JP2001280889A - Plate type heat exchanger - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent the subcooling and freezing in the fluid flow passage for water for a plate type heat exchanger for obtaining cold water by conducting refrigerant and water to flow through the fluid flow passage between laminated heat transfer plates. SOLUTION: Fluid flow passages 6 for refrigerant and for water are formed alternately between a plurality of heat transfer plates 1 while the fluid flow passages 6 for water around the peripheral parts (n) of the refrigerant passage hole 2 of the heat transfer plates 1 are formed as closed spaces Ma, into which water Q will not flow. The closed spaces Ma are surrounded by the brazed parts 7 of the mutual heat transfer plates to prohibit the inflow of water Q into the closed spaces Ma by the brazed parts 7 whereby the subcooling and the freezing of the water Q, which flows through the fluid passages 6 are avoided. The brazed parts 7 are formed simultaneously with one process for brazing the peripheral rims of the plurality of heat transfer plates 1 mutually, whereby the plate type heat exchanger of brazing type having the closed spaces Ma for preventing freezing in the fluid flow passages 6 can be manufactured favorably in the manufacturing process of the same.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a plate heat exchanger in which a plurality of heat transfer plates are laminated and integrated by brazing or the like.

[0002]

2. Description of the Related Art A conventional example of a plate heat exchanger used for an evaporator or the like for obtaining chilled water in a chiller unit is shown in FIGS. 5 to 7. The heat exchanger is composed of a plurality of heat transfer plates 1,. This is a brazing type heat exchanger obtained by laminating a plurality of metal frames 12 and 13 via a brazing material (not shown) and brazing under a high temperature and a vacuum. The heat transfer plate 1 and the metal frames 12 and 13 are, for example, vertically long, substantially rectangular plates made of stainless steel, and are provided at four corners of each heat transfer plate 1 with passage holes 2 through which two kinds of fluids of the refrigerant P and the liquid to be cooled Q flow. , 3 are formed, and nozzles 4, which serve as entrances and exits of the coolant P and the liquid Q to be cooled, penetrate through four corners of one metal frame 12 and are brazed.

The heat transfer plate 1 has a heat exchange heat transfer portion 1a of a corrugated plate and a rim portion 1b formed by bending a peripheral portion of the heat exchange heat transfer portion 1a. Part 1
b is hermetically welded with the brazing material. When a plurality of heat transfer plates 1 are stacked and integrated, the passage holes 2 and 3 formed at the four corners of each heat exchange heat transfer portion 1a communicate concentrically facing each other. As shown in FIG.
The corner passage holes 2 are an inlet-side refrigerant passage hole 2a for allowing the refrigerant P to flow in from the outside and an outlet-side refrigerant passage hole 2b for allowing the refrigerant P to flow to the outside. The remaining two upper and lower corner passage holes 3 are to be cooled. An inlet-side cooled liquid passage hole 3a through which the liquid Q flows in from the outside and an outlet-side cooled liquid passage hole 3b through which the liquid Q flows out.

When a plurality of heat transfer plates 1 are stacked and integrated, as shown in FIG. 7, a fluid flow path 5 through which the refrigerant P flows between the heat transfer plates 1 and a fluid flow through which the liquid to be cooled Q flows The paths 6 are formed alternately. Each of the fluid flow paths 5 and 6 is an uneven space sandwiched by the corrugated heat exchange heat transfer portions 1a of the heat transfer plate 1, and is circulated in a state where the refrigerant P and the liquid to be cooled Q are filled in the entire uneven space. I do. The upper and lower openings of the coolant flow path 5 communicate with the coolant passage holes 2a and 2b, and the upper and lower openings of the coolant liquid flow path 6 communicate with the coolant passage holes 3a and 3b. The periphery of each of the passage holes 2 and 3 of the adjacent heat transfer plate 1 is air-tightly joined and integrated with a brazing material, so that the refrigerant P does not flow from the refrigerant fluid passage 5 into the passage hole 3 to be cooled. The coolant Q is prevented from flowing into the coolant passage hole 2 from the coolant fluid channel 6.

