Effects of air velocity on convective and radiant heat transfer from domestic fowls at environmental temperatures of 20° and 30°c

Abstract

1. The effects of air movement upon sensible heat loss from individual birds at ambient temperatures of 20° and 30°C were determined by partitional calorimetry using a newly developed wind tunnel calorimeter.

2. The relationship between area specific convective heat loss (W/m²) and air velocity (in the range 0.3 to 1.05 m/s) was described by γ=56.5+16.9 log x at an air temperature of 20°C, but at 30°C convective heat loss increased linearly with air speed (γ= 11.8+40.1 x).

3. At 20°C sensible heat exchange (W/m²) was related to air velocity by γ=70.6 exp (0.099 x) and by γ=41.4+25.9 x at 30°C, the proportional increase with air speed being greater at the higher temperature.

4. The differences in the effects of air movement on convective cooling and sensible heat loss at 20° and 30°C reflect the thermoregulatory responses of the birds, induced by the thermal demands of the environment.