Research On Solar Collector With Dual-function Based On Theory And Experiment

As an important device for solar thermal utilization,solar collectors are closely related to people’s life and industrial and agricultural production.How to improve the thermal performance of solar collectors has always been the research focus of scholars at home and abroad.Limited by the climate characteristics of different seasons,a single working medium heat collection module can not make sustainable and efficient use of solar energy resources.The solar collector with dual-function organically combines heated air and heated water,which can realize air heat collection,water heat collection and air/water composite heat collection modes respectively according to seasonal changes,so as to effectively improve the instantaneous thermal efficiency of the collector.Based on theoretical analysis,numerical simulation and experimental test,this paper comprehensively studies the thermal performance of double effect collector.According to the principle of energy conservation,the energy balance diagram of the collector is drawn,and the energy balance equation of each component of the collector is deduced.The theoretical model of solar collector with dual-function is constructed based on ANSYS platform to simulate the effects of working medium flow,inlet temperature and irradiation intensity on the thermal performance of air heat collection mode,water heat collection mode and air/water composite heat collection mode.As for composite heat collection model,four air-water relative flow conditions are innovatively proposed,namely,parallel-same journey,reverse-same journey,parallel-hetero journey and reverse-hetero journey,and the thermal performance of the four air-water relative flow conditions in the change process of the above parameters is further compared and studied.The comprehensive research shows that under the single working medium heat collection mode,increasing the working medium flow can improve the instantaneous heat efficiency of the working medium,and the maximum heat collection efficiency of air and water can reach 55.28%and 71.21%;Increasing the inlet temperature of the working medium will greatly reduce the thermal efficiency of the working medium.When the temperature is increased from 290 K to 310 K,the air heat collection efficiency and water heat collection efficiency are reduced by 14.51%and 16.86%respectively;With the increase of irradiation intensity（300～1000 W/m~2）,the instantaneous heat collection efficiency of water increases gradually,while the instantaneous heat collection efficiency of air increases first and then decreases slowly.Its peak point is related to the flow.The larger the flow is,the later the peak point is.In the composite heat collection mode,increasing the flow rate of a single working medium can effectively improve the heat collection performance of the working medium and the composite heat collection,but it will reduce the heat collection efficiency of another working medium;Increasing the inlet temperature of a single working medium will reduce the thermal efficiency of the working medium and the composite collector,but will strengthen the thermal performance of another working medium;With the increase of irradiation intensity,the instantaneous thermal efficiency of the three is in an upward trend,but the growth of air heat collection efficiency is relatively slow.It is found that performance quality of the three is changed by the increase of mass flow,inlet temperature of single working medium and irradiation intensity.The experimental results of L-type fin collector with lower runner show that under the single working medium heat collection mode,when the air mass flow is 0.034m~3/s,the instantaneous maximum heat collection efficiency and daily average heat collection efficiency are 50.16%and 44.98%respectively,and when the water mass flow is 0.046 kg/s,the instantaneous maximum heat collection efficiency and daily average heat collection efficiency are 73.92%and 55.78%respectively.Under the compound heat collection mode,the maximum heat collection efficiency and daily average heat collection efficiency can reach 95.14%and 73.02%.When the water tank temperature is higher than the collector plate temperature,the water heat collection process in the composite heat collection mode will be negative.From the perspective of energy utilization,water heat collection is suitable for spring and autumn,air heat collection is suitable for winter,and air/water composite is suitable for summer.Figure[45]table[22]reference[55]...