| Specific Pathogen Free Swine is an effective way to solve pig disease, and is conducive to improve production performance of pig and avoid antibiotic residues in pork exceed the standard phenomenon. Pig house environment must be reasonable controlled to prevent SPF from infecting specific disease again in the process of production. However, there is little information about SPF house in China. In this paper, a reconstruction scheme was used to reform the old boar house of Beijing Breeding Swine Center, and then field experiments combined with Computational Fluid Dynamics were used to simulate internal environment in pig house during summer and winter conditions, finally, a theory method was employed to meet uniform ventilation in slurry pit. All the methods mentioned about were expected to provide theoretical basis for further reform of pig house. The results are as follows:1. The field measurement results under pad and fan ventilation system during summer condition showed that the distribution of temperatures is suitable(between22℃and25℃). However, the relative humidity is relatively higher(between70%and). The distribution of velocity is between0.6m/s and1.4m/s, and is suitable at0.6meter(between0.6m/s and0.9m/s).The temperatures under winter without water-heated system is a little lower(between12℃and14℃).The velocity is slow (about0.11m/s).The ammonia concentrations is lower(from2to3mg/L).2. On the base of field measurement, two three-dimensional CFD model of boar building under pad and fan ventilation system and slurry pit ventilation condition were established. The temperature distribution and airflow patterns and ammonia concentration distribution were simulated with standard k-ε turbulent model, the models were validated with field experimental results, the results indicated that the simulated results fitted with the experimental results in high degree. Thus the two CFD model were reasonable, and it also revealed that porous media is an effective method to simplify slatted floor in CFD model.3. The simulated results of pad and fan system indicated that the range of temperature is narrow, the temperature distribution are increased both from pad to fan and floor to ceiling. The velocity is between0.6to1.4m/s, and is uniform from pad to fan direction. However, there is a wide range of velocity from floor to ceiling direction, the velocity in slurry pit are below0.1m/s, while the velocity in pig occupied zone are between0.6to1.2m/s, thus it present an upward in this direction. There are two airflow pattern in boar building, the airflow pattern in slurry pit is similar to wave and above the floor the pattern is almost horizontal in pad to fan direction.4. The simulated results under winter condition showed that there is an upward in temperature from floor to ceiling, comparing with without pig zone the temperature is more higher near pig occupied zone. The airflow figure showed that there are two vortexes in both ceiling air intake sides. The pattern in slurry pit is main toward to fan. However, the airflow is very low far from fan.5. The distribution of internal environment under summer simulation can provide a theoretical basis for temperature detectors’ installation position. It is conducive to exhaust odors by setting ceiling air intake and slurry pit air outlet. However, in the initial scheme the ventilation of slurry is nonuniform. Therefore this paper presents a uniform ventilation duct design method which based on the law of conservation of energy calculation to improve slurry pit ventilation. The area of lateral holes on equal crossover duct is increased from fan to the other end. |
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