03_HRR_Flame_Height_Burning_Duration_Calculations

CHAPTER 3. ESTIMATING BURNING CHARACTERISTICS OF LIQUID POOL FIRE,HEAT RELEASE RATE, BURNING DURATION, AND FLAME HEIGHT Version 1805.0

The following calculations estimate the heat release rate, burning duration, and flame height for liquid pool fire.Parameters in YELLOW CELLS are Entered by the User.

Parameters in GREEN CELLS are Automatically Selected from the DROP DOWN MENU for the Fuel Selected.All subsequent output values are calculated by the spreadsheet and based on values specified in the input parameters. This spreadsheet is protected and secure to avoid errors due to a wrong entry in a cell(s).The chapter in the NUREG should be read before an analysis is made.

INPUT PARAMETERS

Fuel Spill Volume (V)

5.00gallons 0.0189m 3Fuel Spill Area or Dike Area (A dike )9.00ft 2

0.836m 2

Mass Burning Rate of Fuel (m")

0.051kg/m 2-sec Effective Heat of Combustion of Fuel (D H c,eff )43500kJ/kg Fuel Density (r )

760kg/m 3Empirical Constant (k b )

3.6m -1Ambient Air Temperature (T a )77.00

°F

25.00°C 298.00K

Gravitational Acceleration (g)9.81m/sec

2

Ambient Air Density (r a )

1.18kg/m 3

Calculate

Note: Air density will automatically correct with Ambient Air Temperature (T a ) Input

THERMAL PROPERTIES DATA

BURNING RATE DATA FOR LIQUID HYDROCARBON FUELS

Mass Burning Rate Heat of Combustion

Density Empirical Constant Select Fuel Type

m" (kg/m 2-sec)D H c,eff (kJ/kg)r (kg/m 3)k b (m -1)Methanol

0.01720,000796100Scroll to desired fuel type Ethanol 0.01526,800794100Click on selection

Butane 0.07845,700573 2.7Benzene 0.08540,100874 2.7Hexane 0.07444,700650 1.9Heptane 0.10144,600675 1.1Xylene 0.0940,800870 1.4Acetone 0.04125,800791 1.9Dioxane 0.01826,2001035 5.4Diethy Ether 0.08534,2007140.7Benzine 0.04844,700740 3.6Gasoline 0.05543,700740 2.1Kerosine 0.03943,200820 3.5Diesel 0.04544,400918 2.1JP-40.05143,500760 3.6JP-5

0.05443,000810 1.6Transformer Oil, Hydrocarbon 0.03946,0007600.7561 Silicon Transformer Fluid 0.00528,100960100Fuel Oil, Heavy 0.03539,700970 1.7Crude Oil 0.033542,600855 2.8Lube Oil

0.039

46,000

760

0.7

User Specified Value

Enter Value

Enter Value

Enter Value

Enter Value

Reference: SFPE Handbook of Fire Protection Engineering , 3rd Edition, 2002, Page 3-26.

ESTIMATING POOL FIRE HEAT RELEASE RATE

Reference: SFPE Handbook of Fire Protection Engineering , 3rd Edition, 2002, Page 3-25.

Q = m"D H c,eff (1 - e -k b D ) A dike Where Q = pool fire heat release rate (kW)

m" = mass burning rate of fuel per unit surface area (kg/m 2-sec)D H c,eff = effective heat of combustion of fuel (kJ/kg)

A f = A dike = surface area of pool fire (area involved in vaporization) (m 2)k b = empirical constant (m -1)

D = diameter of pool fire (diameter involved in vaporization, circular pool is assumed) (m)

Pool Fire Diameter Calculation A dike =p D 2/4Where A dike = surface area of pool fire (m 2)D = pool fire diamter (m) D = √(4A dike /p )D =

1.032

m

Heat Release Rate Calculation (Liquids with relatively high flash point, like transformer oil, require Q = m"D H c,eff (1-e -k b D ) A dike localized heating to achieve ignition)

Q =

1809.75kW

1715.31Btu/sec

ESTIMATING POOL FIRE BURNING DURATION

Reference: SFPE Handbook of Fire Protection Engineering , 2nd Edition, 1995, Page 3-197.

