Research On Thermoelectric Performance Of Low Concentration Photovoltaic/Thermal System

As a representation of renewable energy,solar energy has advantages of adequate supply,wide distribution and economic viability.With the incessant development of the solar utilization technique,the pace of solar energy replacing fossil energy has been accelerated.Concentration photovoltaic/thermal(C-PV/T)technology that belongs to the solar utilization technique can relieve the decreasing electric efficiency due to the increasing temperature of solar cells,recycle some waste heat and finally realize co-generation.If the C-PV/T technology can be used in architectural domain,its prospect will be considerable.In the thesis,based on C-PV/T module,a theoretical C-PV/T model of performance analysis solution is proposed by combining experimental and theoretical study and conventional theoretical heat transfer model.Besides,the performance optimization and productivity forecast are analyzed.The theoretical model and experimental platform of the C-PV/T module were established and the thermoelectric performance was analyzed by model solving and experimental test.The result shows that the electric and thermal power are initially increased and then decreased with constant flow rate under full-day operation condition,the experimental maximum of which are 470W and 1916W,respectively;the electric and thermal efficiencies are initially decreased and then increased under the same condition,the maximum of which are 17.28%and 59.84%,respectively.By comparing the theoretical and experimental value,there is a relatively large error between them,which can be up to 25.9%.In order to decrease the error,the error correction factor are adapted in the theoretical model.After the correlation,the error is smaller than 5%.Based on the model after correlation,the codes of the model were programmed using the integral form.What's more,the daily productivities of the system under different flow rates were analyzed by adopting environmental parameters on a clear day of June in Beijing.The result shows that the daily power generation and electric efficiency are increased with the increasing flow rate,the maximum of which are 3.38 kW·h and 14.64%respectively;the daily heat generation and thermal efficiency are decreased with the increasing flow rate,the maximum of which are 13.09kW·hth and 51.87%respectively.Take satisfying the users electro-heat demand in summer as a prerequisite,the system is optimized so that it reliability and economy can be insured.The optimization analysis result shows that when the number of the C-PV/T module is 10 and the daily flow rate is 130L/h,the productivities meet the requirement of domestic use and the system has a minimal collection cycle that is about 3 years.