Thermodynamics Analysis of Semi‐Closed Gas Turbine Cycle

ABSTRACT The properties of a semi‐closed combined cycle power system make it a better option for this study than an open system, since it turns an open‐cycle gas turbine into a pollutant‐free power system. Also in the selected cycle, the exhaust is channeled toward a divider rather than being released into the atmosphere, and the exhaust is divided into a separation duct and a return duct by the divider. Part of the exhaust is directed back toward the compressor via the return duct. This study investigates the effect of thermodynamic parameters analysis (turbine inlet temperature, ambient air temperature, pressure ratio, and regenerator effectiveness) on thermal efficiency and specific fuel consumption (S.F.C.) for a semi‐closed system. The properties of a semi‐closed combined cycle power system make it a better option for this study than an open system, since they turn an open‐cycle gas turbine into a pollutant‐free power system. Also in the selected cycle, the exhaust is channeled toward a divider rather than being released into the atmosphere. The exhaust is divided into a separation duct and a return duct by the divider. Part of the exhaust is directed back toward the compressor via the return duct. This study investigates the effect of thermodynamic parameters analysis (turbine inlet temperature, ambient air temperature, pressure ratio, and regenerator effectiveness) on thermal efficiency and S.F.C. for a semi‐closed gas turbine cycle. The operating conditions are taken into account when determining the analytical formulas for assessing thermal efficiency and S.F.C., which are calculated by using thermodynamic equations. The model is constructed using MATLAB®. The results show that the thermal efficiency is increased due to increased turbine inlet temperature, increased regenerator effectiveness, and decreased ambient air temperature. Conversely, S.F.C. decreases. It was also found that when the pressure ratio was roughly 2, the thermal efficiency rose, while the S.F.C. started to decrease. After this value, the thermal efficiency began to decline gradually, and the S.F.C. increased. Also, as the regenerator's effectiveness increased to roughly 0.95, the data indicate that the thermal efficiency achieved its maximum value of 0.60. and at a turbine inlet temperature of about 1600 K, while the S.F.C recorded a minimum value of 0.1394.