t b = 4V / p D 2n Where

t b = burning duration of pool fire (sec)V = volume of liquid (m 3)D = pool diameter (m)

n = regression rate (m/sec)

Calculation for Regression Rate n =m"/r Where n = regression rate (m/sec)

m" = mass burning rate of fuel (kg/m 2-sec)r = liquid fuel density (kg/m 3)

n =0.000067m/sec Burning Duration Calculation t b = 4V/p D 2n t b =

337.33sec 5.62minutes

Note that a liquid pool fire with a given amount of fuel can burn for long periods of time over small area or for

short periods of time over a large area.

ESTIMATING POOL FIRE FLAME HEIGHT METHOD OF HESKESTAD

Reference: SFPE Handbook of Fire Protection Engineering , 2nd Edition, 1995, Page 2-10.

H f = 0.235 Q 2/5 - 1.02 D Where

H f = pool fire flame height (m)

Q = pool fire heat release rate (kW)D = pool fire diameter (m)

Pool Fire Flame Height Calculation f 2/5 H f =

3.67m

12.04ft

Fuel

JP-4

Answer

Answer

Answer

METHOD OF THOMAS

Reference: SFPE Handbook of Fire Protection Engineering , 2nd Edition, 1995, Page 3-204.

H f = 42 D (m"/r a √(g D))0.61Where

H f = pool fire flame height (m)

m" = mass burning rate of fuel per unit surface area (kg/m 2-sec)r a = ambient air density (kg/m 3)D = pool fire diameter (m)

g = gravitational acceleration (m/sec 2)

Pool Fire Flame Height Calculation H f = 42 D (m"/r a √(g D))0.61H f =

3.14m

10.30ft

METHOD OF HESKESTAD 12.04METHOD OF THOMAS

10.30

ESTIMATING POOL FIRE RESULTS FOR RANDOM SIZE SPILLS USING INPUT PARAMETERS

Area (ft 2)

Area (m 2)Diameter (m)

Q (kW)t b (sec)H f (ft) (Heskestad)

H f (ft) (Thomas)

10.090.34201.083035.96 5.28 4.8020.190.49402.171517.98 6.86 6.1130.280.60603.251011.997.997.0340.370.69804.33758.998.907.7750.460.771005.41607.199.678.4060.560.841206.50505.9910.358.9570.650.911407.58433.7110.979.4480.740.971608.66379.5011.529.8990.84 1.031809.75337.3312.0410.30100.93 1.092010.83303.6012.5210.6911 1.02 1.142211.91276.0012.9711.0512 1.11 1.192412.99253.0013.3911.3913 1.21 1.242614.08233.5413.8011.7114 1.30 1.292815.16216.8514.1812.0115 1.39 1.333016.24202.4014.5512.3020 1.86 1.544021.66151.8016.1713.6025 2.32 1.725027.07121.4417.5614.6950 4.65 2.4310054.1460.7222.6218.7075 6.97 2.9815081.2140.4826.2121.53100

9.29

3.44

20108.28

30.36

29.08

23.79

Caution! The purpose of this random spill size chart is to aid the user in evaluating the hazard of random sized spills. Please note that the calculation doe not take into account the viscosity or volatility of the liquid, or the absorptivity of the surface. The results generated for small volume spills over large areas should be used with extreme caution.

The above calculations are based on principles developed in the SFPE Handbook of Fire Protection Engineering, 2nd Edition, 1995.

Calculations are based on certain assumptions and have inherent limitations. The results of such calculations may or may not have reasonable predictive capabilities for a given situation, and should only be interpreted by an informed user.

Although each calculation in the spreadsheet has been verified with the results of hand calculation, there is no absolute guarantee of the accuracy of these calculations.Any questions, comments, concerns, and suggestions, or to report an error(s) in the spreadsheets, please send an email to nxi@https://www.wendangku.net/doc/d715342531.html, or mxs3@https://www.wendangku.net/doc/d715342531.html,.

Prepared by:Date Organization Checked by:

Date

Organization

Additional Information

Revision Log Description of Revision Date

1805.0Original issue with final text. January 2005

Answer

NOTE