JPS6021021B2 - Heat exchanger manufacturing method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a heat exchanger using a highly air permeable porous metal with a large number of continuous voids as fins, and a method for manufacturing the same. Two devices with a temperature difference, such as air-to-air heat exchangers used in units, refrigerators, air-to-air evaporators and condensers used in air conditioners, etc.
It can be used in the field of exchanging heat between fluids.

Technologies similar to the present invention include a heat exchanger that uses a foamed metal body as a fin by introducing a gas-generating substance into the molten metal and foaming the molten metal, and bonding and fixing of metal particles using a broiling method. Heat exchangers that are used as fins are known. In the former case, the connecting parts between continuous pores are extremely thin and constricted, some independent pores are formed inside, which increases the fluid passage resistance, and it is difficult to mold the material to a uniform density throughout. There are problems such as.
Furthermore, in the latter case, the gaps between particles are large enough for fluid to pass through, making it impossible to obtain a very large porosity, and there are also problems such as a long manufacturing time and high cost. Due to the above problems, these heat exchangers have not reached the point of practical use. The most commonly used finned heat exchangers at present are cross-fin type heat exchangers, in which plate-shaped fins are arranged as densely as possible at right angles to the heat transfer tubes to increase the heat transfer area for heat exchange. occupies a portion. In this type of heat exchanger, regardless of whether the heat exchanger tubes are meandering tubes or parallel tubes with header connections, the fins must first be installed in multiple rows, and then the fins and the heat exchanger tubes must be connected. Not only was this complicated, but it also required many assembly steps, resulting in long construction times and low productivity. Furthermore, in a cross-fin type heat exchanger, fluid flows through the gaps between the fins, so unnecessarily narrowing the fin spacing and increasing the number of fins to increase the heating area will increase fluid passage resistance and This was difficult due to the above constraints. The present invention focuses on the fact that conventional heat exchangers have the above-mentioned problems.The present invention makes it possible to eliminate the problems by adopting a new processing technology, improve heat transfer performance, and make it lightweight and compact. This is a new heat exchanger that enables the part corresponding to the fins of the secondary heat exchanger to be integrally molded around the civilian heat pipe that has already been processed into a serpentine pipe or the like. The present invention is characterized in that it can provide a method for manufacturing an exchanger.

An embodiment of the present invention will be described in detail below with reference to the accompanying drawings.

Figure 1 shows the use of the present invention in an air heat exchanger, with 6
It is an integrally molded heat exchanger in which a poisonous heat tube 1 is molded into a meandering shape, and the end of the heat transfer tube 1 is exposed and covered with a fin block 2 formed around the fin block 2 in a mat shape with a thick layer. The heat transfer tube 1 is embedded in the heat exchanger tube 2.

Further, the fin block 2 is made of porous metal in which the fins 3 have a skeleton shape, either in the form of fine lines as shown in the enlarged view in FIG. 2, or in the form of woven lines with various unevenness as shown in the enlarged view in FIG. The air flows through a large number of gaps 4 between the skeleton-shaped fins 3, and heat is exchanged with a fluid such as cold butterfly or water flowing inside the heat transfer tube 1 through the fins 3. It's summery. Next, an example of a method for manufacturing the heat exchanger shown in FIGS. 1 and 2 will be explained with reference to FIG. 4.

First, a resin with good air permeability that has three-dimensional continuous pores such as foamed urethane is used as a model, and after filling the pores of this model with a fluid molding material, the Shinnetsu tube 1 is molded into a serpentine shape. The pipe is buried so that the end of the pipe is exposed.

As a mold material, a slurry consisting of gypsum powder for molds and water, a slurry consisting of gypsum and water to which common salt has been added, 27
A slurry prepared by mixing SiQ powder of 0 mesh or less with a viscous streaking agent consisting of ethyl silicate, industrial ethyl alcohol, and water, and other general mold materials are used. Next, by heating or other operations, the mold material is cured, and at the same time, the resin of the model is vaporized and disappeared, resulting in a fin mold 5 having three-dimensional continuous pores.
to form.

The fin mold 5 thus formed is placed in a metal mold 6 and set in a pressure vessel 8 having a crucible 7 at the bottom. The crucible 7 is filled with metal 10 that has been heated and melted by a heating source 9 such as an electric heater. This metal material includes materials with good thermal conductivity such as AI and Cu, as well as Fe and general iron alloys, Pb, Sn, Zn,
Non-ferrous alloys such as Mg can also be used. Next, the molten metal 10 in the crucible 7 is pressurized to several atmospheres using compressed air from the air inlet 11, and the molten metal 10 is passed through the injection port 12 into the fin mold 5 by the force of the pressurization.
Fill in the pores of. After the pressure is restored and the molten metal 10 is solidified, the fin electrode 5 is taken out from the mold 6 and the mold material is removed. As a result, around the meandering heat exchanger tube 1, a porous metal fin block 2 having continuous pores in which thin wire-like fins 3 take on a skeleton shape is integrally molded. Another manufacturing method is to provide a hole for inserting the heat exchanger when molding the fin block, insert the heat transfer tube into the hole, and then mold the fin block by a casting method as in the above embodiment.

