What are the three types of mass diffusion?
Depending on the conditions, the nature, and the forces responsible for mass transfer, four basic types are distinguished: (1) diffusion in a quiescent medium, (2) mass transfer in laminar flow, (3) mass transfer in the turbulent flow, and (4) mass exchange between phases.
Is mass transfer same as diffusion?
Mass transfer is the movement of mass from one place to another. Diffusion is a form of mass transfer. The main difference between mass transfer and diffusion is that mass transfer may or may not occur across a concentration gradient whereas diffusion occurs across a concentration gradient.
What is Fick’s law of mass transfer?
Fick’s law is applicable for all matter irrespective of it state: solid, liquid or gas. Mass transfer is inversely proportional to molecular spacing. Similar to heat transfer which occurs in direction of decreasing temperature, mass transfer by diffusion also occurs in the direction of decreasing concentration.
What are the theories of mass transfer?
There are different theories dealing with mass transfer among phases, such as the two-film theory, the penetration theory and the surface renewal theory….These theories are briefly discussed below.
- 2.1. Two-film theory.
- 2.2. Penetration theory.
- 2.3. Surface renewal theory.
What are the mechanisms of mass transfer?
There are two basic mass-transport mechanisms, diffusion mechanism and sieving mechanism. In diffusion mechanism, both the solute and the solvent migrate by molecular diffusion in the polymer, driven by concentration gradients set up in the membrane by the applied pressure difference.
What is Eddy mixing?
Eddy diffusion, eddy dispersion, or turbulent diffusion is a process by which substances are mixed in the atmosphere, the ocean or in any fluid system due to eddy motion. In other words, it is mixing that is caused by eddies that can vary in size from subtropical ocean gyres down to the small Kolmogorov microscales.
What is the difference between diffusion and mass transfer?
Diffusion is the macroscopic result of random molecular motion on a microscopic scale. Mass transfer by convection involves the transport of material between a boundary surface (such as solid or liquid surface) and a moving fluid or between two relatively immiscible, moving fluids.
What is the mechanism of mass transfer?
The simplest case is mass transfer in a medium at rest in which the driving force is the difference of concentrations in adjacent regions of the medium and the mechanism is molecular diffusion.
What are the two main types of mass transfer?
The two main types of mass transfer are diffusion and conduction convection and diffusion radiation and convection conduction and radiation 1 diffusion and conduction 2 convection and diffusion 3 radiation and convection 4 conduction and radiation
What is mass transfer by convection?
Mass transfer by convection involves the transport of material between a boundary surface (such as solid or liquid surface) and a moving fluid or between two relatively immiscible, moving fluids. Don’t confuse this phenomenon with the movement of mass caused by a chemical species simply being carried along in a fluid stream (advection).