JP7382202B2 - plate heat exchanger - Google Patents

Description

The present invention has a plurality of heat exchange bodies that perform heat exchange between a first fluid flowing inside and a second fluid flowing outside, and a plate type configured by stacking a plurality of heat exchange bodies. Regarding heat exchangers.

Conventionally, a plate heat exchanger including a plurality of heat exchange bodies in which an upper heat exchange plate and a lower heat exchange plate are joined has been proposed (for example, Patent Document 1). Each heat exchange body has an internal space in which a heat medium, which is a first fluid, flows between an upper heat exchange plate and a lower heat exchange plate, and a combustion exhaust gas, which is a second fluid, that passes through the internal space in a non-communicating state. has a plurality of through holes that communicate in the vertical direction.

The plate heat exchanger is constructed by vertically stacking a plurality of blocks each having at least one heat exchanger. Further, blocks adjacent in the vertical direction are communicated with each other so that a heat medium can flow therethrough. Furthermore, adjacent blocks are configured such that the flow path direction of the heat medium flowing through one block is different from that of the heat medium flowing through the other block. Thereby, the flow path of the heat medium flowing in the heat exchanger becomes longer in accordance with the number of stages of blocks, and thermal efficiency can be improved.

Korean Registered Patent No. 10-1608149

By the way, in a heat exchanger such as the one described above in which the through hole passes through the internal space in a non-communicating state, the peripheral edge of the through hole through which combustion exhaust gas passes is heated the most. Therefore, in order to increase thermal efficiency, it is preferable that the heat exchanger has a structure in which the heat of the combustion exhaust is efficiently transferred to the heat medium at the peripheral edge of the through hole.

In addition, in a plate heat exchanger in which multiple heat exchangers are stacked, the projected plane of the through holes of one heat exchanger is the same as the throughhole of the other heat exchanger when viewed from the gas flow path direction of the combustion exhaust gas. By forming adjacent heat exchange bodies so that they do not overlap, the gas flow path of combustion exhaust gas within the heat exchanger becomes longer, and thermal efficiency can be improved.

However, in a heat exchanger having the through-hole arrangement structure as described above, the through-holes of the upstream heat exchanger face the projected surface of the downstream heat exchanger where no through-holes are formed. Therefore, the combustion exhaust gas that has passed through the through holes of the upstream heat exchanger first collides with the projected surface on one side of the downstream heat exchanger, and then spreads onto the one side of the downstream heat exchanger. , further flows downstream from the through holes of the heat exchanger on the downstream side. Therefore, in the upstream region of the combustion exhaust gas flow path through which high-temperature combustion exhaust flows, the part of the downstream heat exchanger that faces the through hole of the upstream heat exchanger, that is, the part of the downstream heat exchanger that There is a problem in that the periphery of the hole is heated concentratedly, causing local heat. In particular, in the downstream heat exchanger adjacent to the most upstream heat exchanger in the combustion exhaust gas flow path, the most upstream heat exchanger does not exchange heat with the heat medium flowing inside the most upstream heat exchanger. Local heat is likely to occur because the high-temperature combustion exhaust flowing through the through holes of the heat exchanger collides with each other.

The present invention has been made to solve the above problems, and an object of the present invention is to improve thermal efficiency and prevent local heating of the heat exchanger in the upstream region of the second fluid flow path. be.

According to the invention,
A plate heat exchanger comprising a plurality of heat exchange bodies that perform heat exchange between a first fluid flowing inside and a second fluid flowing outside, and configured by stacking the plurality of heat exchange bodies. There it is,
The heat exchange body includes a plurality of through holes formed so that the second fluid flows outside the heat exchange body in a direction intersecting a flow path surface of the first fluid flowing inside the heat exchange body. has
Adjacent heat exchange bodies are formed such that a projected surface of the through hole of one heat exchange body does not overlap with the through hole of the other heat exchange body when viewed from the flow path direction of the second fluid,
The plurality of heat exchange bodies include a heat exchange body (P) having a variable part in which the height of the flow path of the first fluid varies on the projection plane, and a heat exchange body (P) having a variable part in which the height of the flow path of the first fluid fluctuates on the projection plane, and a heat exchange body (P) having a variable part in which the height of the flow path of the first fluid fluctuates, and a heat exchanger (Q) having only a flat portion in which the height of the flow path is substantially constant;
The second heat exchanger adjacent to the downstream side of the most upstream heat exchanger located at the most upstream side of the flow path of the second fluid is provided by a plate heat exchanger constituted by the heat exchanger (Q). be done.

According to the heat exchanger, the heat exchanger (P) has a variable portion in which the height of the flow path of the first fluid varies in the projection plane of the through hole of the adjacent heat exchanger, so that the height of the flow path of the first fluid varies. The flow path resistance increases, and the flow rate of the first fluid flowing inside the projection surface decreases. Moreover, since turbulence of the first fluid occurs when the first fluid passes through the inside of the projection surface, the temperature distribution of the first fluid can be made small. Furthermore, since the surface area of the heat exchanger (P) is increased by the variable portion, the heat receiving area of the heat exchanger (P) is increased. Thereby, the heat received from the second fluid can be efficiently transferred to the first fluid.

