JPH04225793A - Heat exchange pipe and manufacture thereof - Google Patents

Abstract

PURPOSE:To improve a heat transfer rate in a pipe during heating and to enable the decrease of the size of a tube by a method wherein porous products fused and combined together through the covering materials of respective core materials are formed in a plurality of spots on the inner surface of a pipe used for the feed of a refrigerant. CONSTITUTION:A pipe 6 used for the feed of a refrigerant is formed such that a plurality of core materials 4 formed of a steel material with a diameter of approximate 50-200mum are piled up throughout a long range of a plurality of the core materials to produce a porous product 10, and the porous products are attached in a way that the core materials 4 are combined together or the core material 4 and the pipe 6 are combined together through a covering material 5. Namely, the covering material 5 of nickel is heat-treated and molten, the core materials 4 are combined together and the core material 5 and the pipe are combined together to produce the porous product 7. This constitution and method collect a refrigerant, passing through the pipe 6, to the crest of the crest of the porous product 11, reduce heat resistance on the whole of the pipe, and improve condensing performance and heat transfer rate in the pipe during heating.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a heat exchange pipe that improves the condensation performance of refrigerant in the pipe in an indoor unit of a heat pump type room air conditioner, and a method for manufacturing the same.

0002

2. Description of the Related Art FIG. 11 is a perspective view showing a conventional heat exchange pipe. In the figure, 1 is a pipe, and the inner surface of this pipe 1 is provided with a plurality of grooves 2 in the axial direction. 2 is called a wave-grooved pipe because the end surface of the pipe 1 forms a wave shape. Further, this pipe 1 is manufactured by forming grooves 2 on a flat base material by pressing or ironing, then rolling this base material into a pipe shape, and further welding the mating surfaces. By providing the grooves 2 in this manner, the area in contact with the refrigerant flowing inside the pipe 1 is increased, and the evaporation and condensation performance is promoted, thereby improving the heat transfer coefficient within the pipe. Further, the specifications of the groove shape of the pipe 1 having such a groove 2 are as shown in FIG. Appropriate values are given for each H.

0003

[Problems to be Solved by the Invention] Since the conventional heat exchange pipe is constructed as described above, it is effective in accelerating the evaporation of the refrigerant flowing through the pipe 1 during cooling, but the evaporation of the refrigerant during heating is The condensation capacity is about 1/2 of the evaporation capacity, and if the groove 2 is too deep, the film thickness of the refrigerant P accumulated in this groove will increase as shown in Fig. 13.
As shown in Figure 2, the thickness of the pipe becomes thicker, which creates resistance and impedes condensation, leading to problems such as reducing the heat transfer coefficient within the pipe during heating. In this way, the weak point of heat pump air conditioners is their heating performance, and it is necessary to improve this.
Conventional corrugated grooved pipes could not solve this problem. In addition, since grooves 2 are formed in a flat plate material, and then the flat plate is bent into a pipe shape and welded, the grooves 2 of the welded part 3 are crushed, and as a result, the in-pipe heat transfer rate is lower than that of a pipe with complete grooves 2. In the future, as indoor units become smaller and pipes become thinner, there is a problem that the loss of this welded part 3 may become fatal.

[0004] The invention of claim 1 has been made to solve the above-mentioned problem, and improves the heat transfer coefficient in the pipe during heating by providing a porous body inside the pipe.
The purpose is to obtain a heat exchange pipe that can be made into thin tubes.

[0005] Furthermore, the invention of claim 2 allows the porous body to be formed into any pattern by simply placing the coating material inside the pipe or on the base material for pipe construction using a jig and then heating it. It is an object of the present invention to obtain a method for manufacturing a heat exchange pipe that allows the formation of heat exchange pipes.

[0006]

[Means for Solving the Problems] The heat exchange pipe of the invention according to claim 1 is provided with a plurality of core materials and a plurality of core materials and the pipe, respectively, on the inner surface of the pipe used for supplying refrigerant. A porous body fused and bonded with a core material covering material is provided at a plurality of locations.

[0007] The method for manufacturing a heat exchange pipe of the invention according to claim 2 includes stacking the coating material on the inner surface of the pipe or the base material for the pipe using a jig, heating the coating material, The melted coating material of the coating material binds the core materials coated with each other and the core material and the pipe, thereby forming a porous body on the inner surface of the pipe.

[0008]

[Operation] The porous body in the invention of claim 1 functions to collect the refrigerant passing through the pipe here and to reduce the thickness of the refrigerant film in other parts, thereby increasing the thermal resistance of the pipe as a whole. It is possible to improve the condensing performance of the refrigerant by reducing the amount of water, and to improve the heat transfer coefficient within the pipe.

