Abstract
As one of the basic steps of the R & D regarding a "volume heat-trap" solar collector, a general theoretical model was developed on unsteady heat transfer in a fine-particle semitransparent liquid suspension (FPSS) heated by collimated radiation, taking isotropic scattering in the FPSS layer into consideration. The effect of scattering on heat transfer characteristics in the layer was studied by comparing experimental data with calculated results based on the present model.
From the results theoretically calculated with the albedo, ω0, as a parameter, it was observed that increase in ω0 reduces the heat-trap efficiency of the "volume heat-trap" solar collector. However, in the region of ω0 <0.1, the effect of scattering on heat transfer was seen to be negligibly small, and this small effect was demonstrated experimentally in a diethylphthalate-graphite particle suspension. Since the region of ω0 <0.1 covers that of the practical design conditions of the solar collector entirely, a simpler theoretical model that ignores the effect of scattering has enough validity from the viewpoint of practical use.
