【摘要】 <正>当气体通过液相介质时,由于气液界面和气相主体间存在液体蒸汽的浓度差,使液体迅速蒸发,可以大大强化对流传热及沸腾传热.此外,在鼓泡设备中,这种溶剂汽化现象亦可能对气含率及传质带来很大影响.因此,定量地分析液体蒸汽向气泡中传质的过程是很有意义的.此过程为具人体积变化的自由边界问题.对于核状沸腾过程的自由边界问题已有很多研究,其气泡长大的控制步骤为兴高采烈相可能提供的气化潜热速率,而由于气泡中质量传递控制的移动边界问题尚未见有研究.本文提出了液体溶剂向单气泡中传质的数学模型,获得了数值解.并且对各种影响因素进行了讨论.更多还原

【Abstract】 The diffusion process of liquid vapor in a gas bubble has been investigated numerically. With the assumptions of (1) spherical gas bubble; (2) constant temperature at gas-liquid interface; (3) no circulation inside the bubble, the mass transfer equation is developed as:Initial conditionsC(r, 0)=C0 Boundary conditionsC(R, t)=Cf It is also assumed that the pressure within the bubble is in equilibrium withambient pressure during the bubble growthA stepwise approach has been proposed to solve the moving boundary problem.The results show that Dt/R02 and Ps/P are the main factors for the dynamics of bubble growth. Generally speaking, increasing liquid temperature Tc and diffusitivity D, or reducing the ambient pressure P and initial bubble radius R0 favor the mass transfer, especially as PS/P→1, the enhancement of mass transfer is more obvious.更多还原