2.3 General molecular transport equation For Momentum, Heat And Mass Transfer Objectives Gain brief understanding of the three transport phenomena. Understand the general form of molecular transport equations Recognize the analogy of the three laws of transport (Momentum, Heat and Mass) to the general form. CHE315 2.3 General molecular transport equation For Momentum, Heat And Mass Transfer

Rate of a transfer process = driving force / resistance Demonstration Clip All three of transport processes (Momentum, heat or mass) are characterized by the same general type of transport equation: Rate of a transfer process = driving force / resistance This states that a driving force is needed to overcome a resistance in order to transport a property. CHE315 2.3 General molecular transport equation For Momentum, Heat And Mass Transfer

For molecular transport or diffusion of a property, we can formalize by writing: Ψz = - d (dG/dz) z1 z2 G1 G2 Yz Flux Concentration G CHE315 2.3 General molecular transport equation For Momentum, Heat And Mass Transfer

2.3 General molecular transport equation Property Flux Property Concent. Diffusivity Direction Transport Equation General Form Momentum Heat Mass CHE315 2.3 General molecular transport equation For Momentum, Heat And Mass Transfer

Property Concentration Property Flux Property Concentration Diffusivity Direction Transport Equation General Form YZ G d Z Momentum tzx vxr n Heat qz/A rcp a Mass Jzx CA DAB CHE315 2.3 General molecular transport equation For Momentum, Heat And Mass Transfer

General property balance for unsteady state (rate of property in) + (rate of generation of property) = (rate of property out) + (rate of accumulation of property) CHE315 2.3 General molecular transport equation For Momentum, Heat And Mass Transfer