Numerical Simulation On Indoor Hydrothermal Environment And Particle Matter Of The Piggery

The quality of the environment could directly affect the production performance of pigs, which not only thereby influence the pork quality but also the economic benefits of pig raising industry. In particular for the nursery pigs, as they have just undergone weaning stress, they are quite sensitive to the external environment change. Compared with pigs during other growth stages, the piglets are more vulnerable the ambient conditions to resist the diseases. The growth environment for the nursery pigs should be put great emphasis since it could affect the morbidity, mortality and late growth of the pig. The field measurement of the barn environment and its assessment can find the piggeries environmental quality distribution deficiencies promptly and effectively. Thus further the design optimization to improve pig discounted environmental quality could be made. On the basis of computational fluid dynamics (CFD) simulation technology, assessment study on the current advanced form of ventilation for piglet nursery environment and its management is taken under cold weather. This study could be provided as useful suggestions for pig barn structure design and the environment improvement.Based on Navier-Stokes equations and RNG k-? turbulence model of computational fluid dynamics, discrete finite element method was used to simulate the environmental condition of piglet house in Southeast China. With the tools of Gambit, ANSYS Fluent 16.0, CFD-POST, the three dimensional steady simulation of the airflow, temperature, relative humidity and particle concentration were taken. From the results, conclusions can be drawn as followings:1) A weaner house equipped with combined ventilation was simulated for its velocity, temperature and relative humidity field. The results showed that:the airflow speed was 0-0.25m/s. By the far distance west wall it decreased significantly since the inlets were located on the east wall. The air by the west stayed for quite a long time, its age of air reached 15minutes, which equals a quarter of an hour. Although thermal environment in the barn suited for the weanling pig requirements, its temperature remained at 22-26? and relative humidity maintained at 65?73%, yet it was not the best condition Because of the existence of some dead zones, the environment distribution was actually not quite good.2) From the simulation results of air speed, temperature, relative humidity and particle concentration distribution of a piglet house with negative pressure ventilation system, it is known that:when the exhaust fan operated at variable frequency during the winter day, a large part of velocity in the barn was under 0.1 m/s. The cold flow from inlet and flow turbulence that could cause bad effects should be concerned. In the case of local heating lamps, the temperature was at 24?27?, and the relative humidity was 40?65%. These could meet the basic requirements for piglets raising hydrothermal environment. Yet, influenced by airflow movement, concentrations of particulate matter by the wall was higher than other parts, these locations were where piglets lied and rest. Thus it required the reasonable heating lamps distribution that ensures the warm condition for the piglets while reducing polluted particulate matter inhalation.