| Spray disinfection is a necessary measure for large-scale breeding to reduce environmental pollution.At present,most of the domestic pig house spray disinfection operations use manual backpack spray or fixed facilities spray,and the spray head is a traditional flat mouth direct spray head,which has problems such as high labor intensity and unpredictable liquid medicine deposition.Therefore,it is of great theoretical and practical significance to carry out the design of gas-liquid integrated pig house spray sterilizer and the prediction and analysis of droplet deposition based on CFD.The main research contents are as follows:(1)According to the modern breeding mode of finishing pigs,the overall design scheme of the gas-liquid integrated pig house disinfection spray machine was proposed,which was mainly composed of centrifugal fan,air inlet channel,liquid inlet elbow,gas-liquid integrated nozzle,medicine box and rack;According to the disinfection specification of pig house,the main working parameters of spray are calculated as 6～9 L/min,3 m~3/s and 340 Pa for total flow,air volume and air pressure respectively,and the structural parameters of sprinkler installation height and adjustable angle of sprinkler are 1.2 m and-80°～80°respectively;Through Fluent simulation,when the air flow velocity is 6 m/s,the droplet velocity of the gas-liquid integrated nozzle is 37.5%higher than that of the ordinary nozzle.Through statics and modal analysis of the rack,the maximum stress is 0.7 MPa,and the first-order natural frequency is 19.623 Hz,which meets the design requirements and provides a basis for subsequent simulation.(2)According to the size of modern pigsty and the structural design of disinfection spray machine,the numerical model of spray field in pigsty area was constructed;Based on the DPM model,the spatial movement track of the droplets in the pigpen area was obtained,and the Fluent post-processing software was used to analyze the spatial deposition distribution of the droplets under different nozzle angles and spray speeds:in the horizontal and vertical directions,when the nozzle angle is constant,with the increase of the horizontal plane height,the droplet deposition amount increases with the increase of the spray speed.Under different working conditions,on a vertical surface,the maximum droplet concentration is 99%and the minimum is 75%.The highest proportion of fog droplets is 100%,and the lowest is10%.The highest droplet deposition rate is 99%,and the lowest is 7.5%.(3)Based on the pig model added to the spray farm in the pig pen area,the simulation experiment of droplet deposition on the pig surface was carried out;The effects of nozzle flow rate,nozzle angle and spray speed on the droplet deposition on pig surface were investigated,and a prediction model of droplet deposition on pig surface of gas-liquid integrated piggery spray disinfector was established by using multivariate orthogonal polynomial regression design method.When the flow rate was 9 L/min and the nozzle angle was 10°,when the spray speed range was about10～15.4 m/s,the droplet deposition was more than 0.4 L,providing a basis for the optimization of prototype parameters.(4)Trial production of a prototype,conducting comparative experiments on the droplet velocity of different nozzles,as well as experiments on the deposition distribution of droplets on the surface of pig pens and pig models.The results show that when the airflow velocity is 6 m/s,the droplet velocity of the gas-liquid integrated nozzle increases by 36.17%;The maximum error between the proportion of droplet deposition in the pigsty space and the simulation is 2%;The order of significance of the influence on the droplet deposition density on the pig surface is:spray speed,nozzle flow,nozzle angle.The optimal working parameters are the nozzle flow rate of 8.87 L/min,the nozzle angle of 19.51°,and the spray speed of11.97 m/s.At this time,the maximum deposition density is 48.28μl/cm~2,The error with the prediction model is 1.95%. |
