多物理场中热扩散效应对传热传质的影响

为了便于消除或控制室内挥发性有机化合物(VOCs),分析了VOCs在室内环境中的扩散规律。基于不可逆过程热力学原理,在考虑交叉耦合扩散效应的基础上,建立了3个物理量的梯度驱动下封闭空间内自然对流传热传质的数学模型。采用数值方法研究了室内环境中同时存在温度梯度、湿度梯度和VOCs浓度梯度时的自然对流传热传质现象,并着重考察了多物理量的梯度耦合作用下热附加扩散效应对传热传质的影响,展示了流场、温度场和浓度场等热附加扩散准则数STC的变化状况,研究结果表明,多物理场中热附加扩散效应对传热传质具有一定的影响,且具有复杂多解性。

Influence of thermal-diffusion effect on convective heat and mass transfer in multi-physical field

For the purpose of controlling or removing indoor volatile organic compounds(VOCs),the emission and diffusion mechanism of VOCs in indoor air surroundings were investigated.Based on the principle of thermodynamics of irreversible processes and cross coupled diffusive effects,a mathematic model was developed to analyze the characteristics of natural convective heat and mass transfer in multi-physical field.In presence of temperature gradient,VOCs concentration gradient and humidity gradient,the mathematic model was solved numerically by FEM method.The influence of thermal-diffusion(Soret) effect,mass flux induced by temperature gradient,on diffusion of VOCs in indoor surroundings was studied numerically.Profiles of the dimensionless velocity,temperature and concentration were shown for various conditions.The average Nusselt number and Sherwood numbers were presented graphically.The numerical results show that the thermal-diffusion effect should be taken into consideration in simultaneous heat and mass transfer.