Modeling of Combustion Systems A Practical Approach 3 docx

573
Appendix C
Units Conversions
© 2006 by Taylor & Francis Group, LLC
574 Modeling of Combustion Systems: A Practical Approach
TABLE C.1
Common Conversions
TEMPERATURE CONVERSIONS
°C = 5/9 (°F – 32) °F = 9/5°C + 32
K = °C + 273.15 °R = °F + 459.67
From: Baukal, C.E., Heat Transfer in Industrial Combustion, CRC Press, Boca Raton, FL, 2000.
1 Btu = 252.0 cal 1 in. = 2.540 cm
1055 J 25.40 mm
1 Btu/ft
3
= 0.00890 cal/cm
3
1 J = 0.000948 Btu
0.0373 MJ/m
3
0.239 cal
1 Btu/hr = 0.0003931 hp 1 W/sec
0.2520 kcal/hr 1 kcal = 3.968 Btu
0.2931 W 1000 cal
1,000,000 Btu/hr = 0.293 MW 4187 J
1 Btu/hr-ft
2
= 0.003153 kW/m
2
1 kcal/hr = 3.968 Btu/hr
1 Btu/hr-ft-°F = 1.730 W/m-K 1.162 J/sec

1 Btu/hr-ft
2
-°F = 5.67 W/m
2
-K 1 kcal/m
3
= 0.1124 Btu/ft
3
1 Btu/lb = 0.5556 cal/g 4187 J/m
3
2326 J/kg 1 kg = 2.205 lb
1 Btu/lb-°F = 1 cal/g-°C 1 kg/hr-m = 0.00278 g/sec-cm
4187 J/kg-K 0.672 lb/hr-ft
1 cal = 0.003968 Btu 1 kg/m
3
= 0.06243 lb/ft
3
4.187 J 1 kW = 3413 Btu/hr
1 cal/cm
2
-sec = 3.687 Btu/ft
2
-sec 1.341 hp
41.87 kW/m
2
660.6 kcal/hr
1 cal/cm-sec-°C = 241.9 Btu/ft-hr-°F 1 kW/m
2
= 317.2 Btu/hr-ft
2

418.7 W/m-K 1 kW/m
2
-°C = 176.2 Btu/hr-ft
2
-°F
1 cal/g = 1.80 Btu/lb 1 lb = 0.4536 kg
4187 J/kg 1 lb/ft
3
= 0.0160 g/cm
3
1 cal/g-°C = 1 Btu/lb-°F 16.02 kg/m
3
4187 J/kg-K 1 lbm/hr-ft = 0.413 centipoise
1 centipoise = 2.421 lbm/hr-ft 1 m = 3.281 ft
1 cm
2
/sec = 100 centistokes 1 mm = 0.03937 in.
3.874 ft
2
/hr 1 m
2
/sec = 10.76 ft
2
/sec
1 ft = 0.3048 m 1 mton = 1000 kg
1 ft
2
/sec = 0.0929 m
2
/sec 2205 lb

1 g/cm
3
= 1000 kg/m
3
1 MW = 3,413,000 Btu/hr
62.43 lb/ft
3
1000 kW
0.03613 lb/in.
3
1 therm = 100,000 Btu
1 hp = 33,000 ft-lb/min 1 W = 1 J/sec
550 ft-lb/sec 1 W/m-K = 0.5778 Btu/ft-hr-°F
641.4 kcal/hr
745.7 W
© 2006 by Taylor & Francis Group, LLC
Units Conversions 575
TABLE C.2
Unit Dimensions for Some Combustion-Related Quantities
Generic Name Examples
Exponents
Moles Mass Length Time Temperature
[N] [M] [L] [θθ
θθ
] [T]
Acceleration ft/sec
2
m/sec
2
1–2

Area ft
2
m
2
2
Concentration, mass lbm/ft
3
kg/m
3
1–3
Concentration, molar lbmol/ft
3
kgmol/m
3
1–3
Density lbm/ft
3
kg/m
3
1–3
Diameter ft m 1
Energy Btu kJ 1 2 –2
Energy, kinetic lbm ft
2
/sec
2
kg m
2
/sec
2

1 2 –2
Energy, potential lbm ft
2
/sec
2
kg m
2
/sec
2
1 2 –2
Enthalpy, molar Btu/lbmol W/kgmol –1 1 2 –2
Enthalpy, specific Btu/lbm W/kg 2 –2
Enthalpy, volumetric Btu/ft
3
kJ/m
3
1–1–2
Entropy, molar Btu/lbmol °R J/mol K –1 1 2 –2 –1
Flow rate, molar lbmol/h kgmol/h 1 –1
Flow rate, specific lbm/h kg/h 1 –1
Flow rate, volumetric ft
3
/h m
3
/sec 3 –1
Force lbf N 1 1 –2
Free energy, molar Btu/lbmol W/kgmol –1 1 2 –2
Gas constant, universal psia ft
3
/lbmol °R m

3
kPa/kgmol K –1 1 2 –2 –1
Heat Btu/h W 1 2 –3
Heat capacity, molar Btu/lbmol °F J/mol K
–1 1 2 –2 –1
Heat capacity, specific Btu/lbm °F kJ/kg K
2 –2 –1
Heat flux Btu/ft
2
W/m

2

1–2
Heat transfer coefficient Btu/h ft

2

°F W/m

2

K 1 –3 –1
Heating value, molar Btu/lbmol J/mol
1 2 –2
Heating value, specific Btu/lbm kJ/kg 2 –2

© 2006 by Taylor & Francis Group, LLC
576 Modeling of Combustion Systems: A Practical Approach
TABLE C.2 (continued)

Unit Dimensions for Some Combustion-Related Quantities
Generic Name Examples
Exponents
Moles Mass Length Time Temperature
[N] [M] [L] [θθ
θθ
] [T]
Heating value, volumetric Btu/ft
3
kJ/m
3
1–1–2
Kinematic viscosity ft
2
/h m
2
/sec 2 –1
Mass diffusivity ft
2
/h m
2
/sec 2 –1
Mass flux lbm ft
2
kg m
2
1–2
Mass velocity lbm/ft
2
sec kg/m

2
sec 1 –2 –1
Molar density lbmol/ft
3
kgmol/m
3
1–3
Molar velocity lbmol/ft
2
sec kgmol/m
2
sec 1 –2 –1
Molar volume ft
3
/lbmol m
3
/kgmol –1 3
Molecular weight lbm/lbmol kg/kgmol –1 1
Momentum lbm ft/sec kg m/sec 1 1 –1
Momentum, rate of lbm ft/sec
2
kg m/sec
2
1 1 –2
Power Btu/h W 1 2 –3
Pressure lbf/in
2
kPa 1 –1 –2
PV work lbf ft
3

/in
2
kPa m
3
1 2 –2
Rate of reaction per volume lbm/ft
3
h kg/m
3
h 1 –3 –1
Specific volume ft
3
/lbm m
3
/kg –1 3
Stefan–Boltzman constant Btu/h ft
2
°R
4
W/m
2
K
4
1–3–4
Thermal conductivity Btu/h ft °F W/m K
1 1 –3 –1
Thermal diffusivity ft
2
/h m
2

/sec 2 –1
Torque ft lbf N m 1 2 –2
Velocity ft/sec m/sec 1 –1
Viscosity lbm/ft sec kg/m sec 1 –1 –1
Work Btu/h W 1 2 –3
© 2006 by Taylor & Francis Group, LLC