Investigation of thermal comfort in Under-floor air distribution system with different throwing angle of swirling diffusers

Under floor air distribution (UFAD) system has been widely used due to its better performance in indoor air quality and energy saving, compared with conventional mixing ventilation system. As one of the most important devices, the swirling diffuser has been studied for years because of the great impact on the performance of UFAD system. Our research mainly focused on the influences of throwing angle on the capability of swirling diffusers from the view point of thermal comfort. Detailed numerical manikin was built in a validated CFD calculation model, and local thermal comfort of occupants in UFAD system with different throwing angles was compared by adopting the ISO 14505 index. The results indicate that the throwing angle has significant effect on both the local thermal comfort and whole thermal comfort. Meanwhile, as a convenient method to evaluate thermal comfort in stratified environment, the ISO 14505 index is worthy to be further developed.