EP2551626A1

EP2551626A1 - Plate heat exchanger, plate heat exchanger producing method, and heat pump apparatus

Info

Publication number: EP2551626A1
Application number: EP10848381A
Authority: EP
Inventors: Shinichi Uchino; Takehiro Hayashi; Daisuke Ito
Original assignee: Mitsubishi Electric Corp
Current assignee: Mitsubishi Electric Corp
Priority date: 2010-03-25
Filing date: 2010-03-25
Publication date: 2013-01-30
Also published as: WO2011117988A1; EP2551626A4; JP5496321B2; JPWO2011117988A1

Abstract

A nozzle 114a is an inlet port for a refrigerant. A recessed portion 117 (recessed area) is formed in a side plate 110a. The recessed portion 117, in conjunction with the nozzle insertion portion 131 and a bottom surface 133 of a reinforcing plate 113a, defines an inner space 119 which substantially seals the periphery of a nozzle insertion portion 131. The inner space 119 is a so-called doughnut-shaped space which surrounds the periphery of the nozzle insertion portion 131. A brazing filler material is introduced into the inner space 117 through a gap 132, and fills the inner space. As a result of the filling of the brazing filler material, the nozzle 114a, the reinforcing plate 113a, and the inner space 119 constitute a "pillar". The pillar improves the strength of the plate heat exchanger.

Description

Technical Field

The present invention relates to a plate heat exchanger which exchanges heat between a refrigerant and a heat absorbing fluid. The present invention also relates to a plate heat exchanger producing method, and a heat pump apparatus.

Background Art

Plate heat exchangers are generally known to exchange heat between two flow channels which are formed by stacking and brazing a plurality of plates together. Plate heat exchangers are characterized in that a heat-exchanger body can be reduced in size because components therein are joined together by brazing.
Plate heat exchangers are small in size, and therefore used in heat pump apparatuses. Plate heat exchangers, which exchange heat between a liquid fluid and a refrigerant, are used for water heating, sterilization, or the like. In a plate heat exchanger, pressure differs between a refrigerant side where the pressure becomes relatively high, and a fluid side (heat-absorbing medium side) where the pressure does not change much. Therefore, it is important to improve the bearing capacity of a plate heat exchanger to withstand the inner pressure thereof. Patent Document 1 discloses a technology to improve the bearing capacity of a plate heat exchanger to withstand the inner pressure thereof.

Related Art Documents

Patent Document

[Patent Document 1] JP 2001-99588 A

Summary of Invention

Technical Problem

A plate heat exchanger is assembled and fixed almost permanently by a brazing filler material. Therefore, if a heat transfer plate therein is damaged, the damaged heat transfer plate cannot be replaced alone. For this reason, damage on a heat transfer plate results in a failure in the function of the whole plate heat exchanger. When a plate heat exchanger is used in a heat pump unit mainly for heating air or water, if a heat transfer plate is damaged, water and R410A as a typical refrigerant therein are mixed together. This results in an adverse effect both on environment and human health. Therefore, it is essential to improve the reliability of plate heat exchangers, not for the longevity of individual plate heat exchangers, but for all products that use the plate heat exchangers.

(1) A plate heat exchanger is mainly damaged by stress on heat transfer plates therein. The stress is caused by a difference between the inner pressure of the plate heat exchanger and external pressure in an environment where the plate heat exchanger is used. The pressure difference causes "pressure damage". This is a mode in which damage is caused because pressure rises too much in condensation.
(2) There is another mode in which damage is caused by the fatigue of a heat transfer plate which separates a heat-transfer side flow channel and a heat-absorption side flow channel. The fatigue is caused by pressure fluctuations in the flow channels inside the plate heat exchanger. When a plate heat exchanger is installed in a heat pump apparatus, the rotational speed of a compressor therein changes according to the heat pump apparatus being run, deactivated, under capacity control, or the like. Such changes in the rotational speed result in momentary changes in the internal pressure of the plate heat exchanger. This may cause "pressure fatigue damage" on a plate heat exchanger running for a long time.

