An Experimental Investigation on Thermal Analysis of Loop Heat Pipe

With the incremental heat dissipation requirements of the CPU and intricate electronic circuits requiring flexible piping for the extraction of large amount of heat, a loop heat pipe [LHP] is studied and empirically designed. An experimental study of a LHP has been conducted under the natural convection conditions taking into consideration the variable heat inputs and the quantities of working fluid. The LHP made of copper tubing with horizontal evaporator having a brass mesh wick have been studied and presented for various heat inputs 25 W, 50 W, 75 W, 100 W, 125 W and 150 W. The heat was transferred to the evaporator by constructing a parallel flow heat exchanger. The study was conducted at a vertical orientation using distilled water as the working fluid. Exhaustive attempt has been done in analyzing the effect of various quantities of working fluid (120 gm, 125 gm, 130 gm, 135 gm and 140 gm) on heat transfer parameters. The results includes an achievement of an averaged value of LHP efficiency of 94%, irrespective of the power input in the range of 25 W to 150 W, when working fluid is filled at 40% (130 gm) of evaporator volume. Another credited feature is the attainment of a constant value of LHP efficiency within the range of 75 W to 150 W irrespective of the change in the mass of working fluid.Copyright © 2007 by ASME