| 摘要 |
PROBLEM TO BE SOLVED: To provide a refrigerator which can maintain high efficiency even when a coolant suction pressure is low. SOLUTION: In the two-stage compression refrigerator 1, a first stage oil separator 8 is disposed between a first stage compressor 2 and a second stage compressor 3 to circulate oil in the first stage compressor 2, a second stage oil separator 9 is disposed on the discharge side of the second stage compressor 3 to circulate oil in the second stage compressor 3, the number of rotations of the first stage compressor 2 is controlled in accordance with a refrigeration load, a theoretical middle pressure Pmth is calculated from the square root of a product of the suction pressure Ps and a discharge pressure Pd, when the difference between the theoretical middle pressure Pmth and the suction pressure Ps is larger than a predetermined lower limit differential pressureΔPmin, the number of rotations of the second stage compressor 3 is controlled to cause the middle pressure Pm to accord with the theoretical middle pressure Pmth, and when the difference between the theoretical middle pressure Pmth and the suction pressure Ps is the lower limit differential pressureΔPmin or less, the number of rotations of the second stage compressor 3 is controlled to cause the middle pressure Pm to accord with the value obtained by adding the lower limit differential pressureΔPmin to the suction pressure Ps. COPYRIGHT: (C)2012,JPO&INPIT |
