Question

Problem 1 (Marks 3) Smithfield power station in NSW, Australia operates on 4 gas turbines. Each of the gas turbine unit operates on the regenerative Brayton Cycle between the pressure limits of 100 kPa and 700 kPa. Air enters the compressor at 30°C at a rate of 12.6 kg/s and leaves at 260°C. It is then heated in a regenerator to 400°C by hot combustion gases leaving the turbine. Diesel fuel with heating value of 42,000 kJ/kg is burned in the combustion chamber with combustion efficiency of 97 percent. The combustion gases leave the combustion chamber at 871 C and enter the turbine whose isentropic efficiency is 85 percent. Treating combustion gases as air and using constant specific heats at 500°C, determine a) The isentropic efficiency of the compressor b) Effectiveness of the regenerator c) Air-fuel ratio in the combustion chamber d) Net power output e) Back work ratio f Thermal efficiency g) The second law efficiency of the plant h) Second law efficiencies (exergy efficiency) of the compressor, turbine and chamber 100 kPa 400°C 30°C 700 kPa 260 C Compressor Turbine

Answer 1

Scluhom '. Too kPa P2- 700 kpa loo kfa bo 0 DOS67/ .3567 303 700 50 5 38 K 3 02 2 202.3メ 0 87:95

tー11uuỳnd_ 673ra.- Uuma 37273.ss -ma. _ 767 Mm

Cd) Net powes ouput 2212-786 Kw