JP7545835B2 - Plate Heat Exchanger - Google Patents

Description

The present invention relates to a plate heat exchanger that is constructed by stacking multiple blocks each having a heat exchange element.

A plate-type heat exchanger has been proposed that includes multiple heat exchange bodies in which upper and lower heat exchange plates are joined together (for example, Patent Document 1). Each heat exchange body has an internal space between the upper and lower heat exchange plates through which a heat medium flows, and multiple through holes that pass through the internal space in a non-communicating state and through which the combustion exhaust gas flows in the vertical direction.

The plate heat exchanger in Patent Document 1 is constructed by stacking multiple blocks, each having at least one heat exchange body, in the vertical direction. Vertically adjacent blocks are connected to each other so that a heat medium can flow through them. Furthermore, adjacent blocks are constructed so that the flow direction of the heat medium flowing through one block is different from that of the heat medium flowing through the other block. This lengthens the flow path of the heat medium flowing through the heat exchanger in accordance with the number of block stages, thereby improving thermal efficiency.

In the plate heat exchanger, an inflow pipe that supplies a heat medium is inserted into one opening of the most downstream heat exchanger that constitutes the inlet of the most downstream block located at the most downstream of the gas flow path of the combustion exhaust. Furthermore, an opening is provided in a heat exchanger upstream of the most downstream heat exchanger in the gas flow path of the combustion exhaust at a position corresponding to the other opening of the most downstream heat exchanger. An outflow pipe is inserted from the other opening of the most downstream heat exchanger to one opening of the heat exchanger that constitutes the outlet of the most upstream block, thereby connecting the internal space of the heat exchanger having the outlet to the outflow pipe. Therefore, in this plate heat exchanger, the heat medium that flows from the inflow pipe to the most downstream block flows from the most downstream block to the most upstream block and flows out from the outlet of the most upstream block to the outflow pipe. The heat medium that flows out to the outflow pipe flows down the outflow pipe and flows out to the outside of the plate heat exchanger.

JP 2020-85362 A

When manufacturing the plate-type heat exchanger of Patent Document 1, it is necessary to stack a large number of upper and lower heat exchange plates and join the upper and lower heat exchange plates at predetermined locations with a joining means such as brazing material. Therefore, assembly errors are likely to occur, and the length of the heat exchanger side through which the outlet pipe is inserted varies for each product, and there are cases where the upper end of the outlet pipe is not inserted into the outlet of the most upstream block. If the heat medium flows through the heat exchanger in a state where the upper end of such an outlet pipe does not reach the outlet of the most upstream block, the outlet pipe communicates with the internal space of the heat exchanger downstream of the gas flow path of the combustion exhaust gas from the heat exchanger where the outlet of the most upstream block is provided, and the heat medium is short-circuited and flows out from the heat exchanger downstream of the most upstream block to the outlet pipe. As a result, the amount of heat medium flowing into the most upstream block decreases, resulting in a problem of reduced thermal efficiency.

The present invention has been made to solve the above problems, and the object of the present invention is to provide a plate heat exchanger with high thermal efficiency.

According to the present invention,
A plate heat exchanger configured by stacking a plurality of blocks each having at least one heat exchange element,
The heat exchange body is configured to exchange heat between a heat medium flowing through an internal space of the heat exchange body and a combustion exhaust gas flowing outside the heat exchange body,
Each of the plurality of blocks is provided with an inlet for introducing the heat medium into the block and an outlet for discharging the heat medium from the block,
Adjacent blocks among the plurality of blocks are connected such that the heat medium flows from the outlet of one block to the inlet of the other block;
The adjacent blocks are configured such that a flow direction of the heat medium flowing through the internal space of the heat exchange body of one block is different from that of the heat medium flowing through the interior of the heat exchange body of the other block,
A pipe is inserted from one end side to the other end side in the stacking direction of the heat exchange body so as to penetrate a part of the plate-type heat exchanger,
The other end of the pipe is inserted into one of the inlet and the outlet of the other end block so as to communicate with the internal space of the heat exchange body constituting the other end block in which the pipe is located closest to the other end,
A plate-type heat exchanger is provided in which the opening of the other-end block, through which the other-end end of the piping is inserted, is provided with a standing wall protruding from the edge of the opening toward the internal space of the heat exchange body of a block adjacent to the one end side of the other-end block .

According to the above plate-type heat exchanger, the other-end block has a standing wall that protrudes toward one end at the edge of the opening through which the other end of the piping is inserted. Therefore, even if the other end of the piping does not reach the edge of the opening due to an assembly error, the other end can be inserted into the standing wall. This makes it possible to suppress communication between the internal space of the heat exchange body of blocks other than the other-end block and the piping. Therefore, a decrease in the amount of heat medium flowing into the other-end block can be prevented, and high thermal efficiency can be obtained.

