CONTAMINANT AND HEAT REMOVAL EFFECTIVENESS OF THREE VENTILATION SYSTEMS IN NURSERY ROOMS FOR PIGS

In this research, three ventilation systems (ground channel, porous ceiling, and door ventilation) were tested on their performance in supplying fresh air to the animal occupied zone (AOZ), each in a room for 70 weaned piglets. Measurements of the CO2 concentration and temperature of the inlet air, at one point in the AOZ, and in the outlet air were recorded every 36 minutes for three successive batches. Less frequent measurements were done on the CO2 concentration in two other points in the AOZ. System effectiveness was expressed as the contaminant removal effectiveness (CRE) for CO2 and the heat removal effectiveness (HRE): CRE or HRE equals 1 when the CO2 concentration or temperature in the AOZ equals that of the outlet air. Values lower than 1 reflect higher CO2 concentrations or temperatures within the AOZ; values higher than 1 the reverse. In all rooms, the value of CRE or HRE varied in time by varying the ventilation rate. CRE was highest in the room with ground channel ventilation, varying with measurement location. CRE was 1.39 on average and HRE was 1.13 on average in the middle of the pen. CRE was higher closer to the air inlet and lower further to the back of the pen, closer to the outlet, because air renewal was based on displacement of old air by fresh air. In the room with door ventilation, CRE was 1.20 and HRE was 0.95 at a point in the second half of the room in the back of a pen. Air passed over the operator walkway to the back of the room, and back over the pens, resulting in a decreased CRE in the pens closer to the door that acted as an air inlet. In the room with a porous ceiling, CRE values were lower. At one sampling point, CRE was 1.01 and HRE was 0.94. In the lying area of the animals in the back of the room, CRE values were lower than at a sampling point in the front of the room. In the lying area, the heat production of the animals resulted in an upward airflow, which lowered the CRE.