The influence of recycling on double-pass solar air collectors with welding of the
V-corrugated absorber has been studied experimentally and theoretically. Welding the V-corrugated
absorber and the recycle-effect concept to the solar air collector was proposed to strengthen the
convective heat-transfer coefficient due to turbulence promotion. Both the recycle effect and the
V-corrugated absorber can effectively enhance the heat transfer efficiency compared to various designs
such as single-pass, flat-plate double-pass, and double-pass wire mesh packed devices. Recycling
operations and welding the V-corrugated absorber could enhance the collector efficiency by increasing
the recycle ratio, incident solar radiations, and air mass flow rates. The most efficient and economical
operating conditions were found at R ≈ 0.5, with relatively small hydraulic dissipated energy
compensation. It was found that the turbulence intensity increase from welding the V-corrugated
absorber into the solar air collector channel could compensate for the power consumption increase,
when considering economic feasibility.
