Experiment and simulation study on convective heat transfer of all-glass evacuated tube solar collector

Li, Qiong, Gao, Wenfeng, Lin, Wenxian, Liu, Tao, Zhang, Yonggang, Ding, Xiang, Huang, Xiaoqiao, and Liu, Wuming (2020) Experiment and simulation study on convective heat transfer of all-glass evacuated tube solar collector. Renewable Energy, 152. pp. 1129-1139.

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Abstract

Solar collector with horizontal double-row all-glass evacuated tubes has been extensively implemented in the solar water heating system engineering. The temperature distribution and stratification of horizontal double-row all-glass evacuated tube collector with 24 evacuated tubes have been studied. Validation of instantaneous efficiency under different declination angle qm were studied by means of experiments. Moreover, numerical simulations are carried out for four different declination angle qm (0/2/4/6). The results showed that the declination angle qm has significant effect on energy conversion efficiency, flow patterns and stratification inside evacuated tubes. When qm > 0, with the declination angle increased, the instantaneous efficiency also increased, nevertheless, the temperature stratification weakened and the heat loss coefficient demonstrated no significant change. Declination angle 6 allowed to achieve significant higher temperatures, nevertheless, along with inactive area at the bottom of evacuated tubes appears. If declination angle qm < 0, inversion phenomenon appears. With the increase of |qm|, more heat is trapped in the sealed end of the evacuated tube, which is not conducive to the flow heat transfer in evacuated tube solar collector.

Item ID: 62415
Item Type: Article (Research - C1)
ISSN: 1879-0682
Keywords: Solar collector; Evacuated tube; Heat transfer; Declination angle; Natural circulation
Copyright Information: © 2020 Elsevier Ltd. All rights reserved.
Funders: National Natural Science Foundation of China (NNSFC)
Projects and Grants: NNSFC 51866016, NNSFC 11662021
Date Deposited: 06 Mar 2020 02:05
FoR Codes: 40 ENGINEERING > 4012 Fluid mechanics and thermal engineering > 401205 Experimental methods in fluid flow, heat and mass transfer @ 30%
40 ENGINEERING > 4017 Mechanical engineering > 401703 Energy generation, conversion and storage (excl. chemical and electrical) @ 70%
SEO Codes: 85 ENERGY > 8505 Renewable Energy > 850506 Solar-Thermal Energy @ 80%
97 EXPANDING KNOWLEDGE > 970109 Expanding Knowledge in Engineering @ 20%
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