A generalized multiple-spaces equation to accommodate any mix of close-off and fan-powered VAV boxes
- Pennsylvania State Univ., University Park, PA (United States). Dept. of Architectural Engineering
The central thrust of this paper will be to derive a generalized form of the multiple-spaces Equation 6-1 that appears in ASHRAE Standard 62-1989. The multiple-spaces equation currently in the standard is for single-duct systems, such as variable-air-volume (VAV) systems using close-off boxes only. In such systems all recirculated air is assumed to mix with the outdoor air at a central air-handling unit. Since many VAV systems designed and installed today employ fan--powered boxes, there was a sense of urgency associated with deriving the generalization presented here. The new generalized multiple-spaces equation extends the applicability of the multiple-spaces concept to include air distribution systems that can recirculate a portion of the return air from well mixed return plenums directly back into the fan-powered terminal units for mixing with primary supply air. The work also shows that VAV systems employing fan-powered boxes may often comply with the standard while using less outdoor air than would be required in a close-off VAV system.
- OSTI ID:
- 392446
- Report Number(s):
- CONF-960254--
- Country of Publication:
- United States
- Language:
- English
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