Thermo fluid dynamics optimisation of tapered helically-coiled solar thermal collectors

This study investigated the effect of the absorber geometry on the heat transfer performance of a novel low-cost flat-packable tapered helically-coiled solar thermal collector under laminar flow conditions. Importantly, the potential heat transfer enhancement by secondary Dean flows was evaluated. A computational fluid dynamics (CFD) model was developed and validated with experimental data found in the literature. Overall results show that the Nusselt number increases with the Helical number along the tube. However, this difference is only appreciable close to the end of the tube but quite negligible. The collector geometry should therefore be optimised in terms of optical efficiency to maximise the intercepted solar irradiance on the absorber surface.