Krishna Gupta

An innovative technique for pore structure analysis of fuel cell and battery components using flow porometry

Some of the porous sheet materials used in fuel cells and batteries hardly permit gas flow through the thickness of the sheet, although flow parallel to the sheet is appreciable. Determination of the porosity of such materials is not possible by the available techniques. A novel technique based on flow porometry is reported. This technique can measure the pore structure of such porous sheets. A composite porous sheet material containing one of the electrodes and the separator in two layers was investigated. The largest pore diameter, the mean flow pore diameter and the pore size distributions were measured. The pore structures of both layers were identified.

In-plane compression porometry of battery separators

We have designed equipment that measures, by means of capillary flow porometry, the pore structure of sheet materials. The equipment measures the influence of superimposed compressive stress on pore structure as well. The bubble point pressure, mean flow pressure, and flow distribution of a battery separator have been measured, and the influence of compressive stresses on these parameters have been observed. Our results demonstrate that the pore structure for in-plane flow is considerably different from that for flow in the perpendicular direction, and the effect of superimposed compressive stress is appreciable.

A Novel Technique for Determination of Vapor Transmission Rate through Textiles

A novel technique for precise, accurate and fast determination of vapor transmission rate through textiles is discussed. Vapor at a constant pressure is maintained on one side of the textile and the increase in pressure of the vapor on the other side is measured. The technique was used to investigate two textiles. The vapor permeabilityof the textiles is almost five orders of magnitude lower than their air permeability. The air permeability of the textiles are identical, however, they show strong differences in vapor permeability.

Characterization of Water Vapor Transmission Rate Through Fuel Cell Components

An instrument capable of measuring vapor transmission rates under any desired gradient of concentration and pressure is described. The test temperature, pressure, humidity and flow rates are precisely controlled and accurately measured. The instrument is completely automated to obtain objective and accurate results and minimal involvement of the operator. Using this instrument a variety of materials, including a fuel cell component, have been successfully investigated.Copyright

In-Plane and Through-Plane Porosity in Coated Textile Materials

Many industrially important textile materials are in the form of sheets. Their porosity is generally determined by measuring their flow characteristics parallel to the thickness. However, their properties parallel to the thickness direction (through-plane porosity) and parallel to the plane of the sheet (in-plane porosity) are not the same. For many applications, such porosity data are essential for designing more efficient materials. Equipment has been designed to measure pore characteristics in such materials in both in-plane and through-plane directions. The equipment yields reproducible data. The bubble points in the two directions are considerably different from each other. The results are consistent with the fibrous nature of the textile.