Answer: Heat rejected=150000MW
Heat rate= 2.5
Step-by-step explanation:
Thermal efficiency is defined as work out divided by heat in.
Therefore
thermal efficiency = 40/100= 100000 MW/Heat in
Heat in = 250000MW
For a closed system undergoing a cycle the change in internal energy is zero. Therefore the work out of the system is equal to the net heat transfer of the system. Therefore
Work out= heat in - heat out
Therefore heat out = heat in - work out
Heat out = 250000 MW - 100000MW = 150000 MW which is the amount of heat rejected
The heat rate is defined as the inverse of the thermal efficiency expressed in kJ/kWh.Therefore
Heat rate = 1/thermal efficiency
Heat rate = 1/0.4 = 2.5 kJ/kWh
