An open cycle gas turbine takes in air at 300 K and 1 bar and develops a pressure ratio of 20. The turbine inlet temperature is 1650 K. The polytropic efficiency of compressor and turbine each is 90%. The pressure loss in the combustor is 3% and the alternator efficiency is 97%. Take 
=1.128 kJ/kg-K for air and gas respectively. The calorific value of fuel is 42 MJ/kg. Work out the following:
- Sketch the system and show the process on T-S diagram.
- The overall efficiency.
- The specific power output.
- The fuel to air ratio.
- The specific fuel consumption
- Show in general the variation of gas turbine thermal efficiency with compressor ratio for various turbine inlet temperatures.
What is the reason that thermal efficiency of gas turbine plant increases with decrease in compressor inlet temperature?