Commonly used plate heat exchangers are designed to improve reliability against such "pressure damage" or "pressure fatigue damage", by increasing the thickness of heat transfer plates, applying reinforcing materials on the periphery of heat transfer plates, or the like. However, there are limitations such as cost restrictions and appearance restrictions, and therefore a method to improve the reliability at lower cost is required.
An object of the present invention is to improve the strength of a plate heat exchanger against pressure damage or pressure fatigue damage. Solution to Problem
A plate heat exchanger according to this invention includes a plurality of stacked plates in which adjacent plates in a stacking direction are joined together by brazing, the plate heat exchanger exchanging heat between a first fluid being a refrigerant and a second fluid with which the first fluid exchanges heat, the first and second fluids passing through a flow channel for the first fluid and a flow channel for the second fluid which are formed in the plurality of plates. The plate heat exchanger comprises: a nozzle serving as one of an inlet port and an outlet port of one of the first fluid and the second fluid, the nozzle having a hollow center; an outer plate arranged on an outermost side, the outer plate including a nozzle-corresponding hole which has a shape corresponding to a shape of a nozzle end so that the nozzle end passes through the nozzle-corresponding hole, the nozzle end being one of ends of the nozzle; and a first plate arranged adjacent to a bottom surface side of the outer plate, the first plate including a recessed area which, in conjunction with the nozzle end and the bottom surface of the outer plate, defines an enclosed space which substantially seals a periphery of the nozzle end when the nozzle end is inserted through the nozzle-corresponding hole in the outer plate, the recessed area having, at a central portion thereof, a first hole which is aligned with the nozzle-corresponding hole in the stacking direction, The enclosed space is filled with a brazing filler material.

Advantageous Effect of Invention

This invention allows a plate heat exchanger to improve the strength against pressure damage or pressure fatigue damage.

Brief Description of Drawings

Fig. 1 illustrates a configuration of a plate heat exchanger 100 according to a first embodiment.
Fig. 2 is an exploded perspective view of the plate heat exchanger 100 according to the first embodiment.
Fig. 3 is a side view of the plate heat exchanger according to the first embodiment.
Fig. 4 is a front view of the plate heat exchanger 100 according to the first embodiment.
Fig. 5 is a back view of the plate heat exchanger 100 according to the first embodiment.
Fig. 6 shows a section corresponding to an X-X section shown in Fig. 2.
Fig. 7 shows a heat transfer plate 109a and a heat transfer plate 109b according to the first embodiment.
Fig. 8 shows a side plate 10a according to the first embodiment.
Fig. 9 is an enlarged view of an area D shown in Fig. 8.

Description of Embodiment

A plate heat exchanger 100 is described below according to a first embodiment.
Fig. 1 illustrates a configuration of the plate heat exchanger 100 according to the first embodiment. A configuration of the plate heat exchanger 100 is described with reference to Fig. 1. A heat pump unit 10 (heat pump apparatus) includes a compressor 1, a condenser 2 (first heat exchanger), an electronic expansion valve 3, and an evaporator 4 (second heat exchanger).

(1) The compressor 1 compresses a refrigerant 11 by using electric power to increase the enthalpy and pressure of the refrigerant 11.
(2) The condenser 2 exchanges heat between the compressed refrigerant 11 (first fluid) and a heat absorbing fluid (second fluid).
(3) Through the electronic expansion valve 3, the refrigerant 11 from the condenser 2 is adiabatically expanded.
(4) The evaporator 4 exchanges heat between the refrigerant 11 through the electronic expansion valve 3 and an external heat source. Note that the heat pump unit 10 may include an auxiliary component such as a receiver, not shown, to store surplus refrigerant 11.

The compressor 1 to the evaporator 4 form a refrigeration cycle through which the refrigerant 11 circulates. For example, the plate heat exchanger 100 is used as the condenser 2. In this case, the heat of the external heat source (absorbed heat by the evaporator 4) is radiated by the plate heat exchanger 100, thereby heating water introduced into the plate heat exchanger 100. There are many kinds of media, such as air and geothermal heat, used as the external heat source (whose heat is exchanged by the evaporator 4). The plate heat exchanger 100 can be used in all the water heater type heat pump units that use the external heat source. The plate heat exchanger 100 may not be limited to be used only as the condenser (first heat exchanger), but also used as the evaporator (second heat exchanger).
Outlet hot water 12 (also referred to as water 12) circulates through a water circuit 14. Fig. 1 illustrates an indirect heating system. The water 12 flows into the plate heat exchanger 100 as the condenser 2, absorbs heat from the refrigerant 11, and flows out from the plate heat exchanger 100. The outlet hot water 12 discharged from the plate heat exchanger 100 flows into a heater 5, such as a radiator or a floor heater, connected by pipes in the water circuit 14, to be used for room temperature regulation. A water-water heat exchanger tank 6 in which heat is exchanged between the outlet hot water 12 and clean water 13 is also included in the water circuit 14. This allows the clean water 13 heated by the outlet hot water 12 to be used as household water for bath, shower, and the like.
An external shape of the plate heat exchanger 100 is described below with reference to Fig. 2 to Fig. 5.