Preferably, in the plate heat exchanger,
a pipe-side positioning portion provided on the pipe and a block-side positioning portion provided on the one end block located closest to the one end are brought into contact with each other, thereby restricting an insertion length of the pipe from the one end block;
The piping is set so that a first length L1 from the piping side positioning portion to the other end opening is longer than a second length L2 from the block side positioning portion to the base end of the erected wall.

In the plate-type heat exchanger described above, the piping is set so that the first length L1 from the piping-side positioning portion to the other-end opening is longer than the second length L2 from the block-side positioning portion to the base end of the erected wall. Therefore, when the piping-side positioning portion abuts against the block-side positioning portion, the other-end opening of the piping can be positioned on the other-end side of the base end of the erected wall. This can reliably prevent communication between the piping and the internal space of other heat exchange bodies other than the heat exchange body of the other-end block.

Preferably, in the plate heat exchanger,
the other end block has a recess that is recessed toward the one end side at a peripheral portion of the opening through which the pipe is inserted,
The piping is set such that the first length L1 is shorter than the total length (L2+L3) of the second length L2 and the depth L3 of the recess.

In the plate-type heat exchanger described above, the piping is set so that the first length L1 is shorter than the total length (L2 + L3) of the second length L2 and the depth L3 of the recess on the periphery of the opening. This makes it possible to prevent the opening on the other end of the piping from protruding beyond the recess when the piping-side positioning part abuts the block-side positioning part. This restricts the amount of protrusion of the piping into the internal space of the heat exchange body in which the opening is provided, so that the other end of the piping can be reliably inserted into the opening of the other end block, and an increase in the flow resistance of the heat medium flowing in the internal space near the opening can be suppressed.

As described above, according to the present invention, even if an assembly error occurs during the manufacture of the plate heat exchanger, the other end of the pipe can be reliably inserted into the opening of the other end block. This makes it possible to prevent communication between the internal space of the heat exchange body other than the heat exchange body of the other end block and the pipe, thereby providing a plate heat exchanger with high thermal efficiency.

FIG. 1 is a schematic, partially cutaway perspective view showing a heat source unit having a heat exchanger according to an embodiment of the present invention. FIG. 2 is a schematic partially exploded perspective view showing a heat exchanger according to an embodiment of the present invention. FIG. 3 is a schematic diagram illustrating the flow of the combustion exhaust gas and the heat transfer medium in the heat exchanger according to the embodiment of the present invention. FIG. 4 is a schematic exploded perspective view showing two heat exchange elements in an upstream region of a gas flow path of the combustion exhaust gas in a heat exchanger according to an embodiment of the present invention. FIG. 5 is a schematic plan view showing an example of the upper surface of one of the heat exchange plates constituting the heat exchange element in the heat exchanger according to the embodiment of the present invention. FIG. 6 is a schematic plan view showing an example of the upper surface of the other heat exchange plate constituting the heat exchange element in the heat exchanger according to the embodiment of the present invention. FIG. 7 is a schematic partial cross-sectional view of an outflow pipe side showing a part of a heat exchanger according to an embodiment of the present invention.

The plate heat exchanger according to this embodiment and the heat source device equipped with the same will be specifically described below with reference to the attached drawings.

As shown in FIG. 1, the heat source device according to this embodiment is a water heater that heats water (heat medium) flowing into the heat exchanger 1 from the inlet pipe 20 with the combustion exhaust gas generated by the burner 31, and supplies the water to a hot water user (not shown), such as a faucet or shower, through the outlet pipe 21. Although not shown, the water heater is built into a casing. Note that other heat mediums (e.g., antifreeze) may also be used as the heat medium.

In this water heater, from the top, a burner body 3 constituting the outer shell of a burner 31, a combustion chamber 2, a heat exchanger 1, and a drain receiver 40 are arranged. In addition, a fan case 4 equipped with a combustion fan that sends a mixture of fuel gas and air into the burner body 3 is arranged on one side (the right side in FIG. 1) of the burner body 3. In addition, an exhaust duct 41 that communicates with the drain receiver 40 is arranged on the other side (the left side in FIG. 1) of the burner body 3. The exhaust duct 41 discharges the combustion exhaust gas discharged into the drain receiver 40 to the outside of the water heater.

In this specification, when the water heater is viewed with the fan case 4 and the exhaust duct 41 each disposed to the side of the burner body 3, the depth direction corresponds to the front-to-back direction, the width direction corresponds to the left-to-right direction, and the height direction corresponds to the up-to-down direction.

The burner body 3 has a roughly oval shape when viewed from above, and is made of, for example, a stainless steel metal. Although not shown, the burner body 3 is open downward.

The gas inlet, which communicates with the fan case 4, protrudes upward from the center of the burner body 3. The burner body 3 is equipped with a planar burner 31 having a downward combustion surface 30. By operating the combustion fan, mixed gas is supplied into the burner body 3.

