Wednesday, January 27, 2016: 9:45 AM-10:45 AM
Systems and Equipment
Chair:
Alamelu Brooks, ICF International
Analysis of data from a study of fan-powered terminal units indicated that leakage rates depend mainly on the downstream pressure and could be grouped into low, medium and high airflow rate values that can be included into building simulation tools. Two control methods were evaluated to prevent reverse airflow through relief air dampers, return fan speed control and static pressure were two of the inputs required. Although mechanical ventilation systems are designed to provide adequate ventilation air to an occupant, recent measurements show that the convective boundary layer around a human body greatly influences the local transport of contaminants that may not be predicted by room airflow models.
1 Characterizing Air Leakage in Parallel Fan-Powered Terminal Unit (OR-16-027)
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Dennis L. O'Neal, Ph.D., P.E., Baylor University
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Jacob L. Edmondson, New York University Abu Dhabi
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Air leakage data from six parallel fan powered terminal units that utilized electronically commutated motors were evaluated to determine if simple models of air leakage could be developed for applications in building energy simulation programs. The data is from an earlier investigation by Edmondson et al (2011). Units with both 8 in. (20.3 cm) and 12 in. (30.5 cm) primary inlets from three manufacturers were evaluated. The analysis included the impact of downstream static pressure, upstream static pressure, and primary airflow on the leakage from the units.
2 Reverse Relief Airflow Prevention and Building Pressurization with a Decoupled Relief Air Damper in Air-Handling Units (OR-16-028)
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Gang Wang, P.E., University of Miami
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Kaustubh Phalak, University of Miami
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Outdoor airflow rate, building static pressure, supply air duct static pressure and relief air plenum static pressure, as controlled variables, are maintained by modulating the speed of the supply and return fans and the position of the outdoor, recirculating, and relief air dampers in an air handling unit (AHU). In practice, the three dampers are interlinked completely or partially to match independent control inputs with the controlled variables. The traditional damper control has all the three dampers interlinked with no control over the relief air plenum static pressure. The reverse relief airflow might occur as the outdoor air damper approaches the closed position. To prevent the reverse airflow, one of solutions is to decouple the relief air damper and maintain positive static pressure at the relief air plenum. Two control methods are available based on the control loop design.
3 The Air Velocity, Temperature and Pollution Distribution around the Human Body (OR-16-029)
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Dusan Licina, Ph.D., University of California Berkeley
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Arsen Melikov, Ph.D., Technical University of Denmark
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Know Wai Tham, Ph.D., National University of Singapore
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Chandra Sekhar, Ph.D., National University of Singapore
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ASHRAE Grant-in-Aid Graduate Student Research Paper: This study presents a summary of experimental measurements on the airflow characteristics and pollution distribution around a non-breathing thermal manikin. The two objectives are: To examine the extent to which personal (body posture, clothing insulation, table positioning) and environmental factors (room air temperature and ventilation flow) affect the airflow characteristic (velocity and temperature) around the thermal manikin. To examine the pollution distribution within the convective boundary layer (CBL) around a thermal manikin and personal exposure to two types of airborne pollutants under factors that influence the CBL.