On the other hand, in the upstream region of the second fluid flow path, the high-temperature second fluid that has passed through the through hole of the most upstream heat exchanger concentrates on the small-area projection surface of the second heat exchanger. When the variable portion is formed on the projection surface as described above, the flow rate of the first fluid flowing inside the projection surface is likely to decrease. Therefore, if all the heat exchangers are composed of heat exchangers (P) having variable parts, local overheating is likely to occur in the projection plane of the through holes of the most upstream heat exchanger projected onto the second heat exchanger. . However, according to the above-mentioned heat exchanger, the second heat exchange body is a heat exchange body ( Q), the flow path resistance of the first fluid flowing inside the projection surface of the heat exchanger (Q) is smaller than that when it passes through the projection surface of the heat exchanger (P). Therefore, the flow rate of the first fluid flowing inside the projection surface of the heat exchanger (Q) increases. Moreover, since the flat part has no unevenness, the second fluid colliding with the flat part spreads uniformly in all directions. Thereby, concentration of heat on the projection surface of the second heat exchanger can be alleviated.
Moreover, when the projection plane of the through-hole of one heat exchange body is formed in the peripheral part of the other heat exchange body, the through-hole is not formed at least on the peripheral part side of the projection plane. On the other hand, on the projection plane other than the peripheral edge of the heat exchanger, through holes are formed on all sides. Therefore, the amount of heat received from the second fluid increases on the projection surface surrounded by through holes on all sides. As a result, in the heat exchanger in the upstream region of the second fluid flow path, local overheating tends to occur in the projection plane other than the peripheral edge. Therefore, if the flat portion is formed on the projection plane excluding at least the peripheral portion of the heat exchanger (Q), local overheating can be effectively prevented.

Preferably, in the heat exchanger,
The most upstream heat exchanger is composed of the heat exchanger (Q).

According to the heat exchanger, local overheating of the most upstream heat exchanger with which the high-temperature second fluid collides can be prevented.

Preferably, in the heat exchanger,
The second heat exchanger and the most upstream heat exchanger are connected in series so that the first fluid flows through the second heat exchanger and the most upstream heat exchanger in this order.

According to the heat exchanger, all the first fluid flowing through the second heat exchange body flows through the most upstream heat exchange body. Thereby, even when the flow rate of the first fluid supplied to the heat exchanger is small, local overheating of the most upstream heat exchanger and the second exchanger can be effectively prevented.

Preferably, in the heat exchanger,
The through hole of the heat exchanger (Q) has a substantially rectangular shape,
The rectangular through hole is arranged such that at least one vertex projects onto the projection plane.

According to the heat exchanger, the flow rate of the first fluid flowing inside the projection surface becomes faster. Thereby, local overheating can be further prevented.

As described above, according to the present invention, thermal efficiency can be improved and local heating of the heat exchanger in the upstream region of the second fluid flow path can be prevented. Therefore, according to the present invention, it is possible to provide a plate heat exchanger having high thermal efficiency and excellent durability.

FIG. 1 is a schematic partially cutaway perspective view showing a heat source device 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 first fluid and the second fluid in the heat exchanger according to the embodiment of the present invention. FIG. 4 is a schematic partially exploded perspective view showing 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 heat exchange plate constituting the heat exchange body (P) 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 that constitutes the heat exchange body (P) in the heat exchanger according to the embodiment of the present invention. FIG. 7 is a schematic partially exploded perspective view showing the most upstream heat exchanger and the second heat exchanger in the heat exchanger according to the embodiment of the present invention. FIG. 8 is a schematic plan view showing an example of the upper surface of one heat exchange plate constituting the heat exchange body (Q) in the heat exchanger according to the embodiment of the present invention. FIG. 9 is a schematic plan view showing an example of the upper surface of the other heat exchange plate that constitutes the heat exchange body (Q) in the heat exchanger according to the embodiment of the present invention. FIG. 10 is a schematic partial sectional view of a heat exchanger according to an embodiment of the present invention.

Hereinafter, a plate heat exchanger and a heat source device including the same according to the present embodiment will be specifically described with reference to the accompanying drawings.

As shown in FIG. 1, the heat source device according to the present embodiment converts water (first fluid) flowing into the heat exchanger 1 from the inflow pipe 20 into combustion exhaust (second fluid) generated by the burner 31. This is a water heater that heats the hot water and supplies it to hot water users (not shown) such as showers and showers through an outflow pipe 21. Although not shown, the water heater is incorporated within the casing. Note that another heat medium (for example, antifreeze) may be used as the first fluid.

In this water heater, a burner body 3 forming an outer shell of a burner 31, a combustion chamber 2, a heat exchanger 1, and a drain receiver 40 are arranged in order from the top. Moreover, a fan case 4 including a combustion fan that feeds a mixed gas of fuel gas and air into the burner body 3 is disposed on one side of the burner body 3 (on the right side in FIG. 1). Further, on the other side of the burner body 3 (on the left side in FIG. 1), an exhaust duct 41 communicating with the drain receiver 40 is provided. The exhaust duct 41 discharges 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 arranged on the sides of the burner body 3, the depth direction corresponds to the front-rear direction, and the width direction corresponds to the left-right direction. The height direction corresponds to the vertical direction.

