不同吸热涂层平板集热器的热性能衰减研究

为分析不同吸热涂层平板集热器的热性能衰减,以蓝膜、阳极氧化和黑铬集热器为研究对象,基于太阳集热器热性能测试平台,对集热器热性能及空晒老化性能进行测试。分别测试吸热涂层样品的吸收比和发射比,分析空晒前后平板集热器吸收比、发射比和瞬时效率的变化情况及影响因素。研究结果表明:在温度约为18℃的工况下,蓝膜集热器热性能为75.5%,黑铬为73.4%,阳极氧化为69.3%,吸热涂层的光学性能是影响平板集热器热性能的主要因素。平板集热器瞬时效率、吸收比和发射比变化情况的依存关系为Δη≈9.553Δα-1.213Δερ,该式可衡量平板集热器的热性能衰减度。通过空晒老化性能实验可知,提高平板集热器吸热涂层的抗腐蚀、抗氧化能力,可延长集热器的使用寿命。

RESEARCH ON ATTENUATION OF THERMAL PERFORMANCE OF FLAT-PLATE SOLAR COLLECTORS WITH DIFFERENT HEAT-ABSORBING COATINGS

To analyze the attenuation of thermal performance of flat-plate solar collectors(FPSCs),the thermal performance of different FPSCs were researched in the present study. Based on the solar collectors testing platform,the thermal performances and exposure aging properties of different flat-plate solar collectors(FPSCs)with different coatings(the blue-film coating,the anode oxidizing coating or the black chromium coating)were tested. And emissivity and absorptivity of the heat-absorbing coating for different FPSCs were also tested. Meanwhile,the variation relationship about absorptivity,emissivity,and instantaneous efficiency were given. And the influence factors of thermal performance of different FPSCs were analyzed. It was shown that the thermal performance of the blue-film coating FPSC is 75.5%,the black chromium coating is 73.4%,and the anode oxidizing coating FPSC is 69.3% in approximate temperature of 18 ℃.Furthermore,the optical performance of heat-absorbing coating is the main factor of influencing thermal performance of FPSCs. The relational expression among instantaneous efficiency, absorptivity and emissivity is:Δη ≈ 9.553Δα-1.213Δερ,This equation can be used to calculate the attenuation of thermal performance of FPSC. The results of exposure aging experiment showed the service life of FPSCs can be improved by increasing abilities of the anticorrosion and anti-oxidation abilities of coating.