Part load performance analysis of recuperated gas turbines considering engine configuration and operation strategy

The purpose of this study is to analyze the performance characteristics of recuperated gas turbines operating at part load conditions. Differences in part load performance, due to various factors in design and operation, have been investigated. Various part load operation strategies including simple (fuel only control), variable speed and variable inlet guide vane operations for the single-shaft configuration as well as simple and variable area nozzle operations for the two-shaft configuration were considered. Maintaining high turbine exhaust temperature (and thus, the recuperator inlet gas temperature) enhances the part load efficiency considerably. In particular, the variable speed operation of the single-shaft configuration provides the most efficient part load operation. For operations using variable geometry, such as the variable inlet guide vane operation and the variable area nozzle operation, care must be given to minimize the component efficiency degradation in order to fully utilize the advantages offered by higher turbine exhaust temperature. As the design turbine inlet temperature increases, the relative part load efficiency becomes higher. A higher design pressure ratio exhibits better part load efficiency characteristics.