Download - Constant and conversion factors
APPENDIXES
Convection Heat Transfer, Fourth Edition. Adrian Bejan© 2013 John Wiley & Sons, Inc. Published 2013 by John Wiley & Sons, Inc.
A
CONSTANTS ANDCONVERSION FACTORS
CONSTANTS
Universal ideal gas constant P. R = 8.314 kJ/kmol · KPatm = 1.9872 cal/mol · KPatm = 1.9872 Btu/lbmol · ◦RPatm = 1545.33 ft · lbf/lbmol · ◦R
Boltzmann’s constant k = 1.38054 × 10−23 J/K
Planck’s constant h = 6.626 × 10−34 J · sSpeed of light in vacuum c = 2.998 × 108 m/s
Avogadro’s number N = 6.022 × 1023 molecules/mol
Stefan–Boltzmann constant σ = 5.669 × 10−8 W/m2 · K4
Patm = 0.1714 × 10−8 Btu/h · ft2 · ◦R4
Atmospheric pressure Patm = 0.101325MPa
Patm = 1.01325 bar
Patm = 1.01325 × 105 N/m2
Ice point at 1 atm Tice = 0◦C = 273.15 K
Gravitational acceleration g = 9.807m/s2
Patm = 32.17 ft/s2
Calorie 1 cal = 4.187 J
Mole 1mol = sample containing 6.022 × 1023
elementary entities (e.g.,molecules); also abbreviatedas 1 gmol, or
609
610 A CONSTANTS AND CONVERSION FACTORS
1mol = 10−3 kmol
= 10−3 kgmol
= 1
453.6lbmol
Natural logarithm ln x = 2.30258 log10x
log10x = 0.4343 ln x
Important numbers e = 2.71828
π = 3.14159
1◦ = 0.01745 rad
CONVERSION FACTORS
Acceleration 1m/s2 = 4.252 × 107 ft/h2
Area 1 in2 = 6.452 cm2
1 ft2 = 0.0929m2
1 yd2 = 0.8361m2
1 mi2 = 2.59 km2
1 hectare = (100m)2
1 acre = 4047m2
Density 1 kg/m3 = 0.06243 lbm/ft3
1 lbm/ft3 = 16.018 kg/m3
Energy 1 kJ = 737.56 ft · lbf= 0.9478 Btu
= 3.725 × 10−4 hp · h= 2.778 × 10−4 kW · h
1 Btu = 1055 J
= 778.16 ft · lbf= 3412.14 kW · h= 2544.5 hp · h
1 cal = 4.187 J
1 erg = 10−7 J
Force 1 lbf = 4.448N
= 0.4536 kgf
1 dyne = 10−5 N
CONVERSION FACTORS 611
Heat flux 1W/m2 = 0.317 Btu/h · ft21 Btu/h · ft2 = 3.154W/m2
Heat transfer coefficient 1W/m2 · K = 0.1761 Btu/h · ft2 · ◦F= 0.8598 kcal/h · m2 · ◦C
1 Btu/h · ft2 · ◦F = 5.6786W/m2 · KHeat transfer rate 1 Btu/s = 1055W
1 Btu/h = 0.2931W
1 hp = 745.7W
1 ft · lbf/s = 1.3558W
Kinematic viscosity (ν),thermal diffusivity (α),mass diffusivity (D)
1m2/s = 104 cm2/s
= 104 stokes
= 3.875 × 104 ft2/h
= 10.764 ft2/s
Latent heat, specific energy,specific enthalpy
1 kJ/kg = 0.4299 Btu/lbm= 0.2388 cal/g
1 Btu/lbm = 2.326 kJ/kg
Length 1 in = 2.54 cm
1 ft = 0.3048m
1 yd = 0.9144m
1 mile = 1.609 km
Mass 1 lbm = 0.4536 kg
1 kg = 2.2046 lbm
= 1.1023 × 10−3 U.S. ton
= 10−3 tonne
1 oz = 28.35 g
Mass transfer coefficient 1m/s = 1.181 × 104 ft/h
1 ft/h = 8.467 × 10−5 m/s
Power 1 Btu/s = 1055W = 1.055 kW