The burner 31 is of the all-primary air combustion type, and is made of, for example, a ceramic combustion plate with many flame holes (not shown) that open downward, or a combustion mat made of woven metal fibers in a net shape. The mixed gas supplied into the burner body 3 is ejected downward from the downward-facing combustion surface 30 by the supply pressure of the combustion fan. By igniting this mixed gas, a flame is formed on the combustion surface 30 of the burner 31, and combustion exhaust is generated. Therefore, the combustion exhaust ejected from the burner 31 is sent to the heat exchanger 1 via the combustion chamber 2. Next, the combustion exhaust that has passed through the heat exchanger 1 is discharged to the outside of the water heater through the drain receiver 40 and the exhaust duct 41.

In other words, in this heat exchanger 1, the upper side where the burner 31 is provided corresponds to the upstream side of the gas flow path of the combustion exhaust, and the lower side opposite the side where the burner 31 is provided corresponds to the downstream side of the gas flow path of the combustion exhaust.

The combustion chamber 2 has a roughly oval shape when viewed from above. The combustion chamber 2 is made of, for example, a stainless steel metal. The combustion chamber 2 is formed by bending a roughly rectangular metal plate and joining both ends so that it is open at the top and bottom.

As shown in FIG. 2, the heat exchanger 1 has a generally oval shape in a plan view. The heat exchanger 1 is a plate-type heat exchanger in which multiple (here, 13 layers) thin-plate-shaped heat exchange elements 10 are stacked. The heat exchanger 1 may have a housing that covers the periphery thereof.

2 and 3, the heat exchanger 1 is configured by stacking multiple (here, four) blocks 5 having one or more heat exchange bodies 10 in the vertical direction (hereinafter, when these blocks 5 are collectively referred to, they are simply referred to as "blocks 5". Also, according to the gas flow path of the combustion exhaust, the block 5 in the topmost stage is referred to as the "most upstream block 5a", the blocks 5 in the middle stage are referred to as the "first downstream block 5b" and the "second downstream block 5c" from the upstream side, and the block 5 in the bottommost stage is referred to as the "most downstream block 5d"). The most upstream block 5a and the first downstream block 5b are each configured with one heat exchange body 10. The second downstream block 5c is configured with five heat exchange bodies 10 stacked, and the most downstream block 5d is configured with six heat exchange bodies 10 stacked. The heat exchanger 1 may be configured with three or less blocks 5 or five or more blocks 5. As described later, when one block 5 is composed of a plurality of heat exchange bodies 10, water flows in parallel in the same direction inside each heat exchange body 10 constituting one block 5. In addition, adjacent heat exchange bodies 10 in each block 5 are mutually connected so that water flows from below to above. In addition, adjacent blocks 5 are mutually connected so that water flows from below to above. In addition, adjacent blocks 5 are configured so that the flow direction of water flowing inside each heat exchange body 10 in one block 5 is opposite to the flow direction of water flowing inside each heat exchange body 10 in the other block 5. Therefore, the water flow path of each block 5 is folded back between adjacent blocks 5 so that this heat exchanger 1 has four flow paths (four paths) according to the number of stages of blocks 5. As a result, a long water flow path is formed in the heat exchanger 1, and the thermal efficiency can be improved.

Next, the configuration of the heat exchange body 10 will be described. Each heat exchange body 10 is formed by stacking a set of upper heat exchange plate 11 and lower heat exchange plate 12 in the vertical direction, which have a common configuration except for some differences in the configuration such as the positions of the upper and lower through holes and the presence or absence of water holes in the corners, and joining the specified locations described below with a joining means such as brazing material. For this reason, the configuration of one heat exchange body 10 will be mainly described below. Note that each drawing does not necessarily show the actual dimensions, and is not intended to limit the embodiment.

As shown in Figures 2 and 4 to 6, the upper and lower heat exchange plates 11, 12 have a generally oval shape in a plan view. The upper and lower heat exchange plates 11, 12 are formed, for example, from a stainless steel metal plate having a predetermined thickness. The upper and lower heat exchange plates 11, 12 each have a large number of upper through holes 11a and lower through holes 12a formed over substantially the entire surface of the plate except for the corners, and upper through hole flange portions 11c and lower through hole flange portions 12c formed on the periphery of the upper and lower through holes 11a and 12a.

The upper and lower heat exchange plates 11 and 12 are formed with an upper peripheral joint W1 and a lower peripheral joint W2 that protrude upward on their peripheries. The upper and lower peripheral joints W1 and W2 are each formed with an inclined wall that spreads upward at a predetermined angle so that the upper end is located diagonally above and outward from the base end. Therefore, when the upper and lower heat exchange plates 11 and 12 are stacked, the upper heat exchange plate 11 of one heat exchange body 10 is fitted inside the lower heat exchange plate 12. Also, the lower heat exchange plate 12 of the upper heat exchange body 10 is fitted inside the upper heat exchange plate 11 of the heat exchange body 10 adjacent below. Therefore, when multiple upper and lower heat exchange plates 11 and 12 are stacked, the upper and lower heat exchange plates 11 and 12 are arranged so that their peripheral joints W1 and W2 overlap at a predetermined height in the direction of the gas flow path of the combustion exhaust (see FIG. 7).