The burner body 3 has a generally oval shape in plan view, and is made of, for example, stainless steel metal. Although not shown, the burner body 3 is open downward.

A gas introduction part communicating with the fan case 4 projects upward from the center of the burner body 3. The burner body 3 includes a planar burner 31 having a downward combustion surface 30. A mixed gas is supplied into the burner body 3 by operating the combustion fan.

The burner 31 is an all-primary air combustion type, and is made of, for example, a ceramic combustion plate having a large number of flame holes (not shown) that open downward, or a combustion mat made of metal fibers woven into a net. 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 gas is generated. Therefore, the combustion exhaust emitted from the burner 31 is sent to the heat exchanger 1 via the combustion chamber 2. Next, the combustion exhaust gas 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.

That is, 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 gas, and the lower side opposite to the side where the burner 31 is provided corresponds to the gas flow path of the combustion exhaust gas. Corresponds to the downstream side of the road.

The combustion chamber 2 has a generally oval shape in plan view. The combustion chamber 2 is made of, for example, stainless metal. The combustion chamber 2 is formed by curving a substantially rectangular metal plate and joining both ends so as to be open vertically.

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

As shown in FIGS. 2 to 4, the heat exchanger 1 is configured by vertically stacking a plurality of (four stages in this case) blocks 5 each having one or more heat exchangers 10 (hereinafter referred to as When these blocks 5 are collectively referred to, they are simply referred to as "blocks 5." Also, according to the combustion exhaust gas flow path, the uppermost block 5 is referred to as the "most upstream block 5a," and the middle blocks 5 are referred to in order from the upstream side. "first downstream block 5b", "second downstream block 5c", and the lowest block 5 is referred to as "most downstream block 5d"). The most upstream block 5a and the first downstream block 5b each include one heat exchanger 10. Further, the second downstream block 5c is configured by stacking five heat exchange bodies 10, and the most downstream block 5d is configured by stacking six heat exchange bodies 10. Note that the heat exchanger 1 may be composed of three or less blocks 5 or five or more blocks 5. As will be described later, when one block 5 is composed of a plurality of heat exchangers 10, water flows in parallel in the same direction inside each heat exchanger 10 that constitutes one block 5. Adjacent heat exchangers 10 in each block 5 are interconnected so that water flows from below to above. Further, adjacent blocks 5 are interconnected so that water flows from below to above. Further, in the adjacent blocks 5, the flow path direction of water flowing inside each heat exchanger 10 in one block 5 is opposite to the flow path direction of water flowing inside each heat exchanger 10 in the other block 5. It is configured to be oriented. Therefore, in this heat exchanger 1, the direction of the water flow path is turned back for each block 5 so that the water flow path within the heat exchanger 1 has four passes depending on the number of stages of the blocks 5. Thereby, a long water flow path is formed in the heat exchanger 1, and thermal efficiency can be improved.

Next, the configuration of the heat exchanger 10 will be explained. As shown in FIGS. 2 to 9, each heat exchanger 10 has the same basic configuration such as size and shape, but the heat exchanger 10 of the second downstream block 5c and the most downstream block 5d and the most upstream block 5a and the heat exchanger 10 of the first downstream block 5b are different in configuration, such as the shape of the through hole and the presence or absence of a variable part, which will be described later (hereinafter, when the heat exchanger 10 is referred to generically, it will simply be referred to as "heat exchanger 10"). In addition, when the heat exchanger 10 of the second downstream block 5c and the most downstream block 5d is collectively referred to as a "heat exchanger (P)", the heat exchanger 10 of the most upstream block 5a and the first downstream block 5b is When the exchanger 10 is collectively referred to as a "heat exchanger (Q)"). Therefore, below, the structure of the heat exchanger (P) will be explained first, and the structure of the heat exchanger (Q) that is different from the heat exchanger (P) will be mainly explained. Note that each drawing does not necessarily show actual dimensions and does not limit the embodiments.

The heat exchangers (P) of the second downstream block 5c and the most downstream block 5d have a common configuration except for some differences such as the positions of the upper and lower through holes and the presence or absence of water holes in the corners. It is formed by vertically overlapping a set of upper heat exchange plates 11 and lower heat exchange plates 12 having the same structure, and joining them at predetermined locations described below using joining means such as brazing material. As shown in FIGS. 4 to 6, the upper and lower heat exchange plates 11 and 12 of the heat exchanger (P) have a substantially oval shape in plan view. The upper and lower heat exchange plates 11 and 12 are formed, for example, from stainless steel metal plates having a predetermined thickness. The upper and lower heat exchange plates 11 and 12 each have a large number of substantially circular upper and lower through holes 11a and 12a on substantially the entire surface of the plate excluding the corner portions, and upper and lower through hole flange portions formed at the peripheries of the upper and lower through holes 11a and 12a. 11c and 12c. Note that the upper and lower through holes 11a and 12a may have other shapes such as a substantially elliptical shape or a substantially rectangular shape.

Upper and lower peripheral edge joining portions W1 and W2 that protrude upward are formed on the peripheral edges of the upper and lower heat exchange plates 11 and 12, respectively. The lower peripheral edge joint W2 of the lower heat exchange plate 12 is such that when the lower peripheral edge joint W2 and the lower surface peripheral edge of the upper heat exchange plate 11 are joined, the upper and lower heat exchange plates 11 and 12 have a gap of a predetermined height. It is set to be spaced apart.

