Paper 1: Volume 4 No.2 September 2005 Edition
POWBAM0 Mechanical Power
Balances for
Multi-zone
Building
Airflow Analysis
James
W. Axley and Daniel H. Chung
School
of
Architecture
,
Yale
University
,
New Haven
,
CT
,
USA
Abstract
Conventional methods of
multi-zone airflow analysis ignore mechanical energy conservation in
forming the system equations governing building airflows.
As a result, airflows computed using these methods generally
violate this fundamental conservation principal and thereby falsely create
or destroy kinetic energy within building zones.
While the impact of this fundamental oversight has yet to be fully
evaluated, it need not be tacitly accepted.
This paper will present a rigorously detailed theoretical approach
that imposes both mass and mechanical energy conservation to the problem
of multi-zone airflow analysis and, through comparisons with results
computed using computational fluid dynamics (CFD) and the conventional
approach to multi-zone airflow analysis, will demonstrate that a power
balance approach can predict building airflows that satisfy both of
these fundamental conservation principles while offering greater
capabilities than that of the conventional approach.
Furthermore, it will be shown that the conventional approach is a
special limited case of the practical application of the power
balance approach. A
computational prototype, POWBAM0, based on the theory will be introduced.
Key words: computer
modelling, multi-zone airflow analysis, mechanical energy conservation,
hydrostatic field assumption, irrotational field assumption.
ASHRAE (2001) “2001 ASHRAE Handbook –
Fundamentals”. SI Edition, ASHRAE. Atlanta, GA:
Axley JW:
(1987) “Indoor Air Quality Modeling Phase II Report”, U.S. DOC, NBS,
Gaithersburg, MD.
Axley J, Wurtz E and Mora
L: (2002) “Macroscopic Airflow
Analysis and the Conservation of Kinetic Energy.” Room Vent 2002: Air Distribution in Rooms - Eighth International
Conference, Copenhagen Denmark.
Axley JW and Chung D:
(2004) “Zone Resistance in
Embedded CFD Modeling”.
RoomVent 2004 - 9th International
Conference on Air Distribution in Rooms, Coimbra, Portugal: ADAI,
Universidade de Coimbra.
Aynsley RM, Melbourne W,
and Vickery BJ: (1977) “Architectural
Aerodynamics”, London: Applied Science Publishers Ltd.
Aynsley R: (1999) “Unresolved
Issues in Natural Ventilation for Thermal Comfort.” HybVent
Forum '99, Sydney, Australia.
Bird RB, Stewart WE and
Lightfoot EN: (1960) “Transport
Phenomena”, New York: John Wiley & Sons, Inc. 779 pages.
Bird RB, Stewart WE, and
Lightfoot EN: (2002) “Transport
Phenomena”, Second Edition, New York: John Wiley & Sons, Inc.
895 pages.
Blevins RD: (2003) “Applied
Fluid Dynamics Handbook”.
Reprint edition (June, 2003), Melbourne, Florida: Krieger Publishing
Company. 570 pages.
COMSOL, (2003) “FEMLAB
3.0 User's Guide”, COMSOL, Inc.: Burlington, MA.
de Gids WF: (1978)
“Calculation Method for the
Natural Ventilation of Buildings”. Verwarming Vent., (no.
7), pp552-564.
Etheridge DW: (1988) “Modeling
of Air Infiltration in Single- and Multi-Cell Buildings”, Energy
and Buildings, Netherlands: Elsevier Sequoia.
Etheridge DW: (2000a) “Unsteady
flow effects due to fluctuating wind pressures in natural ventilation
design - mean flow rate” Building and Environment,
35, (2), pp111-133.
Etheridge DW: (2000b) “Unsteady
flow effects due to fluctuating wind pressures in natural ventilation
design - instantaneous flow rate”. Building and
Environment, 35, (4), pp321-337.
Feustel HE and Kendon VM:
(1985) “Infiltration Models for Multicellular Structures - A Literature
Review”. Energy and Buildings.
Netherlands: Elsevier Sequoia.
Fried E and Idelchik IE:
(1989) “Flow Resistance: A
Design Guide for Engineers”, New York: Hemisphere Publishing
Corporation. 400 pages.
Fürbringer JM et al:
(1993) “Air Flow Simulation of
the LESO Building Including a Comparison with Measurements and Sensitivity
Analysis”, Indoor Air '93:
The 5th International Conference on Indoor Air Quality and Climate.
Helsinki, Finland: Helsinki University of Technology.
Fürbringer JM Roulet CA
and Borchiellini R eds: (1996) “Annex
23: Multizone Air Flow Modeling: Evaluation of Comis”, Swiss
Federal Institute of Technology, Institute of Building Technology:
Lausanne. Vol. 1/2, 138 pages.
