WATER HEAT EXCHANGER

A water heat exchanger includes: a first layer and a second layer that are stacked upon each other and that exchange heat between a first fluid and a second fluid. The first fluid is water. The second fluid is a refrigerant. The first layer includes first flow paths disposed in a plurality of rows and through which the first fluid flows. The second layer includes second flow paths disposed in a plurality of rows and through which the second fluid flows. When the first layer is viewed in a stacking direction of the first layer and the second layer, each of the first flow paths extends from one end portion to another end portion of the first layer in a direction crossing an arrangement direction of the first flow paths.

TECHNICAL FIELD

The present invention relates to a water heat exchanger, and, particularly, to a water heat exchanger including a first layer and a second layer that are stacked upon each other, and exchanging heat between a first fluid and a second fluid. The first layer has first flow paths formed in a plurality of rows and through which water as the first fluid flows. The second layer has second flow paths formed in a plurality of rows and through which a refrigerant as the second fluid flows.

BACKGROUND

Hitherto, water heat exchangers that exchange heat between water as the first fluid and a refrigerant (such as a chlorofluorocarbon refrigerant, a natural refrigerant, and brine) as the second fluid have been used in, for example, heat-pump air-conditioning devices and heat-pump hot water supply devices. As described in Patent Literature 1 (Japanese Unexamined Patent Application Publication No. 2010-117102), there exists a type of such water heat exchangers including first layers and second layers that are stacked upon each other. Each first layer has first flow paths formed in a plurality of rows and through which the first fluid flows. Each second layer has second flow paths formed in a plurality of rows and through which the second fluid flows.

The above-described water heat exchanger known in the art can realize higher performance and can be made compact as a result of reducing the flow-path cross-sectional area of each first flow path and the flow-path cross-sectional area of each second flow path.

However, when the flow-path cross-sectional area of each first flow path and the flow-path cross-sectional area of each second flow path are made too small, for example, an increase in pressure loss and clogging of the flow paths are concerns. Therefore, it is becoming necessary to, for example, appropriately form the shapes of the flow paths that can, for example, suppress an increase in pressure loss and clogging of the flow paths.

PATENT LITERATURE

Patent Literature 1

Japanese Unexamined Patent Application Publication No. 2010-117102

SUMMARY

One or more embodiments of the present invention provide a water heat exchanger that suppresses an increase in pressure loss and clogging of flow paths by appropriately forming the shapes of the flow paths. The water heat exchanger includes a first layer and a second layer that are stacked upon each other, and exchanges heat between a first fluid and a second fluid. The first layer has first flow paths formed in a plurality of rows and through which water as the first fluid flows. The second layer has second flow paths formed in a plurality of rows and through which a refrigerant as the second fluid flows.

A water heat exchanger according to one or more embodiments includes a first layer and a second layer that are stacked upon each other, and exchanges heat between a first fluid and a second fluid, the first layer having first flow paths formed in a plurality of rows and through which water as the first fluid flows, the second layer having second flow paths formed in a plurality of rows and through which a refrigerant as the second fluid flows. When the first layer is viewed in a stacking direction of the first layer and the second layer, each first flow path extends from one end portion to another end portion of the first layer in a direction crossing a direction of arrangement of the first flow paths. When the second layer is viewed in the stacking direction, each second flow path extends from one end portion to another end portion of the second layer in a direction crossing a direction of arrangement of the second flow paths. Here, when the first fluid is to be heated by the second fluid, the first flow paths are formed so that a flow-path cross-sectional area of a first-fluid outlet vicinity positioned in a vicinity of an outlet for the first fluid is larger than a flow-path cross-sectional area of an upstream-side portion disposed upstream of the first-fluid outlet vicinity.

Here, as described above, since the flow-path cross-sectional area of the first-fluid outlet vicinity of the first flow paths is larger than the flow-path cross-sectional area of the upstream-side portion, disposed upstream of the first-fluid outlet vicinity, of the first flow paths, it is possible to make it less likely for scale deposited when the first fluid is heated to clog the first-fluid outlet vicinity, while a reduction in thermal conductivity caused by a reduction in the flow velocity of the first fluid in the first flow paths is limited to only the first-fluid outlet vicinity. In this way, here, clogging of the first flow paths of the water heat exchanger can be suppressed, while a reduction in thermal conductivity is minimized.