The upper and lower heat exchange plates 11, 12 are set so that when the lower peripheral joint W2 and the lower peripheral edge of the upper heat exchange plate 11 are joined in one heat exchange body 10, the upper and lower heat exchange plates 11, 12 are separated with a gap of a predetermined height. Also, the upper and lower heat exchange plates 11, 12 are set so that when the upper peripheral joint W1 and the lower peripheral edge of the lower heat exchange plate 12 of the heat exchange body 10 adjacent above are joined, the upper heat exchange plate 11 of the lower heat exchange body 10 and the lower heat exchange plate 12 of the heat exchange body 10 adjacent above are separated with a gap of a predetermined height.

Therefore, by joining the upper and lower heat exchange plates 11, 12, an internal space 14 of a predetermined height is formed (see FIG. 3). In addition, by joining multiple heat exchange bodies 10, an exhaust space 15 of a predetermined height is formed between adjacent heat exchange bodies 10 (see FIG. 3).

In the area excluding the peripheral area of the upper and lower heat exchange plates 11 and 12, the upper and lower through holes 11a and 12a, which are approximately square in plan view, are opened in a staggered pattern at a predetermined interval in the front-rear and left-right directions. The upper and lower through hole flange portions 11c and 12c formed on the peripheral portion of the upper and lower through holes 11a and 12a, which are approximately square in plan view, extend approximately horizontally outward in the circumferential direction from the opening edge of the upper and lower through holes 11a and 12a, and have an approximately square outer shape in plan view. In addition, the upper and lower through holes 11a and 12a, which are approximately pentagonal in plan view, are opened at a predetermined interval in the front-rear or left-right directions in the peripheral area of the upper and lower heat exchange plates 11 and 12. The upper and lower through hole flange portions 11c and 12c formed on the peripheral portion of the upper and lower through holes 11a and 12a, which are approximately pentagonal in plan view, extend approximately horizontally outward in the circumferential direction from the opening edge of the upper and lower through holes 11a and 12a, and have an approximately pentagonal outer shape in plan view. The upper and lower through holes 11a, 12a may have other shapes, such as a substantially circular shape or a substantially elliptical shape. All the upper and lower through holes 11a, 12a may have the same size and shape, and all the upper and lower through hole flange portions 11c, 12c may have the same size and shape.

The upper and lower through holes 11a, 12a and the upper and lower through hole flange portions 11c, 12c are formed at positions corresponding to each other when the upper and lower heat exchange plates 11, 12 are stacked. In addition, the upper and lower through holes 11a, 12a and the upper and lower through hole flange portions 11c, 12c are formed on the bottom surface of the inwardly protruding step portion by drawing so that the opposing upper and lower through hole flange portions 11c, 12c are in surface contact when the upper and lower heat exchange plates 11, 12 are stacked.

Therefore, when the upper and lower heat exchange plates 11, 12 are stacked and the upper and lower through-hole flange portions 11c, 12c are joined by a joining means such as brazing material, the upper and lower through-hole flange portions 11c, 12c form a flange portion 16 that closes the internal space 14 (see FIG. 7). In addition, the upper and lower through-holes 11a, 12a form a through-hole 13 that penetrates the internal space 14 in a non-communicating state.

Except for the upper heat exchange plate 11 of the uppermost heat exchange body 10 (hereinafter referred to as the "upstream heat exchange body 10a"), the upper and lower heat exchange plates 11, 12 each have an upper water hole 11e and a lower water hole 12e in at least one corner. The upper and lower water holes 11e, 12e provided in at least one corner of the upper and lower heat exchange plates 11, 12 forming one heat exchange body 10 are open so as to communicate with the internal space 14 formed between the upper and lower heat exchange plates 11, 12 when the upper and lower heat exchange plates 11, 12 are stacked.

The upper water hole flange portion 11f and the lower water hole flange portion 12f are formed on the periphery of the upper and lower water holes 11e and 12e, respectively, and extend substantially horizontally from the opening edges 11h and 12h of the upper and lower water holes 11e and 12e in the circumferential direction outward. The upper water hole 11e and the upper water hole flange portion 11f are formed at positions corresponding to the lower water hole 12e and the lower water hole flange portion 12f of the adjacent heat exchange body 10 when the adjacent heat exchange body 10 is overlapped. In addition, the upper water hole 11e and the upper water hole flange portion 11f are formed on the upper surface of the step portion protruding outward by drawing so that the opposing upper and lower water hole flange portions 11f and 12f are in surface contact when the upper heat exchange plate 11 and the lower heat exchange plate 12 of the heat exchange body 10 adjacent above are overlapped. Similarly, the lower water passage hole 12e and the lower water passage hole flange portion 12f are formed on the bottom surface of the step portion that protrudes outward by drawing so that the opposing upper and lower water passage hole flange portions 11f, 12f are in surface contact when the lower heat exchange plate 12 and the upper heat exchange plate 11 of the adjacent heat exchange body 10 below are overlapped.

