吊顶对湿帘风机纵向通风牛舍环境及牛生理的影响研究
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摘要
为了改善湿帘风机纵向通风系统应用于肉牛舍的降温效果和气流分布的均匀性,同时提高肉牛活动区的风速,该试验在实测的基础上,采用流体力学(computational fluid dynamics,CFD)的方法对安装吊顶的湿帘风机纵向通风肉牛舍的气流场进行模拟。模拟时将牛只按与实物原型等比例引入到模型中,经吻合性验证,风速的平均相对误差,Y=0.7m截面为27%,Y=1.2 m截面为14%,Y=1.7 m截面为13%,认为模型有效。结果表明:安装吊顶后,舍内的气流分布均匀,肉牛活动区域风速适宜,可为肉牛提供更为适宜的饲养环境。舍内Y=0.7 m截面的平均风速为0.75 m/s,Y=1.2 m截面的平均风速为0.88 m/s,Y=1.7 m截面的平均风速为1.00 m/s。未安装吊顶的牛舍,舍外平均温度(35.0±2.7)℃条件下,0.7 m高度处平均温度(30.0±0.7)℃,1.2 m高度处平均温度(30.1±0.8)℃,较舍外平均降温14%;安装吊顶的牛舍,舍外平均温度(37.2±2.1℃)℃条件下,0.7 m高度处平均温度(31.1±0.7)℃,1.2 m高度处平均温度(31.1±0.7)℃,较舍外平均降温16%,说明安装吊顶后降温效果显著。安装吊顶后,舍内平均相对湿度80.9%,有害气体浓度均在饲养标准范围内;呼吸频率为36次/min,平均等温指数(equivalent temperature index,ETI)为23.96,均未达到热应激水平。
In order to improve the airflow condition of vertical ventilation system with fan-pad evaporative cooling system with ceiling in the beef cattle barn applied to the cooling effect and the uniformity of air distribution in the beef cattle occupied zone, as well as to increase the wind speed. This experiment was conducted using computational fluid dynamics(CFD) method on the basis of the measured data to simulate the airflow condition of the vertical ventilation beef cattle barn with fan-pad evaporative cooling system and ceiling. The size of the barn is 52 m×12 m×4.2 m. The lying area of the beef cattle in the barn is along the length direction, and one group is set up at 2-3 intervals, and 8-12 fattened cattle are raised in each group. There were 81 beef cattle which averaged 330 kg of weight included in the study. In order to increase the wind speed in the animal occupied area without affecting the operation of manual feeding, the plastic ceiling was installed 3.3 m away from the lying area of the beef cattle. However, due to gravity, the middle part of the ceiling was downward, so in the CFD model, the ceiling height was 3.0 m. In the simulation, this experiment improved the original model, the number of cattle has increased to 81 and randomly distributed in the model. Measurement experiments were implemented from July to August 2016, which including test temperature, relative humidity, wind speed, enclosure structure temperature, surface temperature of beef cattle, respiration rate and their body size. The measured heights of wind speed were 0.7, 1.2 and 1.7 m above the floor, and the measured heights of temperature and relative humidity were 0.7 and 1.2 m. Measurements were conducted at 10:00, 12:00, 14:00 and 16:00. The temperature of walls, floors and ceiling were recorded by thermal infrared imager(Fluke Ti400), which were used for modeling. The modeling results showed that average relative error of the wind speed was 27% in Y = 0.7 m, 14% in Y=1.2 m and 13% in Y=1.7 m, respectively. The simulation results showed that vertical ventilation system with fan-pad evaporative cooling system and ceiling in this experiment can improve the uniformity of wind speed and air flow in the house. The environmental test results showed that the air flow in the barn with ceiling was uniform and the wind speed in the beef occupied zone was appropriate, which could provide more suitable environment for beef cattle. The average wind speed of the Y= 0.7 m section was 0.75 m/s, the average wind speed of the Y= 1.2 m section was 0.88 m/s, and the average wind speed of the Y= 1.7 m section was 1.0 m/s. Inner average temperature 30.0 ℃, which was lower than the outside by 16%. The average relative humidity was 80.9% and the concentration of harmful gas was within the standard range, and ETI did not reach the level of heat stress. The results can provide a reference for design of this type of beef cattle house.
