4. (14 marks total) A gas turbine operating on a regenerative Brayton cycle has air entering the compressor at P = 100 kPa and T = 20C. The compressor has a pressure ratio P/P = 16 and an isentropic efficiency n = 82%. The effectiveness of the regenerator is & = 0.85, and the temperature of the exhaust gas leaving the turbine is 515C. (a) (2 marks) Sketch this cycle, numbering all points, and draw a T-s diagram for it, clearly showing all processes. (b) (5 marks) Determine the temperature of the air leaving the compressor. (c) (5 marks)Determine the temperature and pressure of the air leaving the regenerator and entering the combustor. (d) (2 marks) With the help of the T-s diagram, explain why a regenerative cycle cannot operate above a certain pressure ratio.