摘要
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.
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 conditions
C(r, 0)=C0 Boundary conditions
C(R, t)=Cf It is also assumed that the pressure within the bubble is in equilibrium with
ambient pressure during the bubble growth
A 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.
出处
《化工学报》
EI
CAS
CSCD
北大核心
1990年第1期118-121,共4页
CIESC Journal
基金
国家自然科学基金
