Combining horizontal evacuated tubes with booster mirror reflector to achieve seasonal reverse output: Technical and experimental investigation

Xiaomeng Chen, Xudong Yang and Muran Li

Renewable Energy, 2022, vol. 188, issue C, 450-464

Abstract: Owing to seasonal fluctuations in solar radiation resources and ambient air temperature, stationary solar collectors have higher output in summer and lower output in winter. However, seasonal heating demand and hot water usage follows an opposite pattern, resulting in insufficient heating in winter and the risk of overheating in summer, reducing the feasibility of solar thermal technology. In this study, a new configuration that combines horizontal evacuated tubes with a mirror reflector was developed to achieve seasonal reverse performance: high performance in winter and low performance in summer. In contrast to conventional collectors, the collector plane of this new module was inversely inclined, pointing to the solar altitude angle on the summer solstice. Together with the bottom mirror reflector, the normal vector of the composed aperture plane was designed to point to the solar altitude angle on the winter solstice. Through experimental and numerical studies, we found that the standardized thermal efficiency of the new module on the winter solstice was comparatively high because it can be regarded as a concentrating collector with a concentration ratio of 0.77. On the summer solstice, the thermal efficiency was extremely reduced due to 100% self-shading of the collector plane. Based on the idea of overcoming the seasonal instability of renewable resources, this designed solar module is expected to enhance the competitiveness of solar heating technology, especially in the decentralized clean heating market.

Keywords: Seasonal reverse output; Solar thermal; Efficiency improvement; Overheating prevention; Mirror reflector (search for similar items in EconPapers)
Date: 2022
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Persistent link: https://EconPapers.repec.org/RePEc:eee:renene:v:188:y:2022:i:c:p:450-464

DOI: 10.1016/j.renene.2022.02.041

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