Experimental investigation for enhancement of heat transfer and friction factor through using V-pattern ribs along with semi-circular perforated mannerOA

The installation of ribs to alter fluid flow patterns and produce swirling flow,which disrupts the thermal boundary layer,is a well-established method for enhancing heat transfer in solar air heaters.However,this approach often leads to pressure loss in the flow channel and heat accumulation at the rib base.To address these issues,perforated ribs have been introduced.This research experimentally investigates the heat transfer enhancement of V-pattern ribs,where the base of the ribs was perforated with semi-circular holes of varying sizes and numbers.The Nusselt number(Nu),friction factor(f)and thermal efficiency(ηeff)were calculated,and the optimization of the rib configurations was evaluated using the thermal performance factor(TPF).In the experiment,air was used as the working fluid in a fully turbulent regime,with a constant irradiation flux provided by a solar simulator.The results demonstrated that semi-circular hole perforations at the rib base effectively reduced pressure drops in the flow channel by allowing smoother fluid flow through the perforations.Simultaneously,heat transfer was enhanced due to flow separation,reattachment,swirling,and jet formation,which disrupted the thermal boundary layer.Compared to non-perforated V-pattern ribs,Nu andηeff increased by 11.44%and 15.06%,respectively,f decreased by 5.24%,and TPF rose by 15.89%,achieving a maximum value of 2.53.Furthermore,the developed correlation equations showed strong agreement with the experimental data,accurately predicting both Nu and f.