Hu Changzeng, Li Lihua, Jia Yuchen, Xie Zongkui, Yu Yao, Huo Limin
College of Mechanical and Electrical Engineering, Hebei Agricultural University, Baoding 071000, China.
Key Laboratory of Broiler/Layer Breeding Facilities Engineering, Ministry of Agriculture and Rural Affairs, Baoding 071000, China.
Animals (Basel). 2024 Sep 9;14(17):2623. doi: 10.3390/ani14172623.
Mechanical ventilation is an important means of environmental control in multitier laying hen cages. The mainstream ventilation mode currently in use, negative-pressure ventilation (NPV), has the drawbacks of a large temperature difference before and after adjustment and uneven air velocity distribution. To solve these problems, this study designed and analyzed a combined positive and negative-pressure ventilation system for laying hen cages. According to the principle of the conservation of mass to increase the inlet flow in the negative-pressure ventilation system on the basis of the addition of the pressure-wind body-built positive-and-negative-pressure-combined ventilation (PNCV) system, further, computational fluid dynamics (CFD) simulation was performed to analyze the distribution of environmental parameters in the chicken cage zone (CZ) with inlet angles of positive-pressure fans set at 45°, 90°, and 30°. Simulation results showed that the PNCV system increased the average air velocity in the CZ from 0.94 m/s to 1.04 m/s, 1.28 m/s, and 0.99 m/s by actively blowing air into the cage. The maximum temperature difference in the CZ with the PNCV system was 2.91 °C, 1.80 °C, and 3.78 °C, which were all lower than 4.46 °C, the maximum temperature difference in the CZ with the NPV system. Moreover, the relative humidity remained below 80% for the PNCV system and between 80% and 85% for the NPV system. Compared with the NPV system, the PNCV system increased the vertical airflow movement, causing significant cooling and dehumidifying effects. Hence, the proposed system provides an effective new ventilation mode for achieving efficient and accurate environmental control in laying hen cages.
机械通风是多层蛋鸡笼舍环境控制的重要手段。目前使用的主流通风模式——负压通风（NPV），存在调节前后温差大、风速分布不均的缺点。为解决这些问题，本研究设计并分析了一种蛋鸡笼舍正负压联合通风系统。根据质量守恒原理，在压力风体式正负压联合通风（PNCV）系统的基础上增加负压通风系统的进风量，进一步通过计算流体动力学（CFD）模拟分析了正压风机进气角度设置为45°、90°和30°时鸡笼区域（CZ）内环境参数的分布情况。模拟结果表明，PNCV系统通过向鸡笼内主动送风，使CZ内的平均风速分别从0.94 m/s提高到1.04 m/s、1.28 m/s和0.99 m/s。PNCV系统在CZ内的最大温差分别为2.91℃、1.80℃和3.78℃，均低于NPV系统在CZ内的最大温差4.46℃。此外，PNCV系统的相对湿度保持在80%以下，NPV系统的相对湿度在80%至85%之间。与NPV系统相比，PNCV系统增加了垂直气流运动，产生了显著的降温除湿效果。因此，所提出的系统为实现蛋鸡笼舍高效精确的环境控制提供了一种有效的新型通风模式。
