Measurement and calculation of the neutral height in a room with displacement ventilation

This paper investigates the relationship between the neutral height for air distribution and the ventilation load in a room with displacement ventilation. An environmental chamber equipped with a displacement ventilation system has been used to carry out the neutral height measurements with the presence of a heated mannequin and other heat sources in the chamber. The total room load used was varied from 104 to 502 W, i.e., corresponding to a ventilation load from 10 to 60 W/m2. The prediction of the neutral height was based on plume theory. Comparison between the experimental data and the predictions showed good agreement. The prediction also showed that human body could draw uncontaminated fresh air from the lower zone, which improves the air quality in breathing zone.