A water heat exchanger according to one or more embodiments is the water heat exchanger according to the above-described embodiments, in which the first flow paths are merged so that the number of flow paths at the first-fluid outlet vicinity is less than the number of flow paths at the upstream-side portion disposed upstream of the first-fluid outlet vicinity.

Here, as described above, by merging the first flow paths so that the number of flow paths at the first-fluid outlet vicinity is less than the number of flow paths at the upstream-side portion disposed upstream of the first-fluid outlet vicinity, the flow-path cross-sectional area of the first-fluid outlet vicinity can be made larger than the flow-path cross-sectional area of the upstream-side portion disposed upstream of the first-fluid outlet vicinity.

A water heat exchanger according to one or more embodiments includes a first layer and a second layer that are stacked upon each other, and exchanges heat between a first fluid and a second fluid, the first layer having first flow paths formed in a plurality of rows and through which water as the first fluid flows, the second layer having second flow paths formed in a plurality of rows and through which a refrigerant as the second fluid flows. When the first layer is viewed in a stacking direction of the first layer and the second layer, each first flow path extends from one end portion to another end portion of the first layer in a direction crossing a direction of arrangement of the first flow paths. When the second layer is viewed in the stacking direction, each second flow path extends from one end portion to another end portion of the second layer in a direction crossing a direction of arrangement of the second flow paths. Here, when the first fluid is to be cooled by the second fluid, the second flow paths are formed so that a flow-path cross-sectional area of a second-fluid outlet vicinity positioned in a vicinity of an outlet for the second fluid is larger than a flow-path cross-sectional area of an upstream-side portion disposed upstream of the second-fluid outlet vicinity.

Here, as described above, since the flow-path cross-sectional area of the second-fluid outlet vicinity of the second flow paths is larger than the flow-path cross-sectional area of the upstream-side portion, disposed upstream of the second-fluid outlet vicinity, of the second flow paths, the second fluid containing a large amount of gas component that increases due to evaporation can smoothly flow in the second-fluid outlet vicinity, while a reduction in thermal conductivity caused by a reduction in the flow velocity of the second fluid in the second flow paths is limited to only the second-fluid outlet vicinity. In this way, here, an increase in pressure loss in the second flow paths of the water heat exchanger can be suppressed, while a reduction in thermal conductivity is minimized.

A water heat exchanger according to one or more embodiments is the water heat exchanger according to the above-described embodiments, in which the second flow paths are merged so that the number of flow paths at the second-fluid outlet vicinity is less than the number of flow paths at the upstream-side portion disposed upstream of the second-fluid outlet vicinity.

Here, as described above, by merging the second flow paths so that the number of flow paths at the second-fluid outlet vicinity is less than the number of flow paths at the upstream-side portion disposed upstream of the second-fluid outlet vicinity, the flow-path cross-sectional area of the second-fluid outlet vicinity can be made larger than the flow-path cross-sectional area of the upstream-side portion disposed upstream of the second-fluid outlet vicinity.

A water heat exchanger according to one or more embodiments is the water heat exchanger according to the above-described embodiments, in which the second flow paths are branched so that the number of flow paths at the second-fluid outlet vicinity is larger than the number of flow paths at the upstream-side portion disposed upstream of the second-fluid outlet vicinity.

Here, as described above, by branching the second flow paths so that the number of flow paths at the second-fluid outlet vicinity is larger than the number of flow paths at the upstream-side portion disposed upstream of the second-fluid outlet vicinity, the flow-path cross-sectional area of the second-fluid outlet vicinity can be made larger than the flow-path cross-sectional area of the upstream-side portion disposed upstream of the second-fluid outlet vicinity. Moreover, here, since this configuration makes the number of flow paths at the vicinity of the inlet for the second fluid smaller, it is possible to properly maintain the distribution performance in the second flow paths for the second fluid.

