| In the context of the rapid development in social civilization and the increase in world population,the global primary energy consumption is increasing.In order to alleviate the problems of energy depletion,environmental pollution and ecological damage caused by the large consumption of traditional fossil energy,solar energy is recognized by the international community as one of the most competitive renewable energy sources because of its abundant reserves and pollution-free advantages.Among them,using solar energy as a medium-low temperature heat source in social life and production processes is not only a high-efficiency and low-cost way,but also has great advantages in terms of resources and environment.To promote the development of solar energy industry,based on the traditional non-imaging concentrator,Multi-section Compound Parabolic Concentrator(M-CPC)is researched via intelligent calculation,and its optical characteristics are analyzed.The integrated system of solar thermal conversion is constructed,and its photothermal conversion features is researched,the study provides a technical reference for the comprehensive design of non-imaging concentrator and has a potential engineering application prospect.The main research contents and conclusions of this thesis are as follows:(1)Based on the traditional Compound Parabolic Concentrator(CPC),using VC++ with Particle Swarm Optimization(PSO)algorithm,a design method to optimize its surface structure is proposed,5 kinds of M-CPC concentrators with multi-section compound planes are obtained,and the number,length and tilt angle of planes with different structures are given.The reliability of M-CPC structure is verified by Monte Carlo Ray Tracing(MCRT)method and laser experiment.The optical efficiency of MCPC,the uniformity of radiation energy flow distribution on absorber surface,the effective working time,the lighting performance and the economic benefit of M-CPC are analyzed.(2)By analyzing its optical properties,the uniformity of the energy flow distribution on absorber surface is improved,especially when the incident angle of solar ray exceeds 30°,the advantage of the uniformity in energy flow distribution is more significant.Moreover,the effective working hours of concentrating beam radiation for M-CPC3,M-CPC4,M-CPC5 and M-CPC6 increased by 1.93%,1.25%,1.86% and1.72%,respectively,which indicates that M-CPC has better adaptability to weather changes.In addition,the optimized design of M-CPC significantly reduces the economic cost,and has excellent convenience in manufacturing and transportation,installation and debugging,operation and maintenance,which is conducive to a wider range of large-scale applications.(3)The integrated system of solar photothermal conversion is constructed by using M-CPC coupled with All-glass Evacuated Collector Tube(ECT),the mathematical model of energy transfer process is established by thermodynamics.Moreover,the thermal performance parameters in the process of photothermal conversion are obtained by VC++ solution program.The stability,reliability and applicability of solar M-CPC system for energy harvesting and photothermal conversion were verified through theoretical model and experimental test.(4)The photothermal characteristics of solar M-CPC system is dynamically analyzed through theoretical model and experimental test.The results indicate that the average thermal efficiency of integrated system was 61%,the average output temperature of the heat collection working medium can reach 77.9℃,and the average relative error between the theoretical and experimental value in temperature rise is 5.1%.It shows that the M-CPC system has the characteristics of less heat loss in the photothermal conversion process,which has good photothermal performance and system integration characteristic.In addition,the energy conversion mechanism of the integrated system is explored by analyzing the thermal resistance network,which provides a certain technical reference for the application of solar thermal system engineering. |
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