Analysis of Heat Transfer and Fluid Flow in a Solar Air Heater with Sequentially Placed Rectangular Obstacles on the Fin Surface

Byeong-Hwa An, Kwang-Am Moon, Seong-Bhin Kim and Hwi-Ung Choi ()
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Byeong-Hwa An: Department of Refrigeration and Air-Conditioning Engineering, Chonnam National University, Yeosu 59626, Republic of Korea
Kwang-Am Moon: Department of Refrigeration and Air-Conditioning Engineering, Chonnam National University, Yeosu 59626, Republic of Korea
Seong-Bhin Kim: Department of Mechanical Engineering, Ulsan National Institute of Science and Technology, Ulsan 44919, Republic of Korea
Hwi-Ung Choi: Department of Refrigeration and Air-Conditioning Engineering, Chonnam National University, Yeosu 59626, Republic of Korea

Energies, 2025, vol. 18, issue 14, 1-14

Abstract: A solar air heater (SAH) converts solar energy into heated air without causing environmental pollution. It features a low initial cost and easy maintenance due to its simple design. However, owing to air’s poor thermal conductivity, its thermal efficiency is relatively low compared to that of other solar systems. To improve its thermal performance, previous studies have aimed at either enlarging the heat transfer surface or increasing the convective heat transfer coefficient. In this study, a novel SAH with fins and sequentially placed obstacles on the fin surface—designed to achieve both surface extension through a finned channel and enhancement of the heat transfer coefficient via the obstacles—was investigated using computational fluid dynamics analysis. The results confirmed that the obstacles enhanced heat transfer performance by up to 2.602 times in the finned channel. However, the obstacles also caused a pressure loss. Therefore, the thermo-hydraulic performance was discussed, and it was concluded that the obstacles with a relative height of 0.12 and a relative pitch of 10 yielded the maximum THP values among the investigated conditions. Additionally, correlations for the Nusselt number and friction factor were derived and predicted the simulation values with good agreement.

Keywords: solar air heater; solar energy utilization; CFD; Nusselt number; friction factor (search for similar items in EconPapers)
JEL-codes: Q Q0 Q4 Q40 Q41 Q42 Q43 Q47 Q48 Q49 (search for similar items in EconPapers)
Date: 2025
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