ISHS Acta Horticulturae 406: II IFAC/ISHS Workshop :Mathematical & Control Applications in Agriculture & Horticulture
AIRFLOW PATTERN CONTROL IN LIVESTOCK BUILDINGS |
| Author: | G. Zhang |
| Keywords: | Airflow pattern, Non-isothermal jets, ventilation control |
| Abstract:
One of the major problems in winter ventilation of livestock buildings is cold air down-draught, which is often caused by incorrect design or tuning of the ventilation control system or inability to control the ratio of buoyancy to jet impulsive force. To overcome the problem, an on-line control algorithm was created for a computerised control system. The algorithm combines system information including the characterization results of the ventilation units based on experimental data, and jet drop distance criteria that related to the inlet Archimedes number, in order to control air jet trajectory and indoor temperature. Fuzzy theory was applied to the quantification of air jet drop positions, which is used to indicate the status of airflow movement and forward control decision making. The algorithm is aimed at direct control of the operating air pressure to manipulate the initial air jet momentum against the thermal buoyancy force. The algorithm was evaluated in a hybrid ventilation (natural and mechanical ventilation) system. The experiment focused on the switching period between natural ventilation and mechanical ventilation. The results showed that a fine tuning could be achieved to control the air trajectory, and at the same time to maintain the indoor temperature at the set-point during the pressure regulation. The potential of the algorithm application is discussed. | |
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