عنوان مقاله [English]
Providing thermal comfort and proper air quality are two main factors when determining the type of HVAC system. The study of new concepts in air conditioning systems is very important and necessary, in order to achieve optimal thermal comfort and air quality.Stratum ventilation and hydronic radiant cooling systems are two modern air conditioning systems considered in the present study, and a hybrid usage of these systems has been studied. The purpose of this study is the evaluation and comparison of the effect of physical-thermal and geometric parameters on thermal comfort and indoor air quality, in order to offer practical suggestions for improving these important parameters. Therefore, thermal and physical parameters, such as air change per hour, inlet air temperature and radiant cooling panel temperature, and also, geometrical parameters, such as cooling ceiling ratio and exhaust location, have been evaluated. In the present investigation, the cooling load ratio, removed by the stratum ventilation and hydronic radiation cooling systems to satisfy thermal comfort and proper air quality, is determined. The results show that despite combined hydronic radiation cooling and conventional displacement ventilation in which the exhaust location is a trivial parameter, the exhaust location, in the present hybrid system of hydronic radiation cooling and stratum ventilation, is the most important parameter in achieving thermal comfort and proper air quality. Increasing the ACH has a significant impact on improving thermal comfort and air quality indices, although this effect at high ACH (Air Change per Hour) is reduced. In addition, increasing the cooling ceiling ratio improves thermal comfort. On the other hand, indoor air quality is reduced because of its influence on air flow patterns and increased return air flow near the surface of the panel. In addition, when 30 to 40 percent cooling load is removed by stratum ventilation, the best condition of thermal comfort and proper air quality is provided. Finally, the present study has introduced a hybrid system of hydronic radiant cooling and stratum ventilation as a new approach to achieve combined thermal comfort and proper air quality.