Fig. 2 is an exploded perspective view of the plate heat exchanger 100.
Fig. 3 is a side view of the plate heat exchanger 100.
Fig. 4 is a front view of the plate heat exchanger 100 (viewed from a direction indicated by an arrow A shown in Fig. 3).
Fig. 5 is a back view of the plate heat exchanger 100 (viewed from a direction indicated by an arrow B shown in Fig. 3).

(Feature of plate heat exchanger 100)

Firstly, a feature of the plate heat exchanger 100 is described.

(1) The plate heat exchanger 100 of the first embodiment is a type of heat exchanger in which components are joined together by brazing. The plate heat exchanger 100 is characterized in that an inner space 119 shown in Fig. 9, described later, is created and filled with a brazing filler material. Although Fig. 9 shows a section, the inner space 119 is ring-shaped (so-called doughnut-shaped), which surrounds the periphery of an insertion portion 131 at a nozzle end. As a result of the filling of the ring-shaped inner space 119 entirely with the brazing filler material, the inner space 119, a reinforcing plate 113a, and a nozzle 114a are unified. The unification allows the nozzle 114a to serve as a "pillar" to support the plate heat exchanger 100, which contributes to the improvement of the strength of the plate heat exchanger.
(2) Among other portions of the plate heat exchanger, a portion in the vicinity of a nozzle, which is required for supplying a fluid into the plate heat exchanger, is vulnerable to damage such as pressure damage or pressure fatigue damage. In a commonly used plate heat exchanger, the surfaces of heat transfer plates are corrugated to increase heat-exchanging area. Every portion where the corrugations of adjacent heat transfer plates meet (a portion where a ridge on the corrugated surface of a heat transfer plate meet a groove on the corrugated surface of the adjacent heat transfer plate above it) is brazed. Every brazed portion serves as a "pillar". In the vicinity of a nozzle where heat is not transferred, on the other hand, there is no corrugation formed, or if there is, the corrugation includes extremely few ridges and grooves. Therefore, few "pillars" are available as supports in the vicinity of a nozzle. It is preferable to have many "pillars" even in the vicinity of a nozzle in order to improve the strength. However, an area in the vicinity of a nozzle is limited, and therefore the structure in which a "pillar" is formed and a flow channel is not blocked is limited.
(3) Therefore, the plate heat exchanger 100 of the first embodiment is configured, as described in (1) above, so that to use the nozzle 114a as a "pillar" to support the plate heat exchanger 100. Further, in the light of the behavior of copper (brazing filler material) during brazing, the "pillar" is made wider than commonly used nozzles in order to improve the reliability of the plate heat exchanger. As shown in Fig. 9, three components, i.e., the nozzle 114a, the reinforcing plate 113a, and a side plate 110a, define the ring-shaped inner space 119 (enclosed space). The inner space 119 is filled with surplus copper remaining after brazing. As a result of the filling of the inner space 119 with brazing filler copper, the nozzle 114a, the side plate 110a and the reinforcing plate 113a constitute a rigid "pillar". Since the "pillar" can be formed by using existing members, the strength can be improved without adding new members.

