JP2691055B2 - Double pipe oil cooler - Google Patents

Description

TECHNICAL FIELD The present invention relates to a double-tube oil cooler for cooling oil in a compressor of a refrigeration system.

[Conventional technology]

FIG. 3 is a system diagram of the helium gas compressor unit. In the figure, the helium gas compressed by the compressor 1 is discharged while containing oil, enters the discharge gas cooler 2, is cooled by the cooling water W1 there, and then is guided to the oil separator 3 where the helium is discharged. Gas and oil are separated. The helium gas from which the oil has been separated enters the adsorber 4, where the oil vapor is removed and sent to an expander (not shown). The low-pressure helium gas that has left the expander is sucked into the compressor 1 via the surge bottle 5. On the other hand, the oil separated by the oil separator 3 returns to the compressor 1 through the oil return pipe 7. The high temperature oil in the oil sump of the compressor 1 is cooled by the cooling water W2 while circulating through the oil cooler 6.

The oil cooler 6 is usually provided to cool the oil in the compressor 1 when the discharge gas temperature in the compressor 1 is high. Cooling water flows, and oil flows between the inner pipe and the outer pipe.

Further, in the conventional oil cooler 6, a finned pipe having fins formed on the outer wall surface is used for the inner pipe in order to enhance the cooling capacity of oil, and heat transfer is promoted by increasing the heat transfer area. ing.

[Problems to be solved by the invention]

In general, since the oil used for lubricating the compressor 1 has a high viscosity, the oil flow is in a laminar flow state even near the flow path wall, particularly the fin. Therefore, the heat transfer coefficient of the oil cooler 6 is small, and the oil cooler 6 is increased in size.

The present invention is intended to solve the above-mentioned drawbacks of the prior art and provide a double-tube oil cooler having improved heat exchange performance.

[Means for solving the problem]

The present invention is to solve the above problems, and an outer tube,
The inner pipe is inserted into the outer pipe and has fins formed on the outer wall surface, and the oil introduced from the compressor is passed between the inner pipe and the outer pipe, and the oil is introduced into the inner pipe. In a double-pipe type oil cooler in which a cooling medium flows, the inner diameter of the outer pipe is made larger than the outer diameter of the fin of the inner pipe, and the inner wall of the outer pipe has a fin on the outer wall surface of the inner pipe. The present invention relates to a double-tube oil cooler in which irregularities are formed at a pitch larger than the pitch.

[Action]

Since the double-tube oil cooler of the present invention has the above-described configuration, the fins formed on the outer wall surface of the inner pipe increase the heat transfer area, and the unevenness formed on the inner wall of the outer pipe causes The oil flow is agitated and mixed to be turbulent, which promotes heat transfer, and these actions improve heat exchange performance.

〔Example〕

FIG. 1 is a cooling system diagram of an embodiment of the double pipe oil cooler of the present invention, and FIG. 2 is a partially enlarged sectional view of the embodiment. In FIG. 1, 1 is a compressor, 21 is an oil reservoir at the inner bottom of the compressor, 22 is a suction gas pipe, and 10 is an oil cooler of this embodiment. A double pipe described later is wound in a coil shape. It is a thing. FIG. 2 shows a part of the above double-tube oil cooler 10, where 11 is an inner tube similar to the conventional one, and 12 is an outer tube having a different shape from the conventional one. 11a is the tubular part of the inner tube 11, 11b
Is a fin protruding outside the tubular portion. Therefore, the inner pipe 11 is a finned pipe. Due to this fin, the heat transfer area of this inner tube is larger than the length of the tube.
Reference numeral 12a denotes an uneven portion formed in a wavy shape on the inner surface of the outer tube at a pitch P, and this uneven portion is formed in a spiral shape in the tube axis direction. Therefore, the outer tube is a so-called corrugated tube.

In the oil cooler having the above structure, the compressor 1
The oil O in the
The cooling water W is guided to and flow between the inner pipe and the inner pipe.
The oil in 11 is flowed in the opposite direction to the oil to cool the oil. The cooled oil O returns to the oil sump 21 of the compressor 1 via the suction gas pipe 22.

In this oil cooler, the fin 11
b is formed in a protruding manner to increase the heat transfer surface per tube length, and the spiral unevenness formed on the inner wall of the outer tube 12
The flow of oil is agitated and mixed by 12a, and the turbulence of the flow is promoted.As a result, the oil flowing near the outer surface of the tubular portion 11a of the inner pipe 11 corresponding to the heat transfer surface and in the vicinity of the fin 11b and the heat transfer Replacement of oil with the oil flowing away from the surface becomes popular, and heat transfer is promoted, so the heat exchange performance of the oil cooler as a whole is improved.

Table 1 shows a performance comparison between the oil cooler of this embodiment and the conventional oil cooler. In the same table, the performance comparison conditions and the resulting heat transfer coefficient on the oil side are shown. The only difference between the present embodiment and the prior art under the performance comparison conditions is the presence or absence of irregularities inside the outer tube. In the comparison under these conditions, the heat transfer coefficient of the oil cooler of this embodiment is four times that of the conventional oil cooler.

2 shows that the outer wall of the outer tube 12 also has an uneven shape, but the gist of the present invention is to give a disturbing action to the flow of oil, so that it is not limited to that shown in the drawing. Instead, the outer wall of the outer tube has a straight tube shape, and unevenness is formed only on the inner wall of the outer tube.

[Effect of the Invention] In the double-tube oil cooler of the present invention, the inner diameter of the outer pipe is set to be larger than the outer diameter of the fin of the inner pipe,
Since the unevenness is formed on the inner wall of the outer tube at a pitch larger than the pitch of the fins on the outer wall surface of the inner tube, the unevenness of the inner wall of the outer tube causes the oil flow on the fin surface of the inner tube to be agitated and mixed. As a result of the turbulence of the flow being promoted, heat transfer is promoted and the heat exchange performance of the oil cooler as a whole is improved.

[Brief description of the drawings]

FIG. 1 is a system diagram of an embodiment of the double-tube oil cooler of the present invention, FIG. 2 is a partially enlarged sectional view of the oil cooler, and FIG.
The figure is a system diagram of the helium gas compressor unit. 1 ... Compressor, 2 ... Discharge gas cooler, 3 ... Oil separator, 4 ... Adsorber, 5 ... Surge bottle, 6 ... Oil cooler, 7 ... Oil return pipe, 10 ... Oil cooler, 11 ... … Inner pipe, 11a …… Tubular part, 11b …… Fin, 12 …… Outer pipe, 12a …… Wave corrugated, 21 …… Oil reservoir, 22 …… Intake gas pipe, O …… Oil, W, W1, W2 ……Cooling water.

Claims (1)

(57) [Claims] 1. An oil pipe comprising an outer pipe and an inner pipe which is inserted into the outer pipe and has fins formed on an outer wall surface thereof. The oil is introduced from the inside of the compressor between the inner pipe and the outer pipe. In a double-tube oil cooler in which a cooling medium flows in the inner pipe, the inner diameter of the outer pipe is made larger than the outer diameter of the fins of the inner pipe, and the inner wall of the outer pipe is A double pipe type oil cooler in which irregularities are formed at a pitch larger than the pitch of fins on the outer wall surface of the inner pipe.