(a) A refrigeration system using R134a as refrigerant is operating at the temperature settings of minus 20C and 40C. Plot the refrigeration on the PH Diagram provided. Given that the Power input to the compressor is 100W, estimate the capacity of cooling in term of Watt (25%) (W). (b) If the refrigerant of the system is changed from R134a to R410a with other parameters remain unchanged, what would be the difference between the two refrigerants in term of Coefficient of Cooling? (25%) (c) A centralized air-conditioning system adopts a 20/80 approach on mixing fresh air and return air. Given that general outdoor conditions in 32C Dry Bulb Temperature (DB) and 80% Relative Humidity (RH) and the return air being 25C DB and 50% RH. Identify the state of the mixed air through the psychrometric chart. (25%) (d) The mixed air will then pass through the cooling coil and the conditioned air will enter indoor area at 15C and 90% RH. Plot the cooling process on the psychrometric chart and calculate the capacity of the cooling coil per unit weight. (25%)