| 摘要 |
Provided is an inexpensive and compact cooling device which does not increase the circulation resistance of a refrigerant, filling quantity of a refrigerant in a natural circulation circuit wherein natural convection of the refrigerant is caused by using a thermo-siphon, and cross-sectional areas of individual passages while maintaining a desired cooling efficiency in the circuit. A secondary cooling device (40) includes a secondary heat exchange section (42) of a cascade heat exchanger (HE) which liquifies a gaseous-phase secondary refrigerant, and an evaporator (EP) which vaporizes a liquid-phase secondary refrigerant. The secondary cooling device (40) is provided with a plurality of natural circulation circuits (48) equipped with liquid pipings (44) and gas pipings (46) which connect the secondary heat exchange section (42) and the evaporator (EP). The evaporator (EP) has evaporation passages (52) of the natural circulation circuits (48) provided in layers vertically apart from one another. The evaporation passage (52) is formed by a spiral fin tube type heat exchanger whose fins are spirally wound on the outer circumference of an evaporation pipe through which the secondary refrigerant circulates. |
