Diffusivity at High Pressure
Diffusion
is the spontaneous movement of molecules from one region to another due to temperature,
pressure, concentration, or other force gradients. The diffusion coefficient is the
proportionality constant between the flux and the gradient. It is dependent on the temperature and
pressure. The pressure dependence is
negligible up to about 20 bar. After
20 bar, the diffusivity decreases with increasing pressure; however, the
correlation between diffusivity and pressure has not been readily
established. Often, processes in
chemical engineering are done at pressures much greater than atmospheric;
as such it is often important to calculate the diffusivity at the higher
pressure in order to correctly model the process. This project will examine the effects of
high pressure on diffusion coefficients using two correlations found in
literature.