Measurement of the evaporative cooling effect: oscillating misting fan

摘要

To determine the thermal effects of an oscillating mist fan (spraying 86L/h of droplets with 25 mu m mean diameter) on worker comfort, its effects on the thermal environment were measured in a large indoor space (37,500m(2)/525,000m(3)). It was found that the temperature dropped by 0.2-2.5K, with local humidity increasing by 5%. Ventilation air-exchange calculations indicate that in hot summer conditions, an 8-h shift could be continuously cooled without creating high humidity, recovering to initial values after 16 h of ventilation at 0.3 ach. The cooling effect of the mist and fan was measured and compared with that of the fan. The mist and fan-cooling effect exceeded 100W/m(2) in all cases, while the mist and fan cooling exceeded the fan alone by 18W/m(2) on average, 24W/m(2) at the peak values and 11W/m(2) average during oscillation. The ASHRAE 55-2013 model is modified to include this additional cooling. Standard effective temperatures (SETs) are calculated with and without the mist fan-cooling effect. Linear approximations for reduction in SET were developed as a function of air temperature and mist-cooling effect. The deployment of this technology would improve thermal comfort for factory workers on hot summer days.