JPH04122986U - Air conditioning heat exchanger - Google Patents

Abstract

(57) [Summary] [Purpose] In an air conditioning heat exchanger for an evaporator in which the entire tube is bent in a meandering pattern, the refrigerant in a gas-liquid two-phase state is sufficiently stirred within the tube, and the refrigerant density at each part in the cross section of the tube is determined. To make the temperature uniform and promote heat exchange. [Structure] The wall thickness of a U-bend pipe that connects the ends of a large number of parallel tubes is made thicker than the wall thickness of the tubes, and a large number of grooves for stirring the refrigerant are formed on the inner surface of the U-bend pipe.

Description

[Detailed explanation of the idea]

0001

[Industrial application field]

The present invention is an air conditioning heat exchanger used as an evaporator, in which the refrigerant flows. When the entire tube is bent in a meandering manner, there is a short U-bend in the curved part. This relates to a pipe in which a large number of grooves are formed on the inner surface of the U-bend part.

0002

[Conventional technology]

Conventionally, an air conditioning heat exchanger used as an evaporator consists of many plates with small gaps. Arrange the tube fins in parallel, align their tube insertion holes, and insert multiple The tubes pass through several tubes and connect the ends of the tubes with a U-bend tube. The entire flow path is bent in a meandering manner. Then, a gas-liquid two-phase refrigerant is circulated inside. At the same time, the airflow is circulated around the outer surface of the tube and the airflow is cooled by the refrigerant. It was something that

0003 The liquid phase of the refrigerant flowing inside such tubes and U-bend pipes is The gas flows along the bottom of the tube, and the gas part flows above it. It becomes. Therefore, the density of the refrigerant was non-uniform on the inner peripheral surface of the tube. In addition, a boundary layer of refrigerant develops near the inner wall of the tube, and this was inhibiting heat transfer. Therefore, conventional methods have been developed to improve heat transfer between this tube and the refrigerant. For this purpose, grooves are formed in the straight part of the tube to increase the contact area of There was a proposal as described in Japanese Utility Model Publication No. 60-26315.

0004

[Problem that the idea aims to solve]

However, as a means to improve heat transfer, the straight portions of the tubes are Even if the grooves shown in the example are formed, they are not sufficient to stir the refrigerant flowing inside. Ta. Also, in order to form grooves in the tube, the wall thickness of the tube must be made thicker. . This has the disadvantage that heat transfer between the inside and outside of the tube deteriorates.

[0005]

[Means to solve the problem]

Therefore, in this invention, when the refrigerant bends in a meandering pattern, a large number of grooves are formed at the bending part. The refrigerant can be effectively and sufficiently stirred in a short distance by Forms a uniform refrigerant density in the tube and prevents the development of a boundary layer near the inner wall of the tube. The purpose is to improve heat transfer properties, and the following configuration is adopted to achieve this purpose. That is, the air conditioning heat exchanger of the present invention has a large number of tubes 1 arranged in parallel on the outer surface thereof. Fins 2 are provided, and a gas-liquid two-phase refrigerant flows within the tube 1. along with that This applies to tubes in which air flows through the outer surface of the tube 1. The main idea here The feature of this plan is that the wall thickness of U-bend pipe 3 is thicker than that of tube 1. , and significantly shorter than the length of the tube. And the cold inside A large number of grooves 4 for stirring the medium are formed. and parallel to both ends of the U-bend pipe 3. The ends of the respective tubes 1 are fitted together to connect them liquid-tightly, and the refrigerant flow path is twisted. It is characterized by being formed in a row.

[0006]

[Effect]

According to the heat exchanger of the present invention, a large number of grooves 4 are formed on the inner surface of the short U-bend pipe 3. The refrigerant is efficiently stirred over a short distance at the part where the refrigerant bends. The refrigerant density in each part of the tube 1 cross section is maintained uniformly, and the refrigerant near the inner wall of the tube is prevents the development of a boundary layer and promotes heat exchange.

[0007]

【Example】

Next, embodiments of the present invention will be described based on the drawings. Figure 1 shows the heat exchanger of this invention. Fig. 2 is an enlarged view of the main part, and Fig. 3 is a cross-sectional view taken along arrows III-III in Fig. 2. It is a schematic diagram. The air conditioning heat exchanger of this example is used as an evaporator. It has a large number of plate-shaped fins 2. This fin 2 is aluminum It is made of a thin metal plate with good heat conductivity, such as aluminum or copper, and has many tube insertion holes on its flat surface. A burring process is formed on the edge of the insertion hole. Such a f The tubes 2 are arranged in parallel with a large number of small gaps, and their respective tube insertion holes are aligned with each other. So In this embodiment, the straight portion of the U-shaped tube 1 is connected to each of the fins 2. Insert the tube into the insertion hole, and then insert the expansion jig inside the straight part of tube 1. The outer surface of the tube 1 and the tube insertion hole of the fin 2 are brought into close contact. Na In some cases, the contact part between tube 1 and fin 2 may be joined by soldering etc. .