A water heat exchanger according to one or more embodiments is the water heat exchanger according to the above-described embodiments, in which when the first fluid is to be cooled by the second fluid, the second flow paths are formed so that a flow-path cross-sectional area of a second-fluid outlet vicinity positioned in a vicinity of an outlet for the second fluid is larger than a flow-path cross-sectional area of an upstream-side portion disposed upstream of the second-fluid outlet vicinity.

Here, as described above, since the flow-path cross-sectional area of the second-fluid outlet vicinity of the second flow paths is larger than the flow-path cross-sectional area of the upstream-side portion, disposed upstream of the second-fluid outlet vicinity, of the second flow paths, the second fluid containing a large amount of gas component that increases due to evaporation can smoothly flow in the second-fluid outlet vicinity, while a reduction in thermal conductivity caused by a reduction in the flow velocity of the second fluid in the second flow paths is limited to only the second-fluid outlet vicinity. In this way, here, an increase in pressure loss in the second flow paths of the water heat exchanger can be suppressed, while a reduction in thermal conductivity is minimized.

DETAILED DESCRIPTION

Embodiments and modifications thereof of a water heat exchanger according to the present invention are described below on the basis of the drawings. Specific structures of the water heat exchanger according to the present invention are not limited to those of the embodiments and the modifications thereof below and are changeable within a scope that does not depart from the spirit of the invention.

(1) Structures and Characteristics

FIGS. 1 to 4each show a water heat exchanger1according to one or more embodiments of the present invention.

The water heat exchanger1is a heat exchanger that exchanges heat between water as a first fluid and a refrigerant as a second fluid in, for example, a heat-pump air-conditioning device and a heat-pump hot water supply device. In the description below, with reference to a near-side surface in a sheet plane of the water heat exchanger1shown inFIGS. 1 to 3, expressions indicating directions, such as “up”, “down”, “left”, “right”, “vertical”, and “horizontal” are used. However, these expressions are used for convenience of description, and do not indicate the actual arrangement of the water heat exchanger1and structural portions thereof.

The water heat exchanger1primarily includes a casing2in which a heat exchanging unit3that exchanges heat between the first fluid and the second fluid is provided, a first pipe4aand a first pipe4bthat are an outlet and an inlet for the first fluid, respectively, and a second pipe5aand a second pipe5bthat are each an inlet and an outlet for the second fluid.

The heat exchanging unit3includes first layers10and second layers20that are stacked upon each other. Each first layer10has first flow paths11formed in a plurality of rows and through which the first fluid flows. Each second layer20has second flow paths21formed in a plurality of rows and through which the second fluid flows. Here, the direction in which the first layers10and the second layers20are stacked upon each other (here, a direction from the near side in the sheet plane to a far side in the sheet plane ofFIGS. 1 to 3) is defined as a stacking direction. The direction in which the plurality of first flow paths11are arranged side by side (here, a left-right direction in the sheet plane ofFIG. 2) is defined as a direction of arrangement of the first flow paths11, and the direction in which the plurality of second flow paths21are arranged side by side (here, an up-down direction in the sheet plane ofFIG. 3) is defined as a direction of arrangement of the second flow paths21. When the first layers10are viewed in the stacking direction of the first layers10and the second layers20, each first flow path11extends from one end portion of the first layer10(an upper end portion of the first layer10inFIG. 2) to another end portion of the first layer10(a lower end portion of the first layer10inFIG. 2) in a direction crossing the direction of arrangement of the first flow paths11(here, the up-down direction or a vertical direction in the sheet plane ofFIG. 2). When the second layers20are viewed in the stacking direction of the first layers10and the second layers20, each second flow path21extends from one end portion of the second layer20(a left end portion of the second layer20inFIG. 3) to another end portion of the second layer20(a right end portion of the second layer20inFIG. 3) in a direction crossing the direction of arrangement of the second flow paths21(here, the left-right direction or a horizontal direction in the sheet plane inFIG. 3). In this way, here, the first flow paths11and the second flow paths20are arranged so as to allow cross-flows.

