Loop-type thermosiphon and stirling refrigerator

Abstract

A loop-type thermosiphon capable of stable operation regardless of fluctuation of heat load and a Stirling refrigerator using the same are provided. The loop-type thermosiphon transferring heat from a high-temperature heat source using a working fluid includes a evaporator having a heat absorption portion and evaporating the working fluid by depriving the high-temperature heat source of heat through the heat absorption portion, a condenser located above the high-temperature heat source and condensing the working fluid that has evaporated in the evaporator, and a pipe connecting the evaporator and the condenser so as to form a loop. In the loop-type thermosiphon, the working fluid that has passed through the condenser is brought in contact with the heat absorption portion before it is pooled in a liquid pool for the working fluid in the evaporator, so as to exchange heat with the same

Description

TECHNICAL FIELD [0001] The present invention relates to a loop-type thermosiphon and a Stirling refrigerator using the same. BACKGROUND ART [0002] A heat sink, a heat pipe, a thermosiphon, or the like is used for cooling a heat-generating instrument or a thermoelectric cooling device. As to the heat sink, temperature distribution is caused in a base portion thereof provided with a heat source. Accordingly, as a distance from the heat source is increased, the heat sink contributes less to heat dissipation. Meanwhile, the heat pipe or the thermosiphon has high heat transfer capability, and is characterized by small temperature variation even when the heat is transferred to a portion distant from the heat source. [0003] On the other hand, with regard to the heat pipe, vapor and liquid of a working fluid flows in the same pipe. As such, if an amount of heat transfer is large, a greater number of pipes are necessary. For example, if it is assumed that a temperature difference is set to 5...

AI Technical Summary

Benefits of technology

[0014] According to such an arrangement, the cooled and condensed working fluid is preheated after falling on the heat absorption portion instead of being directly supplied to the liquid pool, and thereafter it is supplied from above by gravitation. Accordingly, a flow is produced in the liquid pool and evaporation of the working fluid as a whole, including the working fluid in the liquid pool, is promoted. Naturally, evaporation of the working fluid that has been introduced and initially exchanges heat with the heat absorption portion is also promoted in an ensured manner, whereby temperature distribution in the high-temperature heat source can be uniform. In addition, separation of bubbles adhered to the heat absorption portion or the like can be promoted. Therefore, heat exchange adapted to fluctuation of the heat load can be performed, and the temperature of the high-temperature heat source can be stabilized. In addition, as the high-temperature heat source has a cylindrical shape and the evaporator has an annular shape, an apparatus having a compact structure and ensuring heat exchange efficiency can readily be manufactured.

Problems solved by technology

In the loop-type thermosiphon, however, circulation flow rate is less likely to be stabilized and a temperature of the heat source tends to fluctuate in many cases, depending on a type of a contained working fluid or heat load fluctuation in a certain range.

The CFC-based refrigerant, however, is no longer used, and the use of the HCFC-based refrigerant is restricted under the international treaty for protecting ozone layer.

Therefore, types of refrigerants that can be selected as a working fluid for the loop-type thermosiphon are limited from a viewpoint of environmental protection.

In the conventional loop-type thermosiphon, however, unstable circulation flow rate of the working fluid has been likely, resulting in fluctuation of the temperature of the heat source.

In particular, if the conventional loop-type thermosiphon is operated under a load far from a target load in accordance with design, the temperature of the heat source often fluctuates significantly.

If the temperature of the heat source fluctuates significantly, not only performance of heat source equipment becomes unstable, but also the heat source equipment may be damaged.

The loop-type thermosiphon often exhibits an unstable operation under fluctuating heat load.

If the temperature of the high-temperature portion is excessively high, a regenerator of the Stirling cooler may be destroyed.

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