[0009]Furthermore, in the invention of claim 2, the porous body is fixed to the pipe by arranging the coating material in a set pattern on the inner surface of the pipe or on the base material for forming the pipe using a jig, and in this state. This is achieved by heating the coating material coated on the peripheral surface of the core material and melting and solidifying the coating material.

0010

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. In FIG. 1, 6 is a pipe used for supplying refrigerant, and 5 is a plurality of core materials made of steel with a diameter of about 50 to 200 μm. The core materials 6 are stacked to form a porous body, and the core materials 6 and the core materials 6 and the pipe 6 are respectively connected by covering materials. FIG. 2 shows a method of forming such a porous body 11. First, a core material 6 with a coating material 5 such as nickel plating applied around it is placed on the inner surface of a pipe 6.
Stack and fix multiple pieces as shown in Figure 2a,
Thereafter, the covering material 5 is melted by heat treatment, and the melted covering material 5 is used as a bonding material to join the core materials 4 to each other and to the core material and the pipe. This results in
A porous body 7 as shown in FIG. 1 is formed on the inner surface of the pipe 6.

Next, the operation will be explained. First, the components of the plating layer obtained by electroless nickel plating are an alloy containing nickel and a small amount of phosphorus, which is an element that lowers the melting point, and is made of nickel solder (BNi-6 Ni: 89%,
P: 11%). Therefore, the bonding strength (2.8 kgf/mm2) between the coated materials 7 fused by heat treatment is almost the same as that of brazing. In addition, by providing a plurality of ridges of porous bodies 10 on the inner surface of the pipe 6, the surface tension of the refrigerant generated in the gaps between the core materials 4 constituting each porous body 10 causes the inside of the pipe 6 to flow. The flowing refrigerant gathers in a portion A around the porous body 10, as shown in FIG. Therefore, in the other portion B of the inner surface of the pipe 6, the film thickness of the refrigerant P becomes thinner. As a result, refrigerant P tends to condense in areas where the film thickness is thin,
The heat exchange efficiency can be improved by lowering the thermal resistance, and the heat transfer coefficient within the pipe during heating can be improved.

[0012] Also, a method for manufacturing the above heat exchange pipe having the above porous body will be explained. First, as shown in Fig. 2, in this example, copper particles with a particle size of 100 μm are used as the core material 4, and electroless nickel plating (nickel: 87-93%, phosphorus: 4-12%, other 1%) is used. The core material 4 is plated in a solution at 90.degree. C. for 20 minutes to form a nickel plating film that will become the covering material 5 on the core material 4. In this way, a coated material 7 having a nickel plating film of about 3 μm on the copper particles is obtained. Note that FIG. 2 is a schematic diagram, and the thickness of the covering material 5 is drawn thicker than the actual size ratio. Next, we used a jig made of a material that does not react with the nickel plating even when heated, that is, a material with poor wettability and a linear expansion coefficient smaller than that of pipe 6 (here, stainless steel with a strong oxide film). 8, that is, the outside diameter is equal to the inside diameter of the pipe 6, the radial gap with the pipe 6 is smaller than the grain size of the coating material 7, and in this example, the jig 8 has a plurality of grooves 9 extending in the longitudinal direction. Figure 4
Insert it into the pipe 6 as shown. Then, the coating material 7 is put into the groove 9 of the jig 8 by ultrasonic vibration, etc.
It is held by a jig 8 so as not to collapse. This is done in a vacuum (
Place it in a brazing furnace with an atmosphere of about 10-3 Torr,
Heat at 950°C for 30 minutes. Through this heat treatment, the plated coating material 5 melts and is drawn into the contacting parts of the coating materials 7 with each other and the inner surface of the pipe 6 due to surface tension, wettability, etc. The nickel plating layer disappears, and the surface of the core material 4 made of copper is exposed as shown in FIG. After finishing the heat treatment,
In this state, the nickel-plated covering material 5 is solidified and fixed. After that, pull out the jig 8 and attach it to the inner surface of the pipe 6 as shown in Fig.
A heat exchange pipe as a condensing pipe having a plurality of rows of porous bodies 10 as shown in FIG. In the above embodiment, a plurality of porous bodies 10 are arranged in the longitudinal direction (axial direction) of the inner surface of the pipe 6.
However, if a jig 11 having a plurality of spiral grooves 12 as shown in FIG. 6 is used, a plurality of spiral porous bodies 10 as shown in FIG. 7 can be formed. can. The material and outer diameter tolerance of this jig 11 are the same as those of the jig 8, and when pulling out the jig 11, the jig 11 is rotated while being pulled out from the pipe 6.