Here, the heat exchanging unit3having the first layers10and the second layers20that are stacked upon each other includes first plates12and second plates22that are alternately stacked upon each other. Grooves that form the first flow paths11are formed in one surface of each first plate12. Grooves that form the second flow paths21are formed in one surface of each second plate22. Each first plate12and each second plate22are made of a metallic material. The grooves that form the first flow paths11and the grooves that form the second flow paths21are formed by, for example, machining or etching the first plates12and the second plates22, respectively. After stacking predetermined numbers of the first plates12and the second plates22, each being grooved thus, the first plates12and the second plates22are joined to each other by a joining process, such as diffusion joining, to form the heat exchanging unit3including the first layers10and the second layers20that are stacked upon each other. Here, although the grooves that form the flow paths11are formed in one surface of each first plate12and the grooves that form the flow paths21are formed in one surface of each second plate22, it is not limited thereto. Each first plate12may have grooves that form the flow paths11,21in both surfaces thereof, and/or each second plate22may have grooves that form the flow paths11,21in both surfaces thereof.

Here, the first pipe4ais disposed at an upper portion of the casing2, and the first pipe4bis disposed at a lower portion of the casing2. The casing2includes a first header6disposed at the upper portion of the casing2and having a space that allows upper end portions of the first flow paths11to merge, and a first header7disposed at the lower portion of the casing2and having a space that allows lower end portions of the first flow paths11to merge. The first pipe4acommunicates with the upper end portions of the first flow paths11via the first header6, and the first pipe4bcommunicates with the lower end portions of the first flow paths11via the first header7. Here, the second pipe5ais disposed on a left portion of the casing2, and the second pipe5bis disposed on a right portion of the casing2. The casing2includes a second header8disposed at the left portion of the casing2and having a space that allows left end portions of the second flow paths21to merge, and a second header9disposed at the right portion of the casing2and having a space that allows right end portions of the second flow paths21to merge. The second pipe5acommunicates with the left end portions of the second flow paths21via the second header8, and the second pipe5bcommunicates with the right end portions of the second flow paths21via the second header9.

In the water heat exchanger1having such a structure, for example, when the first fluid is to be heated by the second fluid, the first pipe4bcan be the inlet for the first fluid, the first pipe4acan be the outlet for the first fluid, the second pipe5bcan be the inlet for the second fluid, and the second pipe5acan be the outlet for the second fluid. In this case, the water heat exchanger1functions as a heat exchanger in which the first fluid flows through the first flow paths11from bottom to top and is heated and in which the second fluid flows through the second flow paths21from right to left and is cooled. In the water heat exchanger1, for example, when the first fluid is to be cooled by the second fluid, the first pipe4bcan be the inlet for the first fluid, the first pipe4acan be the outlet for the first fluid, the second pipe5acan be the inlet for the second fluid, and the second pipe5bcan be the outlet for the second fluid. In this case, the water heat exchanger1functions as a heat exchanger in which the first fluid flows through the first flow paths11from the bottom to the top and is cooled and in which the second fluid flows through the second flow paths21from the left to the right and is heated.

Here, when water as the first fluid is to be heated by the second fluid, each first flow path11is formed so that a flow-path cross-sectional area S11aof a first-fluid outlet vicinity11apositioned in the vicinity of the outlet for the first fluid is larger than a flow-path cross-sectional area S11b of an upstream-side portion11bdisposed upstream of the first-fluid outlet vicinity11a. Specifically, by forming each first flow path11so that a flow-path width W11a of the first-fluid outlet vicinity11aof each first flow path11is larger than a flow-path width W11b of each upstream-side portion11bdisposed upstream of the first-fluid outlet vicinity11a, each flow-path cross-sectional area S11a is made larger than its corresponding flow-path cross-sectional area S11b. The first-fluid outlet vicinity11arefers to a portion that is disposed closer to the outlet and that has a flow-path length which is 20% to 50% of the flow-path length from an inlet side of the first flow path11(here, an end portion on a side of the first pipe4b) to an outlet side of the first flow path11(here, an end portion on a side of the first pipe4a).

