Planar Microstructure Treatment Of Aluminum And Study On Boiling Heat Transfer Characteristics Of Graphene Nanofluids

With the rapid development of electronic information technology,the heat dissipation problem of high heat flux equipment has attracted much attention,in order to improve the heat dissipation efficiency of electronic devices.In this paper,the improvement of the surface morphology of the heated wall by pool boiling and the graphene nanofluid were studied experimentally.(1)In order to test the heat transfer performance of graphene-like heating wall and graphene nanofluids,a pool boiling experimental test platform was built and debugged in this paper.The pool boiling experimental test platform mainly consists of electric heating system,boiling pool,data acquisition system,high-speed camera shooting,etc.,and the experimental test error is analyzed.(2)By plasma enhanced chemical vapor deposition(PECVD)technique process on the heating wall pure aluminium growth type of microcosmic structure of graphene,before class and in the preparation of graphene microstructure through high resistance vacuum evaporation coating machine for copper plating processing,sample with catalytic graphene growth,through SEM observation under different growth time class microscopic morphology and thickness of graphene The contact Angle was used to characterize the wettability.The results show that the graphene-like microstructure films grown by PECVD method have larger size,relatively complete structure,petal-like shape,good continuity and high degree of integrity.The pool boiling heat transfer coefficient of the graphene-like micro-structured heating wall is significantly higher than that of the pure aluminum heating wall,and the graphene-like heating wall with the growth time of 7200 s is the best,the heat transfer coefficient is increased by 48.46%,and the heat transfer performance is significantly improved.With the increase of thickness,the wettability of graphene-like was gradually improved,and the contact Angle was 79.65°corresponding to the growth time of 7200 s.In addition,the bubble during boiling was analyzed from the perspective of bubble dynamics,and the influence of the force of a single bubble on the detachment diameter and frequency was obtained.A high-speed camera was used to film the formation and detachment of bubbles in the process of boiling heat transfer,and the influence of the microstructure and thickness of the heating wall on the heat transfer performance of the pool boiling was analyzed.(3)The graphene nanofluids with different mass concentrations were prepared by "two-step method",and the stability of graphene nanofluids was characterized by Zeta potential.The results show that the stability of nanofluids with concentrations of 0wt%,0.05wt%,0.10wt% and 0.15wt%increases first and then deteriorates with the increase of nanoparticle concentration.The stability of nanofluids with concentrations of 0.05wt%is the best.After standing for one month,there is no obvious precipitation and agglomeration phenomenon.Compared with different concentrations of nanofluids,the graphene nanofluid with the concentration of 0.10wt%has the best heat transfer performance.When the heat flux is 68.89 k W/m2,the heat transfer coefficient of the graphene nanofluid with the concentration of 0.10wt% is 28.76% higher than that of the pure working fluid.