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 (

η

eff

) 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

and

η

eff

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

.