Further, the upper peripheral edge joint W1 of the upper heat exchange plate 11 is formed when the upper peripheral edge joint W1 and the lower surface peripheral edge of the lower heat exchange plate 12 of the upperly adjacent heat exchange body (P) are joined together. The upper heat exchange plate 11 of the heat exchanger (P) and the lower heat exchange plate 12 of the upper heat exchanger (P) are set to be separated by a gap of a predetermined height.

Therefore, by joining the lower peripheral edge joint W2 of the lower heat exchange plate 12 and the lower surface peripheral edge of the upper heat exchange plate 11, an internal space 14 of a predetermined height is formed (see FIG. 3). Moreover, by joining a plurality of heat exchange bodies (P), an exhaust space 15 of a predetermined height is formed between vertically adjacent heat exchange bodies (P) (see FIG. 3).

The upper and lower through holes 11a and 12a of the heat exchanger (P) are respectively opened in a grid pattern at predetermined intervals in the front and rear and left and right directions over substantially the entire surface of the upper and lower heat exchange plates 11 and 12, excluding the four corners. . Further, the upper and lower through-hole flange portions 11c and 12c are formed so as to extend substantially horizontally outward in the circumferential direction from the opening edges of the upper and lower through-holes 11a and 12a, and to have a substantially regular octagonal outer shape in plan view. Note that in this embodiment, the upper and lower through holes 11a and 12a have the same size and shape. However, if the pair of upper and lower through-holes 11a and 12a that face each other in the vertical direction are formed to have the same size and shape, the upper and lower through-holes 11a and 12a will be different from those of the other pair of upper and lower through-holes 11a and 12a. May be different.

The upper and lower through holes 11a and 12a and the upper and lower through hole flange portions 11c and 12c are respectively formed at positions corresponding to each other when the upper and lower heat exchange plates 11 and 12 are stacked. Further, the upper and lower through-holes 11a and 12a and the upper and lower through-hole flange parts 11c and 12c are drawn so that when the upper and lower heat exchange plates 11 and 12 are overlapped, the opposing upper and lower through-hole flange parts 11c and 12c come into surface contact. It is formed on the bottom surface of the stepped portion that protrudes inward.

Therefore, when the upper and lower through-hole flange parts 11c and 12c are joined by a joining means such as brazing material with the upper and lower heat exchange plates 11 and 12 superimposed, the internal space 14 is closed by the upper and lower through-hole flange parts 11c and 12c. A closing flange portion 16 is formed (see FIG. 10). Further, a through hole 13 is formed by the upper and lower through holes 11a and 12a, which penetrates the internal space 14 in a non-communicating state.

Approximately circular upper and lower recesses 11b and 12b are formed between four upper and lower through holes 11a and 12a that are adjacent to each other in the front and rear and left and right directions, respectively. Further, at the peripheries of the upper and lower heat exchange plates 11 and 12, upper and lower recesses 11b and 12b, which are approximately elliptical in plan view, are formed between two upper and lower through holes 11a and 12a that are adjacent in the front and rear or left and right directions. In addition, upper and lower convex portions 11d and 12d having smaller diameters than the upper and lower concave portions 11b and 12b are formed in the center portions of these upper and lower concave portions 11b and 12b. These upper and lower concave portions 11b and 12b and upper and lower convex portions 11d and 12d are respectively formed at positions corresponding to each other when the upper and lower heat exchange plates 11 and 12 are stacked. Therefore, the upper and lower concave portions 11b and 12b and the upper and lower convex portions 11d and 12d are respectively formed in a lattice shape at predetermined intervals in the front-rear and left-right directions over substantially the entire surface of the upper and lower heat exchange plates 11 and 12 except for the four corners. There is. Further, the distances in the longitudinal and lateral directions between the adjacent upper and lower recesses 11b and 12b are set to be approximately the same as those between the adjacent upper and lower through holes 11a and 12a. For this reason, the upper and lower through holes 11a and 12a and the upper and lower recesses 11b and 12b are formed alternately at approximately equal intervals in the front-rear and left-right directions. Further, the upper and lower recesses 11b and 12b are located approximately at the center of the area surrounded by the four upper and lower through holes 11a and 12a adjacent in the front and rear and left and right directions, excluding the peripheries of the upper and lower heat exchange plates 11 and 12, respectively. is formed. Further, each of the upper and lower recesses 11b and 12b has a diameter smaller than the shortest distance between the upper and lower through-hole flange parts 11c and 12c that are adjacent to each other in the front-back and left-right directions.