Therefore, when the upper and lower heat exchange plates 11, 12 of adjacent heat exchange bodies 10 are overlapped and the upper and lower water hole flange parts 11f, 12f are joined by a joining means such as brazing material, the upper and lower water hole flange parts 11f, 12f form a water hole flange part 64 that closes the exhaust space 15 between the adjacent heat exchange bodies 10. In addition, the upper and lower water holes 11e, 12e facing each other vertically in the adjacent heat exchange bodies 10 form a water hole 63 that communicates with the internal space 14. In addition, the internal space 14 at the periphery of the upper and lower water holes 11e, 12e is wider in the vertical direction than the other internal spaces 14. Therefore, an upper recess 65 that is concave upward is formed on the periphery of the upper water hole 11e, and a lower recess 66 that is concave downward is formed on the periphery of the lower water hole 12e.

As shown in FIG. 7, the lower water passage hole 12e is opened by burring. Therefore, the lower heat exchange plate 12 has a burring portion (standing wall) 12g that protrudes downward (downstream of the gas flow path of the combustion exhaust) from the opening edge 12h of the lower water passage hole 12e. Therefore, the opening edge 12h of the lower water passage hole 12e constitutes the base end of the burring portion 12g. In addition, when the upper and lower heat exchange plates 11 and 12 are overlapped, the burring portion 12g protrudes downward from the upper water passage hole flange portion 11f of the upper heat exchange plate 11 of the heat exchange body 10 adjacent below. The burring portion protruding downward may be formed in the upper water passage hole 11e of the upper heat exchange plate 11, or may be formed in both the upper and lower water passage holes 11e and 12e.

3, the through holes 13 of the heat exchange bodies 10 are arranged so that the through holes 13 of one heat exchange body 10 in the adjacent heat exchange bodies 10 are offset from the through holes 13 of the other heat exchange body 10 in the left-right direction that perpendicularly intersects with the gas flow path direction of the combustion exhaust. That is, the heat exchange bodies 10 adjacent to each other vertically are arranged so that the projected surface of the through holes 13 of one heat exchange body 10 does not overlap with the through holes 13 of the other heat exchange body 10. Therefore, the combustion exhaust gas flowing from the upstream side passes through the through holes 13 of one heat exchange body 10 and then flows out into the exhaust space 15 between that heat exchange body 10 and the heat exchange body 10 adjacent to it on the downstream side. The combustion exhaust gas flowing out into the exhaust space 15 collides with the upper heat exchange plate 11 of the heat exchange body 10 adjacent to the downstream side, and flows further downstream from the through holes 13 of the heat exchange body 10 adjacent to the downstream side. That is, when the combustion exhaust gas flows from the upstream side to the downstream side in the heat exchanger 1, a zigzag gas flow path is formed in the heat exchanger 1. This increases the contact time between the combustion exhaust gas and the upper and lower heat exchange plates 11 and 12 in the heat exchanger 1.

Next, referring to FIG. 3, the flow of the combustion exhaust gas and water in the heat exchanger 1 will be described. Each block 5 has an inlet 71 for introducing water into the block 5 and an outlet 72 for discharging water to the outside of the block 5. The inlet 71 is formed by a predetermined lower water hole 12e of the heat exchange body 10 located at the most downstream of the gas flow path of the combustion exhaust gas in each block 5. The outlet 72 is formed by a predetermined upper water hole 11e of the heat exchange body 10 located at the most upstream of the gas flow path of the combustion exhaust gas in each block 5b, 5c, 5d other than the most upstream block 5a, and a predetermined lower water hole 12e of the heat exchange body 10 in the most upstream block 5a. In addition, in order to avoid complication, some components such as the flange portion 16 and the burring portion 12g are omitted in FIG. 3.

An inlet pipe 20 is connected to a lower water hole 12e in a right front corner of the lower heat exchange plate 12 forming the heat exchange body 10 (hereinafter referred to as the "lowest-stream heat exchange body 10s") located at the most downstream of the gas flow path of the combustion exhaust gas. An outlet pipe 21 extending upward from the most downstream heat exchange body 10s to the most upstream heat exchange body 10a is inserted into the lower water hole 12e in a right rear corner of the lower heat exchange plate 12 forming the most downstream heat exchange body 10s so as to penetrate a part of the heat exchanger 1. The upper end of the outlet pipe 21 is inserted into the lower water hole 12e in a right rear corner of the lower heat exchange plate 12 forming the most upstream heat exchange body 10a. In this embodiment, the most downstream heat exchange element 10s corresponds to one end of the heat exchange element 10 in the stacking direction, the most upstream heat exchange element 10a corresponds to the other end of the heat exchange element 10 in the stacking direction, the most upstream block 5a corresponds to the other end block on the other end side, and the most downstream block 5d corresponds to the one end block on the one end side. Also, the outlet 72 of the most upstream block 5a corresponds to the opening through which the other end of the piping is inserted.

