A new theoretically‐based formula is presented for fully developed steady‐state forced convection heat or mass transfer in turbulent tube flow. This relationship, which is proposed for the frill range range of Prandtl or Schmidt numbers between 0.7 (gases) and 100 000 (liquids), is as follows: Coniparisons a with widely quotcd sets of data show very good agreement IFriend and metzner (heat transfer in liquids), Dcisser and Eian (heat transfer in air), Allen aid Eckert (heat transfer in water), Malina and Sparrow (heat trniisfcr in liquids), Harrott and Hamilton (mass transfcr in liquids)]. Absolute mean deviations vary from 3.6 to 8.1% over the range 0.73 + Pr or Sr ≤ 97 600.

coalderived liquids involves the intraparticle mass transport of large molecules inside a catalyst of cobalt-molybdate supported on alumina. The sizes of molecules in these heavy feedstocks (with molecular weight between 10' and lo5) range between 25 and 150,i, the largest fraction being around 50A (Tschamler and