- 23,708
- 5,924
We need to use the overall mass balance to get the values of ##\phi_m=\rho_mv_m## at the cell boundaries (for use in the other balance equations). This is what we do in model 1.casualguitar said:##\textbf{The overall mass balance for the gas phase:}##
$$\frac{\partial (\epsilon \rho_m)}{\partial t}=-\frac{\partial (\rho_mv_m)}{\partial z}-\sum_{i=1}^{n_c}{\dot{M}_i^"a_s}\tag{1}$$
The rewriting of equation 10 makes sense to me. Just one question on the equations we have. If we have the solid and gas species mass balances, what additional information does having the overall mass balance for the gas phase give us i.e. why would we need this also?
I would be inclined to say that the two l's are the same because the dispersion is essentially mechanical (dominated by axial mixing). You could use different values if you desire, but, if they are the same and equal to ##\Delta x/2##, the resulting simplification is very attractive.casualguitar said:Can we reasonably let ##D_{eff} = v_mL_T## in the mass balance equation also? Effectively saying that ##D_{eff}## has the same value in the mass and heat balances
I'm interested in seeing how you discretize the equations with respect to z.