Performance analysis of gas turbine air-bottoming combined system

The gas turbine engine has low capital cost compared with steam power plants. It has environmental advantages and short construction lead time. However, conventional industrial engines have lower efficiencies. One of the technologies adopted nowadays for improvement is the utilization of combined cycles. In this work, air bottoming cycle instead of steam is suggested and analyzed. Besides reducing the cost of hardware installations, it could achieve a thermal efficiency of about 49%, which does not deteriorate at part load as happens with the basic gas turbine engine. Parametric analysis of the system was performed using a specially designed computer program, enabling variation of the main independent variables, namely R(c), T-03 and r(c) over wide ranges, taking into account losses in different components and variable thermodynamic properties. Results show that a gain of 30% in power and 23% in efficiency when using the combined system relative to the basic gas turbine engine is possible.