Study Of Preparation And Supercooling Characteristics Of Graphene Oxide Nanofluids As Phrase Change Material

Phase change cool storage is an efficient way to change the power grid. However,nowadays the cool storage material has a big degree of supercooling, which requiresthat refrigerating machines drop their evaporating temperature to nucleate crystallize.And it results that the function of refrigerating machine reduces largely. Reducing thedegree of supercooling of phase change cool storage material is always an object ofdifferent researchers. The restrain of degree of supercooling under ultrasonic andnucleation catalyst is a good solution. As a new kind of supercooling material with nanoparticle nucleation catalyst, nano-fluid’s undercooling and nucleation hasn’t beendiscuss deeply. This thesis developes a new kind of medium graphene oxide nano-fluidand carries out researches on its preparation and graphene oxide nano-fluid. Thefollowing are the details.(1) According to the exploration and analysis on the preparation methods ofgraphene oxide nano-fluidand matters need attention, preparation of graphene oxidenano-fluid is affected by the fluid temperature, ultrasonic oscillation power, mixing time,etc. After repeated experiments the best way of preparing graphene oxide nano-fluid isfinally found.(2) This thesis, carrying out experiment text and mechanism investigation on thestability of graphene oxide nano-fluid, analyzing the effects of nanoparticle size andZeta potentialon the stability of nanofluids and studying the internal structure and stressof graphene oxide nano-fluid from an mesoscopic approach, clarifies the microcosmicmechanism that graphene oxide nano-fluid can remain stable for a long time.(3) This thesis measures the supercooling degree of graphene oxide nano-fluid andanalyzes the advantages of graphene oxide nano-fluid in terms of reducing degree ofsupercooling on the basis of nanofluids energy transfer mechanism. The results indicatethat the supercooling degree of graphene oxide nano-fluid decreases as the nanofluidsdensity increases with the existence of the optimum concentration value and thefreezing time of graphene oxide nano-fluid also has a close relationship with itsconcentration.(4) This thesis uses glass rod and ultrasonic waves respectively to stir the grapheneoxide nano-fluid to create external disturbance on its subcooling process and analyzesthe effects on freezing and supercooling in these two different situations. The results indicate that glass rod mixing can bring forward the freezing time and reduce a certaindegree of supercooling, ultrasonic wave mixing, however, while bringing forward thefreezing time, can also eliminate supercooling degree at the same time. Based on theresults, further analysis on the effects of cavatition on the supercooling degree ofgraphene oxide nano-fluid is carried out to explore effective ways of eliminatingsupercooling degree.As a new kind of phase-change material of cool storage medium, graphene oxidenano-fluid can resolve the disadvantages of general cool storage system like highsupercooling degree and long freezing time with the help of ultrasonic. The researchachievement of this thesis has its important academic value on the degree ofphase-change cool storage material. What’s more, it also affects the quick icing and theexploration of efficient and energy saving ice storage material.