Model Experiments of Ventilation by Thermal Buoyancy on Several Types of Poultry Houses

Abstract

Model experiments have been carried out about the air flow pattern and the temperature distribution of a 1/7 scale poultry house model, in order to get the natural ventilation characteristics in summer, when there is no wind. This study applied the similarity principle of Archimedes number. The poultry house types measured were the one-storey house and the elevated-floor house. The cages of the elevated-floor house were set in the second floor. Several dimensions of the monitor roofs and the saw-tooth roof were tested. The area and arrangement of the openings in the floor of the elevated-floor house were also examined. The results obtained were summarized as follows;
(1) Air temperature difference between the inside and the outside of the elevated-floor house was 11-26% lower than that of the one-storey house. The elevated-floor house had an influence on the cool air to blow up from the slits in the floor under the cages, concurrently with the air inflow from the opening area of the side walls.
(2) The temperature difference depended not on the roof type but on the opening area of the roof, that is when the opening area on the side walls was same.
(3) From a comparison of seven types of dimensionally different monitors, it was found out that the temperature difference decreased with the increase of the monitor width. But if the monitor height was larger than 1/2 of the monitor width, the monitor height was not effective on the temperature difference.
(4) In the elevated-floor house, two floor types are experimented; one had the slits all over the floor area, and another had the slits opened only under the cages. The condition of temperature and air flow around the cages improved in the latter type.