Maximum-efficiency architectures for steady-flow combustion engines, II: Work-regenerative gas turbine engines

In this paper we identify the maximum-efficiency architecture allowed by physics for simple-cycle gas turbine engines. This is achieved by functional minimization of total irreversibility using the attractor trajectory optimization approach developed in the first part of this study. It is shown that maximization of efficiency requires the combustion process to be performed in a part-adiabatic and part-isothermal manner. The optimal split of fuel to be burned between the adiabatic and isothermal segments is determined to be a function of turbomachinery irreversibilities and the turbine-blade temperature limit. The resulting optimal architecture has higher efficiency than both the traditional Brayton cycle (that employs only adiabatic combustion) and a fully-reheat cycle (that employs only isothermal combustion).