After filling the pores of a resin model with three-dimensional continuous pores with a fluid mold material, a rod-shaped body made of the same type of material as the resin model is placed in the pores so that both ends thereof are curved. Bury it. Next, the resin model and the twill-shaped body are made to disappear by heating or the like to form a fin mold having three-dimensional continuous holes and through holes. Next, after inserting a U-shaped heat exchanger tube or a straight heat transfer tube into the through hole, molten metal is filled into the mold cavity under pressure, and after the molten metal has solidified, the mold material is removed. In this method, the heat exchanger tubes are inserted after the mold is made, so that the heat exchanger tubes and the fin blocks are bonded well. As a method for molding a fin block around a coal-fired tube, in addition to the method of embedding a meandering heat exchanger tube in advance in the mold of the fin block as described above and bonding it together by integral molding using the above-mentioned casting method. 1) A method of creating holes for heat exchanger tube insertion when molding the fin block, inserting the heat exchanger tubes into these holes, and connecting them with a gangway. A method in which a metal O-material is applied, a cinnabar tube is inserted into a hole made during fin block molding, and the brazing material is melted and bonded by a heating operation, and a glue heat transfer tube is inserted into a hole made during fin block molding. After insertion, a high-frequency current is passed through the heat transfer tube to heat the heat transfer tube, and the fin blocks near the heat transfer tube are melted and bonded. {4} The brazing material applied to the surface of the heat transfer tube is melted by high frequency heating. There are several methods of binding. In method 1, the contact thermal resistance between the heat transfer tube and the fin block is large;
Methods '2 and '3} have a small contact thermal resistance, but require heating operations. In particular, the glue method can shorten the heating time, but must be heated to a relatively high temperature at which the fin block melts. In addition, method {4) has a small contact thermal resistance, a short heating time, and a low heating temperature, but it requires an additional manufacturing process. Unfavorable in terms of appearance etc.
In the heat exchanger manufactured by the above-mentioned manufacturing method, the air to be heat exchanged quickly passes through the numerous open spaces 4 between the skeleton-shaped fins 3 of the fin block 2 with almost no flow resistance. During this flow process, heat is efficiently exchanged between the fluid in the heat transfer tube 1 and the fins 3.

Since the fins 3 in the heat exchanger of the present invention are arranged three-dimensionally in a mesh shape, the heat transfer area can be increased compared to plate-shaped fins, and furthermore, since the fluid passages are intricately arranged in the mesh shape, Fluid is constantly flowing through the system, which has the effect of reducing the development of a temperature boundary layer, resulting in high thermal performance and extremely effective transfer of heat.

In a general heat exchanger, the heat transfer coefficient with air is h wide d-
It is well known that n (generally n>0) is expressed as h: heat transfer coefficient and d: representative diameter.

The above formula shows that the heat transfer coefficient becomes larger when d is 4. The fins 3 of the heat exchanger according to the present invention can be manufactured in the form of very thin pongee lines, and the heat transfer performance can be further improved.

As described above, according to the present invention, compared to a cross-fin type heat exchanger, the heat transfer area per unit volume can be increased, the phosphorescence performance can be increased, and the size can be reduced. Since quality metal has a lightweight structure, the overall weight of the heat exchanger can be reduced.

In addition, during the manufacturing process, the heat exchanger tubes were formed into a serpentine shape in advance, and the fin blocks were cast around them, so the joining of the fin heat exchanger tubes was done at the time of casting. The production process is extremely simple, as the key processing steps can be omitted. Further, when the molten metal is cooled and solidified, the fin flock and the heat transfer tube are bonded well due to shrinkage, etc., and the heat transfer between the fins and the heat transfer tube is improved. Furthermore, since a resin model is used, it has the advantage that the passage resistance of the heat exchanger can be determined in advance using the resin model.

[Brief explanation of the drawing]

FIG. 1 is a perspective view of an embodiment of the heat exchanger according to the present invention, FIG. 2 is a partially enlarged view showing an example of the shape of the fin block in FIG. 1, and FIG. FIG. 4 is a partially enlarged view showing an example of the manufacturing method of the present invention. 1... Heat exchanger tube, 2... Fin block, 3
...Fin, 5...Mold for fin, 7
... Crucible, 8 ... Pressure vessel, 10.
...molten metal. Bath / Box camellia figure Figure 5 * 4 figure

Claims (1)

[Scope of Claims] 1. A resin having three-dimensional continuous pores is used as a model, and after filling the pores in this pattern with a fluid molding material, a heat transfer tube formed in a serpentine shape or the like is placed inside the resin at the end of the tube. The resin model is buried so that it is exposed, and then the resin model is removed by heating or other operations to form a mold with three-dimensional continuous pores.Then, this mold is brought into contact with pressurized molten metal to remove the molten metal. After filling the pores of the mold, the molten metal is solidified, and then the mold material is removed, thereby forming a porous metal with continuous three-dimensional pores around the serpentine heat transfer tube by integrally molding it. A method for manufacturing a heat exchanger, characterized in that: 2. A resin having three-dimensional continuous pores is used as a model, and after the pores of the model are filled with fluid mold material, a rod-shaped body made of the same type of material as the resin model is placed in the resin model so that both ends thereof are exposed. The resin model and the rod-shaped body are then removed by heating or other operations to form a mold having three-dimensional continuous holes and through holes, and then a heat exchanger tube formed into a U-shape or the like is inserted into the through hole. After inserting the tube with its end exposed,
By bringing this mold into contact with pressurized molten metal, the molten metal fills the holes in the mold, solidifies the molten metal, and then removes the mold material to form a continuous part around the serpentine heat exchanger tube. 1. A method for manufacturing a heat exchanger, characterized in that a porous metal having three-dimensional pores is bonded by integral molding.