Thermodynamic Evaluation of HAT Cycle

Abstract

In the HAT (humid air turbine) cycle plant, fuel is burned with highly humid air generated by passing compressed air through a water tank heated by the exhaust gas from the turbine. Basic thermodynamic features of the HAT cycle plant, NO_x formation, temperature at the outlet of the combustion chamber and thermal efficiency, are demonstrated by extensive cycle analysis with varying air ratio, bypass ratio and moisture content of the air. In the evaluation of the thermodynamic properties, thermodynamic equilibrium was assumed. The efficiency obtained is substantially higher than that of the conventional open-type Brayton cycle plant, while the formation of NO_x is reduced. Enthalpy and entropy balances of the ideal gas mixture reacting in a steady open system are described in the appendix.