Numerical simulation of changes in pressure and flow velocity of pollutant gases in a bio filter bed in animal husbandry

This research has focused on study of changing static and dynamic pressure and velocity values in three levels of different bio filter cross sections. The studied factors included gas flow rate, cross sectional area (trapezoidal, square and circular), vertical position (bed center line, front line and rear end) in four elevation ranges from the bottom of the bio filter bed (the first part 0 to 16.75 cm, the second part 16.75 to 29.25 cm, the third part 29.25 to 41.75 cm and the fourth part was 41.75 to 58.5 cm) was examined. The results of studying the pressure and velocity in the three cross sections showed the lowest mean of dynamic and static pressure in the square section and the mean speed was higher due to the absence of the corner at the cross section. The variations of pressure in different ranges of bio filter bed showed a decreasing trend, so that the average of dynamic pressure drop and static pressure drop in these ranges were 87.9 and 44.4%, respectively. While the maximum dynamic pressure has obtained from circle section. At the locations assumed in this study, the maximum average of dynamic pressure estimated 1.509×10-5 Pa at center line. For the other locations the average dynamic pressure obtained 2.502×10-6 Pa at front line and 2.481×10-6 Pa at back