Study of the effect of the heat pipe diameter with stainless steel wick on the thermal performance.
Abstract
The present work aims to study the effects of heat pipe diameter on the thermal performance of the heat pip (HP) with stainless steel screen mesh wick for different tilt angles (0, 30, 60, and 90o). The experiments were conducted using two copper heat pipes with 20.8 mm and 31mm an inner diameter each. The length of the evaporator, the condenser and the adiabatic section are 300 mm, 350 mm and 300 mm, respectively. The working fluid selected was water. The selected filling ratios (FR) were of 50% and 100% of the evaporator volume. The heat input values were 20, 30, 40 and 50 W. A k- type of thermocouple was used to measuring temperatures. In this work, a piece of copper tube (separator) was installed in the adiabatic section to prevent direct contact between the steam line and the liquid line, and for the purpose of ensuring the position of the separator and wick, as well as to be able to watch the evaporation and condensation process of the working fluid, a small camera was installed at the end of the condenser. The water was used as a working fluid for both heat pipes with all values of the input heat, the inclination angles, and the filling ratios. The results showed that the lowest values of thermal resistance as well as the highest value of the heat transfer coefficient were for the large HP and 90o inclination angle. As well as the results showed when recording the temperatures with time the small HP arrival to steady state before the large HP at a rate of 20 to 25 minutes under the same operating conditions.
