Fluid flow and heat transfer evaluation and optimisation of solar-assisted air-heater having multi-arcs with gaps used as roughness elements

Abstract

Solar air heaters are used for drying and room heating purposes. Techniques have been developed to increase their effectiveness by various methods, the most common being the introduction of roughness elements on the underside of the absorber plate. In the current study, a combined approach of response surface methodology and experimental findings has been done to investigate using various dimensionless parameters on the thermo-hydraulic performance parameters of solar air heaters with multi-arc-shaped roughness elements with gaps on the absorber plate. RSM modelling was carried out with objective functions such as maximisation of Nusselt number and minimisation of Friction factor. Optimised calculated values of design parameters for THPP of SAH to provide maximum Nusselt number were estimated as Reynolds Number = 21,000, e/D = 0.0443, d/x = 0.25 and g/e = 1.7323. The enhancement ratio of the Friction factor and Nusselt number was 2.101 and 3.53, respectively.

KEYWORDS:

• Discrete multiple arcs with gaps
• response surface methodology
• solar air heater
• optimisation
• thermo-hydraulic performance

Disclosure statement

No potential conflict of interest was reported by the author(s).