| Popis: |
A 2.5 m (8.2 ft) diameter paddle fan was developed for cooling floor-raised poultry. An experimental prototype with plywood blades was used to determine effects of blade pitch angle and rotational speed on fan power and air velocities near the floor. Prediction equations were obtained for the area-averaged velocity 25 cm (10 in.) above the floor, over an 11 × 17 m (35 × 55 ft) area below the fan. Energy efficiency was defined as the ratio of area-averaged velocity to the power consumption. A fan speed of 150 rpm and blade pitch angle of 15° were determined in order to produce area-averaged velocity of 1.2 m/s (240 ft/min) at maximum energy efficiency. Two commercial prototypes were then developed using gearmotors, hubs made from formed steel plates, and plywood or fiberglass blades. Based on velocity traverses below the fan blades, the fan airflow rate was 12 m3/s (25,000 cfm) for both types of blades, and the conventional energy efficiency (ratio of airflow rate to fan power) was 0.036 and 0.046 m3/(s-watt) (76 and 97 cfm/watt) for the plywood and fiberglass blades, respectively. Area-averaged velocity 25 cm (10 in.) above the floor was 1.11 and 1.23 m/s (218 and 242 ft/min) for the plywood and fiberglass blades, respectively. The fans produced desirable air velocities in turkey and broiler houses in summer conditions without problematic bird crowding behavior. |