Here, when the first fluid is to be cooled by a refrigerant as the second fluid, each second flow path21is formed so that a flow-path cross-sectional area521aof a second-fluid outlet vicinity21apositioned in the vicinity of the outlet for the second fluid is larger than a flow-path cross-sectional area521bof an upstream-side portion21bdisposed upstream of the second-fluid outlet vicinity21a.Specifically, by forming each second flow path21so that a flow-path width W21a of the second-fluid outlet vicinity21aof each second flow path21is larger than a flow-path width W21b of each upstream-side portion21bdisposed upstream of the second-fluid outlet vicinity21a,each flow-path cross-sectional area S211a is made larger than its corresponding flow-path cross-sectional area S21b. The second-fluid outlet vicinity21arefers to a portion that is disposed closer to the outlet and that has a flow-path length which is 20% to 50% of the flow-path length from an inlet side of the second flow path21(here, an end portion on a side of the second pipe5a) to an outlet side of the second flow path21(here, an end portion on a side of the second pipe5b).

In such a water heat exchanger1, as described above, when water as the first fluid is to be heated by the second fluid, since the flow-path cross-sectional area S11a of the first-fluid outlet vicinity11aof each first flow path11is larger than that of the upstream-side portion11b, disposed upstream of the first-fluid outlet vicinity11a,of each first flow path11, it is possible to make it less likely for scale deposited when the first fluid is heated to clog the first-fluid outlet vicinities11a,while a reduction in thermal conductivity caused by a reduction in the flow velocity of the first fluid in the first flow paths11is limited to only the first-fluid outlet vicinities11a. In this way, here, clogging of the first flow paths11of the water heat exchanger1can be suppressed, while a reduction in thermal conductivity is minimized.

In such a water heat exchanger1, as described above, when the first fluid is to be cooled by a refrigerant as the second fluid, since the flow-path cross-sectional area S21a of the second-fluid outlet vicinity21aof each second flow path21is larger than that of the upstream-side portion21b,disposed upstream of the second-fluid outlet vicinity21a,of each second flow path21, the second fluid containing a large amount of gas component that increases due to evaporation can smoothly flow in each second-fluid outlet vicinity21a,while a reduction in thermal conductivity caused by a reduction in the flow velocity of the second fluid in the second flow paths21is limited to only the second-fluid outlet vicinities21a.In this way, here, an increase in pressure loss in the second flow paths21of the water heat exchanger1can be suppressed, while a reduction in thermal conductivity is minimized.

In the water heat exchanger1of the above-described embodiments, when water as the first fluid is to be heated by the second fluid, the flow-path cross-sectional area S11a of the first-fluid outlet vicinity11aof each first flow path11is larger than that of each upstream-side portion11bdisposed upstream of the first-fluid outlet vicinity11a.Moreover, in the water heat exchanger1of the above-described embodiments, when the first fluid is to be cooled by a refrigerant as the second fluid, the flow-path cross-sectional area S21a of the second-fluid outlet vicinity21aof each second flow path21is larger than that of each upstream-side portion21bdisposed upstream of the second-fluid outlet vicinity21a.However, it is not limited thereto. Only the first flow paths11or the second flow paths21may have a structure in which the flow-path cross-sectional area of each fluid outlet vicinity is larger than that of each upstream-side portion disposed upstream of the fluid outlet vicinity.

For example, when the first fluid is to be cooled by a refrigerant as the second fluid, as shown inFIG. 3, the flow-path cross-sectional area S21a of the second-fluid outlet vicinity21aof each second flow path21may be made larger than that of the upstream-side portion21bdisposed upstream of the second-fluid outlet vicinity21a,and, as shown inFIG. 5, the flow-path cross-sectional area (here, the flow-path width) of each first flow path11may be the same from the inlet side to the outlet side of each first flow path11.

For example, when water as the first fluid is to be heated by the second fluid, as shown inFIG. 2, the flow-path cross-sectional area S11a of the first-fluid outlet vicinity11a of each first flow path11may be made larger than that of the upstream-side portion11bdisposed upstream of the first-fluid outlet vicinity11a,and, as shown inFIG. 6, the flow-path cross-sectional area (here, the flow-path width) of each second flow path21may be the same from the inlet side to the outlet side of each second flow path21.

This structure of the present modification can also provide operational effects similar to those of the above-described embodiments.

Although, in the water heat exchangers1of the above-described embodiments and Modification 1, the first flow paths11and the second flow paths21are arranged so as to allow cross-flows, it is not limited thereto.

