جستجوی مقالات مرتبط با کلیدواژه "double-ended cooling" در نشریات گروه "مکانیک"

Heat pipes are one of the most attractive instruments for heat transfer processes. With the development of technology and reducing the dimensions of heat generating equipments, it is essential to provide solutions and innovations to increase the thermal performance of heat pipes. Thus, an experimental study has been investigated on straight heat pipes with double-ended cooling and middle heating. At first, heat pipes fabricated with sintered copper felt wick. Then, two cooling blocks installed on both end of heat pipes and a coil heater placed in the middle as the condenser and evaporator sections respectively. The experiments were conducted at inclinations 0° to 90° for heat inputs 20 to 80 W. The effects of heat input variation, cooling water flow rate and tilt angle on the thermal performance of heat pipes were studied. The obtained results for new structure of heat pipes compared with the conventional heat pipes which had one evaporator and one condenser. The results showed that by using the new cooling approach, the thermal resistance of heat pipes can be reduced significantly. Also, in low heat inputs, increasing the cooling water flow rate increases the thermal performance of heat pipes. The experimental results indicated that the tilt angle has a significant effect on the thermal performance of heat pipes. The minimum thermal resistance and the maximum effective thermal conductivity coefficient values are 0.2533 °C/W and 14072.65 W/m °C respectively, and they were observed at the tilt angle equal to 60° and for heat input of 60 W.

The heat pipe is an efficient heat transfer device and can transfer large amounts of heat with a small temperature difference between the hot and cold sources quickly. In the present study, a two-dimensional numerical simulation method was used to analyze the thermal performance of heat pipes with double-ended cooling with the middle evaporator and to investigate the effect of operating conditions, wick and retaining chamber characteristics on it. The governing equations were discretized by ANSYS Fluent software and then solved using suitable boundary conditions. The wall temperature profile of the heat pipe was obtained. Then, to validate the results and to investigate the effect of using two condensers on the thermal resistance of the heat pipes, an experimental apparatus was used. Numerical results were compared with the valid numerical and experimental results that had very good and acceptable accordance. The results showed that the heat pipes with double-ended cooling with a middle evaporator had a lower thermal resistance than conventional heat pipes. The amount of thermal resistance increased with increasing the thickness and porosity of the wick. However, increasing the evaporators and condensers length, as well as increasing the thickness and internal diameter of the retaining chamber, reduced the thermal resistance. The results also showed that the heat pipes, which the materials with higher thermal conductivity were used in their wick and retaining chamber's manufacturing, had a lower thermal resistance. Finally, it was found that the increase of thermal power had no significant effect on the thermal resistance.