Thermal Analysis And Structure Optimization Of A Flat Plate Solar Collector With Dual Function

The flat-plate solar collector is an important core component of solar thermal utilization system,which is widely used in daily production and life,but the heat efficiency and utilization rate of traditional flat plate is low,which has limited the developing of traditional flat plate.For this reason,there is a kind of flat plate collector with dual function has been put forward,the collector has three kinds of working modes: water mode,air mode and water–air mode,which greatly improves the heat efficiency and utilization rate of the collector.In this paper,the thermal performance of the self-designed and processed flat plate solar collector with dual function is studied by means of experiment and simulation.Through the establishment of experimental platform,the thermal performances of the collectors under the air mode,the water mode,and the air-water combined mode were experimentally studied.The experimental results show that: compared with the air mode and the water mode,the thermal efficiency of the collector has been significantly improved in the air-water mode,and the daily average thermal efficiency of collector based on the lighting area is 73.4%.The total thermal efficiency of collector remains above 70% for most of the time.In order to further study the double-effect plate type solar collector,the heat transfer process of the collector is studied by using the CFD method,the state of flow field inside the fluid domain of the collector and the surface temperature distribution of the absorber plate are obtained.As the same time,making structure optimization for the collector and studies the influence of key parameters on the thermal performance of the collector.Through simulation,it is found that there is a large area of air flow dead zone in the air flow domain of the collector,it causes a local high temperature area in the absorber plate,which leads to the decrease of thermal efficiency of the collector.Aiming at this phenomenon,an optimal collector model with conventional spoiler or perforated spoiler were proposed.After simulation studies,it was found that the thermal efficiency of installing traditional spoiler was improved.In air mode,heat collection was improved.The efficiency increased from 52.1% to 62.9%,but there was still a dead air flow area in the back of the spoiler.Further,the spoiler is optimized for opening holes,air is formed through the openings to form jets,air disturbances on the back of the spoiler areenhanced,the high temperature area is suppressed,and the thermal efficiency of perforated spoiler reaches 66.7%.Finally,using CFD software to study the effects of air mass flow,water mass flow,and ambient temperature on the thermal performance of the double-function collector in the air-water mode,the simulation study found that,in the case of a certain amount of total radiation received by the collector,The heat exchange capacity of the air module and the water module has a mutual restriction relationship.It is could increase the efficiency of the collector by increasing of air mass flow or the water mass flow.When the air mass flow increases,the heat exchange capacity of the air module increases,the air module heat collection efficiency rises,the water module heat exchange amount decreases,and the water module thermal efficiency decreases,and vice versa.As the ambient temperature rises,the heat loss of the collector decreases,and both the air module and the water module thermal efficiency show an upward trend.