CFD analyses of temperature distribution in a hybrid ventilated pig unit.

摘要

CFD methods were used to generate knowledge for optimization of adjustment of ventilations openings and location and adjustments of heat sources in order to minimise temperature differences in the animal occupied zone of a 58 m wide hybrid ventilated pig building. A flexible geometrical model was used to investigated the temperature distribution and the air flow pattern at different outdoor velocities, different outdoor temperatures, different positions of ventilation flaps and different sizes and locations of heat sources. The changes between different positions of ventilations flaps were managed by defining the required surfaces in the geometrical model, and changing the boundary condition for these surfaces from interiors to walls or vice versa. Additional heat sources were defined as User Defined Functions (UDF). The analysed pig unit was assumed to be one in a row of built together units, and due to an assumed symmetry plane the length of the modelled flow domain was 11 m, equal to one half of the length of the unit. This modelled geometry enabled symmetrical 3-dimensional air flow in the unit, but the outdoor weather conditions was delimited to the wind direction orthogonally to the building. Unequal adjustment of the openings in the two sides of the unit was an effective method to equalize the temperature distribution in the two sides of the unit. To some extend this could also be obtained by unequal location of heat sources.