Airflow and contaminants in a swine barn with recirculation-assisted slot inlets

The airflow pattern and contaminant distribution under non-isothermal turbulent flow conditions in a swine growing/finishing building were investigated experimentally and numerically. In the test facility, the ventilation system consisted of discontinuous ceiling inlets with recirculation assisted slots. Air speed, dust and ammonia concentration at selected locations in the-building were measured during the winter ventilation season in a cold climate. The corresponding temperature distribution at one cross section within the air space also was measured. Experimentally it was found that both the ventilation rate and the recirculation rate had a limited effect on the dust concentration. The ventilation rate had a significant effect on the ammonia concentration in the air space, while the recirculation rate did not affect the ammonia concentration.;The FLUENT computer code was used to simulate the air flow pattern and ammonia concentration in the swine building. The numerical simulation model used was the k-;Numerical results also indicated that the heat generated by animals affected the airflow pattern. Increasing the heat load at the floor resulted in increased air speed, temperature, contamination level, turbulence kinetic energy, dissipation rate and effective viscosity along the breathing line.;The placement of the ceiling inlet and the recirculation duct affected airflow patterns, but had only a slight effect on the distribution of temperature and ammonia concentration along the human breathing line. Increasing the flow rate of cleaned recirculation airflow resulted in lower ammonia contaminant level along the human breathing line. However, higher flow rates of cleaned recirculation air means there will be higher fan operation and air cleaning costs. The optimum ratio of ventilation rate to the cleaned recirculation air rate appeared to be approximately 1:4.