Experimental Investigation on Thermal Performance of a Closed Loop Pulsating Heat Pipe without Fin and with Fin Structure

Abstract

Pulsating Heat Pipe (PHP) is a new and emerging cooling technique in the field of thermal management especially in microelectronics. To fulfill the increasing demand of power electronic applications, PHP is a proven technology which works on principle of self-oscillation of the working fluid and phase change heat transfer phenomenon in a capillary tube. In this paper, the thermal performance of a closed loop pulsating heat pipe (CLPHP) without fin and with fin at the condenser section by using Acetone and Water as working fluid has been investigated experimentally. The effects of different parameters include the filling ratios (from 40% to 70% in steps of 10%), the inclination angles ( 0°, 30°, 45°, and 60°), and at various heat input (10 to 10W in the steps of 10W) has been investigated thoroughly. In this study CLPHP is made from long capillary copper tube with inner diameter of 2.0 mm and outer diameter of 3.0 mm. The heat pipe is bent into eighth number of U-turns and divided into three sections, evaporator section (50 mm), adiabatic section (120 mm) and condenser section (80 mm). Adiabatic section is maintained by using aluminum foil surrounded by appropriate insulation. The result shows that, the thermal resistance decreases as heat input increases. But at low heat input i.e. up to 60W, the thermal resistance decreases rapidly and the PHP performance is more sensitive to the inclination angle whereas high heat input i.e. above 60W, the thermal resistance decreases slowly and comparatively less independent to the inclination angle. Evaporator dry out is occurred for acetone at low filling ratio with 40% and 50% at heat input 40W and 50 W respectively. CLPHP with fin structure shows better performance than the CHPHP without fin structure at high heat input. Acetone with 70% filling ratio and water with 50% filling ratio shows the best performance at 0° inclination angle for both structures.