An external view of the plate heat exchanger 100 is described below in detail. Referring to Fig. 2, the plate heat exchanger 100 includes a first flow channel, into which the refrigerant 11 is introduced through a nozzle 114-2 as a refrigerant inlet port, and from which the refrigerant 11 is discharged through a nozzle 114-4 as a refrigerant outlet port. The plate heat exchanger 100 also includes a second flow channel, into which the water 12 is introduced through a nozzle 114-3 as a water inlet port, and from which the water 12 is discharged through a nozzle 114-1 as a water outlet port.
Referring to Fig. 3, the plate heat exchanger 100 includes the reinforcing plate 113a to which nozzles 114-1 to 114-4 are attached, the side plate 110a, a heat transfer plate 109b, a heat transfer plate 109a ... a heat transfer plate 109b, a heat transfer plate 109a, a side plate 110b, and a reinforcing plate 113b, which are arranged in that order in a stacked assembly.
Referring to Fig. 4, the front view (from the arrow A direction of Fig. 3) illustrates four nozzles 114-1 to 114-4 attached to the reinforcing plate 113a.
Referring to Fig. 5, the back view (from the arrow B direction of Fig. 3) illustrates a surface of the reinforcing plate 113b.
A configuration of the plate heat exchanger 100 is now described with reference to Fig. 6 to Fig. 9.
Fig. 6 illustrates a section corresponding to an X-X section shown in Fig. 4. A term "corresponding" is used here for the following reason. There are only four of the heat transfer plates 109a, 109b shown in Fig. 6 for ease of explanation. Further in Fig. 6, the nozzle 114a (corresponding to the nozzle 114-1) is a nozzle at an inlet port for the refrigerant 11. Thus, Fig. 6 and Fig. 4 do not illustrate the same, and therefore the term "corresponding" is used.
Views (a) and (b) of Fig. 7 illustrate the heat transfer plate 109a (third plate) and the heat transfer plate 109b (second plate) of the plate heat exchanger 100 shown in Fig. 6 when viewed from a direction indicated by an arrow C. As shown in Fig. 6, the heat transfer plate 109b is arranged immediately below the side plate 110a, and immediately above the heat transfer plate 109a. In the stacked assembly, flow openings 115a to 115d (second holes) in the heat transfer plate 109b are aligned with flow openings 115a to 115d (third holes) in the heat transfer plate 109a to form the flow channels.

(Side plate 110a)

A view (a) of Fig. 8 illustrates the side plate 110a (first plate) of the plate heat exchanger 100 shown in Fig. 6 when viewed from the arrow C direction. Flow openings 115a to 115d (first holes) in the side plate 110a are aligned with the flow openings 115a to 115d in the heat transfer plate 109b and the flow openings 115a to 115d in the heat transfer plate 109a to form the flow channels. A Y-Y section shown in (a) of Fig. 8 is illustrated in (b).
Fig. 9 is an enlarged view of a portion D shown in Fig. 6.
As shown in Fig. 6, the plate heat exchanger 100 of the first embodiment includes a heat transfer portion 111 as a main structure in which the heat transfer plates 109a, 109b are stacked together to form the flow channels for exchanging heat between the first fluid and the second fluid. A plate heat exchanger core portion 112 (hereinafter, referred to as core portion 112) includes the heat transfer portion 111, the side plate 110a arranged above the heat transfer portion 111, and the side plate 110b arranged below the heat transfer portion 111. The reinforcing plate 113a is arranged above the core portion 112 and the reinforcing plate 113b is arranged below the core portion 112 to sandwich the core portion 112 between the reinforcing plates 113a and 113b. The reinforcing plate 113a is formed with nozzle attachment openings (nozzle-corresponding holes). The nozzles 114a to 114d are attached to the nozzle attachment openings.

(

Heat transfer plate

109a, 109b)

The heat transfer plate 109a and the heat transfer plate 109b shown in Fig. 7 have the same size, and the plate thickness is the same. The heat transfer plate 109a and the heat transfer plate 109b each have the flow openings 115a to 115d at the four corners. The heat transfer plate 109a and the heat transfer plate 109b have corrugated shapes 116a and 116b for disturbing the fluid between the flow openings 115a, 115b and the flow openings 115c, 115d in the long-side direction. The corrugated shape 116a of the heat transfer plate 109a and the corrugated shape 116b of the heat transfer plate 109b are 180-degree inverted to each other. More specifically, the corrugated shape 116b is obtained by rotating the corrugated shape 116a by 180 degrees about a point P in an arrow's direction shown. In Fig. 7, a ridge line 122 of the heat transfer plate 109b indicates a ridge line, i.e., the top of a wave in the corrugation. More specifically, the "top of a wave" means the top of a wave in the direction opposite to the C direction in Fig. 6. The corrugated shape 116b is formed by a series of V-shaped waves with the vertex of each V (bent position of a V) being aligned on a center line 121 of the heat transfer plate 109b. The same is applied to the corrugated shape 116a. As Fig. 6 shows, an area around the periphery of the flow opening 115a of the heat transfer plate 109b is lower than an area around the periphery of the flow opening 115b of the heat transfer plate 109b, when the direction opposite to the C direction is the higher direction. That is, the heat transfer plate 109b has a step 123 with the center line 121 as a boarder in the short-side direction. The step 123 serves as the flow channels when the heat transfer plates are stacked together. The same is applied to the heat transfer plates 109a.