Guffey SE and Fraser DA:
(1989a) “Kinetic Power Model of
Junction Losses” ASHRAE
Transactions, 95, (Part 2),
pp1661-1669.
Guffey SE and Fraser DA:
(1989b) “A Power Balance Model
for Converging and Diverging Flow Junctions”.
ASHRAE Transactions, 95, (Part
2) pp1661-1669.
Haghighat F, Brohus H and
Rao J: (2000) “Modelling air
infiltration due to wind fluctuations--a review”, Building and
Environment, 35 (5)
pp377-385.
Haghighat F and Li H:
(2004) “Building Airflow
Movement - Validation of Three Airflow Models”, Journal of
Architectural and Planning Research,. 21,
(4) pp331-349.
Herrlin MK: (1985) “MOVECOMP:
A Static Multicell Airflow Model”, ASHRAE Transactions, 91,
(Part 2).
Idelchik IE: (1994) “Handbook
of Hydraulic Resistance” 3rd Edition. Boca Raton: CRC Press. 790
pages.
Karava P, Stathopoulos T
and Athienitis AK: (2004) “Wind-Driven
Flow through Openings - A Review of Discharge Coefficients”. International
Journal of Ventilation, 3, (3)
pp255-266.
Kato S: (2004) “Flow
Network Model based on Power Balance as Applied to Cross-Ventilation”,
International Journal of Ventilation, 2,
(4), pp395-408.
Kelley CT: (2003) “Solving
Nonlinear Equations With Newton's Method (Fundamentals of Algorithms)”.
Fundamentals of algorithms, Philadelphia: Soc for Industrial &
Applied Math. 116 pages.
LBNL: (2002a) “VISUALSPARK 1.0.2 USERS GUIDE
Simulation Problem Analysis and Research Kernel”, L.B.N.L. and A.S.A.I.
ASA, Lawrence Berkeley National Laboratory: Berkeley, CA. 72 pages.
LBNL: (2002b) “SPARK
1.0.2 REFERENCE MANUAL - Simulation Problem Analysis and Research
Kernel”, L.B.N.L. and A.S.A.I. ASA, Lawrence Berkeley National
Laboratory: Berkeley, CA. 127 pages.
Li Y: (1993) “Predictions
of Indoor Air Quality in Multi-Room Buildings”, Indoor
Air '93: The 5th International Conference on Indoor Air Quality and
Climate, Helsinki, Finland: Helsinki University of Technology.
Liddament MW: (1983) “The
Air Infiltration Center's Program of Model Validation.” ASHRAE
Transactions, Atlanta: ASHRAE.
Liddament M and Allen C
(1983) “The Validation and
Comparison of Mathematical Models of Air Infiltration”, Technical Note AIVC 11: Air Infiltration and Ventilation Centre.
MathWorks: (2000) “MATLAB
- The Language of Technical Computing m- Using MATLAB Version 6”,
The MathWorks: Natick, MA.
Roulet CA, Fürbringer JM
and Borchiellini R: (1996) “Evaluation
of the Multizone Air Flow Simulation Code Comis”, 5th International Conference on Ar Distribution in Rooms - ROOMVENT '96..
Sahlin P and Bring A:
(1993) “The IDA Multizone Air
Exchange Application”, Swedish Institute of Applied Mathematics
and Department of Building Services Engineering, Royal Institute of
Technology: Stockholm, Sweden.
Saleh J (ed): (2002) “Fluid
Flow Handbook”, McGraw-Hill: New York.
Saraiva JG and Marques da
Silva F: (1999) “Atmospheric Turbulence Influence on Natural Ventilation
Air Change Rates”, Indoor Air 99..
Edinburgh: ISIAQ & AIVC.
Seifert J et al: (2004)
“The Effect of Wall Porosity on
the Flow Rate in a Building Ventilated by Cross Wind”, RoomVent 2004 - 9th International
Conference on Air Distribution in Rooms. 2004. Coimbra, Portugal: ADAI,
Universidade de Coimbra.
Sirén K: (1997) “A
Modification of the Power-Law Equation to Account for Large-Scale Wind
Turbulence.” 18th AIVC Conference - Ventilation and Cooling, Athens, Greece: AIVC.
True JJ et al: (2003) “Wind
Driven Cross-Flow Analysed as a Catchment Problem and as a Pressure Driven
Flow”, International Journal of Ventilation, 1,
(Hybrid Ventilation Special Edition), pp88-102.
Walton G: (1997) “CONTAM96
User Manual”, NIST: Gaithersburg, MD.
White FM: (1994) “Fluid Mechanics” Third
Edition, New York: McGraw-Hill, Inc. 736 pages.
Wolfram Research,
(2004) “MATHEMATICA-5”.
|
