Vessels for the storage and transport of liquid hydrogen

Abstract

The d esign a nd co nstru ction of a lar ge-scale hydr ogen liqu efi er by t he N a tion al Bureau of Standards r eq uired a concurre n t developmen t of large, transpor table liq uid-hydrogen con tainers. These co n tainers, known as D ewar vessels after t he in ven tor, J a mes D ewar, ha d to be capa ble of road a nd air t ranspor t, whi ch implied ruggedness a nd ligh t weig ht . This ar t icle reports o n lar ge-scale liquid-h ydrogen D ewar development condu cted by t he N BS Cr yogenic E ngineerin g L a bor atory. A 440-li ter a nd a n 840-li ter D ewar a re discussed. E ver y effort has been made to design D ewars wi t h ver y low hydrogen-l oss rates within t he limi tations of t he t ransp or t r equire men t . Dewar ConfigurationThe op timum D ewar configuration is spherical, because the sphere has the smalles t area-to-volume ratio of any shape. I n practice, however, such Insulation MethodsOnly two m ethods of D ewar insulation appeared feasible a t the time of the design : the use of powder insulation, su ch as silica aerogel, at a moder ate vacuum, and th e use of an unfilled sp ace at a high vacuum . Although the moder a te vacuum associa ted with powder insulation brings m any advant agessuch as r educing th e impor tance of ver y minute leaks and making th e achievem en t of a static vacuum easier-the insula tion value when used in moder ate thickn ess does not appear to b e as gr ea t as that of an unfilled space a t a high vacuum (up to abou t 0.01-}.L H g pressure) with surfaces having a high refl ectivity (low emissivity). As one of the primary goals was the achievem ent of a low hy drogen loss withou t making the D ewar too bulky, high va cuum r ather than evacuated powder was chosen for t he D ewar insula tion.With high-vacuum insulation, h eat energy flows to th e inner surfaces by three m ech anisms : th ermal radiation, r esidual gas conduction, and solid conduction through piping and insulating suppor ts.Withou t any shielding, thermal r adiation from room temper ature directly to the liquid-hydrogen con tain er would b e excessive and would m ak e it difficul t to develop a low-loss hydrogen D ewar. I n order to r edu ce this thermal r adiation, a liquidni trogen-cooled r adiation shield was planned. This shi eld completely surrounds the liquid-hydrogen 1 Work SUI)ported by the U. S. A tomie E nergy Commission an d t he U. S. Air F orce., Now with Beech Aircraft COrl). a J<' igures in brackets ind icate the li terature references at t he end of t his paper.container and intercepts all ambien t temperat ure radiation from th e outer shell. Thermal radiation to t he liquid-hy drogen container is th en r educed by a factor of at least 200 and b ecomes of the same order of magnitude as the r esidual gas conduction and the solid conduction . Wh en considering hea t t ransfer to the ni trogencooled shield, r esidual gas condu ction for a vac uum of th e order of 0.01-}.L H g is relatively unimportan t compared with thermal r adiation . A low h eat leak to th e nitrogen-cooled shield th er...

Selected topics on hydrogen fuel

“…Hydrogen in gaseous, liquid, or slush form can be transported by pipeline or mobile tanks. Considerable experience has been gained in the space program on the transfer and storage of liquid hydrogen [42,73,74,91,112,[134][135][136][137][138][139]. This experience shows that hydrogen in large quantities can be handled safely with no serious materials problems.…”