Air & Waste Management Association

June 2009 Real-Time Airflow Rate Measurements from Mechanically Ventilated Animal Buildings PDF Download (members/subscribers only) Steven J. Hoff, Dwaine S. Bundy, Minda A. Nelson, and Brian C. Zelle, Agricultural and Biosystems Engineering Department, Iowa State University Larry D. Jacobson, Bioproducts and Biosystems Engineering Department, University of Minnesota Albert J. Heber and Jiqin Ni, Agricultural and Biological Engineering Department, Purdue University Yuanhui Zhang, Agricultural and Biological Engineering Department, University of Illinois Jacek A. Koziel, Agricultural Engineering Department, Texas A&M University David B. Beasley, Biological and Agricultural Engineering Department, NC State University Abstract This paper describes techniques used to determine airflow rate in multiple emission point applications typical of animal housing. An accurate measurement of building airflow rate is critical to accurate emission rate estimates. Animal housing facilities rely almost exclusively on ventilation to control inside climate at desired conditions. This strategy results in building airflow rates that range from about three fresh-air changes per hour in cold weather to more than 100 fresh-air changes per hour in hot weather. Airflow rate measurement techniques used in a comprehensive six-state study could be classified in three general categories: fan indication methods, fan rotational methods, and airspeed measurement methods. Each technique is discussed and implementation plans are noted. A detailed error analysis is included that estimated the uncertainty in airflow rate between 5 and 6.1% of reading at a building operating static pressure, air temperature, relative humidity, and barometric pressure of 20 Pa, 25 °C, 50%, and 97,700 Pa, respectively. Implications Gas and particulate emissions from animal housing systems are coming under increasing scrutiny. This paper discusses the measurement techniques used to assess the airflow rate in animal buildings as part of a larger six-state air emission research effort. Airflow rate measurements are critical to any study involving emissions because any error in airflow rate results in a direct error in emissions. Animal housing facilities pose a unique challenge in that multiple emission points exist, corresponding to the multiple fans used to ventilate these facilities. This paper discusses the various techniques used to assess airflow rate in multiple emission source applications and the expected airflow rate uncertainty.

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