The upper end opening of the outflow pipe 21 is connected to the internal space 14 of the most upstream heat exchange body 10a. In addition, when the outflow pipe 21 is inserted from the most downstream heat exchange body 10s to the most upstream heat exchange body 10a, the outflow pipe 21 penetrates the internal space 14 of the heat exchange body 10 other than the most upstream heat exchange body 10a and all the exhaust spaces 15 between the adjacent heat exchange bodies 10 in a non-communicating state.

Therefore, water flowing into the internal space 14 of each heat exchange body 10 of the most downstream block 5d from the lower water passage hole 12e (inlet 71) at the front right corner flows in one left-right direction within the internal space 14 (from right to left in FIG. 3). Water flowing into the internal space 14 of each heat exchange body 10 of the second downstream block 5c through the upper and lower water passage holes 11e, 12e (outlet 72 and inlet 71) at both the front and rear left corners flows in one left-right direction within the internal space 14 (from left to right in FIG. 3). The flow direction of water circulating through the internal space 14 of the heat exchange body 10 of the second downstream block 5c is opposite to that of the most downstream block 5d. In addition, water flowing into the internal space 14 of the heat exchange body 10 of the first downstream block 5b (hereinafter referred to as the "second heat exchange body 10b") through the upper and lower water passage holes 11e, 12e (outlet 72 and inlet 71) at the front right corner flows in one direction in the left-right direction (from right to left in FIG. 3) in the internal space 14. The flow direction of water flowing through the internal space 14 of this second heat exchange body 10b is opposite to that of the second downstream block 5c. In addition, water flowing into the internal space 14 of the most upstream heat exchange body 10a through the upper and lower water passage holes 11e, 12e (outlet 72 and inlet 71) at both front and rear corners on the left side flows in one direction in the left-right direction (from left to right in FIG. 3). The flow direction of water flowing through the internal space 14 of this most upstream heat exchange body 10a is opposite to that of the second heat exchange body 10b. The water flowing through the internal space 14 of the most upstream heat exchange body 10a flows out into the outlet pipe 21 inserted into the lower water passage hole 12e (outlet 72) at the right rear corner of the most upstream heat exchange body 10a. The water flowing out into the outlet pipe 21 flows down the outlet pipe 21 and flows out to the outside of the heat exchanger 1. In this way, the most upstream heat exchange body 10a and the second heat exchange body 10b in the upstream area of the gas flow path of the combustion exhaust gas are connected in series so that all water flowing into the second heat exchange body 10b flows into the most upstream heat exchange body 10a. In addition, the multiple heat exchange bodies 10 of the most downstream block 5d are connected in parallel so that multiple parallel flow paths are formed. The second downstream block 5c has a similar configuration to the most downstream block 5d.

Next, a method for manufacturing the heat exchanger 1 of this embodiment will be described. One lower frame plate 101, a predetermined number of upper and lower heat exchange plates 11 and 12, and one upper frame plate 102 are stacked while supplying a joining means such as brazing material to predetermined locations of these plates. Although not shown, the outer diameter of the burring portion 12g of the lower water passage hole 12e is set slightly smaller than the inner diameter of the corresponding opening of the lower frame plate 101.

Next, the upper end of the inlet pipe 20, which is the first pipe, is inserted through the lower water passage hole 12e at the front right side of the most downstream heat exchange body 10s through the opening of the lower frame plate 101. Also, the outlet pipe 21, which is the second pipe, is inserted upward from the lower water passage hole 12e at the rear right side of the most downstream heat exchange body 10s through another opening of the lower frame plate 101. Then, a joining means such as brazing material is supplied to the outer circumferential surface of the inlet pipe 20 inserted through the lower water passage hole 12e at the front right side of the most downstream heat exchange body 10s and the outer circumferential surface of the outlet pipe 21 inserted through the lower water passage hole 12e at the rear right side of the most downstream heat exchange body 10s to prepare a subassembly. The heat exchanger 1 can be manufactured by putting this subassembly into a furnace and performing a brazing process.

Figure 7 is a schematic partial cross-sectional view of the outflow pipe 21 side showing a part of the heat exchanger 1 of this embodiment. Note that in Figure 7, only the configuration of the upstream and downstream regions of the gas flow path of the combustion exhaust gas is shown, but the configuration of the midstream region is similar. As shown in Figure 7, the outflow pipe 21 has a small diameter portion 21a having a constant outer diameter from the upper end to the vicinity of the lower end, and a large diameter portion 21b having an outer diameter larger than the outer diameter of the small diameter portion 21a near the lower end. The small diameter portion 21a of the outflow pipe 21 has an outer diameter that is approximately the same as the inner diameter of the upper and lower water passage holes 11e, 12e. In addition, the large diameter portion 21b of the outflow pipe 21 has an outer diameter larger than the outer diameter of the burring portion 12g. Therefore, when the outflow pipe 21 is inserted from the bottom to the top, the upper end of the large diameter portion 21b abuts against the lower end of the burring portion 12g provided in the lower water passage hole 12e of the lower heat exchange plate 12 of the most downstream heat exchange body 10s. This restricts the insertion length of the outflow pipe 21 into the heat exchanger 1. Therefore, the upper end of the large diameter portion 21b of the outflow pipe 21 constitutes the piping side positioning portion, and the lower end of the burring portion 12g constitutes the block side positioning portion.