In order to improve the airflow condition of vertical ventilation system with fan-pad evaporative cooling system with ceiling in the beef cattle barn applied to the cooling effect and the uniformity of air distribution in the beef cattle occupied zone, as well as to increase the wind speed. This experiment was conducted using computational fluid dynamics(CFD) method on the basis of the measured data to simulate the airflow condition of the vertical ventilation beef cattle barn with fan-pad evaporative cooling system and ceiling. The size of the barn is 52 m×12 m×4.2 m. The lying area of the beef cattle in the barn is along the length direction, and one group is set up at 2-3 intervals, and 8-12 fattened cattle are raised in each group. There were 81 beef cattle which averaged 330 kg of weight included in the study. In order to increase the wind speed in the animal occupied area without affecting the operation of manual feeding, the plastic ceiling was installed 3.3 m away from the lying area of the beef cattle. However, due to gravity, the middle part of the ceiling was downward, so in the CFD model, the ceiling height was 3.0 m. In the simulation, this experiment improved the original model, the number of cattle has increased to 81 and randomly distributed in the model. Measurement experiments were implemented from July to August 2016, which including test temperature, relative humidity, wind speed, enclosure structure temperature, surface temperature of beef cattle, respiration rate and their body size. The measured heights of wind speed were 0.7, 1.2 and 1.7 m above the floor, and the measured heights of temperature and relative humidity were 0.7 and 1.2 m. Measurements were conducted at 10:00, 12:00, 14:00 and 16:00. The temperature of walls, floors and ceiling were recorded by thermal infrared imager(Fluke Ti400), which were used for modeling. The modeling results showed that average relative error of the wind speed was 27% in Y = 0.7 m, 14% in Y=1.2 m and 13% in Y=1.7 m, respectively. The simulation results showed that vertical ventilation system with fan-pad evaporative cooling system and ceiling in this experiment can improve the uniformity of wind speed and air flow in the house. The environmental test results showed that the air flow in the barn with ceiling was uniform and the wind speed in the beef occupied zone was appropriate, which could provide more suitable environment for beef cattle. The average wind speed of the Y= 0.7 m section was 0.75 m/s, the average wind speed of the Y= 1.2 m section was 0.88 m/s, and the average wind speed of the Y= 1.7 m section was 1.0 m/s. Inner average temperature 30.0 ℃, which was lower than the outside by 16%. The average relative humidity was 80.9% and the concentration of harmful gas was within the standard range, and ETI did not reach the level of heat stress. The results can provide a reference for design of this type of beef cattle house.
引文
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[11]Boulard T,Kittas C,Roy J C,et al.Convective and ventilation transfers in greenhouses.2.Determination of the distributed greenhouse climate[J].Biosystems Engineering,2002,83(1):1-20.
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[14]Council National Rearch.A Guide to Environmental Research on Animals[M].Washington D C:National of Academy Science,1971.
[15]Baeta F C,Meador N F,Shanklin M D,et al.Equivalent temperature index at temperatures above the thermoneutral for lactating dairy cows[J].American Society of Agricultural Engineers,1987,30(7):76-89.
[16]Bustamante E,Calvet S,Estellés F,et al.Measurement and numerical simulation of single-sided mechanical ventilation in broiler houses[J].Biosystems Engineering,2017,160:55-68.
[17]Blanes-Vidal V,Guijarro E,Balasch S,et al.Application of computational fluid dynamics to the prediction of airflow in a mechanically ventilated commercial poultry building[J].Biosystems Engineering,2008,100(1):105-116.
[18]Chen Qingyan,Srebric J.A procedure for verification,validation,and reporting of indoor environment CFDanalyses[J].HVAC&R Research,2002,8(2):201-216.
[19]赵荣义.空气调节[M].第3版.北京:中国建筑工业,1994.
[20]李如治.家畜环境卫生学[M].第四版.北京:中国农业大学出版社,2011.
[21]Dolby C M.Volume II Animal Production&Aquacultural Engineering,Part I Livestock Housing and Environment,Chapter 1 Characteristics and Performances of Construction Materials[M].CIGR Handbook of Agricultural Engineering,1999,17(4):36-63.
