Numerical Simulation And Optimization Research Of Airflow Field And Temperature Field In A Vertical Ventilated Piggery Based On CFD

The environmental quality of piggery,such as airflow velocity,temperature,relative humidity and harmful gas concentration,directly affects the health and production capacity of pigs,and then affects the quality of pork and the economic benefits of the pig industry.At present,intensive and high-density feeding method has become the mainstream of the development of the breeding industry,but in this closed and high-density feeding process,there are problems such as high temperature,poor airflow and uneven airflow distribution in the piggery.Taking Jiangxi Zengxin ecological breeding demonstration base based on field measurement data,using Soild Works software set up 1:1 piggery three-dimensional physical model,and using Computational Fluid Dynamics(CFD)method for vertical ventilation piggery internal environment simulation,analysis and assessment,compared with the results of simulation in the measured test data based on the research of basic consistent and related analysis,carry out ventilation pillar different Angle of piggery environmental simulation research and experimental proof.The main research contents and conclusions are as follows:1.CFD simulation and experimental verification were carried out on the three-dimensional piggery mode.The results show that the average value of the absolute error between the simulation and the measured air velocity is 0.03m/s,the average value of the relative error is 11.1%,and the maximum absolute error is 0.16m/s.The average value of the absolute error between the simulation and the measured temperature is 0.9℃,the average value of the relative error is 3.9%,and the maximum absolute error is 2.0 ℃.Moreover,Normalized mean square error(NMSE)for evaluating the reliability of CFD simulation meets the requirements.It shows that the simulation value is in good agreement with the measured value,The CFD method used in this paper is feasible to simulate the distribution of airflow field and temperature field in piggery.2.The simulation found that the temperature in the swinery area is basically maintained at 22℃～24℃,which is beyond the suitable temperature of the fatting pig at18℃～22℃.Most of the air velocity in the swinery area is below 0.2m/s,and there are airflow dead zones in some areas,which are unfavorable for heat dissipation of pig and ventilation in the pig active area.After being guided by the ventilating column,the airflow impacts with the ceiling vertically,resulting in energy loss,not conducive to ventilation of the piggery.The air bounced off the roof and flowed into the piggery area,and much of it flowed into the corridor area,which was not conducive to the further improvement of the environment in the pig active area.3.The optimum design of piggery environment was carried out for the tilting angle of ventilation column outlet,and the optimization schemes of different tilting angles of 45°,60° and 75° of ventilation column are put forward.The results show that when the tilt angle of the ventilation column is 45°,the direction of fresh air flowing into the piggery is changed,making the distribution of airflow velocity and temperature field in the piggery more reasonable,and the ventilation effect of piggery is greatly improved.After optimization,the average air velocity in the active area of pig increased by 0.11m/s and41.5%,the unevenness coefficient of air velocity distribution decreased by 29.9%.The average temperature in the active area of the pigs decreased by 2 ℃ and 8.4%,the unevenness coefficient of the temperature distribution decreased by 45.9%.4.The approximate model method was used to make the model test bench of the model and the prototype piggery according to the proportion of the model/prototype =1/5.At the same time,according to the optimization scheme,the ventilation column models with different tilting angles were made,and the simulation analysis and experimental verification of the ventilation column piggery models with different tilting angles were carried out.When the tilt angle is 45°,the distribution of airflow velocity and temperature field is more reasonable,and the ventilation effect is greatly improved.which verifies the reliability of the optimal design of vertical ventilation piggery.This paper provides a reliable,economical and effective method for the design of piggery environment,and also provides a basis and guidance for the design of other livestock and poultry sheds.