For example, each second flow path21extending from the one end portion of the second layer20(the left end portion of the second layer20inFIG. 3) to the other end portion of the second layer20(the right end portion of the second layer20inFIG. 3) in the horizontal direction may be caused to extend from one end portion of the second layer20(a lower end portion of the second layer20inFIG. 8) to another end portion of the second layer20(an upper end portion of the second layer20inFIG. 8) in the vertical direction as shown inFIGS. 7 and 8, to arrange the first flow paths11and the second flow paths21so as to allow counter-flows (or parallel flows). In this case, the second pipe5aand the second header8are disposed at the lower portion of the casing2, and the second pipe5band the second header9are disposed at the upper portion of the casing2. This structure functions as a heat exchanger in which, when the first fluid is to be heated by the second fluid, the first fluid flows through the first flow paths11from the bottom to the top and is heated, and the second fluid flows through the second flow paths21from the top to the bottom and is cooled. This structure also functions as a heat exchanger in which, when the first fluid is to be cooled by the second fluid, the first fluid flows through the first flow paths11from the bottom to the top and is cooled, and the second fluid flows through the second flow paths21from the bottom to the top and is heated.

This structure of the present modification can also provide operational effects similar to those of the above-described embodiments and Modification 1.

Although, in the water heat exchangers1of the above-described embodiments and Modification 1, the first flow paths11and the second flow paths21are arranged so as to allow cross-flows, it is not limited thereto. For example, the second flow paths21may be divided into a plurality of flow path groups and these flow path groups may be connected in series, to arrange the first flow paths11and the second flow paths21so as to allow orthogonal counter-flows (or orthogonal parallel flows). Specifically, in the structure shown inFIG. 9, the second flow paths21are divided into three flow path groups21A,21B, and21C in the direction of arrangement of the second flow paths21(here, in the up-down direction in the sheet plane inFIG. 9). For example, by arranging a partitioning member in the second header9, the space in the second header9is divided into a space9athat communicates with the second pipe5band the right end portions of the second flow paths21of the flow path group21A and a space9bthat communicates with the right end portions of the second flow paths21of the flow path groups21B and21C. Further, for example, by arranging a partitioning member in the second header8, the space in the second header8is divided into a space8athat communicates with the second pipe5aand the left end portions of the second flow paths21of the flow path group21C and a space8bthat communicates with the left end portions of the second flow paths21of the flow path groups21A and21B. Therefore, the flow path groups21A,21B, and21C of the second flow paths21are connected in series via the second headers8and9and are arranged so that the first flow paths11and the second flow paths21allow orthogonal counter-flows (or orthogonal parallel flows). This structure functions as a heat exchanger in which, when the first fluid is to be heated by the second fluid, the first fluid flows through the first flow paths11from the bottom to the top and is heated, and the second fluid flows through the second flow paths21from the top to the bottom in the order of the flow path group21A, the flow path group21B and the flow path group21C while the second fluid makes turns leftwards and rightwards, and is cooled. This structure functions as a heat exchanger in which, when the first fluid is to be cooled by the second fluid, the first fluid flows through the first flow paths11from the bottom to the top and is cooled, and the second fluid flows through the second flow paths21from the bottom to the top in the order of the flow path group21C, the flow path group21B and the flow path group21A while the second fluid makes turns leftwards and rightwards, and is heated. In this case, the flow path group21A positioned in the vicinity of the outlet for the second fluid is defined as second-fluid outlet vicinity21aand the flow path groups21B and21C are defined as upstream-side portion21bdisposed upstream of the second-fluid outlet vicinity21a.The flow-path width W21a of each second flow path21of the flow path group21A is made larger than the flow-path width W21b of each second flow path21of the flow path groups21B and21C. Therefore, when the first fluid is to be cooled by a refrigerant as the second fluid, the second flow paths21can be formed so that the flow-path cross-sectional area S21a of the second-fluid outlet vicinity21ais larger than the flow-path cross-sectional area S21b of the upstream-side portion21bdisposed upstream of the second-fluid outlet vicinity21a.

