Objectives Review exam problems Further discuss final projects Compare VAV systems with DOAS systems
VAV Example One system Multiple Spaces/Zones - VAV box for each space/zone http://www.trane.com/commercial/library/vol242/v24b6.asp
VAV System Terms & Equations (you can find them in ASHRAE Standard 62) Fraction of minimum outdoor air in space/zone supply air Xi = VOAi / VSAi Critical space Space with maximum Xi , Z=max(Xi) Fraction of outdoor air in system supply air X = sum(VOA ) / sum(VSA) Required Fraction of outdoor air: Y=X/(1+X-Z)
Other Issues Related to VAV Reheaters (sizing and control) Fan control Minimum supply air Occupancy sensors
DOAS System www.doas.psu.edu
DOAS with multi-split systems Fresh air?
DOAS fresh air configurations
DOAS fresh air configurations
Issues Related to DOAS Split of sensible and latent load Selection of hydronic system Winter vs. summer operation Winter operation with DX systems (heat pump)