OR-94-16-3 -- Contaminant-Removal Efficiencies in a Model Barn Using a Displacement Ventilation System and a Conventional Supply Slot System PDF

A 2.5-to-1 scale model piggery barn in a laboratory was instrumented to measure air speed, air temperature, and tracer gas concentrations. Two ventilation systems were investigated - displacement ventilation and a conventional, high-wall, slot air supply system. Heat and tracer gases were introduced through model pigs that created two-dimensional temperature differences and airflow and airborne contaminant distributions similar to those in a prototype barn operating in a cold climate. The results showed that the displacement ventilation system was substantially better than the slot inlet system at removing airborne contaminants and for cooling. Contaminant-removal efficiencies up to 155% were measured for the displacement system, and all values were more than 120% in the pig-occupied area. The slot inlet system resulted in contaminant-removal efficiencies of approximately 100%. In addition, the temperature ratios for cooling were found to be significantly better for the displacement system, especially as the difference between inside and outside air temperatures increased.

KEYWORDS: air cleaning, efficiency, farm animal housing, piggeries, cold regions, air temperature, measuring, air, speed, tracers, gas, ventilation, cooling, displacement ventilation