[22]畜禽场环境质量标准:NY/T388-1999[S].
[23]陈幼春.现代肉牛生产[M].北京:中国农业出版社,1999.
[24]Berman A,Folman Y,Kaim M.Upper critical temperatures and forced ventilation effects for high-yielding dairy cows in a subtropical climate[J].Journal of Dairy Science,1985,6(68):1488-1495.
[25]Silva Roberto Gomes Da,Maia Alex Sandro C,Costa Leonardo Lelis De Macedo.Index of thermal stress for cows(ITSC)under high solar radiation in tropical environments[J].International Journal of Biometeorology,2015,59(5):551-559.
[26]贺城,牛智有,齐德生.基于CFX的猪舍内温度和气流场模拟研究[J].畜牧与兽医,2009(11):22-25.
[27]Cheng Qiongyi,Li Hao,Rong Li,et al.Using CFD to assess the influence of ceiling deflector design on airflow distribution in hen house with tunnel ventilation[J].Computers and Electronics in Agriculture,2018,151:165-174.
[28]Smyk E D,Mrozik S,Wawrzyniak.Tabular air deflector in ventilation ducts[C]//23rd International Conference,Svratka,Czech Republic,2017.
[29]Duan Enze,Kong Dandan,Wang Hongying.Study on the indoor environmental simulation and optimal design of rabbit houses in winter based on CFD[C]//2018 ASABE Annual International Meeting,2018.
[30]Li Hao,Rong Li,Zong Chao,et al.Assessing response surface methodology for modelling air distribution in an experimental pig room to improve air inlet design based on computational fluid dynamics[J].Computers and Electronics in Agriculture,2017,141:292-301.
[2]覃智斌,左福元.肉牛热应激研究进展[J].现代畜牧兽医,2007(9):52-54.
[3]Edouard Nadège,Mosquera Julio,van Dooren Hendrik J C,et al.Comparison of CO2-and SF6-based tracer gas methods for the estimation of ventilation rates in a naturally ventilated dairy barn[J].Biosystems Engineering,2016,149:11-23.
[4]Mendes Luciano B,Edouard Nadge,Ogink Nico W M,et al.Spatial variability of mixing ratios of ammonia and tracer gases in a naturally ventilated dairy cow barn[J].Biosystems Engineering,2015,129:360-369.
[5]Rong Li,Nielsen Peter V,Bjerg Bjarne,et al.Summary of best guidelines and validation of CFD modeling in livestock buildings to ensure prediction quality[J].Computers&Electronics in Agriculture,2016,121:180-190.
[6]王校帅.基于CFD的畜禽舍热环境模拟及优化研究[D].杭州:浙江大学,2014.Wang Xiaoshuai.Study on the Indoor Thermal Environmental Simulation and Optimal Design of Livestock Building based on CFD[D].Huangzhou:Zhejing University,2014.(in Chinese with English abstract)
[7]邓书辉,施正香,李保明,等.低屋面横向通风牛舍空气流场CFD模拟[J].农业工程学报,2014,30(6):139-146.Deng Shuhui,Shi Zhengxiang,Li Baoming,et al.CFDsimulation of airflow distribution in low profile cross ventilated dairy cattle barn[J].Transactions of the Chinese Society of Agricultural Engineering(Transactions of the CSAE),2014,30(6):139-146.(in Chinese with English abstract)
[8]Mondaca M,Choi C Y.A computational fluid dynamics model of a perforated polyethylene tube ventilation system for dairy operations[J].Transactions of the ASABE,2016,59(6):1585-1594.
[9]姚家君,郭彬彬,丁为民,等.基于鹅舍气流场CFD模拟的通风系统结构优化与验证[J].农业工程学报,2017,33(3):214-220.Yao Jiajun,Guo Binbin,Ding Weimin,et al.Structure optimization and validation of goose house ventilation system based on airflow field simulation by CFD[J].Transactions of the Chinese Society of Agricultural Engineering(Transactions of the CSAE),2017,33(3):214-220.(in Chinese with English abstract)
[10]陈昭辉,马一畅,刘睿,等.夏季肉牛舍湿帘风机纵向通风系统的环境CFD模拟[J].农业工程学报,2017,33(16):211-218.Chen Zhaohui,Ma Yichang,Liu Rui,et al.Numerical simulation of environmental conditions for fan-pad evaporative cooling system of beef cattle barn in summer[J].Transactions of the Chinese Society of Agricultural Engineering(Transactions of the CSAE),2017,33(16):211-218.(in Chinese with English abstract)
[11]Boulard T,Kittas C,Roy J C,et al.Convective and ventilation transfers in greenhouses.2.Determination of the distributed greenhouse climate[J].Biosystems Engineering,2002,83(1):1-20.
