Field evaluation of temperature and velocity uniformity in tunnel and conventional ventilation broiler houses

This field evaluation compared the temperature and velocity uniformity within two commercial broiler houses. One house used conventional sidewall ventilation and the other used tunnel ventilation strategies. One goal of hot-weather ventilation is to exchange enough air to remove bird body heat. Introducing a significant convective (wind chill) over the birds is the primary objective of tunnel ventilation. The tunnel-ventilated house had average air velocities of 1.7 m/s [335 feet per minute (fpm)] and 2.6 m/s (509 fpm) during the first and second study period, respectively. Wind played an important role in determining air speed and direction within the curtain inlet end of the tunnel-ventilated house. Tunnel air speed at bird level was about two-thirds the air speed at human level. As anticipated, little wind chill was present in the conventionally ventilated house. The average air speed was 0.4 and 0.5 m/s (83 and 100 fpm) during the two 1-h, study periods. About one-half the cross-sectional area exhibited still air [<0.25 m/s (50 fpm)] conditions. Within the tunnel-ventilated house, bird level was the warmest zone in the exhaust fan end of the house despite the high air speeds and substantial air exchange rates. On average, the conventional house temperature was approximately 3.8°C (6.9°F) warmer than the outdoor temperature as compared to 2.6°C (4.7°F) for the tunnel house. Within both houses, the maximum difference between the maximum and minimum monitored temperatures was 2.8°C (5.0°F), which indicated acceptable temperature uniformity.