Work

Exergy, sustainability, and environmental impact analysis of bio-inspired fin double-pass solar air heaters: A comprehensive second-law assessment

Year: 2026

Type: article

Abstract: Double-pass solar air heaters (DPSAHs) are widely employed for low-temperature thermal applications; however, their performance is constrained by the low convective heat-transfer coefficient of air. This study presents a comprehensive thermal, exergy, sustainability, and environmental assessment of a DPSAH integrated with bio-inspired corrugated fins over a Reynolds number range of 3000–21000. Experimentally validated Nusselt number and friction factor correlations were incorporated into the Hottel–Whillier–Bliss thermal model to evaluate thermal performance and exergy destruction. In addition to conventional sustainability indicators, the Environmental Impact Factor (EIF), defined as the ratio of Waste Exergy Ratio (WER) to exergy efficiency, is adopted as a complementary thermodynamic indicator to quantify exergy destruction per unit useful exergy output. Results show that irradiation irreversibility dominates the exergy destruction, accounting for approximately 75% of the total exergy loss under all operating conditions. The bio-inspired fin configuration achieved a maximum thermohydraulic performance factor of 2.77 and an exergy efficiency of 1.38% at Re = 3000 and h/H = 0.50, outperforming the optimized aerofoil fin. Although thermal efficiency increased with Reynolds number, exergy efficiency decreased, causing EIF to increase nearly an order of magnitude over the investigated operating range. The combined exergy and sustainability analyses identified the low-Re/high-h/H operating region (Re = 3000–6000, h/H = 0.50) as the optimum operating window for achieving enhanced thermodynamic performance with minimum environmental burden.

Source: International Journal of Thermofluids

DOI: 10.1016/j.ijft.2026.101691

Authors: Avinash K. Hegde, Niranjana Rai, K. Vasudeva Karanth, Madhwesh N, Arunkumar H S

Institution: Manipal Academy of Higher Education

Language: English

Topic: Heat Transfer Mechanisms

Subfield: Mechanical Engineering

Field: Engineering

Domain: Physical Sciences

SDGs: Affordable and clean energy, Climate action, Responsible consumption and production

Open Access status: gold

Estimated APC paid: $2,520