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| Numerical Simulation of Porous Media on Evaporation for an Anaesthesia Vaporizer |
1 School of Medical Instrument and Food Engineering,University of Shanghai for Science and Technology, Shanghai 200093, China
2 School of Automotive Engineering， Tongji University, Shanghai 200092, China |
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Abstract In order to improve the accuracy of anesthesia drug control and provide a theoretical basis for optimizing the structure of evaporator, the influence of physical characteristics of the porous medium evaporator core on the evaporation was investigated. Actual anesthetic evaporators were measured and a three-dimensional structure model was established with the Pro/E software. The effect of porous media on evaporation process in anesthesia vaporizer was simulated with CFD. Using FLUENT software, we analyzed the influence of physical properties of porous media on the performance of the evaporator and mixing process of the vaporized drugs with air. According to stochastic particle tracking in turbulent flow, the moving track of droplet of anesthesia drug in porous media space was traced. Then, the internal gas flow variation, the concentration distribution of drug volatilization process and mixing process with gas were obtained. Numerical simulation results showed that the porous media permeability, flow resistance during anesthesia drug volatilization and mixing process between anesthesia drug vapor and diluted gas all had influence on the accuracy and stability of the volatilization concentration for anesthesia drugs. The existence of porous medium reduced the flow rate of dilution gas. The increase of the porosity of porous media could promote drug evaporation and uniformity of the mixed gases. Due to the absorption of heat in the porous medium area, the maximum evaporation of drug was needed to determine the range of temperature compensation, ensuring the output stability and accuracy of the anesthetic drug concentration in the evaporator.
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