Question 2 Refrigerant R134a enters a compressor at a pressure of 180 kPa, temperature of -8C,...

 

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Question 2 Refrigerant R134a enters a compressor at a pressure of 180 kPa, temperature of -8°C, and speed of 1.4 m/s. It leaves the compressor at a pressure of 835 kPa, temperature of 52°C, and speed of 0.27 m/s. The mass flow rate of refrigerant is 0.14 kg/s and the outlet is 140 mm above the inlet. There is heat transfer from refrigerant through the compressor walls to the surroundings at a rate of 15 W. (a) Determine the enthalpy of the working fluid at the inlet and the outlet. (b) Calculate the power required by the compressor. (c) Would it be accurate to neglect enthalpy, kinetic energy, potential energy or heat transfer effects in the calculation of power? Support your answers with calculations. [4] (d) [6] [9] Determine the isentropic efficiency of the compressor. Neglect kinetic energy, potential energy and heat transfer effects for the purposes of this calculation. [6] Question 2 Refrigerant R134a enters a compressor at a pressure of 180 kPa, temperature of -8°C, and speed of 1.4 m/s. It leaves the compressor at a pressure of 835 kPa, temperature of 52°C, and speed of 0.27 m/s. The mass flow rate of refrigerant is 0.14 kg/s and the outlet is 140 mm above the inlet. There is heat transfer from refrigerant through the compressor walls to the surroundings at a rate of 15 W. (a) Determine the enthalpy of the working fluid at the inlet and the outlet. (b) Calculate the power required by the compressor. (c) Would it be accurate to neglect enthalpy, kinetic energy, potential energy or heat transfer effects in the calculation of power? Support your answers with calculations. [4] (d) [6] [9] Determine the isentropic efficiency of the compressor. Neglect kinetic energy, potential energy and heat transfer effects for the purposes of this calculation. [6]

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Consider the following diagram T127C T a Obtain the saturation temperature of the refrigerant at p 1... View the full answer