(Formation of flow channels by heat transfer plate 109)

When the heat transfer plate 109a and the heat transfer plate 109b are stacked together, the corrugated shape 116a and the corrugated shape 116b meet by point contact. The point-contact portions are brazed to serve as "pillars" to form the flow channels. For example, the heat transfer plates 109a form the flow channel for water (pure water, tap water, mixed water with antifreeze solution, etc.) and the heat transfer plates 109b form the flow channel for the refrigerant 11 (e.g., a refrigerant used in an air-conditioner, such as R410A as a typical refrigerant). The water flow channel is formed by stacking the heat transfer plate 109a and the heat transfer plate 109b alternately. Then, "water-refrigerant" layers are formed by stacking an additional heat transfer plate 109a. Subsequently, alternate flow channels, such as "water-refrigerant-water-refrigerant...", are formed by increasing the number of the heat transfer plates in the stacked assembly (see Fig. 2). The stacked heat transfer plates constitute the heat transfer portion 111 shown in Fig. 6.

(Side plate 110)

The side plate 110a and the side plate 110b, which sandwich the heat transfer potion 111 at the top and bottom portions thereof, have the same size and thickness as those of the heat transfer plate 109. The side plates 110a and 110b are flat plates without the corrugated shape 116, and have the flow openings 115a to 115d at the four corners. As shown in Fig. 6, the side plate 110a is arranged above the heat transfer portion 111 and the side plate 110b is arranged below the heat transfer portion 111 to form the core portion 112. As shown in Fig. 8, a recessed portion 117 is formed on the periphery of the flow opening 115a, 115c of the side plate 110a, 110b. The recessed portion 117 is in contact with the flow opening 115a, 115c of the heat transfer plate 109a, 109b.

(Recessed portion 117)

As shown in Fig. 6 and Fig. 8, the side plate 110a has the recessed portion 117 (recessed area) formed by drawing on the periphery of the flow opening 115a, 115c.
As shown in Fig. 9, the recessed portion 117 serves to prevent the refrigerant from flowing into a non-heat transfer space 118, which is defined by the side plate 110a and the side plate 110b. The non-heat transfer space 118 is a space which is defined by a flat surface and the corrugated shape 116b, and in which effective heat transfer performance cannot be expected. For this reason, preventing the refrigerant from flowing into the non-heat transfer space 118 can avoid excessive radiation and a reduction in the flow speed of the refrigerant.

(Reinforcing plate 113)

As shown in Fig. 6, the reinforcing plate 113a (outer plate) is arranged above the core portion 112, and the reinforcing plate 113b is arranged below the core portion 112. The reinforcing plate 113 is substantially five times thicker than the heat transfer plate 109 or the side plate 110. With the plate heat exchanger 100, the reinforcing plate 113a has four flow openings as shown in Fig. 2, Fig. 4, etc. The reinforcing plate 113b has no flow opening 115, as shown in Fig. 5. The reinforcing plates 113a and 113b allow the plate heat exchanger 100 to withstand pressure fluctuation fatigue caused by the fluids flowing through the core portion 112, and force caused by differences between the atmospheric pressure and the pressure of the plate heat exchanger 100.

(Nozzle caulking)

As shown in Fig. 2, Fig. 4, Fig. 6, etc., the nozzles 114a to 114d are attached to four flow openings in the reinforcing plate 113a to direct the refrigerant and water passing into the core portion 112. Positions where the nozzles 114 are attached (attachment positions) are determined by the number of flow openings in the reinforcing plate 113a, 113b. If each reinforcing plate has a maximum of four flow openings, a total of eight nozzles 114 are attached per unit of the plate heat exchanger 100. As shown in Fig. 9, the nozzle 114a has the insertion portion 131 at an end portion thereof, which fits into the flow opening of the reinforcing plate 113a. The insertion portion 131 is formed so that a tip portion thereof protrudes by 1 mm or more from a bottom surface 133 of the reinforcing plate 113a. Fig. 9 shows a length H, which is 1 mm or more. Prior to brazing the plate heat exchanger 100, the insertion portion 131 of the nozzle 114 is inserted into the flow opening of the reinforcing plate 113a, and then caulked. The reinforcing plate 113a temporarily fixed with the nozzle 114a by caulking is stacked next to the core portion 112, and the plate heat exchanger 100 is temporarily assembled as a whole. The temporarily assembled plate heat exchanger 100 is sent forward for brazing.

