Investigation of thermal performance of-double pass-flat and v-corrugated plate solar air heaters

► The DPVCPSAH is 11-14% more efficient than the DPFPSAH. ► The increasing in pressure drop through DPVCPSAH than that through DPFPSAH is insignificant. ► The thermo hydraulic efficiency of DPVCPSAH is 14% higher than that of DPFPSAH. ► Optimum values of thermo hydraulic efficiencies of two heaters when m˙=0.02 kg/s.