CFD modelling of airflow pattern and thermal environment in a commercial manure-belt layer house with tunnel ventilation

Abstract

Heat stress has become increasingly challenging for large-scale concentrated layer production. Tunnel ventilation has been widely used to abate heat stress, but it naturally forms large thermal gradients which result in non-uniform production performance and avian health risks associated with heat stress. Knowledge of the three-dimensional spatial distribution and seasonal variation of the indoor thermal environment of layer houses is needed to assess the comfort level of birds and develop mitigation strategies. This study developed a 3D Computational Fluid Dynamics (CFD) model for simulating air velocity, air temperature, humidity, and heat stress indices inside a commercial layer house. The model was successfully validated by field measurements in hot, mild, and cold seasons. Heat stress was found in 69.1%, 78.0%, and 18.4% of cages in summer, autumn, and winter based on temperature-humidity index when the incoming air temperature was 26.0 °C, 15.0 °C, and 2.5 °C with ventilation rates of 85.8, 15.5, and 11.7 air change per hour (ACH), respectively. Cold stress was observed in 18.3% of the cages in winter due to low incoming air temperature and inadequate mixing. Improvement on the ventilation systems is needed to protect the birds from heat and cold stress, which can become more severe in the scenarios of climate changing. The CFD model developed in this paper can be utilised to design and evaluate new ventilation systems for enhanced indoor environment of layer houses.