Experiment And Simulation Study On Thermal And Electrical Performance Of Building Integrated Photovoltaic Coupled With Phase Change Material(BIPV-PCM)

Solar energy as clean and pollution-free renewable energy attracts the extensive attention.In this paper,the PV-PCM system combines photovoltaic technology with phase change storage technology.The temperature of PV modules was regulated by phase change materials to improve the photoelectric conversion efficiency.To provide a new engineering application way for the efficient use of solar energy in the construction,and theoretical basis for the application of building integrated photovoltaic coupled with phase change material.First,the paraffin RT42 with phase transition temperature of 42? was screened as phase change material,and the PV and PV-PCM comparative experiment system was set up.The experiments were carried out considering the three mounting modes of PV modules on the building which are vertical,optimal inclination(35° in Tianjin)and horizontal.The experiment results show that the temperature of the PV-PCM system is lower than that of the PV system.The maximum temperature difference between the two systems was 8.2?,14.5? and 18.1? respectively.The maximum relative percentage increase of efficiency was 6.02%,12.47% and 15.60% respectively.At the same time,using polystyrene and photovoltaic component built enclosure space to simulate building room.The influence of BIPV and BIPV-PCM on the indoor thermal environment was analyzed by contrast experiment.The results show that the indoor temperature of the BIPV-PCM system is always lower than that of the BIPV system during the day,and the night trend is opposite;which indicates that it is necessary to set up an active heat removal device at night when using BIPV-PCM system in hot area or apply this system to buildings that are primarily used during the day,however,energy consumption for heating can be reduced in cold area take advantage of its thermal characteristics.Second,the PV geometric model was simplified by caculating average specific heat capacity and average thermal conductivity etc,then the PV-PCM numerical model was established.The solar radiation is converted into internal heat source of photovoltaic glass cover and photovoltaic cell.The dynamic meteorological conditions were compiled into UDF functions.The numerical heat transfer model was validated by the vertical PV and PV-PCM system experiment.The deviation between experiment and simulation of PV system and PV-PCM system were not more than 5.8% and 4.1% respectively,which indicated that the established numerical model could be used for simulation study on heat transfer performance of PV-PCM system.Finally,Computational Fluid Dynamics software FLUENT was used to optimize the PV-PCM system under the summer operating condition in Tianjin,and the performance in transitional season(spring)and winter was predicted.The results show that the packaging materials with high thermal conductivity is more effective,because it can exchange heat with external environment faster;the optimum thickness of phase change paraffin is 60 mm when the PV-PCM is mounted horizontally in summer;the maximum temperature difference between PV-PCM system and PV system can reach 21.93?;the efficiency can increase by 19.34% maximumly.In spring,the maximum temperature difference between PV-PCM system and PV system can reach 5.8?;the efficiency can increase by 4.31% maximumly.In winter,the maximum temperature of PV cells in PV-PCM system is about 20? with low ambient temperature,weak solar radiation and high wind speed;the phase change temperature does not reach the phase transition temperature,so the phase change material doesn't work.The integration strategy of BIPV-PCM is summarized from three aspects: the integrated position,the design elements and the type of building.