CFD study of the effect of inlet position and flap on the airflow and temperature in a laying hen house in summer

Evaporation pads and tunnel ventilation are commonly adopted in hen houses. To ensure the cooling efficiency of pads and airflow in the building, inlets with pads are often placed in sidewalls. Flaps are often fitted behind inlets to alleviate the sudden temperature drops that can be caused by pads. However, the airflows change their direction after entering from sidewalls with flaps, which affects the environment in the caged-hen occupied zone (OZ). This work explored the effect of inlet position and flap on airflow and temperature in laying hen house using computational fluid dynamics (CFD). The CFD model was validated by field experiments. Results showed that the inlet position and flap significantly affected the airflow and temperature near the inlet. An increased inlet area in the gable wall and a longer distance between cages and sidewall inlets increased air speed, decreased temperature, and improved airflow distribution uniformity in OZ. The maximum increase in air speed, decrease range in temperature, and reduction in the coefficient of air speed variation (CASV) was 0.37 m s−1, 0.19 °C and 11%, respectively. The flap also increased the air speed and decreased the temperature, but it reduced the airflow distribution uniformity. The maximum increase in air speed, decrease range in temperature, and increase of CASV was 0.15 m s−1, 0.07 °C and 6%, respectively. The increase in CASV reduced with the increased distance between the sidewall inlet and cages. Therefore, reducing the overlapping area between sidewall inlets and cages should be considered in practice.