THE BASIS FOR THE PREDICTION OF HIGH THERMAL EFFICIENCY IN W.T.P.I. GAS-TURBINE ENGINES

A high thermal efficiency for an engine requires that a cycle capable of producing high efficiency is first chosen, and that components that can operate at high efficiencies are used. The choices made in both areas are discussed below. The "enabling " technology is a high-temperature, high-effectiveness (0.975) regenerator, with a low pressure drop. This requires only a low cycle pressure ratio (about 2.5:1) for optimum performance. The component efficiencies of compressors and turbines of low pressure ratio are intrinsically high. W.T.P.I. also divides this low pressure ratio among three compressor stages and three turbine stages. Doing so greatly reduces the kinetic energy that is usually lost from single stages, and thus substantially improves the component efficiencies. By these means a shaft-power efficiency of 54 % can be confidently predicted for the 300-kW engine, which when coupled to a high-efficiency electrical generator would lead to an electrical efficiency of about 50%