In addition, in this embodiment, the first length L1 of the small diameter portion 21a from the upper end of the large diameter portion 21b to the upper end of the outflow pipe 21 is set to be longer than the second length L2 from the lower end of the burring portion 12g provided in the lower water passage hole 12e of the lower heat exchange plate 12 of the most downstream heat exchange body 10s to the opening edge 12h of the lower water passage hole 12e of the lower heat exchange plate 12 of the most upstream heat exchange body 10a that forms the outlet 72 of the most upstream block 5a, and shorter than the total length (L2 + L3) of the second length L2 and the depth L3 of the lower recess 66 on the periphery of the lower water passage hole 12e.

As mentioned above, in the plate-type heat exchanger 1, which is constructed by stacking a large number of upper and lower heat exchange plates 11, 12, the length from the lower water passage hole 12e of the lower heat exchange plate 12 of the most downstream heat exchange body 10s to the lower water passage hole 12e of the lower heat exchange plate 12 of the most upstream heat exchange body 10a (i.e., the outlet 72 of the most upstream block 5a) is likely to vary depending on the product due to assembly errors. For this reason, when a single-diameter outlet pipe 21 is used, even if the outlet pipe 21 is inserted into the heat exchanger 1 for a predetermined length, the upper end of the outlet pipe 21 may not reach the lower water passage hole 12e of the lower heat exchange plate 12 of the most upstream heat exchange body 10a depending on the product. Therefore, the internal space 14 of the heat exchange body 10 downstream of the most upstream block 5a is connected to the outlet pipe 21, and water from the internal space 14 of the downstream heat exchange body 10 is short-circuited to the outlet pipe 21 and flows out. As a result, the amount of water flowing into the most upstream block 5a is reduced, and the thermal efficiency is reduced.

However, according to this embodiment, the lower heat exchange plate 12 of the most upstream heat exchange body 10a that forms the outlet 72 of the most upstream block 5a has a burring portion 12g that protrudes downstream from the opening edge 12h of the lower water hole 12e. Therefore, even if the upper end of the outflow pipe 21 is inserted only to a position below the opening edge 12h of the lower water hole 12e due to an assembly error, the upper end of the outflow pipe 21 can be inserted into the burring portion 12g. This makes it possible to prevent water from short-circuiting and flowing out from the heat exchange body 10 downstream of the most upstream block 5a to the outflow pipe 21. Therefore, a reduction in the amount of water flowing into the most upstream block 5a is prevented, and high thermal efficiency can be obtained.

It is also possible to lengthen the insertion length of the outflow pipe 21 into the heat exchanger 1, but assembly errors may result in a shorter length from the lower water passage hole 12e of the lower heat exchange plate 12 of the most downstream heat exchange body 10s to the lower water passage hole 12e of the lower heat exchange plate 12 of the most upstream heat exchange body 10a. Therefore, if the insertion length of the outflow pipe 21 is lengthened, the outflow pipe 21 will protrude significantly into the internal space 14 of the most upstream heat exchange body 10a, blocking the internal space 14. As a result, there is a risk that the flow resistance of the water will increase and the thermal efficiency will decrease.

However, according to this embodiment, the upper end of the large diameter portion 21b provided near the lower end of the outflow pipe 21 abuts against the lower end of the burred portion 12g provided in the lower water passage hole 12e of the lower heat exchange plate 12 of the most downstream heat exchange body 10s, thereby restricting the insertion of the outflow pipe 21 into the heat exchanger 1. The first length L1 of the small diameter portion 21a of the outflow pipe 21 is longer than the second length L2 from the lower end of the burred portion 12g provided in the lower water passage hole 12e of the lower heat exchange plate 12 of the most downstream heat exchange body 10s, with which the upper end of the large diameter portion 21b abuts, to the opening edge 12h of the lower water passage hole 12e of the lower heat exchange plate 12 of the most upstream heat exchange body 10a. Therefore, when the small diameter portion 21a of the outflow pipe 21 is inserted into the heat exchanger 1 until the upper end of the large diameter portion 21b abuts against the lower end of the burred portion 12g provided in the lower water passage hole 12e of the lower heat exchange plate 12 of the most downstream heat exchange body 10s, the upper end opening of the outflow pipe 21 is positioned at least above the opening edge 12h of the lower water passage hole 12e. This makes it possible to reliably prevent water from short-circuiting and flowing out from the heat exchange body 10 downstream of the most upstream block 5a to the outflow pipe 21, even if an assembly error occurs.

