| 摘要 |
PURPOSE: A refrigerating apparatus with two stage compression is provided to prevent supply pressure of oil from excessively increasing by supplying the oil with own discharge pressure to a compressor because an oil separator is installed in a discharge side of the compressor. CONSTITUTION: A refrigerating apparatus with two stage compression comprises a refrigerant circulating passage, a first stage oil passage, a second stage oil passage, a suction pressure detecting unit(12), a medium pressure detecting unit, a discharge pressure detecting unit, a first stage control unit(16), and a second stage control unit(17). The first stage oil passage returns oil, separated by a first stage oil separator(8), to a first stage compressor(2). The second state oil passage returns the oil, separated by a second stage oil separator(9), to a second stage compressor(3). The suction pressure detecting unit detects suction pressure of the first stage compressor. The medium pressure detecting unit detects discharge pressure of the first stage compressor. The discharge pressure detecting unit detects discharge pressure of the second stage compressor. The first stage control unit controls rpm of the first stage compressor according to freezing load. The second stage control unit calculates theoretical medium pressure by taking of square root of the product of the detection value of the suction pressure detecting unit times the detection value of the discharge pressure detecting value. |
