Heat transfer augmentation in a solar air heater with conical roughness elements on the absorber

Alsaiari, Abdulmohsen; Alzahrani, Hassan A. H.; Madhukeshwara, N.; Prasanna, B.M.

doi:10.1016/j.csite.2022.102210

Cited by 15 publications

(1 citation statement)

References 39 publications

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“…The authors have studied much research to understand the physics behind rib turbulators and flow regimes. It is found that few of the researchers accomplished their exertion on the roughness geometry of arc shape, 13 square ribs, 14 broken arc, 15 continuous W‐shaped, 16 discrete W‐ribs, 17 winglet shape, 18 Delta winglet, 19 chamfered grooved type, 20 conical shape, 21 and S‐shaped 22 which have improved the thermal performance of SPAH. Many of the investigators also executed their research work in V‐shaped rib roughness so that more generation of secondary flow could be assessed to augment the desired heat transfer rate and thermal efficiency rate.…”

Section: Introductionmentioning

confidence: 99%

Experimental study for the enhancement of heat transfer characteristics and development of thermal correlations of a roughened solar collector

Kumar,

Layek

2024

Heat Trans

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The thermal performance of the flat plate solar collector is very low. The most beneficial and worthwhile method for increasing the thermal performance of a solar‐powered air heater (SPAH) is to include a roughness element in the working zone of heat transfer that is located beneath the shear layer of the absorber surface. In this research work, efforts are made to enhance thermal performance and develop thermal correlations for the estimation of the Nusselt number and friction factor of a roughened SPAH. Experiments are performed for various ranges of flow, Reynolds numbers, and roughness parameters. The experimental technique of liquid crystal thermography is utilized to assess the dispersal of Nusselt number over the roughened surface for all roughness parameters. A maximum thermal performance enhancement index of 2.69 is obtained with the optimum value of the roughness parameter at a relative roughness pitch (RRP) of 9, a relative staggering distance (RSD) of 4, and a relative roughness length (RRL) of 6.15. Second, a mathematical correlation is developed using a regression model to estimate the Nusselt number and friction factor in terms of nondimensional roughness and flow parameters operated as RRP, RSD, RRL, and Re. The degree of discrepancy between the established the relationships and the findings from the experiment reveals incredibly satisfying results. Hence employing twisted V‐ribs as an artificial roughness element no doubt increases the Nusselt number, and thermohydraulic performance enhancement index, but it also exerts less frictional power across the SPAH duct.

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