Study On Heat Transfer Performance Of Nanofluid Heat Pipes Under Dynamic Load

With the development of electronic information technology and the continuous progress of the aerospace industry,the heat flux of airborne electronic equipment,which shows a trend of miniaturization,high power density and compactness,increases rapidly.Therefore,the means of airborne electronic devices cooling means require higher demands,and Heat pipe technology provided a new idea for the cooling means of airborne electronics.Although the heat pipe has the advantages of good isothermal,cooling efficiency,small size,etc.,limited to the nature of the work medium charged internally,the heat pipe is also very difficult to meet the high heat dissipation requirements at some level.A nanofluid is a fluid containing nanometer-sized particles,called nanoparticles,which are typically made of metals,oxides,carbides,or carbon nanotubes.These fluids are engineered colloidal suspensions of nanoparticles in a base fluid.Compared with traditional heat transfer media,nanofluids have higher thermal conductivity,so the application of nanofluid heat pipe was born.Because of the complexity of the use of airborne electronic equipment,there is still a lack of research on the influence of dynamic load on the heat pipe of nanofluid during the acceleration and deceleration and cornering of aircraft.Based on the overview of construction,working principle of the heat pipe,research status of nanofluid and the numerical research about heat pipe,a numerical model for the heat pipe is built to analyze and study the influence to the nanofluid heat pipe heat transfer.A nanofluid heat pipe,which has the size of 230×18×6 mm and a 60 mm-long evaporator,a 40 mm-long adiabatic and a 130 mm-long condenser,was selected as the main research object in the paper.Under the condition of 18 W,22 W and 24 W,a pure water-copper heat pipe and an Al₂O₃-H₂O nanofluid heat pipe were numerically calculated under dynamic load respectively.Studies have shown that the heat pipe is a very efficient heat dissipating element.The heat transfer efficiency of the Al2O3-H2O nanofluid heat pipe is higher than that of the conventional pure water-copper heat pipe.When the heat pipe is under a small dynamic load environment,the different directions of the dynamic load have different effects on the heat transfer characteristics of the heat pipe,but overall,the heat transfer performance of the Al2O3-H2O nanofluid heat pipe is better than that of the conventional pure water-copper heat pipe.However,for large dynamic load,heat pipes need to be further improved due to the limitation of the working principle of heat pipes.