Air Distribution in a Model Windowless Piggery with a Positive Pressure Ventilation System

Abstract

The 1/3 scaled model test was carried out to determine the characteristics of air distribution in a windowless piggery equipped with the positive pressure ventilation system. This system provided the air from the attic to the piggery room through the slots on ceiling by ventilation fans. The internal air is exhausted through the slits on both side walls. The ventilation rate for the scaled model was adjusted for both summer and winter conditions. The air velocity and the air temperature for the prototype were also estimated using the law of similarity based on Archimedes number.
The airflow patterns on the cross section were affected by the incoming jet air direction under the summer condition. Under the winter condition, the uniformity of air temperature was affected by the number of air changes, and the temperature difference between the air discharged from the attic and the representative point in the piggery room. Longitudinal variation of air velocity and air temperature were not uniformly. The air velocity and the air temperature were depended on the longitudinal position of structure. These were significantly induced by the longitudinal not uniformly variation of incoming jet velocity from the slots on ceiling. The incoming jet from the slots on ceiling was induced by the positive pressure difference between the attic and the piggery room. There are two points would be noticed when a structure with this ventilation system being designed. One is to increase the positive pressure in the attic, and the other is to adjust the positive pressure in the attic uniformity.