Simulation Research On Temperature And Humidity System Of Fresh Air In Large Scale Delivery Sow House

In the large-scale pig house,the reproductive environment of the delivery mother pig house has higher requirements than that of the ordinary fattening pig house.There are strict national standards for ventilation,temperature,relative humidity,CO₂concentration,NH₃concentration and H₂S concentration.The traditional pig farm is difficult to meet the standard requirements,the elimination rate of sows and piglets is high,and sows and piglets have a high market value.Reducing the elimination rate of sows and piglets can greatly improve the income of pigsty.In this study,a new air constant temperature and humidity system was designed.Through the innovative ventilation design,the problem of harmful gas enrichment caused by the confusion of air distribution in the traditional piggery was mainly solved,and then the sows and piglets had a good living environment through constant temperature and humidity to ensure the survival rate.The innovative ventilation mode of the new air constant temperature and humidity system designed in this study is introduced as follows:the system can accurately supply air to the single pigsty in the pigsty.There is a 0.6m deep dung ditch under the pig farm.Each pigsty is equipped with an independent air inlet.The air outlet is designed above the back of the sow to directly supply air to the back of the sow.The exhaust fan is designed on the partition walls at both ends of the dung ditch.In this way,fresh air can be accurately sent to each pigsty,and then pass through the seam floor to reach the dung ditch below,and the air can be discharged from both sides of the dung ditch.At the same time,the harmful gas in the dung ditch can be taken away,and the harmful gas can be treated in a centralized way.This design prevents the harmful gas from flowing back into the pig farm,which leads to the problem of high concentration of harmful gas in the pig farm and large area infection of pigs.The specific research is as follows:（1）Simulation study on temperature and humidity of single pigsty:take the field test data and design requirements as the initial value of single pigsty,combined with the requirements of relevant national standards,the simulation design is carried out.The results show that the temperature and humidity are basically in line with the expected design results under the condition that the circular air outlet is used as the air supply outlet,the wind speed is 0.9m/s,the outlet diameter is 250mm,and the set height is 1.2m from the ground.（2）Simulation of harmful gas concentration in single pigsty:the harmful gases studied in this chapter are CO₂,NH₃and H₂S.According to the different position of the release,it is divided into two simulation studies.The simulated CO₂concentration is 0.0623%,while the standard comfort value is 0.0656%,which is close to the standard critical value.The highest concentration of NH₃and H₂S was in the area under the sow’s belly,and the characteristic point was 0.274mg/m³of NH₃and0.0469mg/m³of H₂S.All of them are far below the national standard.It is proved that the system has a good function of isolating harmful gases.（3）Simulation study on temperature,humidity and harmful gas of the whole pig house:further add complex conditions,introduce wall heat transfer,gas cross between pig pens and other problems,and describe the deviation compared with the previous two single room simulation.The results show that compared with the single room simulation,the overall simulation has a small increase in temperature,humidity and harmful gas concentration,which still meets the national standard.（4）The actual experimental verification research:verify the accuracy of the temperature and humidity field simulation,and reflect the difference between the actual situation and the simulation results.The results show that although the simulation results have some deviation from the actual,and are affected by the external temperature,the basic law of the reaction is consistent,the deviation is also in a reasonable range,and the distribution of temperature and humidity field and harmful gas concentration field are basically in line with the simulation.