Diffusion green body drying

Using these equations for heat conduction in the porous network emd the pseudo-steady state emalysis described for pore diffusion, the time to dry a spherical green body with pore heat conduction as the rate determining step is given by... 

These expressions are good for rate limiting steps of only pore diffusion and pore heat conduction corresponding to the decreasing rate period. Combined with the equations in Table 14.1, all the possible rate controlling steps are established allowing the prediction of the total time, Tjot, to dry a green body ... 

When the constant rate period is over, vapor phase pore diffusion plays an important role in the cracking of ceramic green bodies. The capillary pressure difference, AP, between the surface and interior of the green body during drying can be estimated from the flux of solvent, j, giving... 

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