The viscosity and thermal conductivity of dilute gaseous hydrogen from 15 to 5000 K

Abstract

Meas ure me nts of th e vi scos it y a nd th e rm al co ndu c tivit y of dilute gaseu us pa ra and normal hydro· ge n are c riti ca ll y e valuated a nd co rre la ted b y mea ns of di lut e gas kin e ti c th eo ry. N um e ri cal res ult s are prese nt e d fr o m 15 to 5000 K in c ludin g th e di ssoc ia ti o n region. Key word s: Di ssoc iation; hydroge n ; int e rmol ec ul a r pot e ntial fun c tion s; kin e ti c th eo ry ; quantum gas : th e rmal co ndu c tivit y; viscos it y. l We di sc uss the critical e valuation of th e vi scos ity and thermal conduc tivity coe ffi cie nts of dilute p-, 0-, and n-hydrogen and prese nt tabl es of values for para and norm al hydroge n. New information-parti c ularly with re gard to expe rim e ntal data from our laboratory-justifies a ree valuation of th ese prope rti es of thi s well-known fluid. The tabl es given here differ significantly at th e extre me te mpe ratures from those with (Ib) wh ere T is th e te mperature (K), m th e we ight of a mol ec ule, k Boltzmann 's co ns tant , cr a c ross-sec tion parameter, and D U,s) * (I , s = 1, 2, 3) are th e colli s ion integrals. Equation (1) is applicable to both classical and quantum fluid s provided o ne prop er ly modifi es th e colli sion integrals. For exa mpl e, in th e classical case th e coJli s io n integral s involv e th e class ical cross section Q(l) wh er e / published pre viou sly. The coe fficients are re prese nted by s tandard kin e ti c theory ex press ions but the c alculations are more than m ere routine; to give two examples, at low te mpera-tures, hydroge n behaves as a quantum fluid and at ~ high t e mperatures it dissociates. Furthermore, to I apply the th eoretical expressions in practi ce one needs > to evaluate c ritically experim ental data in the firs t ') place, whi c h is not a c ut-and-dri ed probl e m at all. 1. Formal Equations The r e quire d kinetic th eory e quation s are given and briefly di sc uss e d in thi s sec tion [1-4 J t.