(Brazing process)

In the temporarily assembled plate heat exchanger 100, strips of copper as the brazing filler material are inserted between the heat transfer plates 109a and the heat transfer plates 109b, between the heat transfer portion 111 and the side plate 110a, 110b, and between the core portion 112 and the reinforcing plate 113a, 113b. The brazing filler copper is also inserted between the reinforcing plate 113a and the nozzles 114. In the brazing process, the temporarily assembled plate heat exchanger 100 with the brazing filler material inserted therein is put in a vacuum furnace for vacuum brazing. During the brazing process, the copper melts and penetrates into the joint surfaces of each component. When the penetrated copper is cooled, the components are joined together almost permanently. The plate heat exchanger 100 is thus produced.
Molten copper by brazing penetrates through the joint surfaces of the components (plates, nozzles, etc.). Surplus copper remaining after molten copper having penetrated through the entire joint surfaces accumulates inside the plate heat exchanger 100. The surplus copper under surface tension tends to flow into narrower gaps.

(1) A structure around the periphery of the inner space 119 is described with reference to Fig. 6 and Fig. 9. The nozzle 114a serves as the inlet port of the refrigerant 11. However, the inner space 119 is not limited to be provided at the inlet of the refrigerant 11, and may alternatively be provided at an outlet of the refrigerant 11, an inlet of the water 12, or an outlet of the water 12. The reinforcing plate 113a (outer plate) is formed with nozzle-corresponding holes which have a shape corresponding to that of the nozzle insertion portion 131 (nozzle end) so that the nozzle insertion portion 131 passes through a nozzle-corresponding hole. The side plate 110a is arranged adjacent to the bottom surface 133 side of the reinforcing plate 113a. The side plate 110a is formed with the recessed portion 117 (recessed area) as described with reference to Fig. 8. The recessed portion 117, in conjunction with the nozzle insertion portion 131 and the bottom surface 133 of the reinforcing plate 113a, defines the inner space 119 which substantially seals the periphery of the nozzle insertion portion 131 inserted through the nozzle-corresponding hole. The inner space 119 is created by the recessed portion 117 covered with the reinforcing plate 113a. Thus, the inner space 119 is a so-called doughnut-shaped space which surrounds the periphery of the nozzle insertion portion 131.
(2) The recessed portion 117 has a hole (first hole), at a central portion thereof, which is aligned with the nozzle-corresponding hole in the stacking direction. The recessed portion 117 has a first flat portion which is flat along the periphery of the hole. The first flat portion and an end surface of the nozzle insertion portion 131 create a gap 132 between them. Through the gap 132, the molten brazing filler material is introduced into the inner space 119, which is described later.
(3) The heat transfer plate 109b (second plate) arranged immediately below the side plate 110a has the flow openings formed therein. One of the flow openings in the heat transfer plate 109b, which forms the flow opening in conjunction with the nozzle 114a, has a second flat portion, which is flat and extends outward from the periphery of the flow opening. The second flat portion touches the first flat portion of the side plate 110a.
(4) The heat transfer plate 109a (third plate) arranged immediately below the heat transfer plate 109b has the flow openings formed therein. One of the flow openings in the heat transfer plate 109b, which forms the flow opening in conjunction with the nozzle 114a, has a third flat portion, which is flat and extends outward from the periphery of the flow opening. The third flat portion touches the second flat portion of the heat transfer plate 109b.

