| Concentrating photovoltaic/thermal(CPV/T)system for triple-generation of cold,heat and power is a novel system that can generate electricity and utilize low-temperature solar energy,which provides a guideline for annual comprehensive and cascaded utilization of solar energy.Both theoretical and experimental investigations were carried out in the study.Lighttools,MATLAB and other simulation software were used to theoretically analyze and optimize compound parabolic concentrator(CPC),low concentrating photovoltaic/thermal(LCPV/T),CPV/T-heat pump hybrid system for co-generation of heat and power and CPV/T triple-generation system.In addition,the performances of each research unit and system were analyzed by establishing the experiment platform of CPV/T triple-generation system and the engineering demonstration system.The research work was carried out from the following four aspects:(1)Optimal design of CPCBased on the previous study of our research group,the characteristics of conventional CPC for flat-panel receiver and the influence of light intensity distribution uniformity on the electrical efficiency of PV/T module were considered during the optimal design.By eliminating the secondary reflection,adjusting the receiving surface position,and installing light compensation,a theoretical model for a novel CPC optimal design was proposed and established.Moreover,the real novel CPC was designed.Its geometric concentration ratio,height and non-uniformity of CPC are 4,543.4mm,and 0.106,respectively.(2)Development of LCPV/T module and research on its thermoelectric performanceIn view of the problem that the general commercial crystalline silicon cell and the output electric power of LCPV/T do not match the variations of open-circuit voltage and short-circuit current of crystalline silicon cell with concentrated sunlight intensity were studied.Standard slide design of PV cell for concentrated sunlight was proposed.From application perspective,the conventional 156 mm*156 mm standard cell chip was subjected to 1/4 slice,increasing the open-circuit voltage and decreasing the short-circuit current.Furthermore,theoretical model for the thermoelectric performance of LCPV/T module was established.Experiments on the LCPV/T module with 1/4 slice PV cell were carried out to analyze its performance under concentrated sunlight conditions.The experimental results indicated that the electric power of the LCPV/T module was 3 times higher than the conventional flat-panel PV/T module and that the thermal performance was 2 times higher.To analyze effect of different cooling channels on the performance of the LCPV/T module,three typical cooling channels:aluminum flow channel,microchannel array heat pipe and glass flow channel were adopted and integrated with LCPV/T module in the experiments as well.(3)Experimental study on heating and cooling performance of LCPV/T systemThe matching mechanism of the energy output of LCPV/T system with the heating demand of building and the temperature of the heat source of chiller,relevant theoretical model was established.Besides,experimental benches of LCPV/T coupled heat pump system and LCPV/T-heat pump coupled single-effect lithium bromide absorption chiller were designed and established.In these experimental platforms,capillary network was used as the heating/cooling end.The feasibility of the coupled systems was explored through experiments.The heating performance of LCPV/T with capillary network and LCPV/T coupled heat pump system were studied.The influences of different cooling water flowrates,different heat source temperatures on the cooling COP were investigated under two cooling ends of fan coil and capillary network conditions.(4)Engineering application investigation on CPV/T systemThrough the analysis of experimental data and the optimization of experimental scheme,the optimized demonstration engineering of CPV/T system was proposed and established.On-line monitoring subsystem for the CPV/T system was developed.According to the test data from the demonstration engineering system,near noon time,the electric power,electrical efficiency and heating power were 77kW,12%?13%,and 330kW,respectively.Through the application research on CPV/T system for triple-generation of cooling,heat and power in the paper,relevant theoretical models were established and optimal design for the system was proposed.The results showed that CPV/T triple-generation system can effectively overcome the difficult problem that the traditional system performance was subjected to seasonal constraints,and can realize triple-function of power generation,heating in winter and hot-water supply/cooling in summer.The system proposed in this paper can enhance the practicality of photovoltaic/thermal technology and provide theoretical and technical support for the industrialization of building integrated with PV/T triple-generation system. |
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