Physics and Statistics of Combustion SafetyCombustion Safety. Available draft is draft supplied by...
Transcript of Physics and Statistics of Combustion SafetyCombustion Safety. Available draft is draft supplied by...
![Page 1: Physics and Statistics of Combustion SafetyCombustion Safety. Available draft is draft supplied by the vent system at the flue gas outlet. D a D t ...](https://reader033.fdocuments.us/reader033/viewer/2022041722/5e4f0f1ee94e4662f20703eb/html5/thumbnails/1.jpg)
Brett C. SingerVi H. RappCraig Wray
Environmental Energy Technologies DivisionLawrence Berkeley National Laboratory
Presented to
Building America Stakeholders Meeting
March 1-2, 2012
Physics and Statistics of Combustion Safety
![Page 2: Physics and Statistics of Combustion SafetyCombustion Safety. Available draft is draft supplied by the vent system at the flue gas outlet. D a D t ...](https://reader033.fdocuments.us/reader033/viewer/2022041722/5e4f0f1ee94e4662f20703eb/html5/thumbnails/2.jpg)
Available draft is draft supplied by the vent system at the flue gas outlet.
Da Dt pLoss Dp Db
2008 ASHRAE Handbook – HVAC Systems and Equipment, Chapter 34
![Page 3: Physics and Statistics of Combustion SafetyCombustion Safety. Available draft is draft supplied by the vent system at the flue gas outlet. D a D t ...](https://reader033.fdocuments.us/reader033/viewer/2022041722/5e4f0f1ee94e4662f20703eb/html5/thumbnails/3.jpg)
Da Dt pLoss Dp Db
Theoretical Draft
Flow Losses
Depressurization Boost
Available draft is draft supplied by the vent system at the flue gas outlet.
![Page 4: Physics and Statistics of Combustion SafetyCombustion Safety. Available draft is draft supplied by the vent system at the flue gas outlet. D a D t ...](https://reader033.fdocuments.us/reader033/viewer/2022041722/5e4f0f1ee94e4662f20703eb/html5/thumbnails/4.jpg)
Available draft can be broken down into several physical processes
Da Dt pLoss Dp
![Page 5: Physics and Statistics of Combustion SafetyCombustion Safety. Available draft is draft supplied by the vent system at the flue gas outlet. D a D t ...](https://reader033.fdocuments.us/reader033/viewer/2022041722/5e4f0f1ee94e4662f20703eb/html5/thumbnails/5.jpg)
Da Dt pLoss DpBurner
Size
ApplianceEfficiency
VentDimension
Weather
Vent Location &
Material
Available draft can be broken down into several physical processes
![Page 6: Physics and Statistics of Combustion SafetyCombustion Safety. Available draft is draft supplied by the vent system at the flue gas outlet. D a D t ...](https://reader033.fdocuments.us/reader033/viewer/2022041722/5e4f0f1ee94e4662f20703eb/html5/thumbnails/6.jpg)
Available draft can be broken down into several physical processes
Da Dt pLoss DpBurner
Size
ApplianceEfficiency
VentDimension
Weather
Vent Location &
Material
HeatOutputRate
![Page 7: Physics and Statistics of Combustion SafetyCombustion Safety. Available draft is draft supplied by the vent system at the flue gas outlet. D a D t ...](https://reader033.fdocuments.us/reader033/viewer/2022041722/5e4f0f1ee94e4662f20703eb/html5/thumbnails/7.jpg)
Available draft can be broken down into several physical processes
Da Dt pLoss DpBurner
Size
ApplianceEfficiency
VentDimension
Weather
Vent Location &
Material
Buoyancy
![Page 8: Physics and Statistics of Combustion SafetyCombustion Safety. Available draft is draft supplied by the vent system at the flue gas outlet. D a D t ...](https://reader033.fdocuments.us/reader033/viewer/2022041722/5e4f0f1ee94e4662f20703eb/html5/thumbnails/8.jpg)
Available draft can be broken down into several physical processes
Da Dt pLoss DpBurner
Size
ApplianceEfficiency
VentDimension
Weather
Vent Location &
Material
HeatLoss
![Page 9: Physics and Statistics of Combustion SafetyCombustion Safety. Available draft is draft supplied by the vent system at the flue gas outlet. D a D t ...](https://reader033.fdocuments.us/reader033/viewer/2022041722/5e4f0f1ee94e4662f20703eb/html5/thumbnails/9.jpg)
Available draft can be broken down into several physical processes
