1107:. Hydrogen itself is biologically inert and its only human health hazard as a vapor is displacement of oxygen, resulting in asphyxiation, and its very high flammability and ability to detonate when mixed with air. Because of its flammability, liquid hydrogen should be kept away from heat or flame unless ignition is intended. Unlike ambient-temperature gaseous hydrogen, which is lighter than air, hydrogen recently vaporized from liquid is so cold that it is heavier than air and can form flammable heavier-than-air air–hydrogen mixtures.
731:
537:
759:
747:
66:
454:
449:
42:
533:
775:
51:
615:
538:
795:
1041:
The product of hydrogen combustion in a pure oxygen environment is solely water vapor. However, the high combustion temperatures and present atmospheric nitrogen can result in the breaking of N≡N bonds, forming toxic NOx if no exhaust scrubbing is done. Since water is often considered harmless to the
715:
Hydrogen requires a theoretical minimum of 3.3 kWh/kg (12 MJ/kg) to liquefy, and 3.9 kWh/kg (14 MJ/kg) including converting the hydrogen to the para isomer, but practically generally takes 10–13 kWh/kg (36–47 MJ/kg) compared to a 33 kWh/kg (119 MJ/kg) heating
1206:
536:
705:. Storing it as liquid takes less space than storing it as a gas at normal temperature and pressure. However, the liquid density is very low compared to other common fuels. Once liquefied, it can be maintained as a liquid for some time in thermally insulated containers.
872:
to become the para isomer, with enough energy released as heat to cause some of the liquid to boil. To prevent loss of the liquid during long-term storage, it is therefore intentionally converted to the para isomer as part of the production process, typically using a
554:
863:
are antiparallel, is more stable than orthohydrogen, in which the two are parallel. At room temperature, gaseous hydrogen is mostly in the ortho isomeric form due to thermal energy, but an ortho-enriched mixture is only
462:
429:
814:
published hydrogen's critical temperature as 33 K (−240.2 °C; −400.3 °F); critical pressure, 13.3 standard atmospheres (195 psi); and boiling point, 23 K (−250.2 °C; −418.3 °F).
947:
rocket engines run fuel-rich so that the exhaust contains some unburned hydrogen. This reduces combustion chamber and nozzle erosion. It also reduces the molecular weight of the exhaust, which can increase
1084:. Even with thermally insulated containers it is difficult to keep such a low temperature, and the hydrogen will gradually leak away (typically at a rate of 1% per day). It also shares many of the same
628:
539:
331:
799:
1328:
DOE Hydrogen and Fuel Cells
Program Record: Energy requirements for hydrogen gas compression and liquefaction as related to vehicle storage needs
1042:
environment, an engine burning it can be considered "zero emissions". In aviation, however, water vapor emitted in the atmosphere contributes to
561:
725:
500:
1382:
1088:
as other forms of hydrogen, as well as being cold enough to liquefy, or even solidify atmospheric oxygen, which can be an explosion hazard.
1230:
916:, which operate a large number of liquid hydrogen tanks with an individual capacity up to 3.8 million liters (1 million U.S. gallons).
712:; whereas room temperature hydrogen is mostly orthohydrogen, liquid hydrogen consists of 99.79% parahydrogen and 0.21% orthohydrogen.
1479:
1504:
299:
1327:
697:
needs to be cooled to 20.28 K (−252.87 °C; −423.17 °F). A common method of obtaining liquid hydrogen involves a
682:
289:
1526:
1065:
of just 0.07. Although the specific energy is more than twice that of other fuels, this gives it a remarkably low volumetric
811:
924:
635:
494:
264:
794:
504:
701:
resembling a jet engine in both appearance and principle. Liquid hydrogen is typically used as a concentrated form of
1447:
Nojoumi, H. (2008-11-10). "Greenhouse gas emissions assessment of hydrogen and kerosene-fueled aircraft propulsion".
