3. An ammonia simple saturation cycle operates between evaporator and condenser temperatures of -20°C and 35°C, respectively. The system is to be used in producing 5000 kg of ice at- 12°C from water at 29°C in 20 hours. Assuming losses to be 20 per cent of the heat to be absorbed from the water. Determine (a) the mass flow rate of the refrigerant, (b) the heat rejected at the condenser, and (c) the power required by the compressor.

A medium size power station is used to produce 30 MW net power for a refinery. The station uses steam as the operating fluid and operates according to the Carnot cycle between the pressure limits of 0.4 bar and 35 bar. Steam enters the boiler as a saturated liquid and leaves it as a dry saturated vapour. ist t Reneric o "nd h Ts diaar ntion of s) (ii) Determine the dryness fraction of the steam that is fed to the condenser. (4 marks) (iv) Determine the specific enthalpy values at the four key points of the cycle. (6 marks) Calculat "Fic of the cycle (5 Ma, KS) (vi) Determine the thermal efficiency of the cycle. (1 mark) (vii) Using the highest and lowest temperature values in the cycle, re- calculate the efficiency of the cycle and show that it is equivalent to the result in part (vi). (2 marks) arks). 2.

Considering now the real case, where the turbine and feed pump are not isentropic, and the feed pump electric motor and the electric generator are not 100% efficient, Determine for unit mass flow rate of refrigerant circulated, the quantities (I) to (VI) as listed above, briefly contrasting the values calculated here and those calculated,