Reducing Odor Emission from Pig Production Buildings by Ventilation Control

摘要

Odor emissions from pig buildings have been the topic for many research projects. However, the fact that the odor emission is dependent on air as transportation medium is far less investigated. Therefore, more comprehensive investigations on the effects of odor release of airflow patterns and ventilation airflow rates are needed. The objective of this project was to study the feasibility of reducing ammonia and odor emission by choosing ventilation control strategies. At present, the ventilation capacity of a pig production building is based on an absolute maximum ventilation rate, which is determined according to the largest body weight of the animals during the production cycle. However, in modern batch production systems, the maximum ventilationrate is only required when the animals reach end weight and the outdoor temperature exceeds a certain level. In this study, a ventilation control strategy using a restricted maximum ventilation rate according to the pigs' actual weight in the building was investigated. According to computer simulations, limiting the maximum ventilation rate to the actual body weight is feasible in practical application to reduce odor emission. That is in agreement with a primary investigation performed infield measurements by Danish Pig Production. In addition, the studies on the correlation between emission and airflow characteristics have shown that by choosing a proper ventilation control strategy, emission can be also reduced. The investigations were performed in scale model experiments and CFD (Computational Fluid Dynamics) simulations. Strategies such as constant inlet opening, constant inlet velocity, and constant inlet momentum were studied. The proposed control strategy suggests that the ventilation rates ina pig production building should be controlled to maintain a low inlet air momentum to reduce emission.