A regenerative Brayton cycle has two step isentropic compression with cooling. Air enters the first compression at 300 K and 100 kPa and exits at 300 kPa. It is cooled to 300K and then compressed to 900 kPa. It enters the regenerator with an effectiveness of 0.75. It enters the combustor at 1300 K. The turbine is a single-stage with an adiabatic efficiency of 0.9. Determine the thermal efficiency of the cycle.