Air enters the compressor of a regenerative gas-turbine engine at 300K and 100 kPa, where it is compressed to 800 kPa and 580K. The regenerator has an effectiveness of 72 percent, and the air enters the turbine at 1200K. For a turbine efficiency of 86 percent, determine (a) the amount of heat transfer in the regenerator and (b) the thermal efficiency. Assume constant specific heats at room temperature.