Energetic and exergetic performance evaluation of solar air heater with twisted rib roughness on absorber plate

The present works conducts a stochastic analysis for numerical optimization for energetic and exergetic efficiencies of solar air heater with twisted rib roughness on absorber plate. These efficiencies are evaluated considering design parameters and temperature rise parameter. The energy efficiency criterion does not consider the pumping power to blow air through the duct. Therefore, it becomes an exigent work to evaluate effective and exergetic efficiency to estimate energy distribution of solar air heater. The thermal behavior is taken in account through Nusselt number and friction factor correlations as function of different geometrical configuration performed experimental work for twisted rib roughness and compared with smooth plate and previous results. The exergetic efficiency criterion characterized optimum roughness parameters in terms of temperature rise parameter and insolation. A geometrical configuration of relative pitch roughness of 8, rib orientation angle of 60°, twist ratio of 3 and temperature rise parameter of 0.0125 m2 K/W reported maximum enhancement in thermal, effective and exergetic efficiencies as 1.81, 1.79 and 1.81 times over smooth plate. The comparisons between simulated and experimental results within 6% at maxima considering within acceptable limit. Additionally, present methodology facilitates to prepare design plot for roughness parameter without introducing much investment for real experimentation and also addresses to investigate novel artificial roughness to enhance thermal performance of solar air heater.