Thermo-exergetic and environmental assessment of a spiral solar air heater with non-uniform baffle spacing under radiation-resolved CFD

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Chinese explanation / 中文解读

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Original abstract

Abstract The thermal, exergetic, economic, and environmental (4E) performance of a solar air heater (SAH) incorporating spiral flow geometry with uniform and non-uniform baffle spacing has been investigated using the Discrete Ordinates (DO) model to capture radiative heat transfer through the semi-transparent glazing under diurnal solar conditions. Spiral configurations enhance heat transfer due to curvature-induced secondary flows and increased residence time. With a progressively reducing flow area, SAH with non-uniform baffles yields the lowest absorber plate temperature (10 K reduction), the highest outlet air temperature (up to a 4 K increase), and a thermal efficiency improvement of approximately 4% compared to the conventional SAH. Owing to a 30–35% reduction in heat transfer irreversibility, the exergetic efficiency is highest for the non-uniform baffle configuration. Despite identical capital and embodied energy costs for both baffled designs, the non-uniform configuration achieves the highest exergy gain per unit cost, thereby improving the exergoeconomic performance parameter. In addition, enhanced sustainability, with higher annual CO 2 mitigation and carbon credit earnings, non-uniform baffle spacing in spiral SAHs emerges as a thermodynamically efficient and economically favourable design with marginally improved environmental performance.

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