Study on the heat transfer characteristics of nanofluid spray cooling with ethylene glycol aqueous solution as base fluid
In recent years,due to the improvement of power density,compact packaging and high performance requirements,the heat dissipation demand of high heat flux devices has increased significantly.In view of the above problems,this work plans to use the spray cooling technology to conduct heat transfer research on the Al2O3 nanofluid with ethylene glycol water as the base fluid,focusing on the analysis of the influence of the concentration of the base fluid,the concentration of nanoparticles,and the concentration of the added dispersant on the heat transfer performance of the working medium spray cooling at three different operating conditions of 300,500,and 700 W.The experimental results show that due to the decrease of specific heat capacity and thermal conductivity and the deterioration of spray characteristics,the mass fraction of ethylene glycol increases from 30wt％to 80wt％,and the surface heat transfer coefficient of Al2O3 nanofluid solution decreases continuously,with an average decrease of 41.63％.The surface heat transfer coefficient of Al2O3 nanofluid shows a trend of first decreasing,then increasing,and then slowly decreasing with the increase of nanoparticle mass fraction.When the mass fraction of Al2O3 nanoparticles increases from 0 to 2wt％,the overall average surface heat transfer coefficient of Al2O3 nanofluid solution decreases by 6.94％.The deposition and bubbling effect are the main reasons for weakening the heat transfer.At the same time,the increase in the mass fraction of nanoparticles improves the thermal conductivity of the nanofluid solution,which to some extent enhances heat transfer.In addition,the addition of a low-quality non-ionic surfactant(Tween-20)can improve the foaming effect,making the heat transfer coefficient of spray cooling increase by about 1.52％,but still lower than that of pure base liquid;Adding a higher mass fraction of dispersant can cause aggregation between nanoparticles and further weaken the heat transfer performance of the thermal conductivity solution.
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