Da Dt pLoss DpVent
Material
VentDesign (Bends)
BirdNest
![Page 10: Physics and Statistics of Combustion SafetyCombustion Safety. Available draft is draft supplied by the vent system at the flue gas outlet. D a D t ...](https://reader033.fdocuments.us/reader033/viewer/2022041722/5e4f0f1ee94e4662f20703eb/html5/thumbnails/10.jpg)
Available draft can be broken down into several physical processes
Da Dt pLoss DpExhaust
Fans
CAZ Location
Envelope Tightness
Other Appliances
UsagePatterns
![Page 11: Physics and Statistics of Combustion SafetyCombustion Safety. Available draft is draft supplied by the vent system at the flue gas outlet. D a D t ...](https://reader033.fdocuments.us/reader033/viewer/2022041722/5e4f0f1ee94e4662f20703eb/html5/thumbnails/11.jpg)
Available draft can be broken down into several physical processes
Da Dt pLoss Dp
Weather
Exhaust Fans
CAZ Location
Envelope Tightness
Other Appliances
UsagePatterns
![Page 12: Physics and Statistics of Combustion SafetyCombustion Safety. Available draft is draft supplied by the vent system at the flue gas outlet. D a D t ...](https://reader033.fdocuments.us/reader033/viewer/2022041722/5e4f0f1ee94e4662f20703eb/html5/thumbnails/12.jpg)
Short term tests include some of the physical processes impacting draft
Test Physical ProcessesHouse depressurizationtest with pre-set criteriaDowndrafting test (Worst-Case Depressurization)Backdrafting test (Downdrafting test + Operation)Cold vent establishment pressure (CVEP) test
![Page 13: Physics and Statistics of Combustion SafetyCombustion Safety. Available draft is draft supplied by the vent system at the flue gas outlet. D a D t ...](https://reader033.fdocuments.us/reader033/viewer/2022041722/5e4f0f1ee94e4662f20703eb/html5/thumbnails/13.jpg)
Short term tests include some of the physical processes impacting draft
Test Physical ProcessesHouse depressurizationtest with pre-set criteriaDowndrafting test (Worst-Case Depressurization)Backdrafting test (Downdrafting test + Operation)Cold vent establishment pressure (CVEP) test
Exhaust Fans
Envelope Tightness
![Page 14: Physics and Statistics of Combustion SafetyCombustion Safety. Available draft is draft supplied by the vent system at the flue gas outlet. D a D t ...](https://reader033.fdocuments.us/reader033/viewer/2022041722/5e4f0f1ee94e4662f20703eb/html5/thumbnails/14.jpg)
Short term tests include some of the physical processes impacting draft
Test Physical ProcessesHouse depressurizationtest with pre-set criteriaDowndrafting test (Worst-Case Depressurization)Backdrafting test (Downdrafting test + Operation)Cold vent establishment pressure (CVEP) test
Exhaust Fans
Envelope Tightness
Exhaust Fans
Envelope Tightness
Vent Design
CAZ Location
![Page 15: Physics and Statistics of Combustion SafetyCombustion Safety. Available draft is draft supplied by the vent system at the flue gas outlet. D a D t ...](https://reader033.fdocuments.us/reader033/viewer/2022041722/5e4f0f1ee94e4662f20703eb/html5/thumbnails/15.jpg)
Short term tests include some of the physical processes impacting draft
Test Physical ProcessesHouse depressurizationtest with pre-set criteriaDowndrafting test (Worst-Case Depressurization)Backdrafting test (Downdrafting test + Operation)Cold vent establishment pressure (CVEP) test
Exhaust Fans
Envelope Tightness
Exhaust Fans
Envelope Tightness
Vent Design
Exhaust Fans
Envelope Tightness
Vent Design
BirdNest
CAZ Location
CAZ Location
![Page 16: Physics and Statistics of Combustion SafetyCombustion Safety. Available draft is draft supplied by the vent system at the flue gas outlet. D a D t ...](https://reader033.fdocuments.us/reader033/viewer/2022041722/5e4f0f1ee94e4662f20703eb/html5/thumbnails/16.jpg)
Short term tests include some of the physical processes impacting draft
Test Physical ProcessesHouse depressurizationtest with pre-set criteriaDowndrafting test (Worst-Case Depressurization)Backdrafting test (Downdrafting test + Operation)Cold vent establishment pressure (CVEP) test