[0008] Next, it is sufficiently thicker than the wall thickness of this tube 1 and significantly thicker than the length of the tube. The ends of each tube 1 are connected via a short U-bend pipe 3. This Ube The end tube 3 has a large number of spiral grooves 4 formed therein. This kind of spiral To form the groove 4, first, as shown in FIG. A spiral groove is formed in advance in the part. Next, after bending it as shown in Fig. 6, it is bent as shown in Fig. 7. Both ends of the U-bend pipe 3 are expanded as shown in FIG. 3, and fitting parts 5 are formed there. And this fit The end of the tube 1 is fitted into the fitting part 5, and the fitting part is brazed or soldered. It is sufficient to join them liquid-tightly.

[0009] In the embodiment shown in FIG. 2, the fitting part 5 and the end of the tube 1 are made liquid-tight by the solder 6. It is joined. Note that the groove 4 formed inside the U-bend pipe 3 is It is preferable to set the thickness to about 1/3 to 1/2 of the wall thickness. U-bend tube 3 is different from tube 1. Since the board is thick enough, it can maintain sufficient strength even if grooves 4 are formed inside. Ru. Also, when a straight tube is bent as shown in Figure 6, the cross section of the tube changes from a perfect circle to a slightly flattened one. However, if the fitting portions 5 are then formed at both ends, when forming the fitting portions 5, It can be reshaped into a perfect circle, and the end of the tube 1 with a circular cross section is fitted into the fitting part 5. Then, the consistency will be good and the brazing or soldering accuracy will be high. , resulting in a highly reliable heat exchanger. Next, FIG. 4 is a longitudinal sectional view of the main part of the second embodiment of the present invention, and in this embodiment, the U-bent Fins 2 are also provided on the outer surface of the U-bend pipe 3, allowing efficient heat exchange in the 3-part U-bend pipe. We are planning to do this.

0010

[Effect of the idea]

The air conditioning heat exchanger of the present invention has a large number of grooves for stirring the refrigerant on the inner surface of the U-bend pipe 3. 4, many grooves are formed especially in areas where the refrigerant changes direction. As a result, the refrigerant is efficiently agitated over a short distance by the grooves, and the refrigerant and tube 1 can be effectively transferred. That is, the refrigerant temperature at the center of the tube 1 The temperature of the refrigerant near the inner circumferential surface of the tube is maintained almost uniformly, and the refrigerant temperature near the inner circumferential surface of the tube is can prevent the development of a boundary layer and increase heat exchange capacity. Moreover, is the wall thickness of the U-bend pipe 3 thicker than that of the tube 1? Even if a sufficiently deep groove 4 is formed inside, the U-bend pipe 3 maintains sufficient strength and reliability. It is possible to provide a heat exchanger for air conditioning with high performance. Also, since the length of the U-bend pipe 3 is significantly shorter than the tube length, its wall thickness should be Even if the thickness is increased, the heat conductivity is not affected.

[Brief explanation of drawings]

FIG. 1 is a longitudinal cross-sectional view of a main part of an air conditioning heat exchanger of the present invention.

FIG. 2 is an enlarged view of the main part of FIG. 1.

FIG. 3 is a schematic cross-sectional view taken along the line III-III in FIG. 2;

FIG. 4 is a vertical cross-sectional view of a main part of a second embodiment of the present invention.

FIG. 5 shows the first step of the U-bend pipe manufacturing method of the present invention.

FIG. 6 shows the second step of the U-bend pipe manufacturing method.

FIG. 7 shows the third step of the U-bend pipe manufacturing method.

[Explanation of symbols]

1 tube 2 fins 3 U-bend pipe 4 Groove 5 Fitting part 6 Solder 7 Refrigerant

Claims (1)

[Scope of utility model registration request] 1. A large number of fins (2) are arranged on the outer surface of a large number of tubes (1) arranged in parallel, and the tubes (1)
In an air-conditioning heat exchanger in which a gas-liquid two-phase refrigerant flows inside the tube (1) and an air flow flows through the outer surface of the tube (1), the tube (1) is thicker than the wall thickness and has a length of the tube (1). A large number of refrigerant stirring grooves (4) are formed on the inner surface of the U-bend pipe (3), which is significantly shorter than the U-bend pipe (3), and each of the tubes (1) is arranged in parallel with both ends of the U-bend pipe (3).
1. An air conditioning heat exchanger, wherein the ends of the refrigerant are fitted into each other to be liquid-tightly connected, and the refrigerant flow path is formed in a meandering shape.