JPH08200982A - Water cooler - Google Patents

Abstract

PURPOSE: To improve the refrigerant side heat transfer efficiency by reducing the diameter of a heat transfer tube straight part near a refrigerant inlet side and accelerating the flowing speed of the refrigerant passed at the tube. CONSTITUTION: A U-shaped heat transfer tube is formed of a heat transfer straight part 2 near a refrigerant inlet side and a heat transfer tube straight part 3 having a small outer diameter at the U-shaped part 3 and near a refrigerant outlet side in such a manner that the part 2 is disposed at the position separate from the tube 3 near the outlet side with respect to a shell centerline 5.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a refrigeration system.

[0002]

2. Description of the Related Art In the water cooler described in Japanese Patent Application No. 63-19647, the heat transfer tubes arranged on the refrigerant inlet side and the refrigerant outlet side are line-symmetrical to the shell center line. The total cross-sectional area of the side heat transfer tubes is the same, the dryness of the refrigerant flowing in the heat transfer tubes near the refrigerant inlet side is low, the mixing ratio of the liquid refrigerant is large, and the specific volume is small. Becomes slower, and the heat transfer coefficient on the refrigerant side decreases.

[0003]

In the conventional U-shaped heat transfer tube of the single tube plate fixing system, the straight pipe portion near the refrigerant inlet side and the straight pipe portion near the refrigerant outlet side are in the refrigerant side heat transfer tube. Even though the area is the same, the dryness of the refrigerant is small in the straight pipe part near the refrigerant inlet side, the mixing ratio of liquid refrigerant is large, and even though the heat transfer coefficient on the refrigerant side is the best region, Since the area is directly on the refrigerant outlet side, the refrigerant flow velocity is unnecessarily reduced as compared with the outlet side, and there is a problem that the heat transfer coefficient on the refrigerant side cannot be improved. According to the present invention, the sum of the refrigerant side cross-sectional areas in the straight pipe portion near the refrigerant inlet side is reduced, the refrigerant flow velocity is increased, and the refrigerant side heat transfer coefficient is improved. In addition, the decrease in the cross-sectional area on the refrigerant side leads to an increase in the cross-sectional area on the water side.
It will be necessary to prevent an increase in the cross-sectional area on the water side. Therefore, the centerline of the array of heat transfer tubes is eccentric from the centerline of the shell to prevent an increase in the water-side cross-sectional area and maintain the water-side heat transfer coefficient, thereby improving the heat transfer coefficient of the water cooler. It becomes possible.

[0004]

In a U-shaped heat transfer tube of a single tube plate fixing type, in order to reduce the tube cross-sectional area of the heat transfer tube near the refrigerant inlet side, the heat transfer tube near the refrigerant outlet side is reduced. The tube diameter of the heat transfer tube having only the straight tube portion and the U-shaped portion is reduced so as to be smaller than the cross-sectional area. Further, when the outer diameter of the heat transfer tube is reduced, the water-side cross-sectional area is increased and the cold water flow velocity is reduced, so that the water-side heat transfer coefficient is reduced. Therefore, in order to prevent a decrease in the flow rate of cold water, the center line of the array of straight pipe sections of the heat transfer tubes near the refrigerant inlet side and the center line of the array of straight tube sections of the heat transfer tube near the refrigerant outlet side And, the center line of the straight tube portion group of the heat transfer tubes near the refrigerant inlet side is arranged farther from the center line formed by the shell. This reduces the water side cross-sectional area, maintains the cold water flow rate, and maintains the water side heat transfer coefficient. As a result, the increase in the heat transfer coefficient on the refrigerant side leads to an improvement in the heat transfer coefficient of the water cooler.

[0005]

In the U-shaped heat transfer tube, the straight tube portion and the U-shaped portion of the heat transfer tube near the refrigerant inlet side have a smaller outer diameter of the heat transfer tube than the straight tube portion near the refrigerant outlet side. The cross-sectional area on the refrigerant side is reduced, the flow velocity of the refrigerant is increased, the dryness is small,
In the region where the mixing ratio of the liquid refrigerant is large and the heat transfer coefficient on the refrigerant side is the best, the refrigerant flow speed can be increased to improve the heat transfer coefficient on the refrigerant side. If the cross-sectional area on the refrigerant side is simply reduced, on the contrary, the cross-sectional area on the water side increases, and the effect is canceled out. Therefore, the center line formed by the group of U-shaped heat transfer tubes is arranged farther from the center line formed by the shell by arranging the center line formed by the group of straight tube portions of the heat transfer tube near the refrigerant inlet side. The gap between the inside and the outer diameter group of the heat transfer tube is the same over the entire area of the heat transfer tube, and the same clearance as when the heat transfer tube is arranged in line symmetry with respect to the shell center line to prevent a decrease in the flow rate of cold water, It is also possible to prevent a decrease in heat transfer coefficient on the water side. As a result, only the increase in the heat transfer coefficient on the refrigerant side improves the heat transfer coefficient of the water cooler.

