Study On Comprehensive Performance Of Series Solar Photovoltaic/Thermal Collectors

For more than a century,due to the rapid development of human society,traditional fossil energy has been unable to meet the sustainable needs of human beings.In addition,the use of fossil energy will cause environmental problems such as haze,acid rain and greenhouse effect.Therefore,the development of new energy sources and applications have received much attention.Solar energy in new energy sources is a good choice because of its infinity and cleanliness.In order to promote the effective use of solar energy resources and enhance the promotion and application of solar PV/T collectors,this paper proposes a series solar PV/T heat collection based on the research status of solar PV/T collectors at home and abroad.The air is used as a heat transfer medium,and the air inlet and outlet of the collector are arranged in a diagonal form,and the fan is installed at the outlet to give a certain flow rate of the gas.In this way,the photovoltaic module can be dissipated to improve the power generation efficiency,and on the other hand,the air temperature of the component output can be increased to obtain more heat for daily use.Based on thermodynamic methods and photovoltaic design standards,a series of solar PV/T collectors were designed and fabricated,and an experimental platform was built.Experimental tests on the photothermal and photoelectric performance of series solar PV/T collectors under different flow conditions and different weather conditions were carried out in the cold northwestern regions.The experimental data were analyzed.The results show that the photothermal efficiency of the collector is up to18.43%,the photoelectric efficiency is up to 17.36%,and the highest comprehensive efficiency is 40.36%.As the air mass flow rate increases from 0.024 kg/s to 0.038 kg/s,the instantaneous efficiency of the collector can be obtained:the intercept photothermal efficiency is increased from 12.75%to 18.90%,and the total heat loss coefficient of the collector is obtained.From 13.33W/(m~2K)to 18.37W/(m~2K),the total heat loss coefficient is obviously too large.This is because the collectors are connected in series,which lengthens the length of the air flow path and the seal at the interface is not good,resulting in a set.Heater heat loss is enhanced.Under different weather conditions,the solar PV/T collector has a small change in heat collection efficiency and photoelectric efficiency throughout the day,from sunny days to light snow days,but the heat gain from the whole day is reduced from12.69 MJ to 1.19 MJ,a decrease of 90.62.%,the total day PV output was reduced from 4.53MJ to 0.19MJ,a decrease of 95.81%.This fully demonstrates that the weather conditions have a great impact on the photothermal photoelectric performance of the collector,which seriously restricts the development and application of PV/T collectors,and only strives to expand its new functions and cooperate with other new energy applications.In order to make PV/T collectors more efficient.By comparing with a single PV/T solar collector,the air outlet temperature is raised from 35.00°C to 46.61°C,and the whole-day power generation is increased from 1.98 MJ to 6.31 MJ.The results show that the series solar PV/T collector has the more high air outlet temperature and more power output,so it has obvious advantages in terms of overall performance.In this paper,the energy balance equation and mathematical model of each part of the series solar PV/T collector are analyzed,and the experimental results are verified.The results show that the temperature of the collector outlet is mean square.The root error is 8.43%,the root mean square error of photovoltaic output power is7.06%,and the relative error of collector heat collecting efficiency and photoelectric efficiency is 7.12%and 6.33%.The simulation results are basically consistent with the experimental results,indicating that the model is correct and has certain reference value.The effects of key parameters on the collector performance of the collector were analyzed using validated model theory.The results show that in the process of increasing the wind speed from 0m/s to 4m/s,the efficiency of the collector decreases from 22.9%to 16.7%,which is 6.2%,and the air outlet temperature drops from30.2°C to 22.2°C,which is 8.0°C;As the difference between the air inlet temperature and the ambient temperature increases,the collector heat collection efficiency decreases continuously;the solar radiation intensity has a significant influence on the air outlet temperature,and has little effect on the heat collection efficiency;with the ambient temperature When it rises,the air outlet temperature and the heat collection efficiency increase linearly.