JPH0552558U - Double tube heat exchanger - Google Patents

Abstract

(57) [Abstract] [Purpose] The pressure resistance of the inner pipe can be improved without changing the inner pipe thickness and without using high strength material such as stainless steel for the inner pipe. Even when the height is high, it is possible to prevent the inner tube from buckling. A double pipe is formed by mounting a circular copper inner pipe 2 on a copper outer pipe 1 in which longitudinally extending inward fins 1a are provided at intervals in the circumferential direction. Is bent into a coil shape, the required length of the inner pipe 2 is projected from the outer pipe at the end of the double pipe, and the reinforcing pipe 6 is attached to at least the inner surface of the inner pipe of the projecting portion to form the outer pipe 1 and the inner pipe. A refrigerant supply / discharge header 5 was brazed over the outer pipe and the inner pipe at the end of the double pipe so that the refrigerant could flow between the two.

Description

[Detailed description of the device]

[0001]

[Industrial application]

 The present invention relates to a double-tube heat exchanger for cooling industrial water with a refrigerant.

[0002]

[Prior Art]

 2 to 4 show such a double-tube heat exchanger, and as shown in FIG. 4, a double tube composed of an outer tube 1 made of a copper tube and a circular inner tube 2 made of a copper tube is used. As shown in FIG. 3, it is bent into a coil. The outer pipe 1 is provided with mountain-shaped inward fins 1a extending in the lengthwise direction on the inner peripheral surface of the inner pipe 2 so as to project radially at appropriate intervals in the circumferential direction by integral molding. Abut. The space between the outer pipe 1 and the inner pipe 2 defined by the inward fins 1a serves as the refrigerant passage 3, and the interior of the inner pipe 2 serves as the cooled water passage 4.

As shown in FIG. 3, the end of the inner pipe 2 protrudes a required length from the end of the outer pipe 1 and is connected to a water passage pipe (not shown) as a water inlet and a water outlet. At the end of the outer tube 1 which is shorter than the end, a copper coolant supply / discharge header 5 is provided. The header 5 is brazed to the outer pipe 1 and the inner pipe 2 at the ends of the double pipe, and FIG. 2 shows the details of the installation portion of the header 5.

In this way, the water to be cooled enters the inner pipe 2 from the end of the inner pipe 2, flows through the cooled water passage 4 in the inner pipe 2 and exits from the other end of the inner pipe 2. While flowing, the header 5 enters the refrigerant passage 3 between the outer pipe 1 and the inner pipe 2 during that time, and is cooled by the refrigerant flowing therethrough. In particular, the inward fins 1a are useful for improving the heat exchange performance during such cooling action.

[0005]

[Problems to be solved by the device]

In the double-tube heat exchanger having the above-described structure, when the header 5 is brazed, the outer tube 1 and the inner tube 2 which are copper tubes are softened by heating and their strength is lowered. Therefore, when the refrigerant pressure is high, the inner tube 2 may buckle as shown in FIG. By the way, when the refrigerant pressure is 40 kgf / cm ² or less of static pressure, the inner tube 2 does not buckle, but repeated pressure resistance tests revealed that it buckles after 20,000 cycles or less. The outer tube 1 is reinforced by the presence of the inward fins 1a, so that there is no fear of deformation as much as the inner tube 2.

In order to prevent the buckling of the inner pipe 2, it is possible to increase the wall thickness of the inner pipe 2 or use a high-strength material such as stainless for the inner pipe 2. However, because of the outer tube 1 having the inward fins 1a extending in the longitudinal direction at intervals in the circumferential direction, it is more difficult to bend the coil into a coil shape, which is originally a difficult factor. And Furthermore, since the weight also increases, the cost also increases.

An object of the present invention is to solve the above-mentioned inconveniences and provide a double-tube heat exchanger capable of improving pressure resistance performance while keeping the inner tube made of copper thin.

[0008]

[Means for Solving the Problems]

 In order to achieve the above-mentioned object, the present invention forms a double pipe by mounting a circular copper inner pipe to a copper outer pipe in which longitudinally extending inward fins are circumferentially spaced. The double pipe is bent in a coil shape, the required length of the inner pipe is made to protrude from the outer pipe at the end of the double pipe, and a reinforcing pipe is attached to at least the inner surface of the inner pipe of the protruding portion. The gist of the invention is to braze a refrigerant supply / discharge header over the outer pipe and the inner pipe at the end of the double pipe so that the refrigerant can flow between the inner pipes.

[0009]

[Action]

 According to the present invention, a reinforcing pipe is attached to the inner surface of the inner pipe of which the required length projects from the outer pipe, and the inner pipe is reinforced by the reinforcing pipe to increase strength and prevent buckling. In addition, since it is supplemented by a reinforcing pipe, it is not necessary to increase the wall thickness of the inner pipe itself, and this reinforcing pipe is a part where the header for supplying and discharging the refrigerant is brazed and joined to the outer pipe and the inner pipe at the end of the double pipe. Since it is installed in the area, it will effectively reinforce only the part where the strength is lowered due to softening due to the heating of the brazing.

