he refrigerant R-134a enters the compressor of a refrigeration machine at a pressure of 140kPa and a temperature of -10°C, and exits at a pressure of 1MPa. The volumetric flow of the refrigerant entering the compressor is 0.23m3/minute. The refrigerant enters the throttling valve at a pressure of 0.95MP and at 30 °C, and exits the evaporator as saturated steam at -18 °C. The adiabatic efficiency of the compressor is 78%. Show the cycle in the T-s diagram. a) Power required to start the compressor b) Calculate the heat withdrawn from the cooled environment in unit time, COPSM=? c) Calculate how much the pressure of the refrigerant drops between the evaporator and the compressor and how much the heat gain is.
he refrigerant R-134a enters the compressor of a refrigeration machine at a pressure of 140kPa and a temperature of -10°C, and exits at a pressure of 1MPa. The volumetric flow of the refrigerant entering the compressor is 0.23m3/minute. The refrigerant enters the throttling valve at a pressure of 0.95MP and at 30 °C, and exits the evaporator as saturated steam at -18 °C. The adiabatic efficiency of the compressor is 78%. Show the cycle in the T-s diagram.
a) Power required to start the compressor b) Calculate the heat withdrawn from the cooled environment in unit time, COPSM=? c) Calculate how much the pressure of the refrigerant drops between the evaporator and the compressor and how much the heat gain is.
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