多孔介质对麻醉蒸发器传热传质效果影响的计算分析

Numerical Simulation for Heat And Mass Transfer of Porous Media on Evaporation for An Anaesthesia Vaporizer

目的:研究某型部分填充多孔介质麻醉蒸发器工作原理,并对其结构进行实际测量。利用Darcy扩展方程和N-S方程及能量和组分传递方程分别对多孔介质区域和纯流体区域建立数学模型,分析不同孔隙率下的平均传热传质速率随渗透率的变化。方法:文中采用运用CFD方法分析了多孔介质材料对麻醉蒸发器蒸发效果的影响,并且论述了在蒸发器多孔介质区域内麻醉药液与载气相遇、混合、蒸发过程的变化状况。假定麻醉药物蒸发雾滴与稀释气体存在热交换和动量的相互作用,忽略重力和剪切力在雾滴运动过程当中对其的影响效果,利用湍流随机跟踪模型追踪了在多孔介质区域中的气液两相流离散项麻醉药物蒸发雾滴的运动状况。结果:通过计算得到了不同状态下蒸发器多孔介质区域内气体速度场、密度、麻醉药物质量分数、药物浓度、比热变化,药物浓度场在与稀释气体混合过程中的变化以及麻醉药物挥发等结果。结论:数值模拟结果表明多孔介质特性、渗透率、孔隙率对麻醉蒸发器腔体内传热传质存在不可忽略的影响。

Objective：The function theory of an anasethesia vaporizer was studied and the geometry configuration was mea- sured. The porous media and fluid field model function was derived from Darcy and N-S function. Variety of average heat and mass transfer speed following permeability under different porous ratio was analyzed. Methods： The effect of porous media on evaporation process in anasethesia vaporizer was simulated by using CFD method. The process of meeting, mixing and evapo- ration between gas and drug in anasethesia vaporizer was discussed. The reaction between gas and drug droplet was heat trans- fer and momentum, the influence of the gravity and shearing strength on the droplet in the droplet moving process was ignored. According to stochastic particle tracking in turbulent flow, for the gas-liquid two phase flow discrete phase droplet of anaesthe- sia drug, the moving track of droplet in porous media space was traced. Results： By this way, the results of internal gas flow variation, density, mass concentration, specific heat, the concentration distribution of anaesthesia drug volatilization process and mixing process with gas were ascertained. Conclusions： Numerical simulation results show that, the influence of porous media permeability and flow resistance on anaesthesia drug volatilization and mixing process between anaesthesia drug vapor and diluted gas is clear, the heat and mass transfer is also affected by porous media permeability characteristics.