Carnot Cycle
Carnot Cycle
Carnot Cycle
2. A refrigeration system operates on the reversed Carnot cycle. The minimum and
maximum temperatures are minus 25C and plus 72C, respectively. If the heat
rejected at the condenser is 6000 kJ/min, draw the TS diagram and find, (a)
power input required and (b) tons of refrigeration developed.
Compressor
w = work of compression, kJ/kg
h1 = enthalpy entering the compressor, kJ/kg
h2 = enthalpy leaving the compressor, kJ/kg
m = mass flow rate, kg/s
W = theoretical compressor power, kJ/s or kW
v1 = specific volume of vapor, m3/kg or L/kg
V1 = volume flow rate, m3/s or L/s
Condenser
qc = heat rejected, kJ/kg
h2 = enthalpy entering the condenser
h3 = enthalpy leaving the condenser
Qc = total heat rejected, kJ/s
Expansion Valve
h3 = enthalpy entering the expansion valve
h4 = enthalpy leaving the expansion valve
Evaporator
qe = refrigerating effect, kJ/kg
h4 = enthalpy entering the evaporator
h1 = enthalpy leaving the evaporator
Qc = refrigerating capacity, kJ/s
Efficiency
3. An ammonia simple saturation cycle operates at 247.1 kPa suction pressure and
1169 kPa condenser pressure. For a load of 1688 kJ/min, determine (a) the m3/h
of cooling water in the condenser if the water temperature is increased by 6C°,
(b) the compressor work, and (c) the piston displacement if clearance is 5%.