radon mitigation using ventilation assessment tool group 9 william allred joshua chastain daniel...
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Radon Mitigation using Ventilation Assessment Tool
Group 9William Allred
Joshua ChastainDaniel DiazRyan Nester
12/02/08 Group 9 – Department of Health
Introduction
Natural decay of uranium in soil
Responsible for over 20,000 deaths each year
EPA recommends to test for high levels
12/02/08 Group 9 – Department of Health
Introduction
Radon found in high-rise buildings
Florida standards on amount of air ventilation
Radon mitigation ventilation assessment tool for Florida Department of Health
12/02/08 Group 9 – Department of Health
The Design Concept
Assessment tool: Spreadsheet Input: Radon level and leakage
characteristics of the structure Output: Amount of air ventilation
needed to reduce the radon to a safe level
Assist in the diagnosis of the appropriate ventilation system required
12/02/08 Group 9 – Department of Health
The Design Concept
Microsoft Excel Data Validation & Formulas
12/02/08 Group 9 – Department of Health
Dillution Equation
DtV
Q
lnCi
Cf
V Volume of Room
Q Flow Rate from Ventilation Equation
DtTime for Dillution
CiInitial Concentration
CfFinal Concnetration
Initial Calculations
Ventilation Equation
Q C Pn
C Cwindows Cdoors Cwalls
n .5 Assuming A Fully Turbulent Flow
P Pressure Difference from Inside to Outside
Q Desired Volumetric Flow Rate
12/02/08 Group 9 – Department of Health
Contaminant Equations
ρi is the density in zone iVi is the Volume of the zone iCi is the concentration of the contaminant in zone I
is the contaminant mass flow rate from zone j to i (in) is the filter efficiency (not applicable)
(mass of contaminant a in c.v. i at time t+Δt ) =(mass contaminant a in c.v. i at time t) +
Δt × (rate gain of contaminant a – rate loss of contaminant a)
General Form of Equation
12/02/08 Group 9 – Department of Health
Contaminant Equations
ρj is the density of the air in zone jCj is the concentration of the contaminant in zone jGi is the generation rate of the contaminant in zone i
is the generation of a species from chemical reaction (not applicable) is the contaminant mass flow rate from i to j (out)
is the removal coefficient (not applicable)
12/02/08 Group 9 – Department of Health
CONTAM – Model 1
Supply Duct40 cfm
Return Duct35 cfm
Contaminant SourcePressure Driven
Gen. Rate 100 pCi/s
Double HungWindow
0.424 cfm
WindowFrames0.288 cfm
Door Frames0.051 cfm
Double DoorWeather-stripped
3.9 cfmZone DefinitionArea 100 m2
Volume 300 m3
Initial Concentration20 pCi/L
Pressure Difference
Air Flow
Constant PressureDifference 0.666 Pa
Ambient Zone20 deg C
1 atm
Air Handling Unit
12/02/08 Group 9 – Department of Health
CONTAM – Model 1
12/02/08 Group 9 – Department of Health
CONTAM – Model 2
Apt 1 Zone DefinitionArea: 1000 ft2
Volume: 8000 ft3
Apt 2 Zone DefinitionArea: 1000 ft2
Volume: 8000 ft3
Pressure Difference
Air Flow
Pressure Difference
Air Flow
Pressure Difference
Air FlowDouble Hung WindowNot Weather-stripped
0.968 cfm Contaminant SourcePressure Driven
20 pCi/sAir Handling
Unit
Air HandlingUnit
Supply Duct50 cfm
Supply Duct50 cfm
Return Duct40 cfm
Return Duct40 cfm
Double Hung WindowNot Weather-stripped
0.968 cfm
Contaminant SourcePressure Driven
20 pCi/s
Double DoorNot Weather-stripped
8.06 cfm
Single DoorNot Weather-stripped
4.03 cfm
Single DoorNot Weather-stripped
4.03 cfmHallway
Apt 1
Apt 2
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CONTAM – Model 2
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Summary
Attempts to gain access to conduct on-site testing have still been denied
Currently seeking other suitable locations CONTAM modeling assisted in understanding
contaminant behavior and leakage rates Modeling also assisted in understanding dominating
parameters Determined applicable equations for spreadsheet Results from spreadsheet will be used to assist in the
diagnosis of the mitigation system appropriate for the particular unit.
12/02/08 Group 9 – Department of Health
Future Plans
Continue modeling with CONTAM Continue modifying and formulating
spreadsheet Use results from spreadsheet to determine if
efficiency requirements are met Continue attempts to conduct on-site testing Potential cost analysis, none thus far
12/02/08 Group 9 – Department of Health
References
Design of Fluid Thermal SystemsWilliam S. Janna
NIST Multizone Modeling Website (CONTAM)http://www.bfrl.nist.gov/IAQanalysis/index.htm
Walton, George. “CONTAM 2.4 User Guide and Program Documentation.” http://www.bfrl.nist.gov/IAQanalysis/docs/
NISTIR_7251c.pdf
12/02/08 Group 9 – Department of Health
Acknowledgment
Special thanks to Florida Department of Health
Clark Eldredge Jorge Laguna
FAMU Director of Building Sciences Thomas Pugh
Faculty Advisor Juan Ordoñez