In addition, according to this embodiment, the first length L1 of the small diameter portion 21a of the outflow pipe 21 is set to be shorter than the total length (L2 + L3) of the second length L2 and the depth L3 of the lower recess 66 of the periphery of the lower water hole 12e. Therefore, when the upper end of the large diameter portion 21b abuts against the lower end of the burring portion 12g provided in the lower water hole 12e of the lower heat exchange plate 12 of the most downstream heat exchange body 10s, the upper end opening of the outflow pipe 21 is located above the opening edge 12h of the lower water hole 12e of the lower heat exchange plate 12 of the most upstream heat exchange body 10a and below the upper end of the lower recess 66. As a result, even if the outflow pipe 21 protrudes into the internal space 14 of the most upstream heat exchange body 10a, the flow resistance of the water flowing through the internal space 14 is prevented from increasing, and water can be smoothly discharged from the heat exchange body 10 of the most upstream block 5a to the outflow pipe 21. This can further improve the thermal efficiency.

In this embodiment, water flows into the downstream block 5d from the inlet pipe 20 connected to the inlet 71 of the downstream block 5d, which is the end block on the most one end side, and flows out from the outlet pipe 21 connected to the outlet 72 of the upstream block 5a, which is the other end block on the most other end side. However, the flow of the heat medium may be in the opposite direction. That is, the heat medium may flow into the upstream block 5a and flow out from the downstream block 5d. In this case, the inlet pipe 20 constitutes the outlet pipe, and the outlet pipe 21 constitutes the inlet pipe. Also, the lower water passage hole 12e of the lower heat exchange plate 12 of the upstream heat exchange body 10a constitutes the inlet.

(Other embodiments)
(1) In the above embodiment, the most upstream block is formed from one heat exchange body. However, the most upstream block may be formed from a plurality of heat exchange bodies. In this case, a predetermined lower water passage hole of the heat exchange body located at the most downstream position among the plurality of heat exchange bodies constituting the most upstream block forms the outlet. In this heat exchanger, the first length L1 of the piping is preferably set to be longer than the second length L2 and shorter than the total length (L2 + L3) of the second length L2 and the depth L3 of the recess. This prevents an increase in the flow resistance of the heat medium, and allows the heat medium to smoothly flow out of the internal space of the heat exchange body located at the most downstream position of the most upstream block into the piping.

(2) In the above embodiment, a burner with a downward-facing combustion surface is disposed above the heat exchanger. However, a burner with an upward-facing combustion surface may be disposed below the heat exchanger. In this case, the flow path of the combustion exhaust gas is reversed up and down, so that the top heat exchanger corresponds to the most downstream heat exchanger, and the bottom heat exchanger corresponds to the most upstream heat exchanger. The combustion exhaust gas may also flow left and right through the plate heat exchanger.

(3) In the above embodiment, multiple heat exchange bodies are stacked vertically. However, multiple heat exchange bodies may be stacked horizontally.

(4) In the above embodiment, a water heater is used, but a heat source such as a boiler may also be used.

Reference Signs List 1 Plate heat exchanger 5 Block 10 Heat exchange body 12h Opening edge 14 Internal space 21 Outlet pipe 71 Inlet 72 Outlet

Claims (3)

A plate heat exchanger configured by stacking a plurality of blocks each having at least one heat exchange element,
The heat exchange body is configured to exchange heat between a heat medium flowing through an internal space of the heat exchange body and a combustion exhaust gas flowing outside the heat exchange body,
Each of the plurality of blocks is provided with an inlet for introducing the heat medium into the block and an outlet for discharging the heat medium from the block,
Adjacent blocks among the plurality of blocks are connected such that the heat medium flows from the outlet of one block to the inlet of the other block;
The adjacent blocks are configured such that a flow direction of the heat medium flowing through the internal space of the heat exchange body of one block is different from that of the heat medium flowing through the interior of the heat exchange body of the other block,
A pipe is inserted from one end side to the other end side in the stacking direction of the heat exchange body so as to penetrate a part of the plate-type heat exchanger,
The other end of the pipe is inserted into one of the inlet and the outlet of the other end block so as to communicate with the internal space of the heat exchange body constituting the other end block in which the pipe is located closest to the other end,
a plate-type heat exchanger in which the opening of the other-end block, through which the other end side end of the piping is inserted, is provided with a standing wall protruding from the edge of the opening toward the internal space of the heat exchange body of a block adjacent to the one end side of the other-end block . 2. The plate heat exchanger according to claim 1,
a pipe-side positioning portion provided on the pipe and a block-side positioning portion provided on the one end block located closest to the one end are brought into contact with each other, thereby restricting an insertion length of the pipe from the one end block;
The plate-type heat exchanger is configured such that a first length L1 of the piping from the piping side positioning portion to the other end opening is longer than a second length L2 of the piping from the block side positioning portion to the base end of the erected wall. 3. The plate heat exchanger according to claim 2,
the other end block has a recess that is recessed toward the one end side at a peripheral portion of the opening through which the pipe is inserted,
The plate heat exchanger, wherein the piping is set such that the first length L1 is shorter than the total length (L2+L3) of the second length L2 and the depth L3 of the recess.

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