Control System That Prevents Air From Entering an Air-Handling Unit Through the Exhaust Air Damper.
Control System That Prevents Air From Entering an
Air-Handling Unit Through the Exhaust Air Damper.
Seem, J. E.; House, J. M.
Optimum Ventilation and Air Flow Controls in Buildings.
AIVC 17th Annual Conference. Proceedings. Volume 2.
September 1996, Gothenberg, Sweden, 562-569 pp, 1996.
air flow; air handling unit; indoor air quality;
Traditional air-handling unit (AHU) control systems link
the position of the exhaust air damper, recirculation
air damper, and outdoor air damper. Tests at the
National Institute of Standards and Technology (NIST) on
a variable-air-volume (VAV) AHU have shown that air can
enter the AHU through the exhaust air damper. This can
negatively impact indoor air quality if the exhaust air
duct is located near a pollution source. This paper
presents a new control system for variable air volume
AHU's that use volume matching to control the return
fan. The new control system links only the position of
the exhaust air damper and recirculation air damper.
During occupied times, the outdoor air damper is in the
fully open position. Simulation and laboratory results
are presented to compare the new control system and a
traditional control system. Several cases are simulated
to examine the effect of damper sizing and system load
on airflow in AHU's. The simulations demonstrate that
the new control system can prevent air from entering the
AHU through the exhaust air damper for conditions that
the traditional control system cannot. A case
demonstrating the limits of the new control system to
prevent this phenomenon is included in the simulation
results. The laboratory results provide further
evidence that the new control system prevents air from
entering the AHU through the exhaust air damper for
conditions that cause the phenomenon with the
traditional control system.