CFX12_Multiphase_12_Multicomponent.ppt

Species Transfer in Eulerian Multiphase Transfer of a single species between multicomponent phases Example: spray drier Three components Two phases Coupled heat/mass transfer Modeling Species Transfer Need Two Resistance model for mass transfer Interface conditions on two sides related through equilibrium ratio Model for mass transfer rate similar to Thermal Phase Change but see restrictions on next slide Models for equilibrium ratio: User-defined Henry‘s law for gas dissolution Raoult‘s law for multicomponent evaporation Species Transfer Modeling issues: Model currently assumes small mass transfer rates but see next slide Hence best suited for gas dissolution Model currently neglects thermal effects For these reasons, the model is unsatisfactory for non-isothermal evaporation/condensation Usability issues: Both phases must be multicomponent fluids containing the component being transferred Transfer with a ballast component not permitted Sink Option for Multicomponent Fluids Enthalpy Effects Non-Equilibrium Condensation Non-Equilibrium Condensation Non-Equilibrium Condensation Non-Equilibrium Condensation 12-* ANSYS, Inc. Proprietary ? 2009 ANSYS, Inc. All rights reserved. September 1, 2009 Inventory # Training Manual 12-* ANSYS, Inc. Proprietary ? 2009 ANSYS, Inc. All rights reserved. September 1, 2009 Inventory # CFX Multiphase 12.0Chapter 12 Multicomponent MultiphaseFlows Overview Phase change for multicomponent systems Species transfer for multiphase flows Finite mass transfer effects User defined species transfer Sink option for multicomponent fluids Enthalpy effects and latent heat Source linearization Introduction There are many cases where multiphase flows involve fluids with multiple components which may or may not react. In addition to bulk exchange of liquid and gas, interphasemass transfer can also proceed by transfer of species. Examples include drying of wet solids in a hot air stream or dissolution of a soluble gas phase co