NOMINAL TIME FOR FULL-MIXING OF CONTAMINANT DUE TO

Mixing ventilation was studied by conducting model tests in the laboratory. The contaminant source location and the ventilation air flow rate are the factors tested to understand their effect on the mixing of contaminants internally generated with ventilation air in the model room. The model room represented a typical small room with the mixing ventilation having an inlet on the side wall. The test were conducted under transient isothermal conditions. Pulse tracer technique was applied to test the effects.

Under the same ventilation air flow field , the contaminant source created different mixing of generated contaminants with the ventilation air in the model room due to its location. It implies that the contaminant mixing could be improved by relocating the contaminant source within the room without changing the ventilation system. In this study, it has been found that a certain contaminant source location is significantly better than others in achieving better mixing in the model room.

The ventilation air flow rate also affected the mixing process. The contaminant removal efficiency increased with the ventilation air flow rate, but not linearly. Increasing the ventilation air flow rate, however , could not be always the answer to improve the indoor air quality.

Finally, a strategy to combine the two factors examined is suggested to minimize the requirement for the indoor air quality improvement . The optimal contaminant source location , In particular, needs to be decided by considering the air flow pattern in the room.