Analyzing the thermodynamic performance of a hybrid system consisting of a gas turbine and two Stirling engines in series and parallel configurations

Abstract

This paper aims to analyze the thermodynamic performance of a gas turbine–Stirling engine hybrid system with series and parallel configurations. The proposed hybrid systems include two separate cycles. In the first configuration, a gas turbine is combined with two Stirling engines in series formation, and in the second configuration, this combination is implemented in parallel formation. By conducting a parametric study of the introduced hybrid systems, the effects of the compressor pressure ratio, temperature of turbine inlet gases, type of fluid used in the Stirling engine, number of heater tubes, number of meshes and the matrix porosity of regenerator on the hybrid system’s efficiency and power output are investigated. The findings indicate that by raising the compressor pressure ratio and turbine inlet gas temperature, the system’s efficiency and power generation capacity are increased more in the parallel configuration than in the series configuration. Based on the results of comparison, the power generated by the hybrid system in parallel configuration and series configuration is 2.18 times and 1.8 times the power generated by a simple gas turbine cycle, respectively. The obtained results reveal that the electrical efficiency of the hybrid system in parallel configuration and series configuration is 56% and 49%, respectively, while the efficiency of a gas turbine hybrid system with just one Stirling engine is 42% and that of a simple gas turbine cycle is 30%.