Research On Solar Dish Cogeneration System Based On Receiver Control Strategy

Concentrated solar power(CSP)technology can not only achieve peak shaving with heat storage module,but also can well meet the needs of multiple applications of cooling,heating and power in building energy systems,and will become an important part of solar energy applications and even the entire renewable energy development layout in the future.As one of the four main CSP technologies,the solar dish Stirling system has problems of low energy utilization rate and waste of energy quality,regardless of whether it is purely thermal utilization or purely power generation.The solar dish cogeneration system with refined thermal energy cascade utilization is an effective technical means to improve the comprehensive energy efficiency of the system.Therefore,a new solar dish Stirling cogeneration system based on a positionadjustable heat receiver and its control strategy is constructed in this paper.The core is to change the distance of the receiver relative to the focal point to control the concentration ratio of the solar dish system,and then adjust the temperature of the receiver to adapt to different heat source temperature requirements.In order to verify the performance of the system,a building energy application scenario with three requirements of cooling and heating power is designed in this paper,a complete solar dish cogeneration system including energy conversion equipment and energy storage modules is constructed.Theoretical model is constructed,too.On this basis,according to the heat source temperature demand of energy-consuming equipment and the critical point state parameters of equipment startup,a system control strategy that can realize the switching between power generation and heat production mode and output power adjustment according to the direct solar radiation intensity(DNI)is generated.In order to verify the accuracy of the model and the feasibility of control,the heat collection experiments of the solar dish system under different receiver positions were carried out.The results of the four experiments can control the average relative error of the heat collection power within 10%,which fully verified theoretical model accuracy.In order to analyze the performance of the solar dish cogeneration system,three representative regions with significant differences in DNI levels,Tianjin,Yinchuan,and Lhasa,were selected to compare the technical indicators.The results show that with the support of power storage and thermal storage modules,the electricity load satisfaction rate and heat load satisfaction rate of heating season in Tianjin are 7.95%and 39.07%,respectively,and 19.87% and 74.83% in Yinchuan,74.83% and 81.46%in Lhasa.For the electricity and cooling load satisfaction rates in the cooling season,Tianjin is 33.61% and 41.80%,Yinchuan is 62.30% and 46.72%,and Lhasa is 66.39%and 87.70%.In terms of the comprehensive energy efficiency of the system,the heating season data of Tianjin,Yinchuan and Lhasa are 47.61%,48.78% and 38.74%respectively,and the corresponding cooling season data are 31.37%,30.11% and35.06% respectively.The highest seasonal energy efficiency of single power generation system is only 18.06%.The solar dish cogeneration system shows more superior performance.