FIG. 8 shows another embodiment of the present invention. In this method, a plurality of rod-shaped jigs 14 made of a material that is difficult to get wet with the molten coating material 5 are placed on the base material 13 of the pipe 6 as shown in FIG.
After placing the coating treatment material 7 on it as shown in a, the base material 13 and the jig 14 are heated to a temperature higher than the melting point of the coating material 5.
The core material 4 and the base material 13 are heated at a temperature lower than their melting points to fuse the coated materials 7 and the base material 13 together. This base material 13 is the coating material 7
After the porous body 10 is formed, the jig 14 is removed to form the shape shown in FIG. 8b, which is then bent into a pipe shape, and as shown in FIG. 8c, it is welded at the welding part 6a and heated Considered to be a replacement pipe. Furthermore, by discontinuously arranging piles of the coating material 7 at a plurality of locations on the base material 13 and heating them using a grid-like jig (not shown), a porous body 10 as shown in FIG. 9a is formed. It is possible to obtain a base material 13 having a shape. Therefore, if this is processed into a pipe shape, a heat exchange pipe as shown in FIG. 9b can be obtained.

In the above embodiment, as shown in FIG. 2, the nickel plating film which is the covering material 5 disappears, and the material surface of the core material 4 is exposed. However, the core material 4 is made of an inexpensive iron powder that does not have very high corrosion resistance, and the coating material 5 is nickel plated, which has excellent corrosion resistance.As shown in FIG. 10, the coating material remains intact even after heat treatment. If the thickness of the coating material 5 is controlled so that the nickel plating film 5 does not disappear from the iron surface of the core material 4, a heat exchange pipe having a porous body 10 with excellent corrosion resistance on the inner surface can be obtained. . Further, in the above embodiment, the core material 4 and the pipe 6 are made of copper, but metals such as stainless steel, nickel, and perylium steel, inorganic substances such as glass, and polymers such as styrene may also be used.

[0015]

As described above, according to the invention of claim 1, a plurality of core materials are formed on the inner surface of a pipe used for supplying refrigerant, and the core materials and the pipe are coated with the covering material of the core materials. Since the structure is such that the porous body fused and bonded by is provided at multiple locations, the refrigerant passing through the pipe can be collected in the pile of the porous body, and therefore,
The thickness of the refrigerant film can be made thinner in other parts of the inner surface of the pipe, resulting in a reduction in thermal resistance for the pipe as a whole, which has the effect of improving condensing performance and improving the heat transfer coefficient within the pipe during heating. .

According to the second aspect of the invention, the coating material is stacked on the inner surface of the pipe or the base material for the pipe using a jig, the coating material is heated, and the coating material is heated. The melted coating material joins the core materials covered with this and the core and the pipe,
By forming a porous material on the inner surface of this pipe,
It is possible to easily and quickly fix a pile of porous material in a line shape or other pattern inside a pipe, and this type of heat exchange pipe can be manufactured in large quantities at low cost.

[Brief explanation of the drawing]

FIG. 1 is a perspective view showing a heat exchange pipe according to an embodiment of the present invention.

FIG. 2 is an explanatory diagram showing a procedure for fixing a porous body to a heat exchange pipe according to an embodiment of the present invention.

FIG. 3 is an explanatory diagram showing the state of refrigerant in a pipe in the present invention.

FIG. 4 is a perspective view showing the manufacturing process of the heat exchange pipe of the present invention.

FIG. 5 is a sectional view showing a porous material pattern within a pipe according to the present invention.

FIG. 6 is a perspective view showing a method of manufacturing a heat exchange pipe of the present invention.

7 is a cross-sectional view showing a porous pattern of a pipe manufactured by the method shown in FIG. 6. FIG.

FIG. 8 is a perspective view showing another method of manufacturing the heat exchange pipe of the present invention.

FIG. 9 is a perspective view showing still another method of manufacturing the heat exchange pipe of the present invention.

FIG. 10 is an end view showing another solidification process for the porous pipe of the present invention.

FIG. 11 is a perspective view showing a conventional heat exchange pipe.

FIG. 12 is a specification diagram showing appropriate values for the groove shape in a conventional heat exchange pipe.

FIG. 13 is an explanatory diagram showing the state of refrigerant in a conventional pipe.

[Explanation of symbols]

4 Core material 5　Coating material 6 Pipe 7 Coating treatment material 8 Jig 10 Porous body In addition, in the figures, the same reference numerals indicate the same or corresponding parts.

Claims (2)

[Claims] 1. A pipe used for supplying a refrigerant, and a plurality of core materials, and the core material and the pipe are fused and connected to each other at a plurality of locations on the inner surface of the pipe, respectively, by coating materials of the core materials. A heat exchange pipe equipped with a porous body. 2. A coating material is formed by forming a coating material with a lower melting point on the core material, and the coating material is applied onto the inner surface of the pipe or the base material for forming the pipe using a jig. Heat exchange in which the core materials are stacked at multiple locations and the coating material is melted by heating the coating material, thereby bonding the core materials to each other and the core material to the pipe to form a porous body on the inner surface of the pipe. Method of manufacturing pipes.