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Main Characteristic Data Of Hydrogen

Parameter Value Unit
Molecular weight 2.01594 g/mol
Stoichiometric fraction in air 29.53 vol%
Boiling point (BP) 20.369 K
Melting point (MP) 14.01 K
Triple point (TP)
temperature 13.08 K
pressure 7.2 kPa
Critical point
temperature 33.145 K
pressure 1.2964 kPa
density 31.263 kg/m3
Electro-negativity 2.20 Pauling scale
Density
gas @ NTP 0.08376 g/mol
gas @ STP 0.08990 kg/m3
gas @ BP 1.338 kg/m3
para liquid @ BP 70.78 kg/m3
normal liquid @ BP 70.96 kg/m3
slush with 50 wt% solid @ TP 81.48 kg/m3
para solid @ MP 86.50 kg/m3
solid @ 4K 88.0 kg/m3
Expansion ratio liquid/ambient 845 -
Diffusion coefficient @ NTP 0.61*104 m2/s
Diffusion velocity @ NTP < 0.02 m/s
Buoyant velocity 1.2 - 9.1 m/s
Gas constant 4124.3 J/(kg K)
Specific heat (constant p)
gas @ NTP(2) 14.85 kJ/(kg K)
gas @ STP(1) 14.304 kJ/(kg K)
gas @ BP 12.15 kJ/(kg K)
liquid @ BP 9.66 kJ/(kg K)
Thermal conductivity
gas @ NTP(2) 0.187 W/(m K)
gas @ BP 0.01694 W/(m K)
liquid @ BP 0.09892 W/(m K)
Visocity
gas @ NTP(2) 89.48 μPoise
gas @ BP 11.28 μPoise
liquid @ BP 132.0 μPoise
Surface tension @ BP 1.93*10-3 N/m
Vapour pressure @
Heat of conversion from para to ortho 708.8 kJ/kg
Heat of melting (fusion) @ MP 58.8 kJ/kg
Heat of vaporization @ BP 445.6 kJ/kg
Vaporization index(3) 8.9 K cm3/J
Vaporization rate of LH2 pool 4.2 - 8.3 mm/s
Heat of sublimation 379.6 kJ/kg
Speed of sound
gas @ NTP(2) 1294 m/s
gas @ BP 355 m/s
liquid @ BP 1093 m/s
stoichiometric H2-air mixture 404 m/s
Inversion temperature 193 K
Flammability limits in air 4.0 - 75.0(4) vol%
Detonability limits in air 13 - 70(5) vol%
Minimum ignition energy
for deflagration 1.9*105 J
for detonation ~ 10,000 J
Auto-ignition temperature in air 793 - 1023 (858) K
Hot air jet ignition temperature 943 K
Gross heat of combustion (HHV) @ 15C 286.1 kJ/mol
Net heat of combustion (LHV) @ 15C 241.7 kJ/mol
Adiabatic flame temperature 2318 K
Burning rate of LH2 pool 0.5 - 1.1 mm/s
Laminar burning velocity in air 2.65 - 3.25 m/s
Visible laminar flame speed 18.6 m/s
Deflagration pressure ratio 8.15 -
Quenching distance @ NTP(2) 0.64 mm
Maximum experimental safe gap @ NTP(2) 0.08 mm
Detonation velocity 1480 - 2150 m/s
Chapman-Jouguet (CJ) velocity 1968 m/s
CJ detonation pressure ratio pCJ/po 15.6 -
Energy release 2.82 MJ/kg of mixture
Detonation cell size 15 mm
Critical tube diameter 0.2 m
Detonation initiation energy 1.1 g tetryl
Detonation induction distance @ NTP(2) length/diameter ~ 100 -
TNT equivalent
26.5 kg TNT/kg of H2
2.22 kg TNT/Nm3 of H2

(1) STP (Standard temperature and pressure): 273 K, 101325 Pa.
(2) NTP (Normal temperature and pressure): 293 K, 101325 Pa.
(3) Indicates the relative ease of a substance to vaporize.
(4) LFL is valid for upward propagation of flame. For downward propagation, LFL values is 5.3 vol%.
(5) Valid for weak ignition. For a high-energy igniter, a range of 11.6 - 74.9 was quoted.


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Page last modified on November 20, 2008, at 08:49 AM