The upper and lower recesses 11b and 12b are respectively formed by drawing so that they protrude inwardly into the internal space 14 by a predetermined height when the upper and lower heat exchange plates 11 and 12 are stacked on top of each other. The inward protrusion height of the upper and lower recesses 11b and 12b is set lower than that of the upper and lower through-hole flange parts 11c and 12c. Further, the upper and lower convex portions 11d and 12d are each formed by drawing so as to protrude outward from the internal space 14 by a predetermined height when the upper and lower heat exchange plates 11 and 12 are stacked on top of each other. Therefore, when the upper and lower heat exchange plates 11 and 12 are overlapped, the upper and lower recesses 11b and 12b form a variable portion 17 that reduces the height of the internal space 14, and a narrow internal space with a predetermined height is formed between the upper and lower recesses 11b and 12b. A space 14 is formed (see FIG. 10). Further, a variable portion 18 that increases the height of the internal space 14 is formed by the vertical convex portions 11d and 12d formed at the center of the vertical concave portions 11b and 12b, and a predetermined height is wide between the vertical convex portions 11d and 12d. An internal space 14 is formed (see FIG. 10). Further, although not shown, a water flow path is formed between the variable portion 17 and the adjacent flange portion 16. Note that the upper and lower concave portions 11b and 12b and the upper and lower convex portions 11d and 12d may have other shapes such as a substantially elliptical shape or a substantially rectangular shape. Furthermore, only one of the variable parts 17 and 18 may be formed.

The upper and lower heat exchange plates 11 and 12 of the heat exchanger (P) each have a water passage hole 63 and a water passage flange portion protruding outward from the periphery of the water passage hole 63 in at least one corner. has. The water passage hole 63 provided in at least one corner of the upper and lower heat exchange plates 11 and 12 forming one heat exchanger (P) allows for upper and lower heat exchange when the upper and lower heat exchange plates 11 and 12 are overlapped. It opens so as to communicate with an internal space 14 formed between plates 11 and 12.

As shown in FIGS. 2 to 3 and 7 to 9, the heat exchanger (Q) has different shapes in the upper and lower through holes 11a and 12a and the upper and lower through hole flange portions 11c and 12c, and in the front and rear and left and right directions. No vertical concave portions or vertical convex portions are formed in the area surrounded by the four adjacent vertical through holes 11a and 12a, and two vertical through holes adjacent in the front and rear or left and right directions are formed at the periphery of the upper and lower heat exchange plates 11 and 12. The heat exchanger has no upper and lower recesses between the holes 11a and 12a, and no water passage holes are formed in the upper heat exchange plate 11 that forms the most upstream heat exchanger (Q). It has the same configuration as (P). Furthermore, the heat exchangers (Q) of the most upstream block 5a and the first downstream block 5b are different in some configurations, such as the positions of the upper and lower through holes 11a and 12a and the presence or absence of water passage holes 63 in the corner parts. A pair of upper heat exchange plates 11 and lower heat exchange plates 12 having the same configuration except for the above are stacked vertically and are formed by joining them at predetermined locations using joining means such as brazing material. Therefore, by joining the upper and lower heat exchange plates 11 and 12 that constitute the heat exchanger (Q), an internal space 14 of a predetermined height is formed (see FIG. 3). Moreover, by joining a plurality of heat exchange bodies (Q), an exhaust space 15 of a predetermined height is formed between vertically adjacent heat exchange bodies (Q) (see FIG. 3). In addition, by joining the heat exchanger (P) and the heat exchanger (Q), a predetermined height is created between the vertically adjacent heat exchanger (P) and heat exchanger (Q). An exhaust space 15 is formed (see FIG. 3).

The upper and lower heat exchange plates 11 and 12 of the heat exchanger (Q) each have a large number of substantially square-shaped upper and lower through holes 11a and 12a on substantially the entire surface of the plates except for the corner portions and the periphery. Furthermore, substantially square upper and lower through-hole flange portions 11c and 12c are formed at the peripheries of the substantially square upper and lower through-holes 11a and 12a. Approximately pentagonal upper and lower through holes 11a and 12a are formed at the peripheries of the upper and lower heat exchange plates 11 and 12, respectively. Furthermore, approximately pentagonal upper and lower through-hole flange portions 11c and 12c are formed on the peripheries of the approximately pentagonal upper and lower through-holes 11a and 12a. Note that these upper and lower through holes 11a and 12a may have other shapes such as a substantially circular shape or a substantially elliptical shape. These upper and lower through holes 11a and 12a and upper and lower through hole flange portions 11c and 12c are formed at substantially the same pitch as those of the heat exchanger (P). Therefore, when the upper and lower heat exchange plates 11 and 12 are joined, a substantially square flange portion 16 is formed that closes the substantially square through hole 13 and the internal space 14 except for the peripheral edge of the heat exchanger (Q). Ru. Furthermore, a substantially pentagonal flange portion 16 that closes the substantially pentagonal through hole 13 and the internal space 14 is formed at the peripheral edge of the heat exchanger (Q). In addition, unlike the heat exchanger (P), no uneven parts are formed in the area surrounded by the through holes 13 on all sides, so the heat exchanger (Q) has four through holes adjacent in the front and rear and left and right directions. Between the holes 13, there is a flat portion 19 in which the internal space 14 has a substantially constant height.

The through holes 13 excluding the peripheral edge of the heat exchanger (Q) are approximately the same as those of the through hole 13 in which the four vertices face the front, rear, left, and right peripheral edges of the heat exchanger (Q), and one side of the through hole 13 is adjacent to each other. They are formed parallel to each other. For this reason, the through-holes 13 are arranged so that each vertex projects into a region surrounded by the through-holes 13 when viewed from the direction of the combustion exhaust gas flow path. Further, the flange portion 16 has four vertices (for example, the right side apex) that are closer to each other in the diagonal direction than the opposite side vertices (for example, the left side apex) of the flange portion 16 that are adjacent to each other in the diagonal direction. It is formed so as to be located near the center of the through hole 13.

