Evaluation of a new airflow sensor on large layer house exhaust fan

Yan Chen, Purdue University


Research on agricultural air quality (AAQ), especially for obtaining reliable data of air pollutant emissions from agricultural sources, is critical to protect our environment and ensure sustainable agriculture development. To calculate air pollutant emission rates from an animal building, ventilation rate must be known because emission rate is the product of ventilation rate and pollutant concentration. However, ventilation rate measurement at large concentrated animal feeding operations (CAFO) is very technically challenging. Although several technologies have been developed to improve the ventilation rate monitoring in animal buildings, their technical limitations and high costs prevent them from being used to solve the problem. Therefore, to achieve accurate measurement of airflow rates at the CAFOs, new technologies need to be developed to generate more reliable pollution data that are critical for environmental assessment, policy making, and pollution mitigation. The overall goal of this thesis research is to contribute to the ventilation rate measurement technology for AAQ monitoring study. The following specific objectives were pursued: 1) to assess the state-of-the-art of ventilation measurement technologies in animal buildings; 2) to test and evaluate a new sensor for fan airflow rate measurement under field conditions; and 3) to develop a mathematical model for airflow rate calculation based on the new sensor measurement signals. Current technologies for ventilation rate measurement included Fancom ® airflow transmitter (AFT), Fan Assessment Numeration System (FANS), traverse method, small impeller anemometer based method, fans on/off status based method, fan rotational speed (FRS) based method, and moisture balance, heat balance, and tracer gas balance based methods. These methods were compared and evaluated for their measurement features, field application, and limitations in this thesis. A novel airflow rate sensor was developed and its prototype was tested at a commercial layer farm. The study showed that, compared with existing technologies, the new sensor had a simple design and was easy to install and operate. It was low-cost (<$250) and could be used at CAFOs in North America for direct, continuous, long-term, and more accurate measurement of fan ventilation rate in large wall fans (>1.22 m diameter), which has been a major technical challenge in AAQ studies. Based on theoretical analysis and field test results, this sensor could provide accurate airflow rate measurement by comparing with FANS (error < ±6.6% at 95% confidence) at a range from 7,000 to 13,000 m3/h for a 1.30-m diameter fan. This thesis research demonstrated that the sensor will enable large scale application and significantly improve the data quality of AAQ research in animal agriculture.




Ni, Purdue University.

Subject Area

Agricultural engineering|Mechanical engineering|Environmental engineering

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