Research On Heat Collection Performance Optimization Of Flat Plate Solar Collector

In the current situation of decreasing traditional energy sources and prominent environmental problems,China’s energy consumption structure is developing towards a clean and low-carbon direction.Clean energy represented by solar energy is widely used in various scenarios,among which flat plate solar collector is a common solar thermal utilization device,but it has problems such as low heat collection efficiency and high heat loss.Based on this,this paper first introduces the basic structure,working principle,heat transfer mechanism and performance evaluation method of flat plate solar collector,then analyzes the collector by means of simulation and experiment,and some optimizations have been made to the collector to improve the thermal performance of the collector.The main research contents and results are as follows:(1)In terms of simulation,CFD software is used to model and calculate the collector model,study the influence of operation parameters,environmental parameters and other factors on the thermal performance of the collector.The main conclusions are that within a certain range,the heat collection efficiency increases with the increase of working fluid mass flow rate,ambient temperature,number of riser pipes and inner diameter of riser pipes;while it decreases with the increase of working fluid inlet temperature and ambient wind speed;when inlet temperature is lower than 45℃,single-glazed cover has higher heat collection efficiency than double-glazed cover;when inlet temperature is higher than 45℃,double-glazed cover has higher heat collection efficiency than single-glazed cover.(2)In terms of experiment,a flat plate solar collector experimental system was set up and tested in October 2022.The experimental data were collected and analyzed for thermal performance of collector.By formula calculation,normalized temperature difference-instantaneous efficiency relationship curve was fitted out.The highest instantaneous efficiency was 81.3%,while heat loss coefficient was 4.36 W/(m~2·℃).(3)An optimization design for insulation layer of collector was proposed:aluminum foil sheets were added into bottom insulation layer to reduce radiation heat transfer intensity thus enhancing insulation effect;after connecting to experimental platform for testing compared with before optimization:highest instantaneous heat collection efficiency increased from 81.3%to 83.9%,increased by 2.6 percentage points;heat loss coefficient decreased from 4.36 W/(m~2·℃)to 3.94 W/(m~2·℃),decreased by 9.6%,proving feasibility of this optimization design.Through conclusions drawn from above researches some new ideas were provided for subsequent optimization researches on collectors theoretical basis was provided for wide application fields flat plate solar collectors.