Exhaust Fans
Envelope Tightness
Exhaust Fans
Envelope Tightness
Vent Design
Exhaust Fans
Envelope Tightness
Vent Design
BirdNest
CAZ Location
CAZ Location
Exhaust Fans
Envelope Tightness
Vent Design
BirdNest
CAZ Location
![Page 17: Physics and Statistics of Combustion SafetyCombustion Safety. Available draft is draft supplied by the vent system at the flue gas outlet. D a D t ...](https://reader033.fdocuments.us/reader033/viewer/2022041722/5e4f0f1ee94e4662f20703eb/html5/thumbnails/17.jpg)
Short term tests include some of the physical processes impacting draft
Test Physical ProcessesHouse depressurizationtest with pre-set criteriaDowndrafting test (Worst-Case Depressurization)Backdrafting test (Downdrafting test + Operation)Cold vent establishment pressure (CVEP) test
Exhaust Fans
Envelope Tightness
Exhaust Fans
Envelope Tightness
Vent Design
Exhaust Fans
Envelope Tightness
Vent Design
BirdNest
CAZ Location
CAZ Location
Exhaust Fans
Envelope Tightness
Vent Design
BirdNest
CAZ Location
All tests are impacted by weather at time of test
![Page 18: Physics and Statistics of Combustion SafetyCombustion Safety. Available draft is draft supplied by the vent system at the flue gas outlet. D a D t ...](https://reader033.fdocuments.us/reader033/viewer/2022041722/5e4f0f1ee94e4662f20703eb/html5/thumbnails/18.jpg)
Continuous tests measure more physical processes but are expensive
Test Advantages DisadvantagesContinuous backdrafting
test
• Measures vent pressure• Measures appliance
status
• Does not measure spillage events.
• Cost
Continuous spillage test
• Measures CO/CO2
• Measures spillage zone Temperature
• Measures appliance status
• Thermal radiation• Cost
![Page 19: Physics and Statistics of Combustion SafetyCombustion Safety. Available draft is draft supplied by the vent system at the flue gas outlet. D a D t ...](https://reader033.fdocuments.us/reader033/viewer/2022041722/5e4f0f1ee94e4662f20703eb/html5/thumbnails/19.jpg)
Continuous tests measure more physical processes but are expensive
Test Advantages DisadvantagesContinuous backdrafting
test
• Measures vent pressure• Measures appliance
status
• Does not measure spillage events.
• Cost
Continuous spillage test
• Measures CO/CO2
• Measures spillage zone Temperature
• Measures appliance status
• Thermal radiation• Cost
All tests require two visits, require data analysis, and may not capture weather effects
![Page 20: Physics and Statistics of Combustion SafetyCombustion Safety. Available draft is draft supplied by the vent system at the flue gas outlet. D a D t ...](https://reader033.fdocuments.us/reader033/viewer/2022041722/5e4f0f1ee94e4662f20703eb/html5/thumbnails/20.jpg)
Time dependent parameters can be measured using statistical data
Weather
UsagePatterns
![Page 21: Physics and Statistics of Combustion SafetyCombustion Safety. Available draft is draft supplied by the vent system at the flue gas outlet. D a D t ...](https://reader033.fdocuments.us/reader033/viewer/2022041722/5e4f0f1ee94e4662f20703eb/html5/thumbnails/21.jpg)
Time dependent parameters can be measured using statistical data
Weather
UsagePatterns
Shielding
Location
![Page 22: Physics and Statistics of Combustion SafetyCombustion Safety. Available draft is draft supplied by the vent system at the flue gas outlet. D a D t ...](https://reader033.fdocuments.us/reader033/viewer/2022041722/5e4f0f1ee94e4662f20703eb/html5/thumbnails/22.jpg)
Time dependent parameters can be measured using statistical data
Weather
UsagePatterns
Shielding
Location
Meteorological Data
![Page 23: Physics and Statistics of Combustion SafetyCombustion Safety. Available draft is draft supplied by the vent system at the flue gas outlet. D a D t ...](https://reader033.fdocuments.us/reader033/viewer/2022041722/5e4f0f1ee94e4662f20703eb/html5/thumbnails/23.jpg)
Time dependent parameters can be measured using statistical data
Weather
UsagePatterns
Shielding
Location
Meteorological Data
Number ofResidents
Resident’sAge
Time of Day
Location
Etc...
