Experimental Investigation of Thermal Characteristics of Two-Phase Loop Thermosyphon

Abstract

An experimental investigation on heat transfer characteristics of an evaporator of a two-phase closed-looped thermosyphon is carried out in this study. Experiments are conducted using three different evaporator surfaces, namely Pin Finned Surface (PFS), Rectangular Finned Surface (RFS) and Plain Surface (PS) with three different working fluids Acetone, Ethanol and Methanol. Bubble frequency and bubble density per unit area has been estimated. A fan of 40 W is used to know its effect on heat flux. Ethanol has shown the highest heat flux of 73 kW/m2 and 110 kW/m2 without and with fan respectively and (7-20) % higher than other working fluids. Heat flux can be increased to (20-35) % with the condensing fan. It is found that Rectangular Finned Surface (RFS) can transfer (15-30) % more heat than that of other surfaces among all the working fluids. Heat flux increases with bubble frequency and bubble density per unit area. The heat flux data have been compared with an existing correlation and found ±30% agreement.