Water regulated air flow controller for permeability measurements

Stored agricultural commodities can often be characterised as porous media. Transport processes in the pile are largely influenced by the air now in t he pores. This research is concerned with the design of a water regulated a ir now controller and testing of its operation under conditions of laminar and nearly laminar flows. Using this controller and a pressure difference s ensor one can measure air permeability. Moist wheat straw was used as the t est sample. Forchheimer's relation explained very well our measured pressur e differences (r(2)=0.994-0.999). Also the comparison with measurements usi ng a direct air flow controller gave good results. Copyright (C) 1998 IFAC.