Study On The Process And Equipment Design Of Filling-vacuum For Micro Heat Pipe

Micro heat pipe, as an efficient heat transfer component, is widely used in fields such as electronics cooling. However, the requirements of electronics industry for micro heap pipes are becoming stricter. The filling-vacuum process is the key to the manufacturing process of micro heat pipe, which has a significant impact on the thermal performance. However, currently there is little relevant research on the filling-vacuum process, and further study of the mechanism and process parameters should be done. Therefore, filling-vacuum process for micro heat pipe is studied in this article and an automatic filling device is designed. The mainly research works are summarized as follows:(1) The mechanism of filling-vacuum process for micro heat pipe is investigated. Visualization experiment of filling-vacuum process is carried out. The influence factors of working fluid storage are investigated and analyzed. The influence of process parameters of filling-vacuum on the working fluid storage is studied. The results show that, phenomenons of liquid flooding or not flooding will occur in the process of vacuuming, and working fluid will freeze finally. Vacuuming time rarely affects the working fluid storage and a filling rate that is less than 100% attributes to improving the stability of working fluid storage.(2) A theoretical model of non-condensable gases for micro heat pipe is established. An experimental platform based on water bath is built to test the length of non-condensable gases, and the influence of different bath temperatures on non-condensable gases is also researched, which verifies the correctness of the theoretical model of non-condensable gases.(3) The influence of the process parameters of filling-vacuum on the thermal performance of micro heat pipe with groove-sintered wick is studied. The thermal performances include start-up performance, temperature uniformity, maximum heat transfer power and thermal resistance. The results show that the pipe length is the most influential factor in start-up performance. Longer vacuuming time, less filling rate, shorter pipe length and higher heating temperature of the second vacuuming process lead to better temperature uniformity. The process parameters of the first vacuuming and second vacuuming rarely affect the thermal resistance of evaporation. Filling rate and pipe length have a great effect on maximum heat transfer power and the thermal resistance of condensation. The process of second vacuuming can effectively decrease the thermal resistance of condensation, but has no obvious influence on maximum power.(4) An automatic filling device is designed. The structure designs of automatic out-feed mechanism, feed mechanism, filling mechanism and take up mechanism are completed, and the electrical control system and pneumatic control system are also designed.