Numerical study of mechanically ventilated broiler house equipped with evaporative pads

Abstract

One of the important factors to improve the broiler production is the provision of an optimum indoor environment (air quality, temperature, humidity, air velocity, gases and PMs concentration) with lower possible cost. The internal microclimate can be controlled either passively by selecting appropriate construction geometry and materials or actively by the ventilation systems and the electromechanical (E/M) equipment. In the case of broiler chamber the conditions that constitute optimum internal microclimate vary with respect the birds’ age.In the present work, the ventilation, inside a modern and fully automated broiler chamber equipped with fans and evaporative pads located in Central Greece, is simulated using Computational Fluid Dynamics (CFD) techniques. The transport phenomena inside the broiler house are described with Reynolds Averaged Navier Stokes (RANS) equations solved with the Finite Volume Method (FVM). The flow is assumed 3D, steady state and turbulent. The fans of the broiler chamber abduct air from the interior, forming inside negative pressure distribution, and are modeled as exhaust fans. The air enters the broiler house through evaporative pads which are simulated as porous media and as heat sinks, concurrently. The heat sink term is yielded analytically according to the external climatic conditions and the evaporative pads specifications. The litter and the animals are considered also as porous materials and sources of heat. The birds’ thermal properties and their heat emissions are computed according to their age, the measured birds’ volume, and height and meat composition. The developed CFD model is validated against measurements of temperature (16 points) and air velocity (6 points). According to the simulation results, it is drawn that the vertical temperature gradient should be taken into account when the operational sensors for the cooling devices are positioned inside the chamber since there is a deviation higher than 2 °C between the air content above and among the birds.Also various combinations of the available five fans, operating in two possible modes of the examined poultry chamber are studied in order to assess their effect to the internal microclimate. The operation of two or three central fans are proven to be the optimum choice in terms of temperature, ventilation and air velocity. The operation of only one fan fails to preserve the required temperature, while the operation of more than three fans does not improve the ventilation rates.