| 摘要 |
PROBLEM TO BE SOLVED: To avoid riskiness for damaging a compressor by a liquid compression by accurately calculating an overheat degree at a cooling time and to provide comfortable cooling in a cooling and heating system using a non-azeotropic refrigerant having a temperature slip. SOLUTION: A cooling and heating system comprises a liquid piping temperature sensor 11 provided at a liquid side of an indoor side heat exchanger 7, a gas piping temperature sensor 12 provided at a gas side of the exchanger 7, and a temperature correcting number deciding means 17a for deciding a temperature change corresponding to a pressure loss in the exchanger 7 by using a function of an operating frequency F of a variable displacement compressor 1a and a number (n) of operating constant speed type compressors 1b. In this system, an indoor side expansion valve is controlled with a value obtaining by subtracting the temperature correcting number deciding means from a difference between a sensed temperature of the gas piping sensor and a sensed temperature of the liquid piping sensor as the overheat degree. Thus, the overheat degree is accurately calculated with a low cost constitution, the liquid compression is prevented and a capability control of an indoor unit 10 is suitably executed.
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