Iowa Model Weighs up Farrowing Room Ventilation Options19 September 2013
US - Researchers at the University of Iowa have developed a simulation model to study the effect of ventilation airflow rate with and without filtered recirculation on airborne contaminant concentrations (dust, ammonia, carbon monoxide and carbon dioxide) for farrowing facilities.
According to Jae Hong Park and colleagues, air filtration with recirculation was more cost-effective than pit-only ventilation. They comment that their model is useful to optimise costs/benefits of ventilation in animal rearing facilities.
In their paper in the journal, Computers and Electronics in Agriculture, they explain that they used energy and mass balance equations to simulate the indoor air quality and operational cost for a variety of ventilation conditions over a three-month winter period, using time-varied outdoor temperature. The sensitivity of input and output parameters on indoor air quality and operational cost were evaluated.
Significant factors affecting model output included mean winter temperature, generation rate of contaminants, pit-air-exchange ratio and recirculation ratio.
As mean outdoor temperature was decreased from −2.5°C to −12.5°C, total operational costs were increased from $872 to $1,304.
Dust generation rate affected dust concentrations linearly. When dust generation rates changed −50 per cent and +100 per cent from baseline, indoor dust concentrations were changed −50 per cent and +100 per cent, respectively.
The selection of a pit-air-exchange ratio was found critical to ammonia concentration but has little impact on other contaminants or cost. As the pit-air-exchange ratio was increased from 0.1 to 0.3, the ammonia concentration was increased by a factor of 1.5.
Recirculation ratio affected both indoor air quality factors and total operational cost. As the recirculation ratio decreased to 0, inhalable and respirable dust concentrations, humidity, ammonia and carbon dioxide concentrations decreased and total operational cost ($2,216) was 104 per cent more than with pit-fan-only ventilation ($1,088).
When the recirculation ratio was 1, the total operational cost was increased by $573 (53 per cent) compared to pit-fan-only.
Park and colleagues added that simulation provides a useful tool for examining the costs and benefits to installing common ventilation technology to Confined Animal Feeding Operations (CAFO) and, ultimately, making sound management decisions.
Park J.H., T.M. Peters, R. Altmaier, R.A. Sawvel and T.R. Anthony 2013. Simulation of air quality and cost to ventilate swine farrowing facilities in winter. Computers and Electronics in Agriculture. 98: 136–145.
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