| 摘要 |
PROBLEM TO BE SOLVED: To perform cooling control such that in-box temperature can be returned into a prescribed range in a short time with a smooth temperature change. SOLUTION: Plural box chambers A-C partitioned by heat insulating walls are respectively provided with internal heat exchangers 3-5 with electric expansion valves 7-9, the internal heat exchangers 3-5 are connected to an compressor 1 and an external heat exchanger 2, and the insides of the box chambers A-C can be cooled and heated by changing over solenoid valves 15A-17B. When the in-box temperature becomes less than a set temperature range after coming into a steady state after start-up, a power frequency of the compressor 1 is reduced by one step. When the in-box temperature is yet low after a prescribed time, a fan rotation speed of the corresponding box chamber A-C is reduced by a prescribed ratio. When the in-box temperature is yet low, the power frequency of the compressor 1 is further reduced. When the in-box temperature exceeds the set temperature range, the fan rotation speed of the corresponding box chamber A-C is set to a maximum speed first. When the in-box temperature is still high after a prescribed time, the power frequency of the compressor 1 is increased step by step.
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