为分析空晒对平板太阳能集热器热损的影响,通过准稳态的测试方法,得出3种涂层（蓝膜、黑铬、阳极氧化）集热器的热性能。此外,也分析了总热损系数随吸热板的平均温度、环温和风速等因素的变化趋势。分析结果表明,经过长期的空晒老化,蓝膜、黑铬和阳极氧化太阳能集热器的总热损系数分别为5.072、5.246和5.996 W/（m2·K）,总热损系数的决定性因素为吸热板平均温度和发射率,风速和倾斜角是其重要影响因素,环境温度对总热损系数的影响较小。通过理论计算得出的总热损系数与实验数据拟合得出的系数相对误差不超过4%,说明所给出的不同涂层性能的计算结果具有较好的准确性。通过扫描电镜的观测分析,说明了在抗腐蚀、抗氧化和热稳定性方面,黑铬和阳极氧化涂层优于蓝膜涂层。避免平板太阳能集热器长期高温空晒,降低涂层发射率可有效减小集热器的总热损系数。
Abstract
To analyze the effect of un-load exposure on the heat loss of flat-plate collectors（FPCs）, the thermal performance of three different coatings（the blue-film coating, the anode oxidizing coating and the black chromium coating） of FPCs were tested by the quasi-steady state method. In addition, the variation trend of heat loss with the average temperature of the heat absorbing plate, inclination angle and wind speed were also analyzed. The results show that after un-load exposure aging, the total heat loss coefficient （the blue-film,the anode oxidizing and the black chromium） of the FPCs is 5.0724, 5.2457 and 5.9961 W/（m2·K） respectively. The emissivity of the coating and the average temperature of the heat absorbing plate are the decisive factors for the total heat loss coefficient. Wind speed and inclination angle are the important factors for the total heat loss coefficient, and the environment temperature has little effect on the total heat loss coefficient. The relative error of the total heat loss coefficient obtained by theoretical calculation and the fitting of experimental data is not more than 4%, which shows the better accuracy of the calculation results for the FPCs with different coatings. The observation and analysis by the SEM, it is shown that the black chromium and anode oxidizing coating are superior to the blue-film coating in corrosion resistance, oxidation resistance and thermal stability. Avoiding the long-term high un-load exposure of the FPCs and reducing the emissivity of the coatings can effectively reduce the total heat loss coefficient of flat solar collector.
关键词
平板太阳能集热器 /
稳定性 /
热损系数 /
数值分析 /
热吸收体
Key words
flat-plate solar collectors /
stability /
heat loss coefficient /
numerical analysis /
heat absorber
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基金
国家科技支撑计划（2015BAA02B00）; 中国-老挝可再生能源开发与利用联合实验室（2015DFA60120）; 国家自然科学基金（51966019）
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