Study on a New Solar Thermal Energy Complementary Power Generation System Based on Gas-Steam Combined Cycle

Abstract

The integrated solar energy-driven chiller combined cycle system (SCCC) has a problem of low annual solar energy utilization. The solar thermal efficiency and power output of the traditional integrated solar combined cycle system (ISCC) are limited by the integrated solar mirror field area and Rankine cycle efficiency. This paper presents a new system, on the basis of the combined cycle system with the three pressure HRSG with reheat, the solar energy is integrated into the chiller for cooling the compressor inlet air of gas turbine and the heat recovery steam generator (HRSG) for increasing the power output simultaneously. The Aspen Plus, TRNSYS and EBSILON softwares are applied in this paper to build the models of the overall system. The solar thermal efficiency, annual solar power generation and annual solar thermal efficiency are used to evaluate the performances of the new system, the traditional ISCC system and SCCC system. During the summer solstice, the proportions of solar energy used in cooling and heating are set as 40% and 60% in new system, respectively. The research results show that the new system has a higher power output (406.37MW), thermal cycle efficiency (53.61%) and solar thermal efficiency (48.85%) compared with the traditional ISCC system (385.63MW, 51.67%, and 24.43%, respectively) at the design point. The new system can regulates the proportions of solar energy used in the chiller and HRSG based on the monthly meteorological data, in order to maximize the annual solar energy utilization and annual solar power generation. The new system’s annual solar energy utilization hours (2071h) and solar power generation (25.863GW·h) are far greater than those of SCCC system (1498h, 18.185GW·h, respectively). Therefore, the proposed new system with the simultaneous integrations of solar energy with both the chiller and HRSG not only greatly increases the utilization rate of solar energy, but also has the significant thermodynamic advantages.