为进一步改善平板太阳能集热器（FPSC）冬季水温提升能力的不足,通过搭建的实验平台对FPSC冬季运行策略展开多项实验,分析不同运行模式所对应的集热性能以及适用条件,为平板集热器更高效利用提供参考方案。研究发现：单块FPSC高流速运行的集热效率可达63.74%,各项热性能指标参数优异,但水箱温度偏低;串联、并联系统的水温提升能力较单块模式显著增强,全天温升超过30 ℃,㶲效率达到5.15%。其中,并联系统的热效率、对流换热系数、热损失系数分别为51.52%、41.95 W/（m2·K）、4.74 W/（m2·K）,明显优于串联系统的45.33%、38.74 W/（m2·K）、4.81 W/（m2·K）,集热性能更佳;系统冬季低流速运行将出现断流现象,同时水箱内部温度分层明显;高流速运行工况下,降低水箱容积将缩短有效集热时间,无法充分吸收太阳辐照能;增大水箱容积虽能减少集热损失,但系统温升下降造成热能品质降低。
Abstract
In order to further enhance the ability of the flat plate solar collector （FPSC） to improve the water temperature in winter,a series of experiments on the winter operation strategy of the FPSC were conducted through building experimental platform,and the heating performance as well as the applicable conditions corresponding to different operation modes,which provided a reference for the more efficient utilization of FPSC. The experimental results show that the thermal efficiency of the single FPSC can reach 63.74% under the high mass flow rate,and the index parameters of the thermal performance are excellent. However,the temperature of the water tank is low. The water temperature rise capacity of the series or parallel system is significantly higher than that of the single mode. The temperature rise exceeds 30 ℃ throughout the day,and the exergy efficiency is up to 5.15%. The thermal efficiency,convective heat transfer coefficient,and heat loss coefficient of the parallel system are 51.52%,41.95 W/（m2·K）,and 4.74 W/（m2·K）,respectively,which are significantly better than those of the series system, which are 45.33%,38.74 W/（m2·K）,and 4.81 W/（m2·K）,and the thermal performance of the parallel system is better. The operation of the system under the low mass flow rate in winter will lead to the occurrence of water flow cut-off. The internal temperature of the water tank is stratified,which is not conducive to employing high-temperature hot water. Moreover,under the high mass flow rate conditions of FPSC, reducing the water volume will shorten the available heating time and fail to absorb solar irradiation fully. Although increasing the water volume can reduce the heating loss,the temperature rise of the system will decrease,resulting in a decrease in the quality of thermal energy.
关键词
太阳能 /
集热器 /
热能 /
? /
效率
Key words
solar energy /
solar collectors /
thermal energy /
exergy /
collector efficiency
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基金
安徽省教育厅高校研究生科学研究项目（YJS20210503）; 中国科协优秀中外青年交流计划（2019）; 国家自然科学基金项目（51906020）; 安徽省教育厅高校优秀拔尖人才培育项目（2020）
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