Numerical simulation of heat transfer improvement of a new designed artificially roughened solar air heater using triangular ribs with semi-circular nooks

The present study represents a computational analysis of two-dimensional air flow in a new designed configuration of a solar air heater (SAH). The shape of the installed ribs along the absorber plate is a combination of triangular and semi-circular nooks with variable height of three ribs simultaneously. The objective is to optimize the Thermo-Hydraulic Efficiency Parameter (THEP) of the SAH by characterizing the values of roughness height (e) and pitch (P) of the considered ribs which provides the optimum patterns. Various (e) and (P) values for varied Reynolds number (Re) between 3,800 and 18,000 are investigated. An imposed constant heat flux is considered, and governing equations describing the flow and heat transfer are solved numerically with the selected RNG k-ε for the turbulence modeling. The obtained results indicate that the THEP strongly depends on the different investigated geometric parameters and Re number. The obtimum THEP value of 1.93 could be obtained for the case C1 and Re number of 5,000.