摘要
定量化描述槽式集热器中集热管外热流分布的均匀程度,对于集热器的优化设计有着重要的意义.工程领域中,现有的均匀性评价指标往往只计及物理量在数值上的分布特征,没有考虑物理量在空间相对位置上的分布特征.本文将"均匀度"分解成"均度"和"匀度"两个子指标,从物理量的数值及其相对位置两个层面较为全面地对热流这一物理量分布的均匀程度展开定量化描述.通过对特殊分布和4种典型的集热器中集热管外热流分布的均匀性进行量化评价,验证了该指标的合理性以及在管外热流分布均匀性量化分析中的有效性.同时,新指标具有严格有界、无量纲等特征,便于在集热器的优化设计中使用,同时在其他工程领域也具有应用潜力.
The parabolic trough collector(PTC) is one of the most mature technologies to harvest solar energy for heat applications. However, the non-uniform heat flux distribution on the outer surface of absorber tube can lead to a high local temperature and a large temperature gradient on the tube wall, thus resulting into many issues, such as the degradation of the selective coating, the vacuum loss, the deformation of the absorber tube, and even the breakage of the glass envelope. These issues pose great challenges for the safety and high-efficiency operation of PTC systems. The corresponding effective solution is to increase the uniformity of the heat flux distribution on the absorber tube. Based on this purpose, how to quantify the uniformity of heat flux distribution is of great significance for the design of the parabolic trough collector. In this work, the existing uniformity indexes in engineering are summarized and compared. It is found that there are three problems in the related studies:(1) Some indexes are unbounded, which makes it difficult to compare uniformity of different distribution types;(2) some indexes are dimensioned, and it’s difficult to compare uniformity of different physical quantities distribution;(3) for most of the existing indexes, only the value of physical quantity is considered, while the spatial distribution characteristic of physical quantity is ignored. This phenomenon makes the description of uniformity incomprehensive. In view of this, a new uniformity index is proposed to consider both the value and spatial position of physical quantity by decoupling "uniformity index" into "uniformity index of value" and "uniformity index of spatial position". The "uniformity index of value" is to quantify the dispersion degree of a set of data values from the average, and the "uniformity index of spatial position" is to quantify the amount of dispersion of data values in different spatial zones. The effectiveness of the proposed uniformity index is verified by evaluating the uniformity of three
作者
赵东鹏
赵力
邓帅
汪大海
卢雅妮
邵亚伟
Dongpeng Zhao;Li Zhao;Shuai Deng;Dahai Wang;Yani Lu;Yawei Shao(Key Laboratory of Efficient Utilization of Low and Medium Grade Energy,Ministry of Education of China,School of Mechanical Engineering, Tianjin University,Tianjin 300350,China)
出处
《科学通报》
EI
CAS
CSCD
北大核心
2019年第4期485-492,共8页
Chinese Science Bulletin
基金
国家自然科学基金(51776138)资助
关键词
抛物线型槽式集热器
非均匀热流分布
量化方法
均匀度
parabolic trough collector
non-uniform heat flux distribution
quantitative evaluation method
uniformity index
