Dynamic control of room air temperature for stratum ventilation based on heat removal efficiency: Method and experimental validations

Stratum ventilation can energy-efficiently provide quality indoor air and thermal comfort. The room air temperature in the occupied zone is a dominant parameter for thermal comfort. The non-uniform thermal environment of stratum ventilation challenges the dynamic control of the room air temperature. This study proposes a dynamic control method of the room air temperature for stratum ventilation based on heat removal efficiency. The proposed method requires inputs of only supply air temperature, supply airflow rate and exit air temperature, and can be readily employed by the building management system in practice. Dynamic experiments, with a wide variation range (i.e., from 24.5 degrees C to 30 degrees C), different variation rates (i.e., from 0 degrees C/min to 0.088 degrees C/min) and different variation trends (i.e., increase, decrease and steady) of the room air temperature, are conducted to validate the proposed method. The time interval of the dynamic experiments is 1 min. Furthermore, the effects of the cooling load and room occupancy are also analyzed to demonstrate the robustness of the proposed method. The differences between the predicted room air temperatures by the proposed method and measurements are no more than 0.33 degrees C, and the root mean square errors are no more than 0.18 degrees C. Compared with the conventional method, which assumes that the room air temperature equals to the exit air temperature at the air terminals, the proposed method improves the accuracy in the room air temperature prediction by 79.3%-93.3%. The proposed method can be applied to dynamically control the room air temperature to meet the requirement of thermal comfort.