to return toward the left in a flow path group that is located one stage further below the above flow path group and includes a plurality of first flow paths, and flows toward the refrigerant outlet header.

One second plate-shaped memberincludes a plurality of second flow pathsthat allow water to flow within a range of the plate thickness. The second flow pathis a flow path provided so as to penetrate the second plate-shaped memberin the plate thickness direction and formed by being sandwiched between the first water partition walland the second water partition wall, which are adjacent to the second plate-shaped member, in the front-rear direction. In the present embodiments, the plurality of second flow pathsare arranged in the left-right direction in one second plate-shaped member. The direction in which the plurality of second flow pathsare arranged is defined as an arrangement direction of the second flow paths. Furthermore, each second flow pathextends in the vertical direction. In this manner, when the second plate-shaped memberis viewed along the front-rear direction that is the stacking direction of the second plate-shaped memberand the first plate-shaped member, the second flow pathsextend in the vertical direction in the second plate-shaped memberalong a direction intersecting the arrangement direction in which the plurality of second flow pathsare arranged. Note that, in the present embodiments, when the second plate-shaped memberis viewed along the stacking direction, the second flow pathhas a shape that meanders in the arrangement direction of the second flow pathsas the second flow pathextends in the direction in which the second flow pathextends. The meandering shape can enhance heat transfer performance.

The first flow pathand the second flow pathare, for example, micro flow paths having very small flow path cross-sectional areas, and are formed of flow paths having equivalent diameters of, for example, 1.5 mm or less. The plate heat exchangeris referred to as a micro flow path heat exchanger in some cases.

Furthermore, the plate heat exchangerof the present embodiments is configured such that the refrigerant flowing through the first flow pathand the water flowing through the second flow pathare in counter flow from each other. Furthermore, the plate heat exchangerof the present embodiments is configured such that the refrigerant flowing through the first flow pathand the water flowing through the second flow pathflow orthogonally to each other. This flow relationship can enhance heat transfer efficiency.

Hereinafter, the first refrigerant partition wall, the first plate-shaped member, the second refrigerant partition wall, the first water partition wall, the second plate-shaped member, and the second water partition wall, which form the heat exchange unit, will be described one by one in order.

is a schematic configuration diagram of the first refrigerant partition wallas viewed from the front.

The first refrigerant partition wallis a plate-shaped member including a flat portion, a water inlet communication port, a water outlet communication port, a refrigerant inlet communication port, and a refrigerant outlet communication port

The flat portionis formed to have a substantially rectangular shape in a front view. Both surfaces on the front side and the rear side of the flat portionare formed of flat surfaces. The water inlet communication portis an opening formed in the vicinity of a lower end portion of the first refrigerant partition wallso as to spread entirely in the left-right direction, and penetrates in the plate thickness direction. The water outlet communication portis an opening formed in the vicinity of an upper end portion of the first refrigerant partition wallso as to spread entirely in the left-right direction, and penetrates in the plate thickness direction. The refrigerant inlet communication portis an opening formed in the vicinity of the upper left of the first refrigerant partition wallso as to spread partially in the vertical direction, and penetrates in the plate thickness direction. The refrigerant outlet communication portis an opening formed in the vicinity of the lower left of the first refrigerant partition wallso as to spread partially in the vertical direction, and penetrates in the plate thickness direction.