[0005] One of the two kinds of fluids, refrigerant P, is Freon or liquid nitrogen, and the other liquid to be cooled Q is water. Such refrigerant P rises in the refrigerant flow path 5 from the refrigerant passage hole 2a formed in the lower part of the heat transfer plate 1 and
and flows out from the nozzle 4 connected to the refrigerant passage hole 2b. The liquid to be cooled (hereinafter, referred to as water, if necessary) Q descends through the water flow passage 6 from the water passage hole 3a formed in the upper part of the heat transfer plate 1 and lower water passage hole 3b. Reach Heat is exchanged with high efficiency during the flow of the refrigerant P and the water Q by filling the adjacent fluid flow paths 5 and 6, respectively, so as to communicate with the water passage hole 3b below the water fluid flow path 6. Cold water of a desired temperature is taken out of the nozzle 4 outside.

[0006]

As shown in FIG. 6, water Q is caused to flow from the upper part to the lower part of the vertically long fluid flow path 6, and conversely, the refrigerant P is caused to flow from the lower part to the upper part in the fluid flow path 5, Although efficient heat exchange between the water Q and the refrigerant P is continuously performed, the temperature of the water Q flowing down while lowering the temperature of the water fluid flow path 6 is too low, and the water Q may freeze during the flow. is there. In particular,
The water Q flowing down while lowering the temperature of the water fluid flow path 6 passes through the inlet-side refrigerant passage hole 2a at the peripheral portion (the x mark portion in FIG. 6) n of the inlet-side refrigerant passage hole 2a at the lower part of the heat transfer plate 1. Since the water Q flows so as to detour, the flow velocity decreases, and the water Q is quenched by the refrigerant P at the lowest temperature before heat exchange in this peripheral portion n.
Even when the coolant P flowing into the inlet-side coolant passage hole 2a slightly falls below the freezing point, the water Q in the peripheral portion n may freeze.
When the water Q starts to freeze in the peripheral portion n of the inlet-side refrigerant passage hole 2a located near the outlet side of the water fluid flow path 6, the flow velocity further decreases, the freezing area increases, and the volume of the frozen portion expands. May cause internal damage to the heat exchanger,
This makes maintenance of the heat exchanger including temperature control of the refrigerant difficult.

An object of the present invention is to provide a plate-type heat exchanger in which a liquid to be cooled, such as water, is prevented from freezing inside a heat transfer plate, thereby facilitating temperature control of a refrigerant or the like.

[0008]

SUMMARY OF THE INVENTION In order to achieve the above object, the present invention provides a heat transfer plate having a plurality of heat transfer plates each having two types of fluid inlet-side and outlet-side passage holes. The seed fluid passage holes are laminated in a concentric communication manner, and two kinds of fluid flow paths for allowing two kinds of fluid to flow between the heat transfer plates from the inlet side passage hole to the outlet side passage hole alternately. In the plate heat exchanger formed in the above, the peripheral portion of the heat transfer plate passage hole of the other fluid in the fluid flow path of one fluid is formed as a closed space in which the fluid flowing through the fluid flow path does not flow and bypasses. It is characterized by.

Here, the two fluids are a refrigerant such as Freon and a liquid to be cooled such as water, and a fluid flow path of the two fluids between the heat transfer plates according to heat exchange conditions between the refrigerant and other fluids. One or both of the heat transfer plate passage hole peripheral portions is selectively made a closed space, so that supercooling of another fluid by the refrigerant or freezing due to supercooling is avoided. The partially closed space in the fluid flow path is formed by partial brazing between adjacent heat transfer plates, pressure welding, the interposition of metal gaskets, and the like.

