Analyzing thermal properties of solar evacuated tube arrays coupled with mini-compound parabolic concentrator

En-Tong Xia and Fei Chen

Renewable Energy, 2020, vol. 153, issue C, 155-167

Abstract: Effective utilization of solar energy resource enables to improve the thermal performance of solar evacuated tube. In present work, the back side of solar vacuum tube was coupled with mini-compound parabolic concentrator (mini-CPC). The thermal characteristics of the presented mini-CPC solar vacuum tube were analyzed theoretically and experimentally. A mathematical model of heat transfer for the mini-CPC vacuum tube was established according to the energy conservation, and solved by iterative calculation based on home-built C programming language. The obtained numerical solutions fit in well with the experimental results. Furthermore, analysis indicates the vacuum interlayer plays a crucial role in hindering heat transfer. The thermal-convection resistance (Rco-air,conv) dominates the heat loss from cover tube to ambient rather than thermal-radiation resistance (Rco-sky,rad). The measured final temperature increment of working water for the mini-CPC and ordinary evacuated tube can reach 63.4 K and 49.8 K, respectively. An experimental result also reveals that the thermal efficiency of the mini-CPC vacuum tube is increased by 24.3%–29.2% compared with that of vacuum tube without mini-CPC, considering various weather conditions. Consequently, the designed mini-CPC evacuated tube shows a preferable performance, which may provide a certain reference in technology for engineering applications.

Keywords: Solar energy; Vacuum /evacuated tube; Compound parabolic concentrator (CPC); Heat transfer; Efficiency (search for similar items in EconPapers)
Date: 2020
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Citations: View citations in EconPapers (6)

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Persistent link: https://EconPapers.repec.org/RePEc:eee:renene:v:153:y:2020:i:c:p:155-167

DOI: 10.1016/j.renene.2020.02.011

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