层叠式笼养肉鸭舍冬季环境测试及通风窗位置优化模拟

Winter environment test and ventilation window location optimization of cascading cage-rearing laying duck house

肉鸭产业规模化程度越来越高、空间集聚日益明显,层叠式笼养是发展最为迅速的立体养殖模式。该文对层叠式笼养鸭舍内的温湿度、气流、CO2及NH3质量浓度进行测试,构建了鸭舍的CFD模型,开展温度场和气流场的环境模拟,并提出现有鸭舍气流组织形式的优化方案。研究结果表明,测试期间(2018-12-1800:00-2018-12-2200:00),鸭舍内气温11.35~20.68℃,舍内外平均温差10.86℃;舍内平均相对湿度70.27%,略高于舍外;舍内CO2、NH3平均质量浓度分别为3285、0.33 mg/m^3。模拟原有鸭舍的温度场和气流场,与实测结果进行对比,平均相对误差为6.59%~8.87%,说明该文所建模型的数值模拟与试验数据具有很好的一致性。进一步通过降低一侧通风小窗的高度来优化鸭舍的气流组织,模拟发现优化后模型的舍内温度范围为11.07~19.71℃,其温度波动范围较原模型有明显减小,降低了肉鸭对温度的应激效应;优化后模型北侧第1列底层、第3列中层、第5列上层的平均风速分别为0.34、0.34、0.31m/s,较原模型更加均匀。通过该研究,可为同类型鸭舍合理规划设计与改善舍内环境质量提供理论依据。

In recent years,the meat duck industry in China is mainly dominated by small-scale free rearing.This single-layered flat rearing pattern was characterized by low density,difficulty in feces and sewage management and simple infrastructure,which was weeded out due to the intense pressure for land resources and environment protection.Meanwhile,there was an increasing scale in the development of meat duck industry and an increasing tendency in the spatial aggregation.The cascading cage-rearing laying of meat duck is the rapidly developed stereoscopic breeding pattern.Compared to the traditional duck-rearing pattern,the new meat duck rearing system has an advantage in the improved land use rate,convenient duck feces processing and reduced labor costs.However,there is an accumulation of hazardous gas,particulate matter and airborne microorganism in intensive poultry houses.Poor ventilation not only affects the air quality in poultry houses,but also significantly increases the mirco-environmental humidity,thereby degrading animal’s health and growth.Therefore,the reasonable design and well airflow organization is an important measures for the improvement of environmental quality in houses.Duck house were built at Xintai Ecological Meat Duck Research Base of Shangdong Province(35°30′N,117°27′E).Length,width and ridge height of the meat duck house were 80.0,13.0 and 4.0 m.Roof height was 2.6 m.Upper architectural system of the duck house was light steel,while the wall body was a brick-cement structure.24 ventilation window(length×height=560 mm×360 mm)were each installed in the south and north walls of duck cages.These ventilation window were evenly distributed at the upper parts of the south and north walls.The ventilation window was controlled by 100 mm-thick color steel polystyrene sandwich boards.Lower parts of the ventilation window were 1.94 m to the floor.Three layers×five columns of cascading individually cages(Length×Width×Height=69.8 m×1.0 m×2.02 m)were installed inside the duck house.There were 67 duck cages at each layer.Fifteen Cherry Valley meat ducks were reared in an individual cage which size was 1000 mm×1000 mm×400 mm(Length×Width×Height).To construct the CFD model of duck house,temperature,humidity,CO2 and NH3 concentration in the cascading duck-rearing cages were measured.Temperature field and airflow field of the duck house were simulated and an optimal design for the air conditioning pattern of the present duck house was raised.Results of the study showed that during the test period air temperature in the duck house was 11.35-20.68,℃ while the average temperature difference between the inner and outer side of the duck house was 10.86℃.The average relative humidity inside the duck house was 70.27%,slightly higher than that outside the house.Average concentrations of CO2 and NH3 in the house were 3285 and 0.33 mg/m^3,respectively.The average relative error between the simulated temperature field and airflow field of the original duck house and the measured results was 6.59%-8.87%,suggesting a very good consistence between the digital simulation of the constructed model and the experimental results.Air conditioning was further optimized by lowering the height of ventilation window in either wall.Results of simulation showed that the temperature range of inside the house after model optimization was 11.07-19.71℃.The fluctuation range of temperature was dramatically reduced compared to the original model,which had reduced the temperature-induced stress for ducks.The average air speeds of optimized model W1,W2 and W3 were 0.34,0.34 and 0.31 m/s,respectively.This was more even than the original model.Results of the present study will supply theoretical evidence to the reasonable design and improvement of the environmental quality for the similar kind of duck house.