According to a second aspect of the present invention, in the case where the two kinds of fluids of the first aspect are a refrigerant and a liquid to be cooled which is cooled by the refrigerant, the heat transfer in the fluid flow path of the liquid to be cooled is performed. It is characterized in that a portion around the coolant passage hole of the plate is a closed space. In this case, in order to prevent the liquid to be cooled from being frozen by the refrigerant, a portion around the refrigerant passage hole that is easy to freeze in the fluid flow path of the liquid to be cooled is made a closed space, and the liquid to be cooled is placed around the refrigerant passage hole. I try not to flow.

Further, the invention according to claim 3 limits the place where the closed space of the fluid flow path for the liquid to be cooled according to claim 2 is formed,
A closed space is formed around the refrigerant passage hole of the heat transfer plate downstream of the flow path of the liquid to be cooled in the direction of flow of the liquid to be cooled and upstream of the flow path of the refrigerant in the direction of flow of the refrigerant. And In other words, by making the portion of the cooling liquid fluid flow path where the cooling liquid is most likely to fall in temperature and freeze easily into a closed space into which the cooling liquid does not flow, the cooling liquid liquid flow path as a whole is consequently formed. To prevent the liquid to be cooled from freezing.

Further, according to the present invention, an adjacent heat transfer plate is partially brazed at a boundary portion between a peripheral portion of a passage hole of each heat transfer plate and another portion to form a fluid flow path. A closed space is partially formed. In this case, in a brazing type heat exchanger in which a plurality of heat transfer plates are brazed, the heat transfer plates are stacked and brazed by forming a closed space in the fluid flow path by brazing between the heat transfer plates. The closed space of the fluid flow path can be simultaneously formed in one step, which is advantageous in manufacturing.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention applied to a brazing type plate heat exchanger shown in FIG. 7 is shown in FIG.
This will be described in detail with reference to FIGS. Note that the same or corresponding parts as those in FIGS. 3 to 5 of FIGS. 1 to 4 are denoted by the same reference numerals, to avoid duplication of description.

The plate type heat exchanger of the first embodiment shown in FIG. 1 has the same basic structure as the heat exchanger of FIG.
The two fluids to be heat-exchanged are a refrigerant P and a liquid to be cooled, for example, water Q. A feature different from FIG. 7 in FIG. 1 is that only the peripheral portion n of the heat transfer plate refrigerant passage hole 2a of the water fluid flow path 6 is a closed space Ma so that water Q does not flow into this peripheral portion n. That is. FIG. 3 schematically shows two adjacent heat transfer plates 1 of the heat exchanger. FIG. 3 shows an inlet-side refrigerant passage hole 1a of the heat transfer plate 1 downstream of one vertically long water fluid flow path 6. Is a closed space Ma separated from other portions of the fluid flow channel 6 only in the peripheral portion n of the fluid flow channel 6. In the closed space Ma, for example, as shown by a black circle in FIG. 1, a boundary portion between the periphery n of the refrigerant passage hole of the heat exchange heat transfer portion 1a of the adjacent heat transfer plate 1 and another portion is joined with a brazing material. It is formed by the brazed portion 7 thus formed.

Depending on other types of the heat exchanger, the brazing portion 7 may be formed by a press contact portion between the heat transfer plates or an intervening member such as a metal gasket.

In the heat exchanger of the above-described embodiment, the water Q flowing down one vertically elongated water fluid flow path 6 while lowering its temperature is formed in the peripheral portion of the inlet side refrigerant passage hole 2 a at the lower portion of the heat transfer plate 1. It approaches the closed space Ma of n. This closed space Ma
Is a portion where the flow rate of the flowing water Q drops and is quenched by the coolant P at the lowest temperature before heat exchange, so that the water Q flows through the fluid flow path 6. When it flows down and approaches the peripheral portion n, it is blocked by the brazing portion 7 and the closed space M
a and the water Q does not flow into the peripheral portion n along the brazing portion 7.
Flows to bypass the air flow and reaches the lower outlet side water passage hole 3b. Therefore, even if the refrigerant P flowing into the inlet-side refrigerant passage hole 2a slightly falls below the freezing point,
Since the water Q flows down avoiding the peripheral portion n of the passage hole 2a where the fluid Q is cooled most, there is no fear that the water Q is overcooled and freezes.

