Thermohydraulic performance analysis of an arc shape wire roughened solar air heater

• Published in: Renewable energy 2017-08, Vol.108, p.598-614
• Main Authors: Sahu, Mukesh Kumar, Prasad, Radha Krishna
• Format: Article
• Language: English
• Subjects: Artificial roughness; Effective efficiency; Solar air heating duct; Thermal efficiency; Wire roughness
• ISSN: 0960-1481; 1879-0682
• DOI: 10.1016/j.renene.2017.02.075

In the present paper, a comprehensive investigation on thermal and thermohydraulic performance of solar collector for heating air having circular wire rib roughness in the form of arc shape on the back side of absorber plate, has been carried out. A mathematical model incorporating the operating and system parameters has been developed and the results have been computed by using MATLAB for specified range of these parameters. A conventional solar air heater working under similar conditions has also been considered for the purpose of comparison. At rib height-to-duct hydraulic diameter ratio = 0.0422 and flow-attack-angle = 0.3333 the values of maximum thermal and effective efficiencies were found to be 79.84% and 75.24% respectively for the range of parameters used in the investigation. Further, the thermal efficiency, obtained in the present work has been compared with those obtained for other roughness geometries available in the literature for common roughness parameters and operating parameters to validate the results. Optimization of different parameters of wire roughness for optimum thermohydraulic (effective) efficiency of solar air heater duct has also been investigated. •A comprehensive theoretical analysis to evaluate thermal (ηth) and thermohydraulic (ηeff) efficiency of arc shaped roughened solar air heater has been done.•ηth and ηeff were found to be 79.84% and 75.24% respectively at rib height-to-duct hydraulic diameter ratio e/D = 0.0422 and flow-attack-angle α/90 = 0.3333 and Rib pitch-to-height ratio P/e = 10.•The maximum values of ηeff with temperature rise parameter ΔT/I have been optimized.•Thermal Efficiency Improvement Factor (TEIF) of various roughness geometries has been compared.