1400:"Optimising air quality co-benefits in a hydrogen economy: a case for hydrogen-specific standards for NOx emissions"
547:
1182:
1147:
956:
453:
1561:
1531:
1521:
1172:
992:
983:, and others. Due to its similarity, builders can sometimes modify and share equipment with systems designed for
838:
739:
1566:
1347:
1177:
850:
709:
581:
1076:
storage technology such as special thermally insulated containers and requires special handling common to all
1010:. Since neutrons and hydrogen nuclei have similar masses, kinetic energy exchange per interaction is maximum (
448:
1167:
913:
730:
1541:
1536:
1122:
984:
905:
763:
476:
441:
88:
78:
1003:
is used, a severe gas-displacement effect also hampers maximum breathing and increases pumping losses.
1022:
826:
690:
1551:
1132:
886:
869:
803:
758:
508:
118:
833:. The first synthesis of the stable isomer form of liquid hydrogen, parahydrogen, was achieved by
486:
1429:
1302:
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1007:
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152:
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65:
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237:
50:
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183:
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284:
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1026:
927:
the nozzle and other parts before being mixed with the oxidizer, usually
874:
818:
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1416:
1399:
980:
686:
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224:
1058:
363:
605:
Except where otherwise noted, data are given for materials in their
1057:
The density of liquid hydrogen is only 70.85 kg/m (at 20
212:
17:
976:
932:
793:
773:
757:
745:
729:
248:
163:
151:
141:
909:
203:
999:, the hydrogen volumes needed for combustion are large. Unless
855:
The two nuclei in a dihydrogen molecule can have two different
1103:
Due to its cold temperatures, liquid hydrogen is a hazard for
885:, platinized asbestos, rare earth metals, uranium compounds,
1006:
Liquid hydrogen is also used to cool neutrons to be used in
49:
40:
1374:
Cryogenic
Engineering, Second Edition, Revised and Expanded
750:
Liquid hydrogen bubbles forming in two glass flasks at the
868:
when liquified at low temperature. It slowly undergoes an
1014:). Finally, superheated liquid hydrogen was used in many
975:
have been built using this form of hydrogen, such as the
531:
623:
568:
102:
Hydrogen (cryogenic liquid), Refrigerated hydrogen; LH
1095:of hydrogen is at 13.81 K and 7.042 kPa.
689:. However, for it to be in a fully liquid state at
987:(LNG). Liquid hydrogen is being investigated as a
762:A large hydrogen tank in a vacuum chamber at the
1472:
1470:
1033:, also known as hydrogen-2, for nuclear fusion.
419:−252.87 °C (−423.17 °F; 20.28 K)
409:−259.14 °C (−434.45 °F; 14.01 K)
236:
1495:Cengel, Yunus A. and Turner, Robert H. (2004).
955:Liquid hydrogen can be used as the fuel for an
535:
127:
742:, a leading global supplier of liquid hydrogen
1333:(Report). United States Department of Energy.
931:, and burned to produce water with traces of
399:0.07085 g/cm (4.423 lb/cu ft)
8:
1285:
1283:
1281:
1080:. This is similar to, but more severe than
1342:
1340:
1050:). Liquid hydrogen also has a much higher
191:
29:
1486:. Almc.army.mil. Retrieved on 2011-08-28.
1415:
272:
1449:International Journal of Hydrogen Energy
653:
589:571 °C (1,060 °F; 844 K)
359:
1227:Information specific to liquid hydrogen
1199:
1054:than gasoline, natural gas, or diesel.
859:states. Parahydrogen, in which the two
336:
304:
1497:Fundamentals of thermal-fluid sciences
1260:"We've Got (Rocket) Chemistry, Part 1"
726:Timeline of low-temperature technology
1207:Thermophysical Properties of Hydrogen
952:, despite the incomplete combustion.
806:, which are used with liquid hydrogen
666:. Hydrogen is found naturally in the
311:Key: UFHFLCQGNIYNRP-UHFFFAOYSA-N
171:
7:
963:. Various submarines, including the
923:fueled by liquid hydrogen, it first
802:placards indicating the presence of
27:Liquid state of the element hydrogen
1348:"Liquefaction of "Permanent" Gases"
1221:
1219:
1217:
1215:
227:
211:
1404:Environmental Science: Atmospheres
1237:, harvard.edu, accessed 2009-06-12
25:
1398:Lewis, Alastair C. (2021-07-22).
