Obando Vega Felipe Andrés, Montoya Ríos Ana Paola, Osorio Saraz Jairo Alexander, Andrade Rafaella Resende, Damasceno Flávio Alves, Barbari Matteo
Facultad de Ciencias Agrarias, Universidad Nacional de Colombia, Carrera 65 N∘ 59A-110, Medellín 050034, Colombia.
Department of Agricultural Engineering, Federal University of Viçosa, Av. Peter Henry Rolfs, University Campus of Viçosa, Viçosa 36570-900, Brazil.
Animals (Basel). 2022 Jul 11;12(14):1776. doi: 10.3390/ani12141776.
Evaporative cooling is one of the most efficient techniques to reduce heat stress in cows in agricultural facilities. Additionally, compost-bedded pack barn has been shown to improve the welfare and production of cows. Two techniques were combined and analysed by developing a computational fluid dynamics (CFD) model of a tunnel-ventilated compost-bedded packed barn that integrated the heat and airflow dynamics of an evaporative pad cooling system. This allowed us to study the distribution of dry-bulb temperature, relative humidity and airflow velocity inside the barn based on the external environmental conditions, thickness of the pad, water temperature and specific manufacturer characteristics of the pad, providing optimal cooling pad location, size and operating conditions in the barn. Employing experimental data the CFD model was validated showing good agreement. The Equivalent Temperature Index for dairy Cattle (ETIC) was used to determine the level of stress of the cows considering the airflow velocity. It was found a moderate stress due to high relative humidity and low airflow velocity. From the predicted results, it was recommended to increase the airflow velocity above 3 m s-1 when simultaneously the external dry-bulb temperature and relative humidity exceed 30 °C and 55%, respectively, simultaneously. Additionally, installation of baffles at the pad outlet to drive the airflow to the floor was suggested to improve the drying of the compost-bedded closed to the pads, where a low airflow velocity region was established.
蒸发冷却是降低农业设施中奶牛热应激最有效的技术之一。此外，已证明堆肥垫料仓可改善奶牛的福利和生产性能。通过开发一个隧道通风堆肥垫料仓的计算流体动力学（CFD）模型，将这两种技术结合起来进行分析，该模型整合了蒸发垫冷却系统的热动力学和气流动力学。这使我们能够根据外部环境条件、垫料厚度、水温以及垫料的特定制造商特性，研究牛舍内干球温度、相对湿度和气流速度的分布情况，从而确定牛舍内最佳的冷却垫位置、尺寸和运行条件。利用实验数据对CFD模型进行了验证，结果显示吻合度良好。考虑到气流速度，使用奶牛等效温度指数（ETIC）来确定奶牛的应激水平。发现由于高相对湿度和低气流速度导致了中度应激。根据预测结果，建议在外部干球温度和相对湿度分别超过30℃和55%时，将气流速度提高到3米/秒以上。此外，建议在垫料出口处安装挡板，将气流引导至地面，以改善靠近垫料处堆肥垫料的干燥情况，此处存在气流速度较低的区域。
