Study On Fine Environment Control Methods For Confined Pig House In Northern China

Since the 1990s,with the rapid development of China’s economy,people’s living standards have been continuously improved,and people’s demand for meat is also growing.With the strong support of the government and policies,China has achieved remarkable achievements in the pig industry and has become the world’s largest pig industry country.With the large-scale development of the pig industry,China has gradually shifted from traditional methods to large-scale pig farming.From the year 2001 to present,the scale of pig industry in China has been increasing year by year.However,the problems in large-scale pig farming have gradually exposed with the rapid development of pig industry.Among them,poor sanitary conditions,easily spreading diseases,low pork quality,and poor animal welfare caused by bad pig environment of pig house seriously restrict further development of pig industry in China.Aiming the problems above,this paper takes confined pig houses of northern China as the research object,and proposed a fine,automatic method for the regulation of pig house environment.The research included the following aspects:（1）Construction of environmental climate model of pig house.The temperature model,relative humidity model and harmful gases predicting model were constructed.The temperature model was constructed based on energy conservation law,the relative humidity model was constructed based on conservation of mass,and the harmful gases predicting model was constructed based on BP neural networks and RBF neural networks.The results of simulations for predicting carbon dioxide（CO₂）and ammonia（NH₃）suggested that the predicting model based on BP neural networks and RBF neural networks had excellent performance.The goodness of fit achieved above 92%.（2）Construction of ventilation and environmental parameters relationship.The main researches were on the effects of ventilation on the environmental parameters in pig houses.A ventilation-temperature relationship model,a ventilation-relative humidity relationship model,and a ventilation-harmful gases concentration relationship model were constructed.Furthermore,according to the actual conditions of the northern winter cold,the ventilation-temperature compensation relationship model and the ventilation-humidity compensation relationship model were constructed,and the calculation method for determining the compensation coefficients were given.（3）Construction of fine regulation models for confined pig houses.Two decoupled fuzzy controllers were designed based on fuzzy control theory to solve the contradictions between ventilation,heat preservation and moisturizing during winter in northern cold regions of China.The temperature,relative humidity,and harmful gas concentration in the pig house are controlled by the fuzzy control algorithm.The parameters were adjusted and the control algorithm was simulated by programming.（4）Analysis of the fine regulation of the environment in pig houses.According to the simulation results of fine environmental regulation,the steady-state fluctuation variance of environmental parameters and the power consumption of the equipments under the two decoupled fuzzy controllers were analyzed.The results showed that one of the decoupled fuzzy controllers had more excellent regulation performance,and were able to make all environmental parameters of the pig house within a suitable range with a small steady-state fluctuation variance.Compared with the manual regulation,the regulation equipments were able to save power consumption 35%in day time.The fine environmental regulation method of confined proposed in this paper were able to effectively regulate the environmental parameters.The parameters including temperature,relative humidity,and harmful gases concentration（NH₃,CO₂）.The method were also able to save power consumption and reducing farming costs.