Optimal design of a louver face ceiling diffuser using CFD to improve occupant's thermal comfort

The present study aims to investigate the characteristics of airflow inside the room through 5-blade square louver face ceiling diffuser using CFD. Several diffuser models are installed inside 3D room model by changing blade angles (60 degrees, 65 degrees and 45 degrees) and lip angles (0 degrees, 5 degrees, 10 degrees and 15 degrees). Besides, the model with 60 degrees blade angle and 0 degrees lip angle is installed inside different room models with various return air inlet positions. The realizable k-epsilon turbulence model is used in simulation process. The results indicated that the diffuser model with 65 degrees blade angle provide jet and terminal air velocities beside airflow patterns cling with ceiling higher than the models 60 degrees and 45 degrees. Therefore, it is suitable to install in the space with larger size and relatively higher noise level to reaches to the comfort criteria faster than the other models to reduce the energy consumption. On the other hand the model with 45 degrees blade angle is applicable to installed in the spaces with larger height due to airflow patterns out in cone shape. In addition, increasing lip angle to 15 degrees leads to relatively reduce the cling of airflow patterns with room ceiling, and reach to comfort conditions with less energy consumption faster than 0 degrees lip angle. Moreover, the room geometry model with two return air inlets on the ceiling with adequate size is produced ideal design of a fully mixed air distribution system with relatively constant temperature gradient.