Experimental investigation of the loop thermosyphon with different adiabatic lengths charged with different working fluids

This paper reports an experimental investigation of a closed-loop thermosyphon system charged with water and other low saturation fluids, such as ethanol, acetone, and methanol, for different adiabatic lengths, filling ratios, and heat loads. The closed-loop thermosyphon with two inline vertical heaters in the evaporator section and forced air-cooled plate-type heat exchanger in the condenser section, connected by a changeable adiabatic length, is investigated at different working conditions. Out of five filling ratios used in the analysis, at 0.6 filling ratio, the loop thermosyphon is seen to be operated at its best. The acetone-charged loop thermosyphon shows the lowest values (up to 72% reduction) of overall thermal resistance than that of other fluids and significantly higher effectiveness, due to the plate-type forced air-cooled condenser. For the acetone-filled thermosyphon, an almost 15% increase in the effectiveness is observed by changing the adiabatic length from 800 to 200 mm. This study suggests that the limitation of the loop thermosyphon with a water-cooled condenser to cool electronic components, computational clusters, and data centers is well fulfilled by the loop thermosyphon with plate-type forced air-cooled condenser. The nucleate pool boiling correlation is developed and validated for the loop thermosyphon system to determine the evaporator heat transfer coefficient.