Investigation Of Mini Flat Plate Heat Pipe

The heat pipe is a heat transfer device that utilizes the phase change of working liquid in it. It has many essential characteristics that make it useful in a wide variety of applications in electronic engineering: the compact structure, the high heat thermal conductivity, the excellent isothermal property, the variability of the heat flux density, the ability to make the heat flux direction reverse, the ability to maintain constant evaporator temperature under different heat flux level, the ability to adapt the environment etc. With the rapid development of electronic technology, the high calculation speed of the electronic component and the denseness, the heat transfer increases rapidly of electronic component per unit volume in recent years. The development of electronic technology needs the excellent heat transfer measures. Therefore, the manufactories of heat pipe have focused their attentions on the investigation and development of mini heat pipe for electronics cooling. However, the internal investigation has not been conducted. In addition, the CMOS chip, the circuit board and CPU are all flat shape. If we used tubular shape heat pipes in those applications, we would add 'cold board' and 'hot board' to them. At the same time, the heat resistance and the temperature gradient would increase. Because the mini flat plate heat pipe has many advantages, this paper designs and manufactures a mini flat plate heat pipe for electronics cooling. What's more, the theoretical analysis and experimental investigation on the heat transfer performance are conducted.DESIGNATION and MANUFACTUREBasically, the heat pipe design consists of three major components: selection of case material and working fluid, and the design of wicking structure. Because of the high thermal conductivity, resisted oxidation and less density, phosphor copper is selected as the case material. Because the vaporization and condensation of the working fluid are the basic process for operation of a heat pipe,the selection of a suitable working fluid is perhaps the most important aspect of the designation and manufacture process. Factors that affect the selection of an appropriate working fluid include the operating temperature range, the vapor pressure, the thermal conductivity, the compatibility with the wick, the case materials, stability and so on. With consideration of these factors, distilled water, acetone and ethanol are selected as the working fluid. According to the actual requirement of the heat pipe/heat sink , the length and width of the heat pipe are 80㎜and 65mm. And the thickness is 4mm. The configuration of wicks is 5 layers of phosphor copper filter. The quality of the flat plate heat pipe was largely depended on the manufacture technology, which includes the cleaning of the case, the envelopment of the terminals, the leak checking process, the vacuum process, filling up and sealing. In the thesis, the envelopment of the terminals and sealing is the key process by which the performance of the flat plate heat pipe was decided.Thermal Performance Measuring System for Heat Pipe/Heat Sink The Thermal Performance Measuring System for Heat Pipe/Heat Sink Applied on CPU is developed by the LabVIEW6.1, which is the program platform of graphic programming. With the abilities of data collection,storage,analysis, the measuring system can real-timely monitor the entire experiment and adapt other applications by easily altering some parameters. The system was composed by setting panel, control panel, data acquisition ,data processing, help. Applied on the simulation acquisition, the system must carefully take many factors into account such as the input model,resolution,input scales,sampling frequency ,precision,noise and so forth.In order to improve the precision, many measures are applied in this system such as follows: 1,thermocouple cold end compensate;2,nonlinear compensate for thermocouple;3,eliminating big errors;4,digital filtering of signals. THEORETICAL ANALYSISand EXPERIMENTAL INV...