Developing the Computational Simulator to Control the Ventilation Condition of Poultry House and Optimize the Production

In livestock and specifically poultry houses, controlling the internal environment conditions is a key factor to increase animal productivity and prevent their casualties. Controlling the atmospheric conditions like the air temperature and gas concentration in semi-enclosed spaces like poultry houses can improve the living conditions. Experimental tests on the atmospheric conditions of livestock and poultry houses are challengeable and due to limitation of measurement points, unstable climate conditions and experimental errors. Simulation of the air temperature and momentum conditions is used unlimitedly with computer resources by Computational Fluid Dynamics (CFD) methods to overcome the limitations of experimental tests. This method has vast abilities of parametric analysis and predicting the optimum range of functional parameters. So in this research, the air temperature and velocity distribution of a poultry house were simulated using CFD to achieve the best condition for the air ventilation and uniform temperature distribution.   

In the present study, the geometrical model of poultry house was created using Gambit software and meshed. The mesh independence study was also performed. According to the results, 166550 elements were enough to solve the problem with an acceptable accuracy.The Reynolds-averaged Navier-Stokes (RANS) equation was selected to simulate the momentum transfer inside the poultry house. The k-ε model is one of the most used turbulence models for industrial applications. The main assumption in this model is that the flow is incompressible and that the fluid is Newtonian. A transient heat transfer equation within the fluid domain was selected to predict the air temperature that describes a time-dependent process that includes the conduction and convection terms. All the boundary condition was measured experimentally during 24 hours and their temperature was modeled using the proper mathematical models and applied to the developed model. The mathematical models were solved simultaneously in ANSYS- FLUENT software. The developed simulator was validated experimentally by measuring the air temperature of some specified locations (13 points).

The results demonstrate that the model enjoyed satisfactory accuracy so that the RMSE value between the measured and predicted air temperature was in the range of 0.405 to 1.29 and the simulator could predict the air temperature with the accuracy of 0.6 degrees. Therefore, it is possible to use the validated simulator for the real-time controlling of poultry houses to optimize the ventilation process. According to the results, the high heterogeneity in the air temperature and about an 18-degree difference was observed in the air temperature distribution at various locations of poultry houses. In addition, the air velocity was not uniform at the different plans of poultry house; especially in the central points of poultry house, it was higher than 1 m/s that is higher than the recommended value. Therefore, the simulator was used to improve the ventilation of the poultry house. The results of various simulations carried out indicated that the angle of the air inlets vents affects the air turbulence. Also, the air temperature and velocity distribution were more uniform when the air inlet vents were across each other. Therefore, some new gates were opened and the angle of the existing gates was changed to improve the ventilation condition of the poultry house. By such modification, the ventilation condition of the poultry house was improved and the air velocity and temperature distribution in the optimized house were more uniform than that observed in the primary one. The air temperature and velocity were in the range of 291 to 297 K (18 to 24 °C) and 0.23 and 0.46 m s-1, respectively. These values are at the recommended condition for poultry houses.

The opening angle of the vents had a significant effect on the air distribution. Application of across vents in the  side-walls of poultry house led to uniform distribution of air velocity and temperature. The developed simulator has good performance and accuracy to design and construct poultry houses.