Influência do fluido de trabalho no desempenho térmico de termossifões

Abstract

Thermosyphons are passive devices that use latent heat to perform heat exchange with a small temperature difference. It is composed of a metallic tube evacuated and filled by diverse working fluids, each of these fluids have characteristics that define the operability of the thermosyphon. In this research, an experimental investigation was performed of the thermal performance of different working fluids in thermosyphons that can be used in thermal control of electronic equipment. The working fluids were considered acetone, water, ethanol, and methanol. The thermosyphons are manufactured of copper with an outer diameter of 9.45 mm, an inner diameter of 7.75 mm, a total length of 200 mm, whereas an evaporator of 80 mm length, an adiabatic region of 20 mm in length and a condenser of 100 mm in length. They were loaded with 1.39 mL of the working fluid, corresponding to a filling ratio of 40% of the evaporator volume. Experimental tests were performed in a vertical position considering thermal loads from 5 W and 25 W in an environment with temperature controlled at 20 ºC inside the Laboratory of Thermal Control (LabCT) of the Academic Department of Mechanics (DAMEC) of the Federal University of Technology - Paraná (UTFPR) Ponta Grossa Campus. The thermosyphons operated satisfactorily in all the tests. The operating temperature distribution as a function of time and the heat resistance behavior as a function of power dissipation have been presented for each analyzed working fluid. the results obtained indicated that acetone is the working fluid that has the best thermal performance.