Thermo-hydraulic performance of roughened solar air heater by design of experiment and meta-heuristic approach

•The design modelling of roughened solar air heater with response surface methodology.•The effect of geometric roughness parameters on thermo-hydraulic performance is examined.•The PSO and TLBO technique is adopted for optimization of geometric roughness parameters.•The thermo-hydraulic performance is determined using RSM, PSO and TLBO is compared with each other.•The TLBO technique shows better convergence result with experimental result.