A solute trapping model is developed based on a so-called solute drag treatment.By adopting a basic approach of phase-field models,and defining the free energy density in the interfacial region,a suitable interface sh...A solute trapping model is developed based on a so-called solute drag treatment.By adopting a basic approach of phase-field models,and defining the free energy density in the interfacial region,a suitable interface shape function is introduced to derive the current model,in which the equilibrium and non-equilibrium interface behaviours can be described using a dimensionless parameter L (i.e.an important parameter in the present interface shape function).When applying the current model to Si-9%As (molar fraction) alloy with L=0.5,a good prediction of the steeper profile for high interface velocity,which is analogous to that using a phase-field model of DANILOV and NESLTER,has been obtained.展开更多
An improved CFD model of gas flow and particle interception in a fiber material which fiber size is Y-shape was developed in this work. The porous medium model was used to build the model of the whole size of fiber fi...An improved CFD model of gas flow and particle interception in a fiber material which fiber size is Y-shape was developed in this work. The porous medium model was used to build the model of the whole size of fiber filter medium. Mixture model was adopted. The algorithm of particle interception in the whole size of fiber filter medium was derived and UDF(User Defined Function) that described kinds of particle filtering mechanisms in filter fibrous media was added to the Fluent default conservation equation as source term for simulation. The inertial resistance of the filter was taken into consideration, which provided a more precise measurement of the smoke flow and the particle interception in the filter under higher smoke speed conditions. The commercial software, Fluent 6.3, was used to simulate the smoke flow and particle interception in the filter in a single suction. The velocity and pressure profiles of smoke or nicotine particle in the filter, as well as nicotine particle volume fraction profile were well simulated. Finally, the comparisons of nicotine particle filtration efficiency between Fluent simulation results in this work and experimental results, as well as the model prediction in the literature were made to validate the simulation model. The comparisons showed that the particle entrapment model from simulation results was in good agreement with that from the experimental results. In addition, the Fluent simulation results are closer to reality both at the beginning and the end of the smoke process comparing with the model predicted results in the literature.展开更多
The continuous affinity- recycle extraction (CARE) process is extended ic a system with ultrafiltration membranes. The mathematical model of the process is established by taking into account membrane rejections to th...The continuous affinity- recycle extraction (CARE) process is extended ic a system with ultrafiltration membranes. The mathematical model of the process is established by taking into account membrane rejections to the components in a crude mixture. The process performance, defined as concentration factor (CF ), purification factor (PF ) and recovery yield (REC), is analyzed by computer simulations. The results show that CF and REC increase, but PF decreases with the membrane rejection. It is likely that optimum operating conditions exist to give the best process performance because the increases in eluant and affinity-recycle flow rate improve REC but decrease PF.展开更多
基金Projects(50501020, 50395103, 50431030) supported by the National Natural Science Foundation of China Project(NCET-05-870) supported by Program for New Century Excellent Talents in University of China Project(CX200706) supported by the Doctorate Foundation of Northwestern Polytechnical University,China
文摘A solute trapping model is developed based on a so-called solute drag treatment.By adopting a basic approach of phase-field models,and defining the free energy density in the interfacial region,a suitable interface shape function is introduced to derive the current model,in which the equilibrium and non-equilibrium interface behaviours can be described using a dimensionless parameter L (i.e.an important parameter in the present interface shape function).When applying the current model to Si-9%As (molar fraction) alloy with L=0.5,a good prediction of the steeper profile for high interface velocity,which is analogous to that using a phase-field model of DANILOV and NESLTER,has been obtained.
基金Supported by Technology Center,China Tobacco Hunan Industrial Co.,Ltd.(KY2014KF0002)the National Natural Science Foundation of China(21536003)+2 种基金Innovative Research Team Development Plan-Ministry of Education of China(IRT1238)Key project of international®ional scientific and technology plan(2014WK2037)China Outstanding Engineer Training Plan for Students of Chemical Engineering&Technology in Hunan University(2011-40)
文摘An improved CFD model of gas flow and particle interception in a fiber material which fiber size is Y-shape was developed in this work. The porous medium model was used to build the model of the whole size of fiber filter medium. Mixture model was adopted. The algorithm of particle interception in the whole size of fiber filter medium was derived and UDF(User Defined Function) that described kinds of particle filtering mechanisms in filter fibrous media was added to the Fluent default conservation equation as source term for simulation. The inertial resistance of the filter was taken into consideration, which provided a more precise measurement of the smoke flow and the particle interception in the filter under higher smoke speed conditions. The commercial software, Fluent 6.3, was used to simulate the smoke flow and particle interception in the filter in a single suction. The velocity and pressure profiles of smoke or nicotine particle in the filter, as well as nicotine particle volume fraction profile were well simulated. Finally, the comparisons of nicotine particle filtration efficiency between Fluent simulation results in this work and experimental results, as well as the model prediction in the literature were made to validate the simulation model. The comparisons showed that the particle entrapment model from simulation results was in good agreement with that from the experimental results. In addition, the Fluent simulation results are closer to reality both at the beginning and the end of the smoke process comparing with the model predicted results in the literature.
文摘The continuous affinity- recycle extraction (CARE) process is extended ic a system with ultrafiltration membranes. The mathematical model of the process is established by taking into account membrane rejections to the components in a crude mixture. The process performance, defined as concentration factor (CF ), purification factor (PF ) and recovery yield (REC), is analyzed by computer simulations. The results show that CF and REC increase, but PF decreases with the membrane rejection. It is likely that optimum operating conditions exist to give the best process performance because the increases in eluant and affinity-recycle flow rate improve REC but decrease PF.