1326:Gardiner, Monterey (2009-10-26).
800:U.S. Department of Transportation
1292:, iupac.org, accessed 2020-01-01
782:tank for liquid hydrogen at the
613:
452:
447:
64:
1477:Hydrogen As an Alternative Fuel
1209:, nist.gov, accessed 2012-09-14
609:(at 25 °C , 100 kPa).
1461:10.1016/j.ijhydene.2008.11.017
1:
599:LEL 4.0%; UEL 74.2% (in air)
897:Liquid hydrogen is a common
889:, or some nickel compounds.
1046:(to a lesser extent than CO
908:application and is used by
812:Zygmunt Florenty Wróblewski
734:The global headquarters of
36:
1583:
1377:. CRC Press. p. 401.
1303:"Liquid Hydrogen Delivery"
1183:Liquid hydrogen tanktainer
1148:Gasoline gallon equivalent
971:, and others, and concept
957:internal combustion engine
848:
723:
1173:Hydrogen-powered aircraft
1072:Liquid hydrogen requires
839:Karl Friedrich Bonhoeffer
740:Trexlertown, Pennsylvania
681:must be cooled below its
603:
428:
423:
344:
327:
295:
111:
99:
87:
77:
72:
63:
35:
1178:Liquid hydrogen tank car
851:Spin isomers of hydrogen
845:Spin isomers of hydrogen
710:spin isomers of hydrogen
495:Precautionary statements
1168:Hydrogen infrastructure
995:. Because of the lower
829:and his invention, the
677:To exist as a liquid, H
1499:, McGraw-Hill, p. 78,
1371:Flynn, Thomas (2004).
1351:(PDF of lecture notes)
807:
791:
771:
755:
743:
542:
54:
45:
1527:Hydrogen technologies
1123:Liquefaction of gases
985:liquefied natural gas
797:
777:
764:Glenn Research Center
761:
749:
733:
724:Further information:
541:
89:Systematic IUPAC name
53:
44:
827:regenerative cooling
691:atmospheric pressure
524:(fire diamond)
1133:Compressed hydrogen
1069:, many fold lower.
887:chromium(III) oxide
870:exothermic reaction
804:hazardous materials
716:value of hydrogen.
381: g·mol
32:
1482:2008-08-08 at the
1417:10.1039/D1EA00037C
1233:2009-07-17 at the
1023:thermonuclear bomb
1008:neutron scattering
969:Type 214 submarine
965:Type 212 submarine
808:
792:
790:, Germany, in 2008
772:
756:
754:laboratory in 1955
744:
636:Infobox references
543:
55:
46:
30:
1384:978-0-203-02699-1
1163:Metallic hydrogen
1012:elastic collision
997:volumetric energy
973:hydrogen vehicles
937:hydrogen peroxide
825:in 1898 by using
821:was liquefied by
784:Museum Autovision
644:Chemical compound
642:
641:
477:Hazard statements
389:Colorless liquid
153:Interactive image
59:
58:
16:(Redirected from
1574:
1562:Industrial gases
1532:Hydrogen storage
1522:Hydrogen physics
1507:
1493:
1487:
1474:
1465:
1464:
1455:(3): 1363–1369.
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1271:
1256:
1250:
1244:
1238:
1223:
1210:
1204:
1063:relative density
1001:direct injection
989:zero carbon fuel
950:specific impulse
883:activated carbon
768:Brook Park, Ohio
703:hydrogen storage
657:
626:
620:
617:
616:
595:Explosive limits
570:
563:
556:
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514:
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502:
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367:
352:Chemical formula
276:
240:
229:
215:
195:
175:
155:
131:
68:
37:
33:
31:Liquid hydrogen
21:
1582:
1581:
1577:
1576:
1575:
1573:
1572:
1571:
1567:1898 in science
1512:
1511:
1510:
1494:
1490:
1484:Wayback Machine
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1468:
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1266:. 15 April 2016
1258:
1257:
1253:
1245:
1241:
1235:Wayback Machine
1224:
1213:
1205:
1201:
1197:
1192:
1188:Hydrogen tanker
1143:Expansion ratio
1138:Cryo-adsorption
1128:Hydrogen safety
1113:
1101:
1078:cryogenic fuels
1052:specific energy
1049:
1039:
946:
942:
895:
879:iron(III) oxide
853:
847:
728:
722:
696:
680:
673:
662:of the element
655:
651:
648:Liquid hydrogen
645:
638:
633:
632:
631: ?)
