Porosimetry flow-through

Many water-management advances have been made (Figure 2). However, fundamental properties associated with two-phase flow in porous media, including capillary pressure, liquid water content and, intrinsic and relative permeabilities, are still lacking and are needed for predictive models. This situation is due to the absence of measurement methods for thin materials. Contact porosimetry [57] does not presently allow measurement of the permeabilities or during wetting (to evaluate the presence of hysteresis). Fluorescence microscopy [58] can provide additional information about liquid water flow through porous media. 

Two standard methods (mercury porosimetry and helium pycnometry) together with liquid expulsion permporometry (that takes into account only flow-through pores) were used for determination of textural properties. Pore structure characteristics relevant to transport processes were evaluated fiom multicomponent gas counter-current difhision and gas permeation. For data analysis the Mean Transport-Pore Model (MTPM) based on Maxwell-Stefan diffusion equation and a simplified form of the Weber permeation equation was used. 

For porous particles with small pores, the particle volume in Eq. (15) should be replaced with the envelope volume of the particle as if the particles were nonporous as shown in Fig. 2. This would be more hydrodynamically correct if the particle behavior in the flow field is of interest or if the bulk volume of the particles is to be estimated. For total weight estimation, then the skeleton density should be known. The skeleton density is defined as the mass of the particle divided by the skeletal volume of the particle. In practice, the pore volume rather than the skeletal volume is measured through gas adsorption, gas or water displacement, and mercury porosimetry. These techniques will be discussed in more detail later. There are also porous particles with open and closed pores. The closed pores are not accessible to the gas, water or mercury and thus their volume cannot be measured. In this case, the calculated skeleton density would include the volume of closed pores as shown in Fig. 2. For nonporous particles, the particle density is exactly equal to the skeleton density. For porous particles, the skeleton density will be larger than the particle density. 

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