Improving the overall thermal performance of parabolic trough solar collectors using porous media

Abstract

The use of a porous insert constituted by a metalmatrix of copper Raschig Rings is proposed here for parabolictrough solar collectors. The CFD analysis, based on a well-established numerical model, allows computing a significantincrease in the thermal performance of the tube considered in theanalysis, when equipped with the porous insert, with respect to asmooth pipe. The useful power grows up to ~96 % of theabsorbed incident power. A reduction of a factor of s in theradiative and convective losses is computed, due to a large dropin the pipe surface temperature. The length of the porous inserthowever,should be carefully evaluated in view of the significantadditional pressure drop caused by the insert.