Numerical study of mechanically ventilated broiler house equipped with evaporative pads
Numerical study of mechanically ventilated broiler house equipped with evaporative pads
复制标题
DOI：
10.1016/j.compag.2017.10.016
复制
发表时间：
2018-06-01
影响因子：
8.3
通讯作者：
Kittas, Constantinos
中科院分区：
文献类型：
--
作者：
Fidaros, Dimitris;Baxevanou, Catherine;Kittas, Constantinos
提高肉鸡生产的重要因素之一是以尽可能低的成本提供最佳的室内环境（空气质量、温度、湿度、风速、气体和PMs浓度）。室内微气候可以通过选择适当的结构几何形状和材料被动控制，也可以通过通风系统和机电（E/M）设备主动控制。在肉鸡室的情况下，构成最佳内部微气候的条件随鸟的年龄而变化。在目前的工作中，通风，在一个现代化的和全自动的肉鸡室内配备风扇和蒸发垫位于希腊中部，使用计算流体动力学（CFD）技术进行模拟。采用有限体积法求解雷诺平均Navier-Stokes（RANS）方程，描述了肉鸡舍内的输运现象。假设流动为三维、稳态和湍流。肉鸡室的风扇从内部吸取空气，形成内部负压分布，并被建模为排气风扇。空气通过同时模拟为多孔介质和散热器的蒸发垫进入肉鸡舍。根据外部气候条件和蒸发垫规格，解析地得出散热器项。垫料和动物也被认为是多孔材料和热源。根据鸡的年龄、体积、身高和肉的组成计算了鸡的热特性和热辐射。所开发的CFD模型针对温度（16个点）和空气速度（6个点）的测量进行了验证。根据模拟结果，得出当用于冷却装置的操作传感器被定位在腔室内时，应当考虑垂直温度梯度，因为在上方的空气含量和在鸟之间的空气含量之间存在大于2摄氏度的偏差。在两种可能的模式下运行的被检查的家禽室进行了研究，以评估其对内部小气候的影响。两个或三个中央风扇的运行被证明是温度，通风和风速方面的最佳选择。只有一个风扇的运行不能保持所需的温度，而三个以上的风扇的运行不会提高通风率。
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 degrees 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.