Experimental and theortical study of the thermal performance of heat pipe heat exchanger

Abstract

Heat pipe heat exchanger (HPHE) considers one of the most useful devices for the recovery of waste heat energy. An Experimental study has been carried out on air to -air HPHE constructed of thermosyphon heat pipes with distilled water as the working fluid and a fill ratio of 75% from the evaporator length. Its model was composed of 4 rows, each row contains 12 copper tubes, each tube have ID= 9.5 mm, OD=10mm and length =950 mm and the rows of tubes were arranged in a staggered manner. Aluminum wavy plate fins of 0.1mm thickness were fixed among the tubes to increase the heat transfer area. Tests were conducted at various flow rates (air flow rate through evaporator and condenser sections) ranged between 0.12 and 0.37 kg/s and at different temperatures of air entering evaporator section (90, 100,110) °Cto indicate discontinuity in the effectiveness when the flow rate ratio equal to one . The results show that the maximum value of effectiveness for the four heat pipe heat exchanger occurs when (me= 2mc) . Theoretical model based on (ϵ-NTU) has been developed by using visual basic language computer program to analysis of the temperature distribution along heat pipe heat exchanger. The results from this model were compared with experimental results. A comparison between the experimental and theoretical results shows little discrepancy.