The closed space Ma hardly contributes to the heat exchange between the refrigerant P and the water Q. However, since the closed space Ma is a small volume portion occupying a very small part of one fluid passage 6, the closed space Ma is closed. The heat exchange efficiency of the fluid flow path 6 is hardly reduced due to the presence of the fluid flow path 6, and does not cause a problem in the performance of the heat exchanger. Further, when the fluid passage 6 is formed by brazing the adjacent heat transfer plates 1, a part of the fluid passage 6 is formed as a closed space Ma at the same time by forming the brazing portion 7. A brazing-type plate heat exchanger can be manufactured in the brazing process, and can be manufactured using the existing heat transfer plate 1 as shown in FIG. 7 as it is.

The plate heat exchanger according to the second embodiment shown in FIGS. 2 and 4 has another closed space together with the closed space Ma in the water fluid flow path 6 in the heat exchanger according to the first embodiment. Mb is formed, and a pair of closed spaces Mc and Md are also formed in the refrigerant fluid flow path 5. The closed space Mb in the water fluid flow path 6 shown in FIG. 4 is partially brazed to the peripheral portion of the outlet side refrigerant passage hole 2b on the upper part of the heat transfer plate 1 like the other closed space Ma. It is formed.
Further, one closed space Mc in the refrigerant fluid flow path 5 is formed in the peripheral portion of the inlet-side water passage hole 3a at the upper portion of the heat transfer plate 1, and the other closed space Md is formed at the lower outlet of the heat transfer plate 1. The closed spaces Mc and Md are formed in the peripheral portion of the side water passage hole 3b, and each of the closed spaces Mc and Md is formed by a brazing portion 7 'in which the adjacent heat transfer plates 1 are partially joined as shown in FIG.

In the heat exchanger of the second embodiment,
The freezing of the water Q is prevented in the closed space Ma in the two water fluid flow paths 6. In the case of the second embodiment, the back surface of the flow path in which the water Q flowing down the water fluid flow path 6 bypasses the closed space Ma and flows to the outlet side passage hole 3b is the refrigerant closed space Md. Since the refrigerant P does not flow into the space Md, the water Q
The overcooling and freezing of the steel are more reliably and effectively prevented.

Further, in the case of the second embodiment, even when the water Q freezes in the peripheral portion of the outlet side refrigerant passage hole 2b on the upstream side of the water fluid flow path 6, this freezing is prevented by the closed space Mb.
To prevent. Further, as shown in FIG. 4, since the two adjacent heat transfer plates 1 and 1 are vertically symmetrical, there is provided a heat exchanger having no problem even when the heat exchanger is installed and used upside down. it can.

The above embodiment is an embodiment in which the present invention is applied to a heat exchanger of two kinds of fluids, a refrigerant and water. However, the non-refrigerant fluid of the two kinds of fluids is not limited to a liquid to be cooled such as water but may be a gas or the like. The structure of the present invention is effective in a heat exchanger using a fluid other than a refrigerant and water, which does not have a fear of freezing, in order to avoid a trouble caused by supercooling of the fluid.

[0022]

According to the first aspect of the present invention, during the heat exchange operation between the refrigerant and another fluid such as water, even if the fluid approaches the periphery of the refrigerant passage hole of the heat transfer plate and is excessively cooled. Since the excessively cooled fluid flow path is a closed space for preventing the inflow of the fluid, supercooling of the fluid is avoided, and there is little trouble caused by supercooling of the fluid.
It is possible to provide a plate-type heat exchanger that can easily control the temperature of the refrigerant for preventing the fluid from being excessively cooled.