As shown in Fig. 9, the tip portion of the insertion portion 131 of the nozzle 114a is positioned closely to the recessed portion 117 of the side plate 110a to create the gap 132. Three components, i.e., the insertion portion 131 (nozzle end) of the nozzle 114a, the bottom surface 133 of the reinforcing plate 113a, and the side plate 110a (recessed portion 117), define the inner space 119 (enclosed space). Since the tip portion of the insertion portion 131 and the flat portion of the recessed portion 117 (recessed area) of the side plate 110a are positioned closely to each other to create the narrow gap 132, surplus copper remaining after brazing flows into the inner space 119 (enclosed space) through the gap 132. Thus, the inner space 19 is filled with the brazing filler copper. The gap 132 is designed so that molten copper under surface tension penetrates through the gap, and does not flow out through the gap while the copper is cooled in the brazing process. For example, the gap 132 is between several µm and several dozen µm.
As shown in Fig. 6, the plate heat exchanger 100 is configured as follows: the side plates 110a, 110b and the reinforcing plates 113a, 113b are arranged above and below, respectively, the heat transfer portion 111 where the plurality of heat transfer plates 109a, 109b are stacked together. The heat transfer portion 111 sandwiched between the side plates 110a, 110b and the reinforcing plates 113a, 113b is brazed all together by vacuum brazing. The recess is formed on the periphery of the refrigerant side flow channel opening in the side plate 110a. The heat transfer plates 109 and the side plates 110 are joined together on the periphery of the flow openings 15, respectively. Surplus brazing filler material remaining after brazing flows through the gap 132 into the inner space 119 which is defined by the temporarily fixed portion of the nozzle 114a by caulking, the side plate 110a, and the reinforcing plate 113a, and fills the inner space 119. As a result of the filling with the brazing filler material, the entire inner space 19 can serve as a pillar to support the inside of the plate heat exchanger.
According to the plate heat exchanger 100, the "pillar" made of three components, i.e., the nozzle 114a, the reinforcing plate 113a, and the side plate 110a, is formed as a result of the filling of the inner space 119 with copper. The "pillar" based on the joint area of the recessed portion 117 of the side plate 110a and the heat transfer portion 111 can be thus obtained. Therefore, a pressure receiving area is increased and stress is reduced, which improves the reliability against internal pressure fatigue damage caused by refrigerant pressure fluctuations and pressure damage caused by differences between the internal pressure of the plate heat exchanger and the atmospheric pressure. At the central portion of the plate heat exchanger, load is distributed and therefore the strength is high since there are a lot of "pillars" formed by the corrugated portions of the heat transfer plates being joined together. On the other hand, existing plate heat exchangers have lower strength since there are a small number of "pillars" available in the vicinity of nozzles where no corrugated shape is provided. The plate heat exchanger 100 of the first embodiment allows large-sized "pillars" to be obtained in the vicinity of the nozzles without adding a "pillar" which blocks a fluid flow. Therefore, the reliability of the strength is improved.
Filling the inner space 119 with copper can prevent a corrosive fluid such as water from flowing into the inner space 119. When a corrosive fluid is introduced into a space such as the inner space 119, there is a higher risk of corrosion by long-term use even if a high corrosion-resistant SUS material is used. Therefore, it is effective in terms of corrosion to eliminate an empty space such as the inner space 119.
According to the plate heat exchanger 100 of the first embodiment, the reinforcing plate (pressure resistance plate), the side plate, and the nozzle constitute the solid "pillar", by filling the inner space, which is defined by the reinforcing plate (pressure resistance plate), the side plate, and the nozzle, with the brazing filler material for joining each plate together and each nozzle and plate together, in brazing using a vacuum furnace. The "pillar" can improve the strength of the plate heat exchanger 100 against the inner pressure fluctuations thereof.
When the plate heat exchanger 100 is used as a condenser in a heat pump unit, the strength can be improved by forming the "pillar" at a nozzle as a refrigerant inlet port, if there are differences between atmospheric pressure and refrigerant pressure, and there are refrigerant pressure fluctuations in the heat pump unit.

Reference Signs List

1 compressor
2 condenser
3 electronic expansion valve
4 evaporator
5 heater
6 water-water heat exchanger tank
7 clean water using device
10 heat pump unit
11 refrigerant
12 outlet hot water
13 clean water
14 water circuit
109, 109a, 109b heat transfer plate
100 plate heat exchanger
110, 110a, 110b side plate
111 heat transfer portion
112 core portion
113, 113a, 113b reinforcing plate
114a to 114d, 114-1 to 114-4 nozzle
115, 115a to 115b flow opening
116, 116a, 116b corrugated shape
117 recessed portion
118 non-heat transfer space
119 inner space
121 center line
122 ridge
123 step
131 insertion portion
132 gap

Claims

A plate heat exchanger, including a plurality of stacked plates in which adjacent plates in a stacking direction are joined together by brazing, the plate heat exchanger exchanging heat between a first fluid being a refrigerant and a second fluid with which the first fluid exchanges heat, the first and second fluids passing through a flow channel for the first fluid and a flow channel for the second fluid which are formed in the plurality of plates, the plate heat exchanger comprising:
a nozzle serving as one of an inlet port and an outlet port of one of the first fluid and the second fluid, the nozzle having a hollow center;

an outer plate arranged on an outermost side, including a nozzle-corresponding hole which has a shape corresponding to a shape of a nozzle end so that the nozzle end passes through the nozzle-corresponding hole, the nozzle end being one of ends of the nozzle; and

