1. http://www.eqstar.org http://www.syracusecoe.org http://www.eqstar.org http://www.syracusecoe.org Personal Ventilation Nathan Tainter John Dannenhoffer H. Ezzat Khalifa

2. EPA SAC 7/26-27/06 2 Overview o Introduction u Background u Previous work u Simple jet model u Problem definition o Overall experimental and computational plan u Canonical jet experiment u Experimental results u Computational results o Tentative conclusions u Response to SAC concerns o Next steps u Tracer gas experiments u Personal Environment Lab (PEL)

3. EPA SAC 7/26-27/06 3 Background o Clean air in offices improves: u personal health u productivity o Personal ventilation can be used to improve an occupant’s micro-environment u locally improved air quality u locally improved thermal comfort o Personal ventilation is likely to be adopted only when associated with non-increased energy consumption o Personal environments are difficult to design in a real environment u interaction with building ventilation (especially under-floor ventilation) u interaction with other micro-environments Source: www.ie.dtu.dk

4. EPA SAC 7/26-27/06 4 Comparison with previous work - LBNL o PVDs studied u Floor-based unit (TAM) u Desktop unit (PEM) u Desk-edge unit (EDD) o Measurements u Air change effectiveness (ACE) u Pollutant removal efficiency (PRE) u Age of air u Manikin heat loss u Thermal comfort o Conclusions u Outside air improves IAQ u Use of PVDs requires less outdoor air for IAQ u EED configuration provided best IAQ Source: Faulkner & Fisk, 1999, 2001

5. EPA SAC 7/26-27/06 5 Comparison with Previous Work - DTU o PVDs studied u Movable panel (MP) u Computer monitor panel (CMP) u Horizontal/vertical grille (HDG/VDG) u Personal Environmental Module (PEM) o Measurements u Personal exposure effectiveness (PEE) u Predicted percent dissatisfied (PPD) o Conclusions u Increased thermal comfort with cooler air through PVD u Interaction between personal ventilation and general ventilation is important Source: www.ie.dtu.dk

6. EPA SAC 7/26-27/06 6 Simple Jet Model – Approximations I have not done this yet

7. EPA SAC 7/26-27/06 7 Simple Jet Model – Results for Different Ventilation Rates this is made-up data --- I will fix tonight

8. EPA SAC 7/26-27/06 8 Problem definition o Objective: u Develop a model for personal ventilation that can be used to design systems that Fimproves quality of air delivered to occupant Fimproves thermal comfort Frequires no more energy than standard ventilation o Approach: u Experimental measurements to provide data for computations Fcanonical experiment FPEL verification experiment u Computational simulations to derive engineering model

9. EPA SAC 7/26-27/06 9 Overall Experimental and Computational Plan o Canonical jet u verify effectiveness of turbulence models for PV jets Flow speed Fbuoyant Fcross-flow Fimpingement on heated plate u experimental measurements u comparison with simulated results o Personal ventilation u experimental measurements u comparison with simulated results

10. EPA SAC 7/26-27/06 10 Canonical Jet Experiment – Setup o Flow seeded with neutrally buoyant particles o Laser sheet illuminates particles in vertical center plane of jet o Cameras obtain two images a fraction of a second apart o PIV software tracks particles from first image to second to produce a velocity field Jet flow Crossflow Heated plate

11. EPA SAC 7/26-27/06 11 Canonical Jet Experiment – PIV Field Results o Two cameras set up side-by-side u first image from nozzle to x/D  5 u second image for x/D  5 to near plate o Ensemble averaged over ~400 images Shadow of nozzle Nozzle exit Average velocity vectors

12. EPA SAC 7/26-27/06 12 Canonical Jet Experiment – PIV Profile Results Potential core ends at x/D  3.6 TI in potential core < 5% TI in mixing region ~15-20% Axial velocity profiles Turbulence intensity

13. EPA SAC 7/26-27/06 13 Canonical Jet Computations – Setup o AIRPAK used to set up computational domain o FLUENT used for calculations u standard k-  u realizable k-  o Computational grid u ~ 667,000 hexahedral grid cells u concentrated near jet picture of computational domain picture of global grid picture of grid near jet

14. EPA SAC 7/26-27/06 14 Canonical Jet Computations – Contours of Velocity neutral jet w/crossflow standard k-e cool jet w/crossflow realizable k-e warm jet w/crossflow realizable k-e highlight end of potential core in each case neutral jet w/crossflow realizable k-e

15. EPA SAC 7/26-27/06 15 Canonical Jet Computations – Contours of SF 6 Concentration neutral jet w/crossflow standard k-e cool jet w/crossflow realizable k-e warm jet w/crossflow realizable k-e neutral jet w/crossflow realizable k-e

16. EPA SAC 7/26-27/06 16 Canonical Jet Computations – Average SF 6 in Target Zones this is made-up data --- I will fix tonight

17. EPA SAC 7/26-27/06 17 Tentative Conclusions o Buoyancy effects are important when examining effectiveness of personal ventilation u buoyancy deflects the jet centerline u warm jets spread more than neutral jets o Realizable k-  model yields computations that agree with experiment u both predict a vortex core length x/D  3.6 u on-going experiments will be used to verify that contaminant profiles are modeled effectively too o Low flow rates associated with energy-neutral setups require innovation to provide significant exposure improvements

18. EPA SAC 7/26-27/06 18 SAC Concerns from 2005 o Nothing new; approach geared to persons seated at desk only; ensure that “shared” office air is not compromised o PV and personal microenvironment investigations were not well integrated o Tracer gas protocol not able to measure age of air o Experimental studies should include realistic sources of air mixing

19. EPA SAC 7/26-27/06 19 Next Steps – Tracer Gas Experiments o Same canonical jet setup as before o Same conditions as before u neutral jet, negligible crossflow, adiabatic plate u neutral jet, small crossflow, heated plate u warm jet, small crossflow, heated plate u cool jet, small crossflow, heated plate o Jet seeded with SF 6 o Simultaneous measurements u velocity u SF 6 concentration o Comparison with CFD results

20. EPA SAC 7/26-27/06 20 Next Steps - Personal Environment Lab (PEL) o Chamber: u transparent acrylic enclosure to allow optical access. o Ventilation: u under-floor air plenum u personal ventilation u single exhaust in ceiling o Control: u Flow rates u Temperatures u Contaminant concentrations o Manikin u 20 independently heated thermal/fluid zones (control temperature or heat flux as well as perspiration) u breathing through mouth and nose Funded by EQS/CoE capital…

21. EPA SAC 7/26-27/06 21 Next Steps – PEL Instrumentation & Control

22. EPA SAC 7/26-27/06 22 Acknowledgements o David Marr and Dr. Mark Glauser u help with PIV experiments and turbulent jet theory o Chris Sideroff and Dr. Thong Dang u help with CFD calculations o Jim Smith u help with PEL lab design and construction