Performance evaluation of ductless personalized ventilation combined with impinging jet ventilation

Abstract

Despite the high ventilation efficiency of the impinging jet ventilation, two local discomfort risks (draught and excessive thermal stratification) should be highlighted owing to the cool air being supplied directly to the occupied zone. Ductless personalized ventilation, as one type of different personalized ventilation air terminal devices, shows the potential to improve thermal comfort and reduce the draught and excessive thermal stratification risks. In this study, twenty-four cases were studied using the validated numerical simulation method when integrating the impinging jet ventilation and personalized ventilation. According to simulation results, local cooling provided by ductless personalized ventilation reduces the air temperature around the face by a maximum of 3.7 °C. The vertical temperature difference is reduced to less than 1 °C with personalized flow rates greater than 6 l/s. The use of ductless personalized ventilation has no negative effect on the stratification of impinging jet ventilation in the studied conditions. Because of the ductless personalized device, the impinging jet ventilation can be used in a warm environment, reducing the risk of draughts. Finally, it was concluded that the system that combined ductless personalized ventilation and impinging jet ventilation could improve thermal comfort while also having the potential to save energy when used in warm conditions.