الفهرس | Only 14 pages are availabe for public view |
Abstract The purpose of tins study is to investigate the performance of low-temperature heat pipes. A special machining technique has been developed for production of heat pipes with internally axial grooves and internal smooth surface. Experiments are performed to investigate the effect of heat load, cooling water flow rate, filling ratio, (volume of working fluid to the evaporator volume) and the inclination angle on heat pipes performance. Two heat pipes are used which are made of copper with 2.54 cm outside diameter. They have 31 cm long evaporator, 32cm long adiabatic section, and 31 cm long condenser, with acetone as the working fluid. The first has an axial groove heat pipe with a groove width 0.8 mm and a depth 1 mm and tile second has wrapped screen heat pipe using 100 mesh copper screen wick. The inclination angle in this study is varied from 0° (vertical position) to 90° (horizontal position). The experimental test rig consists of a copper/acetone heat pipes, a heater for evaporator section equipped with a digital clamp-meter to measure electrical power, a direct jacket calorimeter for heat removal (condenser), temperature measurement equipment, a vapor temperature probe and some other auxiliary equipment. Wick fabrication and insertion was accomplished using a wooden mandrel with suitable dimensions. Heat pipe wall surface temperature was measured at three different locations in each section. Computer programs were constructed III order to calculate entrainment limit, boiling limit, temperature DROP, and heat transfer coefficient for the two types of the heat pipes. Results of present study showed that: |