Theoretical Research Of MHD Pulsating Heat Pipe Flow And Heat Transfer Characteristics

The development of science and technology makes the integration level of electronic equipment higher and higher, as a consequence, unit area of the equipment accumulates more and more heat at work, Too high temperature can make the chip failure or damage, so a great efficient equipment to transfer redundant quantity of heat is required.According to the Newton Cooling formula, the enhancement of heat transfer can consider three aspects:area,temperature difference and heat transfer coefficient. Most of engineering research focus on expanding the cooling area, but this method is insufficient optimization in microscale heat dissipation.Pulsating heat pipe is a kind of special heat pipe with high heat transfer performance and low cost, the advantages of its application in industry gradually become outstanding, it is able to build a low thermal resistance in heat transfer channel, in order to transfer heat for cooling in the better space.Therefore, the optimization of PHP’s heat transfer performance has the important value of improving the level of electronic equipment thermal control in engineering application.This article adopts numerical simulation to optimize the heat transfer performance of PHP with Fe-water nanofluid which has high thermal conductivity.It analyzes the effect of heating capacity, heating temperature, the volume concentration and magnetic field on heat transfer of pulsating heat pipe.The main research content is as follows:(1)The magnetic liquid is handled as incompressible single fluid, using the method of experimental test results compared with semi-empirical formula, the accurate calculation model is established,which is used to calculate density/specific heat/thermal conductivity /viscosity of Fe-water nanofluid with the different volume concentration (0%-5%) and magnetic field.(2)Evaporation and condensation model is established for square pulsating heat pipe with water, in the different heating power, FLUENT simulates the distribution of the temperature in the heat pipe. As a result,the calculation of the thermal resistance and literature trend is the same that can verify the feasibility of the model.(3)Conbining evaporation and condensation model which is established with Mixture model of FLUENT software,study the influence of the volume concentration and magnetic field on heat transfer performance of pulsating heat pipe at constant wall temperature and constant heat flux boundary condition.The results show:in a certain range,with the increase of the volume concentration, two kinds of boundary conditions of heat pipe heat transfer(4)performance are improved.Constant magnetic field and gradient magnetic field to a certain extent can reduce the thermal resistance.Especially,gradient magnetic doubles.