JPH0473595A - plate heat exchanger - Google Patents

Abstract

PURPOSE:To prevent a brazing joint part between a frame and a heat transfer plate from being cracked and hence improve durability of a heat exchanger and stabilize heat exchanger performance by directing hot water through opposite side flow passages respectively closest to a pair of frames. CONSTITUTION:In a heat exchanger two kinds of heat transfer plates 11a, 11b are alternately laminated and a hot water flow passage A and a water supply passage B are alternately formed between the plates. Upon operation being re-started, one hot water is directed through passages A, A located respectively most close to frames 15, 16, the plates 11a, 11b adjacent to the frames 15, 16 are rapidly raised in temperatures by the hot water. Thereupon, since the frames 15, 16 take time to raise the temperatures, a temperature difference is produced between the frames and the plates. Since the plates 11a, 11b are more expanded thermally than the frames 15, 16, a brazing junction part between the adjacent plates undergoes compression force to prevent a brazing material or the plates from being cracked.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a plate heat exchanger used in water heaters and the like.

[Conventional technology]

Used as a heat exchanger for water heaters that use hot water as a heating source. As shown in Figures 2 to 4, a plate heat exchanger consists of two types of heat transfer plates (-(Ia) and (1b)) stacked alternately in the required number, and heat is transferred between each heat transfer plate. Water flow path (
)\) and water supply channels (B) are formed alternately, and the adjacent heat transfer plates (la> (lb) are bent into an abbreviated shape at the periphery of the rims (2a) (2b) and the four corners. are permanently joined by brazing around the hot water or feed water inlet/outlet (3a) (3b), and the plates adjacent to the surfaces of each heat transfer plate (la) (Ib) are in contact with each other. Together, corrugated portions (4a) and (4b) are formed which form support points for promoting heat transfer by making the hot water and supply water in the channels (A) and (B) turbulent, and the support points is soldered. A pair of frames (5) are placed on both sides of the combined heat transfer plate assembly.
(6) are permanently joined by brazing, and one of the frame (5) is connected to the lead-in/outlet (3a) (3b
) to connect the nozzles (7) and (8).

[Problem to be solved by the invention]

By the way, in this type of conventional plate heat exchanger, water supply is conducted through one of the pair of frames (5) and (6), for example, through the flow path (B) closest to the frame (5). Therefore, after a while after operation is stopped, the temperature of the entire heat exchanger including the frame (5) reaches approximately 60℃, and when operation is restarted in this state, the temperature of the heat exchanger (including the frame (5)) reaches When supply water at 5 to 20°C is passed through the nearby channel (B),
The heat transfer plate (1a) in contact with the frame (5) is rapidly cooled by water supply and its temperature drops, but the heat transfer plate (1a) in contact with the frame (5)
It takes time for the frame (5) to cool down to the same temperature as the supply water temperature, and therefore, a temperature difference occurs between the frame (5) and the heat transfer plate (la) in contact with the frame (5). In this way, the frame (5) and the heat transfer plate in contact with it (la
), the frame (5) will contract later than the heat transfer plate (Ia) in contact with it, so even if the heat transfer plate (la) in contact with the frame (5) tries to contract, the frame ( 5) Tensile stress acts on the joint by brazing with the adjacent heat transfer plate (1b). Therefore, if such operation is repeated, there is a problem in that repeated fatigue results in cracking of the brazing material or the plate, and a solution to this problem has been desired.

This invention was made to solve the above problem.
The purpose is to provide a plate heat exchanger that improves durability by alleviating thermal stress that occurs when operation is stopped for a while and then restarted.

[Means to solve the problem]

In order to achieve the above object, the present invention stacks a required number of heat transfer plates to alternately form hot water channels and water supply channels between them, and connects adjacent heat transfer plates to their peripheral edges and They are permanently joined together by brazing around the inlet/outlet for guiding hot water or supply water to and from each flow path, and a corrugated portion is formed on the surface of each heat transfer plate. , brazing supporting points that intersect and abut the corrugated portions of adjacent heat transfer plates, and sandwiching the heat transfer plate assembly between a pair of frames, and brazing both sides of the assembly to the pair of frames. This plate heat exchanger has an integral structure, and is configured so that hot water is passed through channels on both sides that are closest to the pair of frames.

[Effect]

By passing hot water through the channels on both sides that are closest to the pair of frames, when the operation is stopped for a while and then restarted, the heat transfer plate in contact with the frame expands thermally to a greater extent than the frame. The brazing material or the plate is prevented from cracking by applying a compressive force to the brazed joint with the adjacent heat transfer plate.

