OPTIMUM CONTROL STRATEGY FOR A LOW-TEMPERATURE SOLAR KALINA CYCLE POWER GENERATION UNDER OFF-DESIGN CONDITIONS

Low-temperature Kalina cycle power generation system shows great potential in the region of solar energy utilization. The variation in solar radiation affects the heat source temperature of Kalina cycle, and additionally the cooling water temperature also varies with the seasons. In this paper, the mathematical model of a Kalina cycle used for low-temperature solar power generation is established to investigate the off design performance of the Kalina cycle under off-design heat source and cooling water temperature using three control strategies including constant pressure regulation method, sliding pressure regulation method and modified sliding pressure regulation method. The results show that when the heat source temperature varies, the modified sliding pressure regulation method could keep the cycle performance and the efficiencies of turbine and pump at a relatively high value, and it could be applied in a wider range of heat source temperature. When the cooling water temperature varies, different control strategies have similar influence on the variations of the cycle performance and the efficiencies of turbine and pump. Based on performance comparison, the modified sliding pressure regulation method is determined to be the optimum control strategy for the Kalina cycle under off-design conditions.