According to the second aspect of the present invention, even when the liquid to be cooled by the refrigerant approaches the peripheral portion of the refrigerant passage hole of the heat transfer plate, the fluid flow for the liquid to be cooled formed in the peripheral portion is formed. Since the detour is made without passing through the closed space of the road, freezing due to supercooling of the liquid to be cooled is avoided, and a long-life, high-reliability plate-type heat exchanger with less damage inside the heat exchanger due to freezing of the liquid to be cooled is provided. it can.

According to the third aspect of the present invention, a closed space for preventing freezing is formed in a part where the liquid to be cooled, which is cooled by the refrigerant through the liquid flow path for the liquid to be cooled, is most easily cooled and frozen. As a result, the freezing of the liquid to be cooled is more reliably prevented, and the volume occupied by the closed space in one fluid passage for the liquid to be cooled can be minimized, so that the heat exchange efficiency is easily reduced. Can be prevented.

According to the fourth aspect of the present invention, since the closed space is formed in the fluid flow path by partially brazing the periphery of the fluid passage hole of the adjacent heat transfer plate, a plurality of heat transfer plates can be formed. At the same time, the closed space can be formed in one brazing step of the brazed brazing type heat exchanger, and the existing method such as a heat-transfer plate can be used without using any special member. Can be manufactured.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of a main part of a plate heat exchanger according to a first embodiment of the present invention.

FIG. 2 is a sectional view of a main part of a plate heat exchanger according to a second embodiment of the present invention.

FIG. 3 is a perspective view showing an outline of a heat transfer plate in the heat exchanger of FIG. 1;

FIG. 4 is a perspective view schematically showing a heat transfer plate in the heat exchanger.

FIG. 5A is a front view of a conventional plate heat exchanger including a partly omitted portion, and FIG. 5B is a side view.

FIG. 6 is a perspective view showing an outline of a heat transfer plate in the heat exchanger.

FIG. 7 is an enlarged sectional view taken along line TT in FIG.

[Explanation of symbols]

 P fluid, refrigerant Q fluid, liquid to be cooled, water 1 heat transfer plate 2 passage hole 2a upstream passage hole 2b downstream passage hole 3 passage hole 3a upstream passage hole 3b downstream passage hole 5 fluid passage 6 fluid passage Ma closed space Mb-Md closed space n refrigerant passage hole peripheral portion 7, 7 'brazing portion

Claims (4)

[Claims] 1. A heat transfer plate having two kinds of fluid inlet holes and an outlet side passage hole are laminated in a state where the corresponding two kinds of fluid passage holes are concentrically communicated with each other. In a plate heat exchanger in which two kinds of fluid flow paths for alternately forming two kinds of fluids between plates on the inlet side passage hole to the outlet side passage hole are formed between the plates, the other fluid in the one fluid path The plate heat exchanger characterized in that a peripheral portion of the heat transfer plate passage hole is formed as a closed space in which a fluid flowing through the fluid flow path does not flow in and bypasses. 2. The method according to claim 1, wherein the two fluids are a coolant and a coolant to be cooled by the coolant, and a portion around the coolant passage hole of the heat transfer plate in the fluid flow path of the coolant is a closed space. The plate heat exchanger according to claim 1, wherein 3. A closed space is formed in the vicinity of the refrigerant passage hole of the heat transfer plate located downstream of the flow path of the liquid to be cooled in the direction of flow of the liquid to be cooled and upstream of the flow path of the refrigerant in the direction of flow of the refrigerant. 3. The plate heat exchanger according to claim 2, wherein: 4. A partially closed space is formed in a fluid flow path by partially brazing an adjacent heat transfer plate to a boundary portion between a peripheral portion of a passage hole of each heat transfer plate and another portion. The plate heat exchanger according to any one of claims 1 to 3, wherein: