Effect of fabricated V-rib roughness experimentally investigated in a rectangular channel of solar air heater: a comprehensive review.

Solar power is one of the main sources of renewable energy which helps for protecting the environmental and reducing pollution. Technologies and systems for utilizing solar power are the area of research and development for a number of decades. In a solar air heater (SAH), use of fabricated irregularities on its wide face is an effective technique to augment heat discharge for flowing air with a moderate rise in frictional conduct. The necessary conditions for building an effective roughness design are to pick roughness patterns and its geometrical factors such that they may govern the nature of fluid flow with a rise in the heat discharge and lowering pumping losses. Continuous efforts are being carried out by various researchers to optimize the roughness parameters that deliver high heat release rates with low cost of pressure penalty or better thermo-hydraulic performance parameter (THPP). The researchers dominantly studied V-shaped of roughness design because of its better performance characteristics. The main intent of the present paper is to appraise or compile the influence of various V-shaped rib roughness on the thermal behavior of SAH. The outcomes of different V-designed rib roughness in terms of Nusselt number (Nu), and friction factor (f), statistical correlations established related to geometrical parameters and THPP are summarized. A comparative study using different V-designed ribs are also discussed to guide the future research and improvements.