POTENTIAL OF A REHEAT GAS TURBINE SYSTEM USING INVERTED BRAYTON CYCLE

ABSTRACT The concept of a small reheat gas turbine system is proposed and discussed. This reheat gas turbine consists positive-pressure part (Brayton cycle), negative-pressure part (inverted Brayton cycle) and heat exchangers. The system components are interchangeable with the micro gas turbine. This system can supply hot water and steam. This paper describes that the introduction of reheat and an inverted cycle to a fixed Brayton cycle is explored from various views. The thermal efficiency of electric power output (EFF EP ) has a peak and thermal efficiency of heat output of hot water 1 (EFF QHW1 ) decrease with increase of the pressure ratio of Vacuum Turbine (PR VT ). The thermal efficiency of heat output of hot water 2 (EFF QHW2 ) increases monotonously with PR VT . The overall efficiency of the improved cycle for cogeneration increases with PR VT although the overall efficiency of the original cycle decreases monotonously with PR VT . The PURPA efficiency of improved cycle has the peak around PR VT = 4. In the type2 cycle EFF EP has a weak peak of 31.4% when the inlet pressure of combustor 2 (P comb2 ) is 0.14MPa. The overall efficiency increases with P comb2 . PURPA efficiency has a weak peak at P comb2 = 0.16MPa. Two axes system is examined. EFF EP reaches to 30.2% at the maximum. EFF QHW1 decreases slightly with increase of PR VT . EFF QHW2 increases with PR VT . The overall efficiency increases with PR VT . The PURPA efficiency also increases with PR V