EXPERIMENTAL EVALUATION OF THERMAL PERFORMANCE OF A HEAT EXCHANGER USING THERMOSYPHONS

Abstract

Heat exchangers are devices that aim to improve heat exchange between two fluids at different temperatures, without them mixing. The characteristics that differentiate the types of exchangers are their geometric and constructive shapes, exemplified by the shell and tubes, serpentine, finned, plate, and double tube types, among others. For the present paper, a heat exchanger tube is used, which is connected by thermosyphons to carry out the thermal exchange between the fluids without mixing them. In order to increase the thermal efficiency of the heat exchanger, it is necessary more efficient thermal exchange devices. For this purpose, in this case, we use thermosyphons. The goal of this experimental study is to evaluate the thermal efficiency of the heat exchanger using thermosyphons. In this study, the thermosyphons were manufactured in copper with outer diameter of 9.45mm, an inner diameter of 7.75mm, and a total length of 180mm. The condenser, evaporator, and adiabatic sections all have the same size of 60mm. Three thermosyphons connected the two fluids of the heat exchanger, each one filled with distilled water with a filling ratio of 40% of the evaporator volume and experimentally tested with an angle of 67.5º relative to the horizontal with the surfaces at fixed temperatures (Dirichlet conditions) and the cooling being carried out by convection forced water. The thermal analysis was based on the temperature distribution along the length, the operating temperature, and the thermal resistance. Given the results observed for the thermal resistance, it was possible to find the thermal efficiency of the heat exchanger.