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586:
583:
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444:
378:
361:
357:
354:
340:
335:
334:
323:
320:
319:
313:
312:
309:
308:InChI=1S/H2/h1H
303:
302:
279:
259:
243:
230:
218:
198:
178:
158:
145:
134:
121:
107:
106:, para-hydrogen
105:
95:
94:
93:Liquid hydrogen
83:
28:
23:
22:
15:
12:
11:
5:
1580:
1578:
1570:
1569:
1564:
1559:
1554:
1549:
1544:
1539:
1534:
1529:
1524:
1514:
1513:
1509:
1508:
1488:
1466:
1439:
1410:(5): 201–207.
1390:
1383:
1363:
1336:
1318:
1294:
1277:
1251:
1239:
1211:
1198:
1196:
1193:
1191:
1190:
1185:
1180:
1175:
1170:
1165:
1160:
1158:Solid hydrogen
1155:
1153:Slush hydrogen
1150:
1145:
1140:
1135:
1130:
1125:
1120:
1118:Industrial gas
1114:
1112:
1109:
1100:
1097:
1067:energy density
1047:
1044:global warming
1038:
1035:
1029:, used liquid
1016:bubble chamber
944:
940:
921:rocket engines
914:U.S. Air Force
894:
891:
849:Main article:
846:
843:
721:
718:
708:There are two
694:
683:critical point
678:
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634:
612:
611:
607:standard state
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318:InChI=1/H2/h1H
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26:
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14:
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10:
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3:
2:
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1506:
1505:0-07-297675-6
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1248:GESTIS 007010
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1119:
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1086:safety issues
1083:
1082:liquid oxygen
1079:
1075:
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1068:
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1060:
1055:
1053:
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1036:
1034:
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1028:
1024:
1019:
1018:experiments.
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1002:
998:
994:
990:
986:
982:
978:
974:
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966:
962:
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951:
939:. Practical H
938:
934:
930:
929:liquid oxygen
926:
922:
917:
915:
911:
907:
903:
900:
892:
890:
888:
884:
880:
876:
871:
867:
862:
861:nuclear spins
858:
852:
844:
842:
840:
836:
832:
828:
824:
820:
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813:
805:
801:
796:
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748:
741:
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719:
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443:
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418:
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415:Boiling point
413:
412:
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406:
405:Melting point
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86:
80:
76:
71:
67:
62:
52:
48:
43:
39:
38:
34:
19:
1542:Rocket fuels
1537:Liquid fuels
1496:
1491:
1452:
1448:
1442:
1407:
1403:
1393:
1373:
1366:
1355:. Retrieved
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582:Autoignition
520:
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249:RTECS number
112:Identifiers
100:Other names
902:rocket fuel
823:James Dewar
685:of 33
584:temperature
463:Signal word
386:Appearance
345:Properties
173:CHEBI:33251
1552:Cryogenics
1516:Categories
1357:2017-10-16
1312:2022-07-30
1307:Energy.gov
1195:References
1105:cold burns
1037:Properties
1021:The first
866:metastable
788:Altlußheim
699:compressor
442:Pictograms
374:Molar mass
274:7YNJ3PO35Z
184:ChemSpider
140:3D model (
119:CAS Number
79:IUPAC name
1434:236732702
1426:2634-3606
1290:IPTS-1968
1270:3 October
1264:NASA Blog
1074:cryogenic
1031:deuterium
961:fuel cell
841:in 1929.
810:In 1885,
770:, in 1967
668:molecular
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433:labelling
285:UN number
256:MW8900000
129:1333-74-0
1557:Hydrogen
1547:Coolants
1480:Archived
1231:Archived
1111:See also
1027:Ivy Mike
993:aircraft
919:In most
912:and the
906:rocketry
877:such as
875:catalyst
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