[0006]

EXAMPLE An example of the present invention will be described below.

FIG. 1 is an illustration of a water cooler embodying the present invention.

FIG. 2 is a side view of the U-shaped heat transfer tube of the present invention.

FIG. 3 is a sectional view of a water cooler embodying the present invention.

The low-temperature, low-pressure evaporative liquid refrigerant that has flowed into the refrigerant inlet portion 1 passes through the inside of the heat transfer tube 2 on the inlet side of the U-shaped heat transfer tube whose outer diameter is reduced. Since the entire outer diameter of the heat transfer tube group is small in this part, the dryness is low, the mixing ratio of the liquid refrigerant is large, and the refrigerant flow velocity increases even if the specific volume of the refrigerant is small. The amount of heat exchange in the part with the highest refrigerant heat transfer rate is increasing. The heat-exchanged refrigerant in this portion has a higher degree of dryness and a larger specific volume, and after passing through the U-shaped portion 3, passes through the inside of the heat transfer tube 4 in which the outer diameter of the heat transfer tube on the outlet side is increased. At this time, on the chilled water side, as shown in FIG. 3, the U-shaped heat transfer tube has a distance a of the center line 6 formed by the tube group of the heat transfer tubes 2 whose outer diameter on the refrigerant inlet side is reduced from the shell center line 5 The gap is larger than the distance b from the shell center line 5 to the center line 7 formed by the tube group of the heat transfer tubes 4 on the refrigerant outlet side, and the shell dimension C of the center line formed by the tube groups and the total dimension of the outer diameters of the tube groups are excluded. Since the shell dimension e of the center line formed by the tube group arranged at the distance b from the shell center and the area d and the clearance cross-sectional area f excluding the total dimension of the tube group outer diameter are the same, The chilled water flow velocity is the same in the gap cross-sectional areas d and f, and the water-side heat transfer coefficient does not decrease. As a result, the heat transfer rate g on the refrigerant side is improved, and the heat transfer rate i (1 / i = 1 / g + 1 / h) obtained by reciprocating the sum of these reciprocals is improved without lowering the water side heat transfer rate h. It becomes possible. The distance a≈distance b + 25 mm is generally the optimum size.

[0011]

According to the present invention, the straight pipe portion of the heat transfer pipe near the refrigerant inlet side of the water cooler has the best heat exchange in the whole area, and the water side heat transfer coefficient is lowered in this portion. Without doing so, the heat transfer coefficient on the refrigerant side is improved and the heat transfer coefficient of the water cooler is improved.

[Brief description of drawings]

FIG. 1 is a sectional view of a water cooler embodying the present invention.

FIG. 2 is a side view of the U-shaped heat transfer tube of the present invention.

FIG. 3 is a sectional view of a water cooler embodying the present invention.

[Explanation of symbols]

1 ... Refrigerant inlet part, 2, 4 ... Heat transfer tube part, 3 ... U-shaped part, 5 ...
Shell center line, 6, 7 ... Center line, 8 ... Cooling outlet part.

Claims (1)

[Claims] 1. In a water cooler of a refrigeration system including a compressor, a condenser, an expansion valve and a water cooler, a U-shaped heat transfer tube of a single tube plate fixing type is a liquid having a low degree of dryness which flows in from a refrigerant inlet side. Since the mixture ratio of the refrigerant is large and the specific volume is small, the liquid refrigerant heat-exchanges with the cold water to gasify only the heat transfer tube straight pipe part and the U-shaped part in the part of the refrigerant flow path where the refrigerant flow velocity becomes small. A water cooler characterized by a smaller cross-sectional area compared to a straight tube portion of a heat transfer tube which is a refrigerant passage near the refrigerant outlet side where the specific volume is large and the refrigerant flow velocity is fast.