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ARS Home » Southeast Area » Mississippi State, Mississippi » Poultry Research » Research » Publications at this Location » Publication #298640
Title: Effect of air deflectors on fan performance in tunnel-ventilated broiler houses with a dropped ceiling

Author
item Purswell, Joseph - Jody
item LUCK, B - Mississippi State University
item DAVIS, J - Mississippi State University

Submitted to: Applied Engineering in Agriculture
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/27/2014
Publication Date: 7/15/2014
Citation: Purswell, J.L., Luck, B.D., Davis, J.D. 2014. Effect of air deflectors on fan performance in tunnel-ventilated broiler houses with a dropped ceiling. Applied Engineering in Agriculture. 30(3):471-475.

Interpretive Summary: Maintaining proper air velocity is essential for managing modern commercial broiler at market weight to provide sufficient cooling during warm weather. To achieve additional air speed in broiler hosues, many growers have installed additional fan capacity or air deflectors in the ceiling peak to reduce building cross-sectional area. While deflectors have traditionally been recommended only for buildings with open ceilings, an increasing number of growers have installed deflectors in dropped ceiling houses to increase in air velocity without additional fan capacity. However, adding additional restriction in the flow path of the air increases the working pressure of the fans and can reduce fan output. Fan flow rates were measured in three tunnel-ventilated commercial broiler houses equipped with air deflectors with the deflectors in the deployed (down) and retracted (up) position. Flow rate and static pressure data were collected for each fan for each deflector position with all fans operating to simulate tunnel ventilation during warm weather. The results show that deploying air deflectors reduced fan flow rate by 11% as a result of increasing static pressure. The results of the current study show that use of air deflectors are likely not appropriate in broiler houses with dropped ceilings when fan performance and energy use are taken into consideration, and should be sized at higher static pressures.

Technical Abstract: Air velocity is a critical design parameter for modern commercial broiler houses, owing to the beneficial effects of increased cooling on live performance and thermal comfort in broiler chickens. As a result, design velocities have increased over the last 15 years and broiler growers have installed additional fan capacity or air deflectors in the ceiling peak to reduce building cross-sectional area. While deflectors have traditionally been recommended only for buildings with open ceilings, an increasing number of growers have installed deflectors in dropped ceiling houses to provide local increases in air velocity without additional fan capacity and improve air velocity uniformity across the house. However, adding additional restriction can increase static pressure and reduce fan performance. Fan flow rates were measured in three tunnel-ventilated commercial broiler houses equipped with air deflectors with the deflectors in the deployed (down) and retracted (up) position. The broiler houses measured 15.2 × 144.8 m and were equipped with 12 tunnel exhaust fans (137.2 cm diameter) and nine air deflectors at 12.2 m intervals, beginning after the tunnel inlet area and ending 15.2 m before the fans. Flow rate and static pressure data were collected concurrently for each fan for each deflector position with all fans operating to simulate tunnel ventilation during warm weather. Data were analyzed using ANOVA and least square means were separated using Fisher’s LSD. The results show that deploying air deflectors significantly reduced mean fan flow rate by 11% (p < 0.0001) and increased static pressure by 11.2 Pa (p < 0.0001). The results of the current study suggest that use of air deflectors are likely not appropriate in broiler houses with dropped ceilings when fan performance and energy use are taken into consideration, unless sized at increased pressure.