The mass transfer coefficient in gas-solid fluidized beds has been correlated with the dimensionless expression [J. C. Chu, J. Kalil, and W. A. Wetteroth, Chem. Engr. Prog., 49, 141 (1953)] Gkp(D)2/3=1.77((1)dGM~)0.44 where kp is the mass transfer coefficient (moles per (length) 2 time pressure), G is total convective flux (moles per (length) 2 time pressure), d is particle diameter, and is bed porosity. You are studying 0.1cm particles of coal burning in a bed with =0.42 fluidized by air at 1,250C. The air flux at 1.7 atm is 380lb/ft2hr. What is the film or unstirred-layer thickness around these particles? (H. Beesley) The mass transfer coefficient in gas-solid fluidized beds has been correlated with the dimensionless expression [J. C. Chu, J. Kalil, and W. A. