Effect of heat transfer and pressure drop characteristics on the performance analysis of an artificially roughened solar air heater

• Published in: Heat and mass transfer Vol. 59; no. 5; pp. 891 - 907
• Main Authors: Kumar, Amit, Layek, Apurba
• Format: Journal Article
• Language: English
• Published: Berlin/Heidelberg Springer Berlin Heidelberg 01.05.2023; Springer Nature B.V
• Subjects: Air heaters; Air masses; Angle of attack; Engineering; Engineering Thermodynamics; Fluid flow; Friction factor; Heat and Mass Transfer; Heat transfer; Industrial Chemistry/Chemical Engineering; Liquid crystals; Mass flow rate; Original Article; Pressure drop; Reynolds number; Roughness; Thermodynamics; Thermography
• ISSN: 0947-7411; 1432-1181
• DOI: 10.1007/s00231-022-03296-x

In the present work, performance analysis of solar air heaters comprised of winglet type roughness element embedded on the surface plate has been presented using liquid crystal thermography (LCT) approach to evaluate the collector heat transfer enhancement as well as the pressure drop characteristics across the rectangular test section. The important factors that directly affect heat transfer enhancement value and the pressure characteristics are based on the present case of roughened surface which is compared with the smooth surface under a similar flowing condition. The non-dimensional parameters for the roughness element considered as relative roughness pitch (P/e) of 5–12, attack angle (alpha) values of 30°–75°, relative roughness width(W/ w ) of 3–7, and Reynolds number (Re) range between 3000 – 22,000 in terms of different values of air mass flow rate (m) has also been evaluated. The following values of parametric condition and its effect on Nusselt number, friction factor, and the pressure drop characteristics across the given test section were analyzed. Thus, its optimum improved value due to roughened surface has been compared with the smooth surface. However, the higher value of pressure drop across the test section is also compared to that of the smooth one under the given condition.