Although, in the structure shown inFIG. 9, the space in the second header8is partitioned into the spaces8aand8band the space in the second header9is partitioned into the spaces9aand9bso that the flow path groups21A,21B, and21C are connected in series, it is not limited thereto. For example, as shown inFIG. 10, a connecting flow path29ahaving the same function as the space8bmay be disposed on the left end portions of the second flow paths21, and a connecting flow path29bhaving the same function as the space9bmay be disposed on the right end portions of the second flow paths21. That is, the connecting flow path29athat makes the left end portions of the second flow paths21of the flow path group21A and the left end portions of the second flow paths21of the flow path groups21B communicate with each other and the connecting flow path29bthat makes the right end portions of the second flow paths21of the flow path group21B and the right end portions of the second flow paths21of the flow path group21C communicate with each other are formed in the second layer20. Here, grooves that form the connecting flow paths29aand29bcan be formed in the second plate22. In this case, the second header8can have a space only corresponding to the space8aas shown inFIG. 9, and the second header9can have a space only corresponding to the space9aas shown inFIG. 9.

This structure of the present modification can also provide operational effects similar to those of the above-described embodiments and Modification 1.

In the water heat exchangers1of the above-described embodiments and Modifications1to3, when water as the first fluid is to be heated by the second fluid, each first flow path11is formed so that the flow-path width W11a of the first-fluid outlet vicinity11a,positioned in the vicinity of the outlet for the first fluid, of each first flow path11is larger than the flow-path width W11b of the upstream-side portion lib, disposed upstream of the first-fluid outlet vicinity11a,of each first flow path11. Therefore, when water as the first fluid is to be heated by the second fluid, the flow-path cross-sectional area S11a of each first-fluid outlet vicinity11a is larger than the flow-path cross-sectional area S11b of each upstream-side portion11bdisposed upstream of the first-fluid outlet vicinity11a,to suppress clogging of outlet vicinity portions of the first flow paths11caused by deposition of scale.

However, the structure for forming the first flow paths11so that, when water as the first fluid is to be heated by the second fluid, the flow-path cross-sectional area S11a of the first-fluid outlet vicinity11ais larger than the flow-path cross-sectional area S11b of the upstream-side portion11bdisposed upstream of the first-fluid outlet vicinity11ais not limited thereto.

Specifically, when water as the first fluid is to be heated by the second fluid, the first flow paths11may be merged so that the number of flow paths at the first-fluid outlet vicinities11aof the first flow paths11is less than the number of flow paths at the upstream-side portions, disposed upstream of the first-fluid outlet vicinities11a,of the first flow paths11. For example, as shown inFIG. 11, by merging two first flow paths11adjacent to each other in the direction of arrangement of the first flow paths11into one first flow path11at the first-fluid outlet vicinity11a,the flow-path width W11a of the first-fluid outlet vicinity11aafter the first flow paths11have been merged may be made larger than the total of the flow-path widths W11b of the upstream-side portions11b,disposed upstream of the first-fluid outlet vicinity11a, before the first flow paths11have been merged. Therefore, when water as the first fluid is to be heated by the second fluid, the flow-path cross-sectional area S11a of the first-fluid outlet vicinity11aafter the first flow paths11have been merged can be made larger than the total of the flow-path cross-sectional areas S11b of the upstream-side portions11b,disposed upstream of the first-fluid outlet vicinity11a,before the first flow paths11have been merged.

In the water heat exchangers1of the above-described embodiments and Modifications1to4, when the first fluid is to be cooled by a refrigerant as the second fluid, each second flow path21is formed so that the flow-path width W21a of the second-fluid outlet vicinity21a, positioned in the vicinity of the outlet for the second fluid, of the second flow path21is larger than the flow-path width W21b of the upstream-side portion21bdisposed upstream of the second-fluid outlet vicinity21a.Therefore, when the first fluid is to be cooled by a refrigerant as the second fluid, the flow-path cross-sectional area S21a of each second-fluid outlet vicinity21ais larger than the flow-path cross-sectional area S21b of each upstream-side portion21bdisposed upstream of the second-fluid outlet vicinity21a,to suppress an increase in pressure loss in the second flow paths21caused by an increase in the amount of gas component flowing in the second flow paths21due to evaporation of the second fluid.

