临界条件(0℃)下溶液蒸发冷冻过程中的传质规律

Mass transfer of liquor in evaporation-refrigeration process under critical condition

通过对相际间力学特性的分析,结合湍流的流动特征,考虑了冰体存在孔隙和毛细作用,给出了临界条件(0℃)湿度差驱动下溶液蒸发冷冻过程中的质扩散分析模型,并对溶液在不同状态下(液态、液固共存和固态)气流界面间的质扩散变化规律进行了研究,结果表明,随着溶液从液态向固态的转变,其表面质扩散系数逐渐减小,即表面质扩散能力逐渐减弱,因此,对于溶液自身蒸发冻结过程而言,为了强化溶液表面的质传递和冻结,应控制冻结过程中溶液表面的结冰状况。这一研究结果为蒸发冷冻传质的研究以及强化蒸发冻结的工程应用提供了理论指导和参考。

Different forces at gas-liquid interface with turbulent air flow sweeping over liquid surface were analyzed.With the flow characteristics and the effect of capillary and porosity of ice considered,a model is presented for the mass transfer in evaporation-refrigeration process driven by humidity difference under the critical condition of 0℃.The mass transfer between gas and liquid in different state,such as liquid,solid or their coexisting state,was studied.The results show that the mass transfer coefficient on liquid surface decreases gradually as the liquid changes to a solid.Hence the icing of liquid should be controlled in order to improve the mass transfer and freezing of liquid.The research would be in favor of engineering applications of evaporation-refrigeration.