| 摘要 |
PROBLEM TO BE SOLVED: To provide a very low temperature freezing apparatus wherein it is operational without trouble even when fresh air temperature is very low and further it has very high freezing capability. SOLUTION: There is provided an outdoor temperature sensor 32 for detecting fresh air temperature and a compressor 11 including a heater 31 on an outdoor compression unit 1. A control device 33 controls the heater 31 on the basis of a signal from the outdoor temperature sensor 32. Once the outdoor temperature becomes lower than temperature t1 where freezing efficiency lowers in a very low temperature freezing apparatus, the control device 33 applies predetermined voltage to the heater 31 to heat the compressor 11 and helium gas that is refrigerant gas through the compressor 11. When viscosity of oil in the compressor 11 is reduced, abnormal interruption of the compressor 11 is avoided, and pressure of the helium gas rises to increase the flow rate of suction gas in the compressor 11 and hence ensure freezing capability of the very low temperature freezing apparatus.
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