However, the structure for forming the second flow paths21so that, when the first fluid is to be cooled by a refrigerant as the second fluid, the flow-path cross-sectional area S21a of the second-fluid outlet vicinity21ais larger than the flow-path cross-sectional area S21b of the upstream-side portion21bdisposed upstream of the second-fluid outlet vicinity21ais not limited thereto.

Specifically, when the first fluid is to be cooled by a refrigerant as the second fluid, the second flow paths21may be merged so that the number of flow paths at the second-fluid outlet vicinities21ais less than the number of flow paths at the upstream-side portions disposed upstream of the second-fluid outlet vicinities21a.For example, as shown inFIG. 12, by merging two second flow paths21adjacent to each other in the direction of arrangement of the second flow paths21into one second flow path21at the second-fluid outlet vicinities21a,the flow-path width W21a of the second-fluid outlet vicinity21aafter the second flow paths21have been merged may be made larger than the total of the flow-path widths W21b of the upstream-side portions21b,disposed upstream of the second-fluid outlet vicinity21a,before the second flow paths21have been merged. Therefore, the flow-path cross-sectional area S21aof the second-fluid outlet vicinity21aafter the second flow paths21have been merged can be made larger than the total of the flow-path cross-sectional areas S21b of the upstream-side portions21b,disposed upstream of the second-fluid outlet vicinity21a,before the second flow paths21have been merged.

In contrast to the structure shown inFIG. 12in which the flow-path cross-sectional area S21a is made larger than the total of the flow-path cross-sectional areas S21b by merging the second flow paths21at the second-fluid outlet vicinities21a,the total of the flow-path cross-sectional areas S21a may be made larger than the total of the flow-path cross-sectional areas S21b by branching the second flow paths21so that the number of flow paths at the second-fluid outlet vicinity21ais larger than the number of flow paths at the upstream-side portion21bdisposed upstream of the second-fluid outlet vicinity21a.For example, in the structure, such as that of Modification 3 above, in which the second flow paths21are divided into the plurality of flow path groups21A,21B, and21C and in which these flow path groups21A,21B, and21C are connected in series, as shown inFIG. 13, the flow path group21A positioned in the vicinity of the outlet for the second fluid may be defined as a second-fluid outlet vicinity21a,the flow path groups21B and21C may be defined as an upstream-side portion21bdisposed upstream of the second-fluid outlet vicinity21a,and the number N21a of the second flow paths21of the flow path group21A may be larger than the number N21b of the flow paths of the flow path groups21B and21C. Here, the flow-path widths W21a and W21b (the flow-path cross-sectional areas S21a and S21b) of the second flow paths21are equal to each other, and the flow-path cross-sectional area S21a of the flow path group21A and the total of the flow-path cross-sectional areas S21b of the flow path groups21B and21C are changed by changing the number of flow paths. In this way, the structure in which the number N21a of flow paths at the second-fluid outlet vicinity21ais larger than the number N21a of flow paths at the upstream-side portion21bdisposed upstream of the second-fluid outlet vicinity21anot only suppresses an increase in pressure loss in the second flow paths21of the water heat exchanger1, but also can properly maintain the distribution performance in the second flow paths21for the second fluid by reducing the number of flow paths near the inlet for the second fluid. In particular, when, not only the number N21a of flow paths of the flow path group21A is made larger than the number N21b of flow paths of the flow path groups21B and21C disposed upstream of the flow path group21A, but also the number of flow paths of each flow path group is decreased in the order of the flow path group21A, the flow path group21B, and the flow path group21C, that is, the number of flow paths are decreased as a distance from the inlet for the second fluid decreases, the distribution performance of the second flow paths21for the second fluid is effectively improved.

INDUSTRIAL APPLICABILITY

One or more embodiments of the present invention can be widely applied to a water heat exchanger that includes a first layer and a second layer that are stacked upon each other, with the first layer having first flow paths formed in a plurality of rows and through which water as a first fluid flows and the second layer having second flow paths formed in a plurality of rows and through which a refrigerant as a second fluid flows and that exchanges heat between the first fluid and the second fluid.

REFERENCE SIGNS LIST