Special Problems SP39 and SP40 for ME 200 - Spring 2016 Due Friday, April 22, 2016 SP39: A vapor compression refrigeration cycle is used to maintain...

The questions are in the attached pdf file

SP39: A vapor compression refrigeration cycle is used to maintain a refrigerated space ata temperature of -20°C. The working fluid is ammonia. The fluid at the compressor inletis a superheated vapor with a pressure p1 = 1.50 bar and a temperature T1 = -22°C. Thecompressor pressure ratio p2/p1 = 10.67, the fluid exits the condenser as a saturatedliquid, and the mass flow rate is 0.8 kg/sec. Heat transfer from the condenser occurs tosurroundings at 35ºC. The isentropic efficiency of the compressor work input is 0.65.Assume that the pressure drops in the evaporator and condenser are negligible.(a) On a T-s diagram, label the states 1, 2, 2s, 3, and 4, and indicate the processpath.(b) Calculate the quality x4 at state 4.(c) Calculate the coefficient of performance for the cycle.(d) Calculate the rate of heat rejection from the condenser.(e) Calculate the rates of entropy production in each of the four systemcomponents. Assume that the boundary temperature for heat transfer into theevaporator is -20°C. Assume that the boundary temperature for heat transferout of the condenser is 35ºC; also 0 0 T C p bar  35 , 1   .SP40: A heat pump using refrigerant-134a heats a house by using underground water at8oC as the heat source. The house is losing heat at a rate of 20 kW when the indoor airtemperature is maintained at 20oC. The refrigerant enters the compressor as saturatedvapor at 280 kPa, and it leaves at 1 MPa and 60oC. The compression process is adiabatic.The refrigerant exits the expansion valve with a specific enthalpy of 91.49 kJ/kg.(a) Draw the process on a T-s diagram and label the states. (Use 1 for compressor inlet, 2 for compressor exit, 3 for condenser exit, and 4 for evaporator inlet)(b) Complete the table below.(c) Find the refrigerant flow rate, in kg/s.(d) Calculate the power input to the heat pump, in kW.(e) Find the rate of entropy production of the evaporator in kW/K.(f) Compute the coefficient of performance of the heat pump.