Experimental Study On Anti-gravity Performance Of Micro Heat Pipe And Testing Equipment Development

A micro heat pipe is a kind of component with high heat transfer capability, which iscomposed of vessel, working fluid and wick. High heat transfer is based on phase change andcapillary force which can force working fluid flowing back, so its thermal conductivity canreach to at least two magnitudes of that of conventional materials. Micro heat pipe can be usedin various kinds of moving objects especially in the state of anti-gravity, for example, tank onwetting and uneven road, lauching rocket, submarine in the deep ocean and even areas ofmilitary and aviation. So study on anti-gravity performance of micro heat pipe expercially overone unit of gravity can promose the use of micro heat pipe in some limit state. The paper willstudy several kinds of micro heat pipe with the length of200mm and the outer diameter of8mmin the state of anti-gravity both experimentally and theorially.firstly, an equipment for testing is developed in the principle of centrifugal force simulatinggravity. Solidworks is used for structure design and Labview is used for programing. Erroranalsys of centripetal acceleration and testing is studied and the new equipment is compared bythe traditional one for enhancing the credibility of testing data.Secondly, models of evaporator and condenser thermal resistance are built for micro-grooved heat pipes, micro-sintered heat pipes and micro-groove-sintered composite heat pipesfor study the effects of structural parameters on heat pipe thermal resistance. Capillaryexperiment is designed and the capillary factor is calculated as a way of study the effect ofgravity on working fluid flowing back. The result shows that the capillary of sinterd wicks andcomposite sintered wicks are better, while grooved wicks are worst whose capillary factor is90%less.Thirdly, the anti-gravity performance form0g to2.5g of three kinds of micro heat pipe arestudied, which includes the re-start performance with the power input of20W, the thermostaticperformance with vary power input, the toral thermal resistance, eveperator thermal resistanceand the condenser thermal resistance. The result shows that, before the micro heat pipe dryingout the values of experiment and theory are closed, while the value of experiment will be largerwhen it drys out as well as the time of restart longer and the thermostatic performance worse.With input power of20W, the maximum acceleration of grooved micro heat pipes can stand up is less than0.5g, that of sintered micro heat pipes with outer diameter of6mm is larger than1g,that of composite micro heat pipes sggx (outer diameter of6mm and sintered length propotionof1), sgg (5.5mm,1) and sggh (5.5mm,0.5) is larger than1.5g,2g and0.5g respectively.