1 Btu/h = 0.293W
1W = 3.412 Btu/h
= 9.48 × 10−4 Btu/s
1 HP = 0.746 kW
= 0.707 Btu/s
612 A CONSTANTS AND CONVERSION FACTORS
Pressure, stress 1 Pa = 1N/m2
1 psi = 6895N/m2
1 atm = 14.69 psi
= 1.013 × 105 N/m2
1 bar = 105 N/m2
1 torr = 1mmHg
= 133.32N/m2
1 psi = 27.68 in H2O
1 ft H2O = 0.4335 psi
Specific heat, specificentropy
1 kJ/kg · K = 0.2388 Btu/lbm · ◦F= 0.2389 cal/g · ◦C
1 Btu/lbm · ◦F = 4.187 kJ/kg · KSpeed 1 mi/h = 0.447m/s
= 1.609 km/h
1 km/h = 0.278m/s
= 0.622 mi/h
1m/s = 3.6 km/h
= 2.237 mi/h
Temperature 1 K = 1◦C1 (K) = (9/5)◦FT (K) = T(◦C) + 273.15
T (◦C) = 5/9[T(◦F) − 32]
T (◦F) = T(◦R) − 459.67
Temperature difference �T (K) = �T (◦C)= 5/9 �T (◦F)= 5/9 �T (◦R)
Thermal conductivity 1W/m · K = 0.5782 Btu/h · ft · ◦F= 0.01W/cm · K= 2.39 × 10−3 cal/cm · s · ◦C
1 Btu/h · ft · ◦F = 1.7307W/m · KThermal resistance 1 K/W = 0.5275◦F/Btu · h
1◦F/Btu · h = 1.896 K/W
Viscosity (µ) 1N · s/m2 = 1 kg/s · m= 2419.1 lbm/ft · h= 5.802 × 10−6 lbf · h/ft2
1 poise = 1 g/s · cm
DIMENSIONLESS GROUPS USED IN THIS BOOK 613
Volume 1 L = 10−3 m3 = 1 dm3
1 in3 = 16.39 cm3
1 ft3 = 0.02832m3
1 yd3 = 0.7646m3
1 gal (U.S.) = 3.785 L
1 gal (imperial) = 4.546 L
1 pint = 0.5683 L
Volumetric heat generationrate
1 Btu/h · ft3 = 10.35W/m3
1W/m3 = 0.0966 Btu/h · ft3
DIMENSIONLESS GROUPS USED IN THIS BOOKa
Bejan number Be = (�PL2)/µα
Biot number Bi = hL/ksBoussinesq number Bo = (gβ �T H3)/α2
Eckert number Ec = U2/(cP �T)
Fourier number Fo = αt/L2
Graetz number Gz = D2U/αx = ReD Pr (D/x)
Grashof number Gr = (gβ �T H3)/ν2
Lewis numberb Le = α/D = Sc/Pr
Mass transfer Rayleigh numberb Ram = (gβc �ρiH3)/νD
Mass transfer Stanton number Stm = hm/U
Nusselt number Nu = hL/kfPeclet number Pe = UL/α = Re Pr
Porous medium Bejan numberc Be = (�P K)/µα
Porous medium Peclet numberc Pe = UL/α
Porous medium Prandtl numberc Pr = (ν/α)(H/bK)
Porous medium Rayleigh number,Darcy flowc
Ra = (KgβH �T)/αν
Porous medium Rayleigh numberbased on heat flux, Darcy flow
Ra* = Kgβq′′H2/ανk
Prandtl number Pr = ν/α = Sc/Le
aSubscripts: (·)s = solid, (·)f = fluid.bD is the mass diffusivity (m2/s).ck and α are properties of the fluid-saturated porous medium.
614 A CONSTANTS AND CONVERSION FACTORS
Rayleigh number Ra = gβ�TH3/αν
Rayleigh number based on heatflux
Ra* = gβq′′H4/ανk
Reynolds number Re = UL/ν
Schmidt numberb Sc = ν/D = Le Pr
Sherwood numberb Sh = hmL/D
Stanton number St = h/ρcPU = Nu/Re Pr
Stefan number Ste = (cf �T)/hsfTurbulent Prandtl number Prt = εM/εH