Assessing air velocity distribution in three sizes of commercial broiler houses during tunnel ventilation

Authors: LUCK, BRIAN - University Of Wisconsin; DAVIS, JEREMIAH - Auburn University; Purswell, Joseph - Jody; KIESS, AARON - Mississippi State University; HOFF, STEVEN - Iowa State University

Submitted to: Applied Engineering in Agriculture
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/3/2017
Publication Date: 7/20/2017
Citation: Luck, B.D., Davis, J.D., Purswell, J.L., Kiess, A.S., Hoff, S.J. 2017. Assessing air velocity distribution in three sizes of commercial broiler houses during tunnel ventilation. Applied Engineering in Agriculture. 60(4):1313-1323. https://doi.org/10.13031/trans.12107.
DOI: https://doi.org/10.13031/trans.12107

Interpretive Summary: Convective cooling is a critical management strategy for maintaining a housing conditions to promote production efficiency, thermal comfort, and animal well-being in commercial broiler production. Variations in house size, design, and equipment configuration of production buildings contribute greatly to the air velocity distribution within the building. This study assessed total air flow and air velocity distribution in three commercial broiler houses of different sizes. House sizes included in the study measured 60 × 560 ft, 50 × 475 ft, and 40 × 440 ft. Total air flow of each building was measured with a Fan Assessment and Numeration System (FANS) and air velocity distribution patterns were characterized with a large array of hot wire anemometers. Air velocity distribution within the test buildings was variable, with maximum velocity occurring immediately downstream of the tunnel inlets and minimum velocity occurring near the leading end of the evaporative pads and the exhaust fans. Feeder and drinker equipment within the buildings had an impact on air velocity distribution by creating reduced cross-sectional area, resulting in localized increases in air velocity. The total bird level floor area in each building experiencing air velocities below 300 fpm was 4800, 4920, and 1600 ft2, for test building 1, 2, and 3, respectively. The effective design velocity (Effective design velocity) was calculated from total air flow using the measured building cross-sectional area. For test buildings 1, 2, and 3, effective design velocity measured 585, 482 and 460 fpm. Test building 1 showed 26.5% of the total house length below Effective design velocity while test building 2 and 3 only had 20.8% and 17.5% below effective design velocity, respectively. The lower velocity regions were due to the length of evaporative cooling pad inlet and the use of tunnel doors and exhaust fan placement in test building 1 on the side-walls created an additional pronounced low velocity area. Placement of tunnel ventilation fans on the end-wall of the building, rather than the side-wall, eliminated the low air velocity region at the exhaust end of the building. Modifications to current broiler production building construction and evaporative cooling pad inlet installation practices would be required to minimize the low air velocity region at the inlet end of these buildings. Consideration of house width and physical arrangement of inlets, tunnel fans, and internal equipment are critical for improving uniformity of air velocity in commercial broiler houses.

Technical Abstract: Convective cooling is a critical management strategy for maintaining a production environment to promote production efficiency, thermal comfort, and animal well-being. Variations in house size, design, and equipment configuration of production facilities contribute greatly to the air velocity distribution within the facility. This study assessed total air flow, air velocity distribution, and normalized mean cross-sectional air velocities of three broiler production facilities . Test facility 1 was an 18.3 × 170.7 m solid side-wall broiler house, test facility 2 was a 15.24 × 144.8 m solid side-wall broiler house, and test facility 3 was a 12.19 × 121.9 m curtain side-wall broiler house. Total air flow of each facility, measured with a Fan Assessment and Numeration System, was 512,730, 389,495, and 329,270 m3 h-1 for test facilities 1, 2, and 3, respectively. Air velocity distribution patterns were characterized in each house with a Scalable Environment Assessment System (SEAS) and spatial statistics. Air velocity distribution within the test facilities was variable, with notable maxima immediately downstream of the tunnel inlets which serves as a well-defined vena contracta and local minima near the leading end of the evaporative pads and the exhaust fans. Equipment within the facility had an impact on air velocity distribution by creating reduced cross-sectional area within the facility creating localized increases in air velocity. The total bird level floor area in each facility experiencing air velocities below 1.5 m s-1 was 447, 457, and 149 m2, for test facility 1, 2, and 3, respectively. The effective design velocity (Ved) was calculated from total air flow using the measured building cross-sectional area. For test facilities 1, 2, and 3, Ved measured 2.97, 2.45 and 2.34 m s-1. Mean cross-sectional air velocity (Vcs) was calculated from SEAS data and normalized using each facility’s Ved to account for differences in building size for comparison. Test facility 1, the largest of the three houses, generated substantially higher Vcs/Ved than that of test facilities 2 and 3. Test facility 2 and 3 maintained a larger proportion of Vcs above Ved than did test facility 1. Test facility 1 showed 26.5% of the total house length below Ved while test facility 2 and 3 only had 20.8% and 17.5% below Ved, respectively. The lower velocity regions were due to the length of evaporative cooling pad inlet and the use of tunnel doors and exhaust fan placement in test facility 1 on the side-walls created an additional pronounced low velocity area. Placement of tunnel ventilation fans on the end-wall of the facility, rather than the side-wall, eliminated the low air velocity region at the exhaust end of the facility. Modifications to current broiler production facility construction and evaporative cooling pad inlet installation practices would be required to minimize the low air velocity region at the inlet end of these facilities. Consideration of house width and physical arrangement of inlets, tunnel fans, and internal equipment are critical for improving uniformity of air velocity in commercial broiler houses.