![Page 24: Physics and Statistics of Combustion SafetyCombustion Safety. Available draft is draft supplied by the vent system at the flue gas outlet. D a D t ...](https://reader033.fdocuments.us/reader033/viewer/2022041722/5e4f0f1ee94e4662f20703eb/html5/thumbnails/24.jpg)
Time dependent parameters can be measured using statistical data
Weather
UsagePatterns
Shielding
Location
Meteorological Data
StatisticalDistributions
Number ofResidents
Resident’sAge
Time of Day
Location
Etc...
![Page 25: Physics and Statistics of Combustion SafetyCombustion Safety. Available draft is draft supplied by the vent system at the flue gas outlet. D a D t ...](https://reader033.fdocuments.us/reader033/viewer/2022041722/5e4f0f1ee94e4662f20703eb/html5/thumbnails/25.jpg)
We can simulate physics to better understand the statistics of failure
PhysicalProcesses
Weather
UsagePatterns
Probability Probability of Failure
![Page 26: Physics and Statistics of Combustion SafetyCombustion Safety. Available draft is draft supplied by the vent system at the flue gas outlet. D a D t ...](https://reader033.fdocuments.us/reader033/viewer/2022041722/5e4f0f1ee94e4662f20703eb/html5/thumbnails/26.jpg)
We can simulate physics to better understand the statistics of failure
PhysicalProcesses
Weather
UsagePatterns
Probability Probability of Failure
Appliance and Vent Specs Shielding
LocationTightness, Fans, CAZ
Household Info+ Safe or
Not?
![Page 27: Physics and Statistics of Combustion SafetyCombustion Safety. Available draft is draft supplied by the vent system at the flue gas outlet. D a D t ...](https://reader033.fdocuments.us/reader033/viewer/2022041722/5e4f0f1ee94e4662f20703eb/html5/thumbnails/27.jpg)
Appliance and Vent Specs Shielding
LocationTightness, Fans, CAZ
Household Info+ Safe or
Not?
Probability Probability of Failure
Goal: Diagnostic Tool
![Page 28: Physics and Statistics of Combustion SafetyCombustion Safety. Available draft is draft supplied by the vent system at the flue gas outlet. D a D t ...](https://reader033.fdocuments.us/reader033/viewer/2022041722/5e4f0f1ee94e4662f20703eb/html5/thumbnails/28.jpg)
Open Questions
• What is acceptable probability / frequency of spillage? This is a policy question.
• Assess for currently installed (often bad) exhaust fans, or assume what should be there?
• Assess for current occupants, or assume standard or high intensity occupant use patterns?
• Do we need separate measurement of CAZ air tightness – or is envelope tightness good enough?
![Page 29: Physics and Statistics of Combustion SafetyCombustion Safety. Available draft is draft supplied by the vent system at the flue gas outlet. D a D t ...](https://reader033.fdocuments.us/reader033/viewer/2022041722/5e4f0f1ee94e4662f20703eb/html5/thumbnails/29.jpg)
Extra Slides
![Page 30: Physics and Statistics of Combustion SafetyCombustion Safety. Available draft is draft supplied by the vent system at the flue gas outlet. D a D t ...](https://reader033.fdocuments.us/reader033/viewer/2022041722/5e4f0f1ee94e4662f20703eb/html5/thumbnails/30.jpg)
Termination location of chimneys and single-wall pipes