The water passage holes 63 provided in at least one corner of the upper and lower heat exchange plates 11 and 12 forming each heat exchanger (Q) are arranged so that when the upper and lower heat exchange plates 11 and 12 are overlapped, the upper and lower heat exchange plates It opens so as to communicate with an internal space 14 formed between 11 and 12.

As shown in FIG. 3, in both heat exchangers (P) and (Q), the projection plane of the through hole 13 of one heat exchanger 10 in the adjacent heat exchanger 10 is the same as that of the through hole 13 of the other heat exchanger 10. It is shifted in the left-right direction perpendicularly intersecting the direction of the combustion exhaust gas flow path so as not to overlap with the hole 13 . Therefore, the combustion exhaust gas flowing from the upstream side passes through the through hole 13 of one heat exchanger 10 and then enters the exhaust space 15 between that heat exchanger 10 and the adjacent heat exchanger 10 on the downstream side. It flows out. Then, the combustion exhaust gas flowing 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 hole 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 within the heat exchanger 1, a zigzag gas flow path is formed within the heat exchanger 1. This increases the contact time between the combustion exhaust gas in the heat exchanger 1 and the upper and lower heat exchange plates 11 and 12. Furthermore, the variable parts 17 and 18 of the heat exchanger (P) and the flat part 19 of the heat exchanger (Q) described above are each projected plane 55 of the through hole 13 of the adjacent heat exchanger 10 (see FIG. 10). will be placed in The relationship between the through holes 13 of the heat exchanger (P) and the through holes 13 of the heat exchanger (Q) is also the same as described above (see FIGS. 3 and 10).

Next, with reference to FIG. 3, the flow of combustion exhaust 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 introducing water to the outside of the block 5. These inlet ports 71 and outlet ports 72 are constituted by predetermined water passage holes 63 of the heat exchanger 10 located at the most downstream and most upstream ends of the combustion exhaust gas flow path of each block 5, respectively. Note that, in order to avoid complication, the flange portion 16 and uneven portions around the through hole 13 are omitted in FIG.

A water passage hole 63 in the front right corner of the lower heat exchange plate 12 forming a heat exchanger (P) located at the most downstream position of the combustion exhaust gas flow path (hereinafter referred to as the "most downstream heat exchanger 10s"). An inflow pipe 20 is connected to the inflow pipe 20 . In addition, the water passage hole 63 at the rear right corner of the lower heat exchange plate 12 forming the most downstream heat exchange body 10s is provided with a heat exchanger located at the most upstream side of the combustion exhaust gas flow path from the most downstream heat exchange body 10s. An outlet pipe 23 is inserted that extends upward to the exchanger (Q) (hereinafter referred to as the "most upstream heat exchanger 10a"). The upper end of the outlet pipe 23 is connected to a water passage hole 63 at the rear right corner of the lower heat exchange plate 12 forming the most upstream heat exchange body 10a. The outer peripheral surface of the outlet pipe 23 is joined to the inner peripheral edge of the water passage hole 63 at the rear right corner of the lower heat exchange plate 12 forming the most downstream heat exchange body 10s by joining means such as brazing material. Further, the upper end opening of the outlet pipe 23 communicates with the internal space 14 of the most upstream heat exchanger 10a. Furthermore, when the outlet pipe 23 is inserted from the most downstream heat exchanger 10s to the most upstream heat exchanger 10a, the outlet pipe 23 is inserted into the internal space 14 of the heat exchanger 10 other than the most upstream heat exchanger 10a and all the exhaust spaces. 15 in a non-communicating state.

Therefore, water flowing into the internal space 14 of each heat exchanger (P) of the most downstream block 5d from the water passage hole 63 in the right front corner part flows in the internal space 14 in one direction in the left and right direction (in FIG. , flows from right to left). In addition, water flowing into the internal space 14 of each heat exchanger (P) of the second downstream block 5c from the water passage holes 63 in both the front and rear corners on the left side flows in the internal space 14 in one direction in the left and right direction (Fig. 3, flowing from left to right). The flow path direction of water flowing through the internal space 14 of the heat exchanger (P) of this 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 exchanger (Q) (hereinafter referred to as "second heat exchanger 10b") of the first downstream block 5b from the water passage hole 63 in the right front corner part is as follows: It flows in the internal space 14 in one direction from left to right (from right to left in FIG. 3). The flow path direction of water flowing through the internal space 14 of the second heat exchanger 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 exchanger 10a from the water passage holes 63 in both the front and rear corners on the left side flows in one direction in the left and right direction (from the left to the right in FIG. 3) within the internal space 14. flows to The flow path direction of water flowing through the internal space 14 of this most upstream heat exchanger 10a is opposite to that of the second heat exchanger 10b. The water flowing in the internal space 14 of the most upstream heat exchanger 10a flows out into the outlet pipe 23 inserted into the water passage hole 63 at the right rear corner of the most upstream heat exchanger 10a. The water flowing into the outlet pipe 23 flows down the outlet pipe 23 and flows out of the heat exchanger 1 from the outlet pipe 21 connected to the most downstream heat exchanger 10s. In this way, the most upstream heat exchanger 10a and the second heat exchanger 10b in the upstream region of the combustion exhaust gas flow path are such that all the water flowing into the second heat exchanger 10b is absorbed by the most upstream heat exchanger 10a. are connected in series so that they flow into each other. Moreover, the plurality of heat exchangers (P) of the most downstream block 5d are connected in parallel so that a plurality of parallel flow paths are formed. The second downstream block 5c is also similar to the most downstream block 5d.

