Effects of different alternative control methods for gas turbine on the off-design performance of a trigeneration system

Abstract

Thermodynamic and economic performance of the combined cooling, heating and power system (CCHP) is mainly affected by its configuration and operation strategy. In this paper, the reducing turbine inlet temperature (TIT) and inlet air throttling (IAT) control methods for gas turbines following the electric load (FEL) are used to analyze the primary energy consumption (PEC), operational cost (COST) and carbon dioxide emission (CDE) in a case of a CCHP system that satisfies the cooling, heating and electric demands of a five-star hotel in Beijing, China. The results indicate that the CCHP system with both TIT and IAT control methods has better off-design performance than separate system except for transition seasons. Since the more production of high-temperature flue gas, the IAT control method significantly reduces the fuel consumption of the auxiliary boiler to satisfy the thermal demand of the reference building, especially in hot summer and cold winter. In January, the IAT control method can decrease fuel consumption by 7.53% compared with TIT control method. Moreover, it is found that improved energy saving performance and decreased operation cost and carbon dioxide emission of the CCHP system are presented with the IAT control method at the annual performance. Finally, the sensitivity analysis of the electric price and gas price is presented for the operation cost and shows that the gas price is the most sensitive variables for the operation cost of the CCHP system.