Paper Conference

Proceedings of SimBuild Conference 2004: 1st conference of IBPSA-USA


An Extended Model for Under Floor Air Distribution

Q. A. Liu, P. F. Linden
University of California, San Diego, Department of Mechanical and Aerospace Engineering

Abstract: Previous work on an Underfloor Air Distribution (UFAD) system with a single heat source and a single cooling diffuser at floor level developed by Lin (2003) has been extended to study the effects of the vertical location of the heat source and of multiple cooling diffusers. This is an attempt to produce more realistic models of UFAD systems. Both experimental and theoretical modeling are described in this paper. In the experiments, a plume and fountains represent a heat source and cooling diffusers, respectively. The experiments suggest how the entrainment rate of ambient fluid into the fountain at the interface changes with the local Richardson number. They show that for a fixed ventilation rate, as the source elevation is increased, the return temperature remains unchanged and the height of the cooler, lower zone increases. The effect of multiple cooling diffusers is to decrease the height and the temperature of the cooler zone for a fixed ventilation rate, and to cool both layers for a fixed under floor plenum pressure.
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