Parametric investigation on the thermo-hydraulic performance of a novel solar air heater design with conical protruded nozzle jet impingement

A numerical investigation is carried out on heat transfer behaviour of a novel solar air heater (SAH) design with impinging jets through conical protruded nozzles using CFD simulations. The impact of non-dimensional parameters is analyzed by varying the nozzle length ratio (Ln/Dh) from 0.0434 to 0.434, nozzle throat diameter ratio (D-nt/D-h) from 0.0217 to 0.1086 and nozzle base diameter ratio (D-nb/D-h) from 0.0434 to 0.1086 for Reynolds number (Re) variations from 2900 to 14300. The present results with jet impingement design have been compared with a conventional parallel flow SAH under similar conditions and also with some existing designs. Results show that for a combination of L-n/D-h = 0.2608, D-nt/D-h = 0.0217, and D-nb/D-h = 0.0652, the highest thermal efficiency of 91.25 % and exergy efficiency of 3.55 % are obtained at Re value of 14,300 and 2900, respectively. Also, the highest Nusselt number (Nu) of 223.18 is observed for the same combinations at Re = 14300, whereas the highest thermo-hydraulic performance parameter (THPP) of 3.65 is observed for Re = 5740 owing to minimum pressure drop across the collector. With much improved thermal efficiency and THPP, the proposed design and the developed CFD model can be used for further development of impinging jet SAH design.