Analysis of Heat Pipe Solar Collector with different Heat Pipe Parameters

Abstract

Heat Pipe Solar Collector (here after referred as HPSC) has better collecting efficiency compared to the conventional collector, besides overcoming some of the drawbacks encountered with the later one.  In this paper, numerical simulation & theoretical analyses of HPSC parameters are presented.  The effects of Lc/Le (Condenser length /Evaporator length) ratio and L/di (length/diameter) ratio of heat pipe on HPSC were analysed.   Simulated results were compared with experimental values.   Heat pipes (Five numbers each) having two different Le/Lc, with two different L/di have been designed, fabricated, and used in the solar collector absorber.  Copper and Stainless steel have been used as container and wick material of heat pipe and Methanol has been used as working fluid.  Heat pipes are designed to have heat transport factor of around 194 W and 260 W of thermal energy.  The experiments were conducted during summer season with a collector tilt angle of 11o &13o to the horizontal. It was found experimentally that the collector with less L/di ratio was more efficient.  This improved efficiency is due to increase in heat transport factor of heat pipe, which increases with decrease in L/di ratio.  Numerical simulation also shows that when the L/di increases, the efficiency of the collector decreases.  Similarly the performance of HPSC was found to be better with higher Lc/Le value.  The numerical simulation also has the same trend.