Design And Ventilation Optimization Of Closed Piglet Breeding Barn Based On CFD

In recent years,with the expansion and development of the field of pig breeding,pig health problems have also attracted wide attention.In addition to the variety,genetics and nutrition of pigs,environmental factors(ventilation,temperature and humidity,harmful gases)play an increasingly important role in pig health breeding.In order to achieve real-time monitoring and effective control of piglet growth environment and meet the needs of scientific research and production,a closed piglet breeding barn was designed.The main work of this paper is as follows:The overall design of piglet breeding warehouse.The breeding bin is designed with feeding cage,feeding and drinking water device,heating device,defecating device,environmental monitoring device and ventilation device.The feeding cage was fixed with transparent acrylic plate and aluminum profile;feeding by double open-door feeding,drinking water using piglets easy to find nipple type drinking water;the heating device consists of a temperature controller,a temperature sensor and a resistance wire;the defecating device is a two-stage defecating device,which is composed of defecating track and defecating collecting tank;environmental monitoring device consists of hardware and software;the ventilation device adopts positive pressure ventilation.Ventilation system design of piglet breeding barn.Four piglets with the maximum body weight of 15 kg were raised in the breeding bin.The length of the inlet side was15 cm and the diameter of the tube hole was 5 cm by calculating the maximum ventilation in summer.According to the air volume and pressure,the axial fan is selected,and the inverter is used to stepless speed control of the fan.In order to meet the needs of healthy breeding of piglets,three ventilation modes were designed,including transverse ventilation,longitudinal ventilation and U-type ventilation.The three ventilation modes were positive pressure ventilation,and the circular tube hole with diameter of 5 cm was set on the inner ventilation tube,and the direction was vertical downward.The difference between transverse ventilation,longitudinal ventilation and U-shaped ventilation is that the number of pipe holes is different,and the distribution position and inlet direction of internal pipes are different.Ventilation system simulation and optimization of breeding barn.Computational Fluid Dynamics(CFD)simulation and analysis of three ventilation modes(transverse ventilation,longitudinal ventilation and U-type ventilation)were carried out.The results show that the temperature change trend of transverse ventilation and U-type ventilation is basically the same in the temperature field.Taking piglets as the center,the temperature decreases gradually around,and the longitudinal ventilation temperature increases step by step from the front to the rear of the breeding bin,and the temperature difference between the front and rear is obvious.In the airflow field,the airflow velocity in the rear of the longitudinal ventilation breeding bin is greater than that in the front.The airflow dead angle in the U-type ventilation breeding bin is the most,and the airflow distribution in the transverse ventilation is more uniform than that in the other two ventilation modes.Therefore,the transverse ventilation is selected as the ventilation mode,and the pipe diameter,the number of pipe holes and the distribution position of the inner pipe of the transverse ventilation are optimized and simulated.The results show that in the temperature field,the temperature field changes of the optimization design of the pipe diameter and the optimization design of the distribution position of the inner pipe are basically the same.The low temperature distribution range of the optimization design of the number of pipe holes increases,and the temperature decreases faster around.In the airflow field,the airflow distribution of the optimized tube hole diameter is more uniform than that of the other two optimization designs,and the airflow velocity is closer to the suitable growth range of piglets.Through experimental verification,it is found that the maximum error between the simulated and measured temperature is 1.2°C,the relative error is between 1.8%and 6.1%,and the average relative error is 3.22%.The maximum error between the simulation value of airflow velocity and the measured value is 0.05m/s,the relative error is between 7.1% and 20%,and the average relative error is 13.02%,which confirms the validity of the simulation results.The environmental monitoring system of breeding barn was designed based on Labview.The hardware includes oxygen sensor,carbon dioxide sensor,temperature and humidity sensor,ammonia sensor,methane sensor,USB-to-485 module and 485 bus produced by Shandong Renke Co.,Ltd.In terms of software,COM3 is selected at the serial port setting.According to the Modbus communication protocol and the transmission characteristics of RS-485 bus,the program block diagram is compiled.The front panel is arranged by the interface design control of the option card in Labview software.