TO-98-01-1 -- Contaminant and Heat Removal Effectiveness and Air-to-Air Heat/Energy Recovery for a Contaminated Air Space PDF

Measured contaminant and heat removal effectiveness data are presented and compared for a 3:1 scale model room, which represents a smoking room, lounge, or bar with a two-dimensional airflow pattern. In the experiments, heat and tracer gases were introduced simultaneously from a source to simulate a prototype smoking room. High-side-wall and displacement ventilation schemes were investigated, and the latter employed two different types of ceiling diffuser, low-velocity slot and low-velocity grille.

Results show that thermal energy removal effectiveness closely follows contaminant removal effectiveness for each of the ventilation schemes throughout a wide range of operating conditions. The average mean thermal and contaminant removal effectiveness agreed within ±20%. Local contaminant removal effectiveness ranged from a low of 80% for a high-wall slot diffuser to more than 200% for a low-velocity ceiling diffuser with displacement ventilation. Temperature differences between the supply and the indoor air were between 0.2°C (0.36°F) and 41.0°C (73.8 °F) and ventilation airflow rates ranged from 9.2 to 36.8 air changes per hour at inlet conditions. For small temperature differences between supply and exhaust air, all three ventilation schemes showed increased contaminant removal effectiveness near the supply diffuser inlet with decreasing values toward the exhaust outlet. For the high-side-wall slot diffuser, effectiveness was up to 140% near the inlet and 100% near the exhaust, but for the second displacement scheme (low-velocity grille) the effectiveness was more than 200% near the inlet and 110% near the exhaust.

This paper also shows a potential significant reduction in cooling load for a 50-person-capacity smoking lounge that utilizes an air-to-air heat/energy exchanger to recover heat/energy from the exhaust air.

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