Air enters a gas turbine with two stages of compression and two stages of expansion at 100 kPa and 17 degrees Celcius. This system uses a regenerator as well as reheating and intercooling. The pressure ratio across each compressor is 4 ; 300 kJ/kg of heat are added to the air in each combustion chamber; and the regenerator operates perfectly while increasing the temperature of the cold air by 20 degrees Celcius. Determine this system's thermal efficiency. Assume isentropic operations for all compressor and the turbine stages and use constant specific heats at room temperature.