Next, with reference to FIG. 10, the flow of the combustion exhaust gas in the upstream region of the combustion exhaust gas flow path and the flow of water in the internal spaces 14 of the heat exchangers (P) and (Q) will be described. In addition, in FIG. 10, a partial cross-sectional view of the heat exchangers (P) and (Q) in a direction inclined with respect to the front and back and left and right directions is shown to make the difference between the heat exchangers (P) and (Q) clear. It is shown.

Water flows between water passage holes 63 separated in the left-right direction of each heat exchanger (P) and (Q). At this time, the heat exchanger (P) has variable parts 17 and 18 in a region surrounded by the through holes 13, in which the height of the water flow path increases or decreases. Therefore, when the water flowing from the upstream side in the internal space 14 passes through the inside of the variable parts 17 and 18, the flow resistance of the water increases and the flow rate of the water decreases. Moreover, when water passes through the insides of the fluctuating parts 17 and 18, turbulent flow of water occurs, and the temperature distribution of the water becomes small. Furthermore, since the surface area of the heat exchanger (P) is increased by the variable parts 17 and 18, the heat receiving area of the heat exchanger (P) is increased. Thereby, the heat received from the combustion exhaust gas can be efficiently transferred to the water on the downstream side of the combustion exhaust gas flow path. By layering a heat exchanger (P) with excellent heat transfer properties on the downstream side of the heat exchanger (Q), the sensible heat of the high temperature combustion exhaust is absorbed by the upstream heat exchanger (Q), The latent heat of the combustion exhaust can be absorbed by the heat exchanger (P) on the downstream side. Thereby, thermal efficiency can be improved.

On the other hand, in the present embodiment, combustion exhaust gas flows vertically through the through holes 13 that penetrate each heat exchanger 10 . Therefore, the through holes 13 of each heat exchanger 10 are arranged so that the combustion exhaust gas flows through the outside of the heat exchanger 10 in a direction substantially perpendicular to the flow path surface of the water flowing inside each heat exchanger 10. is formed. Further, the through holes 13 are formed on substantially the entire surface of each heat exchanger 10 at substantially constant intervals in the front-rear and left-right directions. Therefore, the combustion exhaust gas flowing from the upstream side of the gas flow path collides with the entire surface of the most upstream heat exchange body 10a except for the through holes 13, and heats the most upstream heat exchange body 10a. That is, in the most upstream heat exchanger 10a, the portion excluding the through holes 13 becomes a heat receiving surface. On the other hand, adjacent heat exchange bodies 10 are formed such that the projected plane 55 of the through hole 13 of one heat exchange body 10 does not overlap with the through hole 13 of the other heat exchange body 10. Therefore, the combustion exhaust gas flowing through the through holes 13 of the most upstream heat exchanger 10a first collides with the small-area projection surface 55 on the second heat exchanger 10b. The combustion exhaust gas that collides with the second heat exchanger 10b exchanges heat with the high-temperature combustion exhaust gas that is not in contact with the most upstream heat exchanger 10a (that is, the water flowing through the internal space 14 of the most upstream heat exchanger 10a). It also includes combustion exhaust (for which combustion exhaust gas is not used). Therefore, when the heat exchanger 1 is configured only with a heat exchanger with variable parts (P) having variable parts 17 and 18, the second heat exchanger 10b adjacent to the downstream side of the most upstream heat exchanger 10a Local overheating is likely to occur.

However, according to the present embodiment, the second heat exchange body 10b is constituted by a heat exchange body (Q) with a flat portion having a flat portion 19 in which the height of the water flow path is substantially constant. This flat portion 19 is formed in a region surrounded by the through holes 13 on all sides, that is, in the projection plane 55 of the through holes 13 of the most upstream heat exchanger 10a (see FIGS. 7 to 10). Therefore, the flow path resistance of water flowing inside the projection surface 55 of the heat exchanger (Q) is smaller than that of water flowing inside the projection surface 55 of the heat exchanger (P). Q) The flow rate of the first fluid flowing inside the projection surface 55 increases. Moreover, since the flat part 19 has no unevenness, the combustion exhaust gas colliding with the flat part 19 spreads uniformly in all directions. As a result, it is possible to alleviate the concentration of heat on the projection surface 55, where the combustion exhaust concentrates and collides. Thereby, local overheating of the second heat exchange body 10b can be prevented.

