Study On The Optimization Design Of Integrated Solar Combined Cycle System

In recent years,with the worsening of energy and environmental problems,the use of renewable energy to replace traditional fossil energy has become a trend in the future.In all kinds of energy sources,solar energy has the most promising development prospect because of its infinite reserve and clean nature.However,the solar-only thermal utilization has problems of high cost,unstable operation and low solar thermal efficiency.In this paper.the off-dcsign model of the integrated solar combined cycle system(ISCC)is modeled and the performance of the ISCC system is comprehensively analyzed,and the integrated characteristic and operation mode of the ISCC system are researched in detail.The thermodynamics performance in different integration modes is analyzed,and the integration and innovation of the ISCC system are analyzed.The detailed research contents are as follows:(1)The thermodynamic performances of ISCC system under design/off-design conditions are studied.The model of ISCC system under design/off-design conditions is built in this paper based on some literaturs,the off-design operation characteristics of the ISCC are studied under different gas turbine operation strategies,and the gas turbine operation strategy of the optimal ISCC system is obtained.The general characteristics of ISCC system under different ambient conditions are also given.The results show that the IGV angle over-operned is unfavorable for efficient operation of the gas turbine cycle,but is favorable tor the ISCC.The influence of the operation strategy on the steam turbine cycle is greater than that of the gas turbine cycle.To obtain the optimum operation performance of the ISCC unit under off-design conditions,IGVT3-650-F scheme should be adopted as far as possible.Compared with the effect of the direct normal irradiance(DNI)on steam turbine cycle of ISCC system,the influence of the ambient temperature on the overall ISCC system is zore notable and plays a leading role.(2)The performance analysis of a novel ISCC system is studied.Based on the traditional ISCC system,a novel ISCC system with solar-driven lithium bromide absorption refrigeration system is proposed,in which the solar-driven lithium bromide absorption refrigeration system is used to cool the inlet air temperature of the gas turbine.The system models of both the single-effect lithium bromide absorption refrigeration system and ISCC systm are built by using Aspen Plus/Ebsilon softwares.Both the thermodynamic and economic perfromance analysis of ISCC system are investigated deeply.The results show that compared with the traditional ISCC system,both the thermodynamic and economic performance of the novel ISCC system are obviously improved.(3)A new operation optimization strategy of ISCC system based on changeable integration mode under different DNI is studied.An optimization operation strategy based on switching the solar energy integration mode according to the solar irradiance is proposed in this paper.Both the thermodynamic and preliminary economic perfromance analysis of ISCC system using the new operation strategy are investigated deeply.The results show that higher solar-to-electricity conversion efficiency and lower levelized cost of electricity for the proposed system are achieved compared wth a reference ISCC system.The novel operation strategy offers a new way for adequately utilizing the solar energy in ISCC system.