Distribution of permeable porous channels of porous medium sizes from pneumatic characteristics

Abstract

A method for estimation of the permeability coefficients distribution by the sizes of the pore channels of filter materials based on the analysis of parameters tangent to the displacement curve is proposed. The distribution of permeability coefficients by the sizes of pore channels in a polymer filtering material with a filtration fineness of 3 μm is obtained. It is shown that in the specified filter material, the most permeable pores through which the main stream passes (more than 75% of the total gas flow) are in the range of their diameters 13.8 - 22.4 μm. The development of agriculture in Ukraine provides for the widespread use of materials resistant to aggressive media, including porous polymeric materials. One of the significant trends in the field of polymer materials is the development and study of porous materials based on polytetrafluoroethylene (PTFE). The most important performance characteristics of filter materials are their fineness and permeability [1]. The permeability of the filter material is an integral characteristic reflecting the capacity and the number of pore channels of a certain diameter. In the filter materials there is a distribution of pore channels according to their permeability. For practical purposes in the specified distribution it is advisable to allocate a group of pore channels, which accounts for the main stream of the filtered medium. Note that this group also determines the fineness of cleaning the filter. To study the distribution of permeability of the pore channels and the selection of the interval of pore channel diameters that provide the main flow of the medium being filtered, it is advisable to use the method of liquid displacement from the pores [2]. Earlier [3], this method established the distribution of pore channels according to their diameters, which only indirectly allows us to judge the filtering ability of this material. Note that when analyzing these data, the authors [4] using the method of “crossing” through points of the displacement curve analytically determined the gas flow increment caused by the opening new pore channels. However, this approach is not completely correct, because it does not reflect the physical essence of the process of displacing fluid from the pores with subsequent purging of the opened pore channels with compressed gas, which ultimately leads to a sharp distortion of data on the distribution of pore channels in their diameters.