Experimental comparison of thermal, economic, and environmental outcomes in open-cut fin solar air heaters

Abstract

This experimental study investigates the thermal, exergetic, economic, and environmental performance of Solar Air Heaters (SAHs) with three open-cut fin geometries (V-shaped, semi-circular, and rectangular) to address inadequate convective heat transfer that limits SAH efficiency. This work provides a systematic comparison of open-cut fin geometries under identical experimental conditions, contributing new insights to an area where prior studies have not offered direct comparative evaluation. The experimental setup comprised four parallel channels (1 m × 0.01 m × 0.015 m) with one plain absorber and three open-cut fin geometries, each having uniform geometry (0.09 m height, 0.02 m cut) with eight fins. Testing was conducted at two flow rates (0.002 and 0.0035 kg/s) throughout daylight hours. Results show V-shaped fins exhibit higher performance, achieving maximum outlet temperature of 58 °C with 23.4 % increase over plain absorber, peak energy efficiency of 66 %, and heat transfer coefficient of 23.5 W/m²K representing 70.3 % enhancement. Semi-circular fins showed intermediate performance, reaching 55 °C with 17 % improvement, while rectangular fins achieved 51 °C with 8.5 % enhancement. Economic analysis revealed V-shaped fins demonstrated shortest energy payback period of 2.82 years and lowest levelized cost at $0.156/kWh, achieving 34 % cost reduction. Environmental assessment showed maximum CO₂ mitigation of 5.38 tons over 20-year lifetime, generating $102.22 carbon credits. Study limitations include testing under specific geographical conditions and evaluation of only two mass flow rates with fixed fin dimensions. Future research should focus on parametric optimization and comprehensive lifecycle assessments with region-specific economic analysis.