Development of a “volume heat-trap” type solar collector using a fine-particle semitransparent liquid suspension (FPSS) as a heat vehicle and heat storage medium Unsteady, one-dimensional heat transfer in a horizontal FPSS layer heated by thermal radiation

Abstract

The objective of this work is to develop a “volume heat-trap” solar collector in which a fine-particle semitransparent liquid suspension (FPSS) is used as a heat vehicle and heat storage fluid. In the first step of our fundamental research, a multiband model, taking into consideration the effect of fine particle suspension in a continuous fluid on radiation and absorption characteristics, was formulated to analyze the unsteady one-dimensional heat transfer in a horizontal FPSS layer heated by thermal radiation. The experiments were conducted for three kinds of suspensions: diethylphthalate-graphite, -carborundum and -silicon dioxide. The time-changes of temperature distributions within the suspension layer were measured under step- and intermittent-radiative heating conditions, using an infrared lamp bundle as a simulated model of solar radiation. The experimental data obtained for the rate and efficiency of heat collection, as well as for the unsteady temperature distribution within the FPSS layer, show satisfactory agreement with calculations based on the proposed theoretical analysis. It is the feelings of the authors that the FPSS used as a heat collection fluid in this work has a good heat transfer characteristics to enable the development of high efficient solar collector.