[12]Gebremedhin K G,Wu B.Simulation of flow field of a ventilated and occupied animal space with different inlet and outlet conditions[J].Journal of Thermal Biology,2005,30(5):343-353.
[13]尹洁,金米娜,肖安,等.江西夏季高温天气期间副高特征与预报方法[J].气象与减灾研究,2011(2):19-25.Yin Jie,Jin Mina,Xiao An,et al.The subtropical high features and prediction method of temperature during summer in Jiangxi province[J].Meteorology and Disaster Reduction Research,2011(2):19-25.(in Chinese with English abstract)
[14]Council National Rearch.A Guide to Environmental Research on Animals[M].Washington D C:National of Academy Science,1971.
[15]Baeta F C,Meador N F,Shanklin M D,et al.Equivalent temperature index at temperatures above the thermoneutral for lactating dairy cows[J].American Society of Agricultural Engineers,1987,30(7):76-89.
[16]Bustamante E,Calvet S,Estellés F,et al.Measurement and numerical simulation of single-sided mechanical ventilation in broiler houses[J].Biosystems Engineering,2017,160:55-68.
[17]Blanes-Vidal V,Guijarro E,Balasch S,et al.Application of computational fluid dynamics to the prediction of airflow in a mechanically ventilated commercial poultry building[J].Biosystems Engineering,2008,100(1):105-116.
[18]Chen Qingyan,Srebric J.A procedure for verification,validation,and reporting of indoor environment CFDanalyses[J].HVAC&R Research,2002,8(2):201-216.
[19]赵荣义.空气调节[M].第3版.北京:中国建筑工业,1994.
[20]李如治.家畜环境卫生学[M].第四版.北京:中国农业大学出版社,2011.
[21]Dolby C M.Volume II Animal Production&Aquacultural Engineering,Part I Livestock Housing and Environment,Chapter 1 Characteristics and Performances of Construction Materials[M].CIGR Handbook of Agricultural Engineering,1999,17(4):36-63.
[22]畜禽场环境质量标准:NY/T388-1999[S].
[23]陈幼春.现代肉牛生产[M].北京:中国农业出版社,1999.
[24]Berman A,Folman Y,Kaim M.Upper critical temperatures and forced ventilation effects for high-yielding dairy cows in a subtropical climate[J].Journal of Dairy Science,1985,6(68):1488-1495.
[25]Silva Roberto Gomes Da,Maia Alex Sandro C,Costa Leonardo Lelis De Macedo.Index of thermal stress for cows(ITSC)under high solar radiation in tropical environments[J].International Journal of Biometeorology,2015,59(5):551-559.
[26]贺城,牛智有,齐德生.基于CFX的猪舍内温度和气流场模拟研究[J].畜牧与兽医,2009(11):22-25.
[27]Cheng Qiongyi,Li Hao,Rong Li,et al.Using CFD to assess the influence of ceiling deflector design on airflow distribution in hen house with tunnel ventilation[J].Computers and Electronics in Agriculture,2018,151:165-174.
[28]Smyk E D,Mrozik S,Wawrzyniak.Tabular air deflector in ventilation ducts[C]//23rd International Conference,Svratka,Czech Republic,2017.
[29]Duan Enze,Kong Dandan,Wang Hongying.Study on the indoor environmental simulation and optimal design of rabbit houses in winter based on CFD[C]//2018 ASABE Annual International Meeting,2018.
[30]Li Hao,Rong Li,Zong Chao,et al.Assessing response surface methodology for modelling air distribution in an experimental pig room to improve air inlet design based on computational fluid dynamics[J].Computers and Electronics in Agriculture,2017,141:292-301.