| 摘要 |
PROBLEM TO BE SOLVED: To provide a freezer capable of rapidly and adequately controlling the opening of an expansion valve to the change of the degree of superheat of an evaporator. SOLUTION: A water-side heat exchanger 1, a screw compressor 2, an air-side heat exchanger 3, and an expansion valve 4 are successively connected to each other. The present SH of intake refrigerant is detected based on the detected value of an intake temperature sensor 8 and an intake pressure sensor 9 provided on an intake pipe of the screw compressor 2, and the drive quantity of the expansion valve 4 is calculated by PI operation based on the difference between the present SH and the target SH. An expansion valve drive means 6 drives the expansion valve 4 so as to realize the calculated drive quantity. When the capacity of the screw compressor 2 is increased as a predetermined change in the operational condition, the multiplier of the PI operational formula is changed and corrected to calculate the drive quantity of the expansion valve 4. COPYRIGHT: (C)2004,JPO&NCIPI
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