a first plate arranged adjacent to a bottom surface side of the outer plate, including a recessed area which, in conjunction with the nozzle end and the bottom surface of the outer plate, defines an enclosed space which substantially seals a periphery of the nozzle end when the nozzle end is inserted through the nozzle-corresponding hole in the outer plate, the recessed area having, at a central portion thereof, a first hole which is aligned with the nozzle-corresponding hole in the stacking direction,

wherein the enclosed space is filled with a brazing filler material.
The plate heat exchanger according to claim 1, wherein the recessed area includes a first flat portion which is flat and formed along a periphery of the first ho le, and wherein a gap is formed between the first flat portion and an end surface of the nozzle end inserted through the nozzle-corresponding hole so that a molten brazing filler material flows into the enclosed space through the gap.
The plate heat exchanger according to claim 2, further comprising:
a second plate arranged adjacent to the first plate, including a second hole which is aligned with the first hole in the stacking direction, and a second flat portion which is flat and extends outward from a periphery of the second hole, the second flat portion being in contact with the first flat portion of the recessed area in the first plate.
The plate heat exchanger according to claim 3, further comprising:
a third plate arranged adjacent to the second plate, including a third hole which is aligned with the second hole in the stacking direction, and a third flat portion which is flat and extends outward from a periphery of the third hole, the third flat portion being in contact with the second flat portion in the second plate,
The plate heat exchanger according to any one of claims 1 to 4, wherein the outer plate is thicker than the first plate.
The plate heat exchanger according to claim 5, wherein the outer plate is substantially five times thicker than the first plate.
The plate heat exchanger according to any one of claims 1 to 6, wherein the nozzle serves as the inlet port through which the first fluid of the refrigerant flows.
A method of producing a plate heat exchanger, including a plurality of stacked plates in which adjacent plates in a stacking direction are joined together by brazing, the plate heat exchanger exchanging heat between a first fluid being a refrigerant and a second fluid with which the first fluid exchanges heat, the first and second fluids passing through a flow channel for the first fluid and a flow channel for the second fluid which are formed in the plurality of plates, the method comprising:
brazing:
a nozzle serving as one of an inlet port and an outlet port of one of the first fluid and the second fluid, the nozzle having a hollow center;

an outer plate arranged on an outermost side, including a nozzle-corresponding hole which has a shape corresponding to a shape of a nozzle end so that the nozzle end passes through the nozzle corresponding hole, the nozzle end being one of ends of the nozzle; and

a first plate arranged adjacent to a bottom surface side of the outer plate, including a recessed area which, in conjunction with the nozzle end and the bottom surface of the outer plate, defines an enclosed space which substantially seals a periphery of the nozzle end when the nozzle end is inserted through the nozzle-corresponding hole in the outer plate, the recessed area having, at a central portion thereof, a first hole which is aligned with the nozzle-corresponding hole in the stacking direction, and

filling the enclosed space with a brazing filler material.
A heat pump apparatus, including a first heat exchanger, an expansion mechanism, and a second heat exchanger which are connected together by pipes, the heat pump apparatus comprising:
a plate heat exchanger as at least one of the first heat exchanger and the second heat exchanger, the plate heat exchanger including a plurality of stacked plates in which adjacent plates in a stacking direction are joined together by brazing, the plate heat exchanger exchanging heat between a first fluid being a refrigerant and a second fluid with which the first fluid exchanges heat, the first and second fluids passing through a flow channel for the first fluid and a flow channel for the second fluid which are formed in the plurality of plates, the plate heat exchanger comprising:
a nozzle serving as one of an inlet port and an outlet port of one of the first fluid and the second fluid, the nozzle having a hollow center;

an outer plate arranged on an outermost side, including a nozzle-corresponding hole which has a shape corresponding to a shape of a nozzle end so that the nozzle end passes through the nozzle corresponding hole, the nozzle end being one of ends of the nozzle; and

a first plate arranged adjacent to a bottom surface side of the outer plate, including a recessed area which, in conjunction with the nozzle end and the bottom surface of the outer plate, defines an enclosed space which substantially seals a periphery of the nozzle end when the nozzle end is inserted through the nozzle-corresponding hole in the outer plate, the recessed area having, at a central portion thereof, a first hole which is aligned with the nozzle-corresponding hole in the stacking direction,

wherein the enclosed space of the plate heat exchanger is filled with a brazing filler material.