| Summary: | 碩士 === 國立清華大學 === 動力機械工程學系 === 95 === Loop Heat Pipes (LHPs), which are generally and widely used with cylindrical evaporators, have a great potential for applications on spacecrafts and electronic cooling due to the advantages of high transfer capacity and long transport distances. However, the cylindrical evaporators of loop heat pipes cannot work on a flat thermo-contact surface without saddle. The saddle creates an extra thermal resistance. To avoid the above disadvantages, we utilize the flat evaporators of loop heat pipes. According to the literature, however, the heat leak problem is more serious in the flat evaporators than in the cylindrical evaporators. This problem also makes more difficult start-up and higher thermal resistance of flat evaporators. Hence this study uses stainless steel mesh and compares the affect of one or two primary wick structure. The results show that that method can ease heat leak problem, when flat evaporators of loop heat pipes have stainless steel mesh and two primary wick structures. Then loop heat pipes can start-up and work more easily at low load. Vapor flow resistance drops by four times and increases heat transfer when diameter of vapor line increases from 3mm to 4mm. When the temperature of the heater is less than 100 oC and the sink temperature is at 30oC, the maximum heat capacity reaches 140W for horizontal orientation and 170W for vertical orientation.
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