Performance degradation analysis of combined cycle power plant under high ambient temperature

Abstract

The mechanism of performance degradation of a natural gas combined cycle (NGCC) power plant under high ambient temperature is studied by analysing the performance characteristics and thermal properties of the working fluids. Real operating data under typical seasonal conditions are collected and studied. The results reveal that the power output of the NGCC system decreases by 22.6 %, and the energy efficiency decreases from 57.28 % to 56.3 % when the ambient temperature increases from 5-35?C. GT total power output and ST power output decrease by 17.0 % and 16.2 %, respectively, as ambient temperature increases from 5-35 0C. The enthalpy difference of the flue gas between the turbine inlet and outlet change slightly with varying ambient temperature. The fuel and air input decrease by 16.0 % and 16.2 %, respectively, as ambient temperature increases from 5-35?C. By analysing the calculated results, the decrement in air and fuel input d is considered as the immediate cause of system power output reduction. The proportion of power consumed by AC reaches 50.4 % at 35?C. This is considered to be caused by air compressor idle.