〔Example〕

An embodiment of the present invention will be described below with reference to FIG.

FIG. 1 is a schematic cross-sectional view illustrating the laminated structure of heat transfer plates in a plate heat exchanger according to the present invention,
The required number of two types of heat transfer plates (lla) (11b) are stacked alternately, and a hot water flow path (
A) and a water supply passage (B) are formed alternately.

Each heat transfer plate (lla) (Ilb) is bent in an abbreviated shape at the periphery to form a rim (12a>(12b)), and the four corners are connected to respective flow paths for hot water or water supply. and an inlet/outlet (13a) for guiding from each flow path.
) (13b), and the adjacent heat transfer plate (
11a) (llb) are permanently joined together by brazing around the rims (12a) (12b) and the outlet/outlet (13a) (1, 3b). Each heat transfer plate (11a
> On the surface of (11b), supporting points are provided to promote heat transfer by cross-butting the adjacent plates to create a turbulent flow of hot water and feed water in the channels (A) and (B). Corrugated portions (14a) and (14b) are formed, and their supporting points are brazed. Then, a pair of frames (15) and (16) are joined by brazing to both sides of the assembled heat transfer plate assembly, and the lower frame (1
5) Attach nozzles (17) and (18) that communicate with the outlet and outlet ports (13a) and (13b).

A feature of the plate heat exchanger according to the present invention is that it is configured so that hot water is passed through the flow channels (A) and (A) on both sides closest to the pair of frames (15) and (16), respectively. It is.

In this way, after a while after the operation is stopped, the entire heat exchanger including the frames (15) and (16) will be approximately 60mm long.
℃, when the operation is restarted and hot water of about 80℃ is passed through the channels (A) (A) closest to the frames (15) and (16), the temperature of the frames (15) and ( The heat transfer plates (Ila) and (11b) in contact with the frame (16) are rapidly heated by the hot water and their temperature increases;
) and (16) are heated to the same temperature as the hot water, and it takes time to raise the temperature, so the frames (15) and (16) and the heat transfer plates (lla) and (
11b). In this way, when a temperature difference occurs between the frames (15) and (16) and the heat transfer plates (H, a) and (11b) in contact with them, the heat transfer plates in contact with the frames (15) and (16) Since (lla) and (11b) thermally expand more than frames (15) and (16), compressive force is applied to the brazed joints between them and the adjacent heat transfer plates (11b) and (11a). As a result, cracking of the brazing material or plate can be prevented.

〔Effect of the invention〕

According to this invention, it is possible to prevent cracking of the brazing material or plate at the joint portion due to brazing between the heat transfer plate in contact with the frame and the adjacent heat transfer plate, thereby improving the durability of the plate heat exchanger. In addition, it can exhibit an effect that greatly improves the level of conventional equipment in terms of stabilizing the heat exchange function.

[Brief explanation of drawings]

FIG. 1 is a schematic cross-sectional view illustrating a laminated structure of heat transfer plates of a plate heat exchanger according to the present invention. FIG. 2 is a schematic cross-sectional view illustrating the laminated structure of heat transfer plates of a conventional plate heat exchanger, and FIGS. 3 and 4 are plan views of heat transfer plates structuring the plate heat exchanger. be. (lla) (llb) - heat transfer plate, (12a>
(12b) - Rim, (13a) (13b) - Outlet/outlet, (14a
> (14b)-Waveform part, (15) (16L--
Frame, (17) (181-nozzle, (A)-hot water passage, (B)-water supply passage. Patent applicant: Hikyoku Seisakusho Co., Ltd.~
Hitachi Cable Co., Ltd. Representative Gangwon Province
Figure 7 Figure b ＼ 4b 1, . 1

Claims (1)

[Claims] (1) Stack the required number of heat transfer plates to alternately form hot water channels and water supply channels between them, and connect adjacent heat transfer plates to their peripheral edges and to separate hot water or water supply channels into each other. The heat transfer plate is permanently joined by brazing around the outlet and outlet for leading to and from the respective flow paths, and a corrugated portion is formed on the surface of each heat transfer plate to match the corrugation of the adjacent heat transfer plate. The plate type has an integrated structure in which the support points that intersect with the parts are brazed, the heat transfer plate assembly is sandwiched between a pair of frames, and both sides of the assembly are brazed to the pair of frames. A plate heat exchanger characterized in that the heat exchanger is configured such that hot water is passed through channels on both sides closest to the pair of frames.