[0010]

【Example】

 Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 is a vertical sectional side view of an essential part showing one embodiment of a double-tube heat exchanger according to the present invention, in which the same constituent elements as those in FIG. 2 showing the conventional example are designated by the same reference numerals.

The overall structure of the double-tube heat exchanger of the present invention is the same as that of the conventional example, which is bent in a coil shape as shown in FIG. 3, and has a length on the inner peripheral surface as shown in FIG. A double tube composed of an outer tube 1 made of a copper tube in which radially extending inwardly directed fins 1a are integrally formed and radially projected at appropriate intervals in the circumferential direction, and a circular inner tube 2 inserted into the outer tube 1. It is of structure. Such a double-tube structure is obtained by mounting the inner tube 2 on the outer tube 1 and drawing it so that they are integrally fitted.

Then, the end of the inner pipe 2 is projected a required length from the end of the outer pipe 1 and is connected to a water passage pipe (not shown) as a water inlet and a water outlet. A header 5 for supplying and discharging a cooling medium made of copper is provided at one end by brazing. In the present invention, a reinforcing pipe 6 is attached to the inner surface of the protruding portion of the inner pipe 2 from the end of the outer pipe 1. The end of the reinforcing pipe 6 reaches the inside of the end of the outer pipe 1 corresponding to the portion where the header 5 for supplying and discharging the refrigerant is provided.

The material of the outer tube 1 is a JIS C1220T phosphorous deoxidized copper tube, and the material of the inner tube 2 and the header 5 for supplying and discharging the cooling medium are also the JIS C1220T phosphorous deoxidizing copper tube. As the reinforcing pipe 6, a JIS C1220T white copper pipe for a condenser was used. In consideration of the fact that the pressure loss of the refrigerant flowing through the inner pipe 2 increases when the reinforcement pipe 6 is attached, the material of the reinforcement pipe 6 is assumed to be as thin as possible and strong.

It should be noted that the inner pipe 2 and the reinforcing pipe 6 can be fixed to each other by originally brazing silver, but if abnormal corrosion is feared due to residual silver braze flux, the inner pipe 2 The ends of the reinforcing pipe 6 and the reinforcing pipe 6 may be joined by TIG welding 7.

In this way, the pressure resistance of the inner pipe 2 is improved by the reinforcing pipe 6, and the buckling of the inner pipe 2 is not observed when the refrigerant pressure is static pressure of 90 kgf / cm ² or less.

[0016]

[Effect of the device]

 As described above, in the double-tube heat exchanger of the present invention, a circular copper inner tube is attached to a copper outer tube in which longitudinally extending inward fins are circumferentially spaced. To form a double pipe, bend the double pipe into a coil shape, and project the required length of the inner pipe from the outer pipe at the end of the double pipe and prevent the refrigerant from flowing between the outer pipe and the inner pipe. In a heat exchanger in which a refrigerant supply / discharge header is brazed across the outer and inner pipes at the end of the double pipe so that the inner pipe can remain thin and the inner pipe is made of stainless steel, etc. It is possible to improve the pressure resistance of the inner pipe without using the high-strength material and to prevent the inner pipe from buckling even when the refrigerant pressure is high.

[Brief description of drawings]

FIG. 1 is a vertical cross-sectional side view of essential parts showing an embodiment of a double-tube heat exchanger of the present invention.

FIG. 2 is a vertical sectional side view of a main part showing a conventional example.

FIG. 3 is a side view of the entire double-tube heat exchanger.

FIG. 4 is a partial cross-sectional view of a double pipe heat exchanger.

FIG. 5 is a partial cross-sectional view of a double pipe heat exchanger showing buckling of an inner pipe.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Outer pipe 1a ... Inward fins 2 ... Inner pipe 3 ... Refrigerant passage 4 ... Cooled water passage 5 ... Header 6 ... Reinforcement pipe 7 ... TIG welding

Claims (1)

[Scope of utility model registration request] 1. A double copper pipe is formed by mounting a circular copper inner pipe on a copper outer pipe having longitudinally extending inward fins circumferentially spaced from each other. It is bent in a coil shape, and the required length of the inner pipe is projected from the outer pipe at the end of the double pipe, and a reinforcing pipe is mounted on at least the inner surface of the inner pipe of the protruding portion, and a refrigerant is provided between the outer pipe and the inner pipe. A double-pipe heat exchanger characterized in that a header for supplying and discharging a refrigerant is brazed over an outer pipe and an inner pipe at the ends of the double pipe so that the heat can flow therethrough.