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Molecular dynamics simulations on evaporation of a suspended binary mixture nanodroplet
International Journal of Refrigeration ( IF 3.9 ) Pub Date : 2021-08-27 , DOI: 10.1016/j.ijrefrig.2021.08.023
Xinghui Wu 1 , Zhen Yang 1 , Yuanyuan Duan 1
Affiliation  

Mixture working fluids have the advantages of active design and adjustable physical properties, therefore it has a promising future in many power and refrigeration applications. Studies on the evaporation process of mixture nanodroplets are helpful to reveal the mechanism of heat transfer at the interface of mixture working fluids. However, at present, there are few studies on the evaporation of mixture droplet, and the conclusions on the pure fluids evaporation cannot be directly applied to the mixture working fluids, thus it is necessary to carry out specific research on the evaporation of mixtures. In this study, molecular dynamics simulation was used to study the evaporation process of R32/R1234yf nanodroplets with different compositions (xR32=0, 0.2, 0.4, 0.6, 0.8, 1) in a large space. The dynamic changes of evaporation rates of droplets with different components were compared, and the evaporation characteristics of droplet with different concentrations were analyzed in combination with the density, temperature and concentration field distribution near the liquid-vapor interface during the evaporation process. The results show that the evaporation rate of the mixture nanodroplets is lower than the linear interpolation with those of the two components, which is similar to the heat transfer deterioration of the mixture working fluids in pool or flow boiling. The prediction deviation of R32/R1234yf mixture nanodroplet evaporation by the D2 law is around 80%. Considering the scale effect and the interfacial concentration gradient, the prediction accuracy of the D2 law can be improved.



中文翻译:

悬浮二元混合物纳米液滴蒸发的分子动力学模拟

混合工质具有设计主动、物理性质可调的优点,因此在许多电力和制冷应用中具有广阔的前景。对混合物纳米液滴蒸发过程的研究有助于揭示混合物工作流体界面处的传热机制。然而,目前关于混合物液滴蒸发的研究较少,纯流体蒸发的结论不能直接应用于混合工质,因此有必要对混合物的蒸发进行专门的研究。在这项研究中,分子动力学模拟用于研究R32 /剂R1234yf纳米液滴具有不同组合物的蒸发过程(X R32=0, 0.2, 0.4, 0.6, 0.8, 1) 在大空间中。对比了不同组分液滴蒸发速率的动态变化,结合蒸发过程中液气界面附近的密度、温度和浓度场分布,分析了不同浓度液滴的蒸发特性。结果表明,混合物纳米液滴的蒸发速率低于两种组分的线性插值,这类似于混合工质在池或流动沸腾中的传热劣化。D 2对R32/R1234yf混合物纳米液滴蒸发的预测偏差法律是80%左右。考虑尺度效应和界面浓度梯度,可以提高D 2定律的预测精度。

更新日期:2021-08-27
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