EFFECT OF COLD-WALL TEMPERATURE ON HE-3-HE-4 SEPARATIVE PERFORMANCES OF CRYOGENIC-WALL THERMAL-DIFFUSION COLUMN

By using the two-dimensional rigorous numerical solution of flow and c onvection-diffusion equations, the He-3-He-4 separative performances o f 0.3 mmphi hot-wire thermal diffusion column with 1,500 mm-height, 15 mm-radius cold-wall was analyzed with pressure P, cold wall temperatu re T(c) and feed rate F being parametrically changed, while the temper ature difference between hot wire and cold wall being constant 1,200 K . Separative analysis using the Dymond-Alder potential for the cryogen ic-wall (less than 77.35K) column has revealed in comparison with the ordinary 288K cold-wall column with the same condition except T(c) tha t: (i) The degree of separation is remarkably larger and the total sep aration factor alphabeta exceeds 10(5) (at 0.020 MPa) when T(c)=10 K, F=1 cm3 (converted at 288.15 K, 0.1 MPa)/min and theta=0.1, while alph abeta=approximately 13 (at 0.148 MPa) for T(c)=288K. (ii) Even for the higher feed rate F of 50 cm3/min, alphabeta remains 2.1x10(3) (at 0.0 24 MPa), while alphabeta=approximately 7 (at 0.170 MPa) for T(c)=288K. In addition, (iii) Pressure dependence of the total separation factor given for the column with continuous feed and draw-offs were found to follow the similarity relation derived for the total reflux operation .