摘要
为提高太阳能集热管供热水平,研究不同流速对太阳能集热管效率的影响,解决传统集热管受光面小、热损率高等突出问题,该文设计了一种具有高效吸收光热和保温性能的循环集热晒管。循环集热晒管由真空石英直管、石英弯管和连接段组成,真空石英直管之间采用串联循环方式连接,以扩大受光面积,增加接收的太阳热能。通过微元分析法推导循环集热晒管内双流体的液相与气相的能量平衡方程,建立了循环集热晒管内两相流数学模型;对两相流模型求解区域进行离散化和迭代求解,获得不同入口质量流量下晒管内水蒸气产生的位置和质量分数;设计并开展试验以验证两相流模型,分析单相流、两相流条件下循环集热晒管的热性能。研究表明:在入口质量流量4.42 kg/h条件下,循环集热晒管内流体达到饱和温度,开始汽化;晒管内流体温度与入口质量流量呈反相关,最高温度可达120℃,而晒管集热效率与入口质量流量呈正相关,最高集热效率可达0.87。综合考虑流体温度和集热效率,最优入口质量流量为4.15kg/h;两相流模型(压力为0.1 MB)得到的晒管集热效率理论曲线与试验测定曲线基本相符,误差在±2%以内。该文成果是真空管内两相流动分析的有益补充,为南疆盐碱水淡化的工程应用提供参考。
The flood irrigation method adopted in the saline-alkali land in Southern Xinjiang produced a large amount of brackish water, so realizing the resource utilization of brackish water had an important value for improving the local water shortage. Vacuum glass tube had a long history of development and a proven production process, and it was one of the indispensable components of the brackish water desalination device using solar energy. In order to improve the heating level of solar collector, study the influence of different entrance mass flow on the heating efficiency of solar collector, and solve the outstanding problems such as small receiving surface area and high heat loss rate, this paper studied and designed a kind of circulating solar heat tube with high efficiency of absorbing light and heat preservation. The circulating solar heat tube was composed of quartz vacuum straight tube, quartz elbow and connection segment. A vacuum was formed between the inner and outer tubes of the quartz straight tube to reduce the convective and conduction heat loss, and such tubes were connected in series to expand the surface area and increased the received solar energy. In this paper, the energy balance equations of the liquid phase and the gas phase of the two-fluid in the circulating solar heat tube were deduced by the micro-element analysis method, and the mathematical model of the two-phase flow in the circulating solar heat tube was established. The solution region of the two-phase flow model was discretized and iteratively solved, so that the position and mass fraction of water vapor generated in the tube under different entrance mass flow were obtained. An experiment was designed to verify the two-phase flow model. The thermal performance of the circulating solar heat tube under single-phase flow and two-phase flow conditions were analyzed, and the entrance mass flow was optimized synthetically. The results showed that the entrance mass flow of 4.42 kg/h was the critical value for the division of single-phase flow
作者
孙志林
胡秋月
涂文荣
方诗标
杨洋
Sun Zhilin;Hu Qiuyue;Tu Wenrong;Fang Shibiao;Yang Yang(Ocean College,Zhejiang University,Zhoushan 316021,China;Tarim University,Alar 843300,China;College of Civil Engineering and Architecture,Zhejiang University,Hangzhou 310058,China;Shenzhen Research Institute,China University of Geosciences,Shenzhen 518057,China)
出处
《农业工程学报》
EI
CAS
CSCD
北大核心
2019年第24期246-254,共9页
Transactions of the Chinese Society of Agricultural Engineering
基金
兵团重大科技项目(2018AA003)
自治区重大科技专项(2016A03008-02)
国家自然科学基金重大研究计划(91647209)
关键词
太阳能
传热
真空管
气液两相流
数学模型
迭代求解
solar energy
heat transfer
vacuum tube
gas-liquid two-phase flow
mathematical model
iterative solution