Further, the highest temperature combustion exhaust collides with the most upstream heat exchanger 10a, and the peripheral edge of the through hole 13 through which the combustion exhaust passes is heated the most. Therefore, when the flow rate of water is low, there is a possibility that local overheating may occur in the most upstream heat exchanger 10a. However, according to the present embodiment, the most upstream heat exchanger 10a is composed of a heat exchanger (Q), and the most upstream heat exchanger 10a has a region surrounded by through holes 13 on all sides, that is, a second The projection surface 55 of the through hole 13 of the heat exchanger 10b has a flat portion 19. Thereby, local overheating of the most upstream heat exchanger 10a can be prevented.

Further, according to the present embodiment, the most upstream heat exchanger 10a and the second heat exchanger 10b in the upstream region of the gas flow path of combustion exhaust gas are 10a are connected in series so that they flow in this order. Therefore, all the water flowing through the second heat exchange body 10b flows into the most upstream heat exchange body 10a. Therefore, even when there is little water supplied into the heat exchanger 1, local overheating in the second heat exchanger 10b and the most upstream heat exchanger 10a can be prevented.

Further, according to this embodiment, the through holes 13 of the most upstream heat exchanger 10a and the second heat exchanger 10b have a substantially square shape. Further, the through-holes 13 are arranged such that each vertex projects into a region surrounded by the through-holes 13, that is, into the projection plane 55, when viewed from the direction of the combustion exhaust gas flow path. Therefore, the flow rate of water flowing through the area surrounded by the through holes 13 becomes faster. Thereby, local overheating can be further prevented.

In addition, in the present embodiment, the heat exchanger (Q) constituting the most upstream heat exchanger 10a and the second heat exchanger 10b has a convex portion that protrudes outward between adjacent through holes 13 on the periphery. has. A projection surface 55 is also formed at these peripheral edges, but the through hole 13 is not formed on the peripheral edge side of this projection surface 55. On the other hand, on the projection surface 55 other than the peripheral edge of the heat exchanger (Q), through holes 13 are formed on all sides. Therefore, on this projection surface 55, the amount of heat received from the combustion exhaust increases, and local overheating tends to occur. Therefore, if the flat portion 19 is formed on the projection surface 55 excluding at least the peripheral portion of the heat exchanger (Q), local overheating can be effectively prevented. Furthermore, by forming a variable part such as a convex part or a concave part between adjacent through holes 13 on the peripheral edge of the heat exchanger (Q), the heat of the combustion exhaust can be efficiently transferred to the water. .

As described above, according to the present embodiment, it is possible to improve thermal efficiency and to prevent local heating of the heat exchanger 10 in the upstream region of the combustion exhaust gas flow path. Therefore, according to the present embodiment, it is possible to provide a plate heat exchanger having high thermal efficiency and excellent durability.

(Other embodiments)
(1) In the above embodiment, the heat exchanger downstream of the second heat exchanger is composed only of the heat exchanger (P) having a variable part. However, if local overheating occurs in heat exchangers downstream of the second heat exchanger, heat exchangers (Q) may be used instead of some of the heat exchangers (P).
(2) In the embodiments described above, the burner having a downward combustion surface is disposed above the heat exchanger. However, a burner with an upwardly directed combustion surface may also be arranged below the heat exchanger.
(3) In the above embodiment, a plurality of heat exchangers are stacked one above the other. However, the plurality of heat exchangers may be stacked on the left and right.
(4) In the above embodiment, a water heater is used, but a heat source device such as a boiler may also be used.

1 Heat exchanger 10 Heat exchange body 10a Most upstream heat exchange body 10b Second heat exchange body 13 Through hole 17, 18 Variable part 55 Projection plane

Claims (4)

A plate heat exchanger comprising a plurality of heat exchange bodies that perform heat exchange between a first fluid flowing inside and a second fluid flowing outside, and configured by stacking the plurality of heat exchange bodies. There it is,
The heat exchange body includes a plurality of through holes formed so that the second fluid flows outside the heat exchange body in a direction intersecting a flow path surface of the first fluid flowing inside the heat exchange body. has
Adjacent heat exchange bodies are formed such that a projected surface of the through hole of one heat exchange body does not overlap with the through hole of the other heat exchange body when viewed from the flow path direction of the second fluid,
The plurality of heat exchange bodies include a heat exchange body (P) having a variable part in which the height of the flow path of the first fluid varies on the projection plane, and a heat exchange body (P) having a variable part in which the height of the flow path of the first fluid fluctuates on the projection plane, and a heat exchange body (P) having a variable part in which the height of the flow path of the first fluid fluctuates, and a heat exchanger (Q) having only a flat portion in which the height of the flow path is substantially constant;
A plate heat exchanger, in which a second heat exchanger adjacent to the downstream side of at least the most upstream heat exchanger located at the most upstream side of the flow path of the second fluid is constituted by the heat exchanger (Q). The plate heat exchanger according to claim 1,
The most upstream heat exchanger is a plate heat exchanger including the heat exchanger (Q). The plate heat exchanger according to claim 1 or 2 ,
The second heat exchanger and the most upstream heat exchanger are connected in series so that the first fluid flows through the second heat exchanger and the most upstream heat exchanger in this order. Plate heat exchanger. The plate heat exchanger according to any one of claims 1 to 3 ,
The through hole of the heat exchanger (Q) has a substantially rectangular shape,
In the plate heat exchanger, the rectangular through-hole is arranged such that at least one vertex projects onto the projection plane.

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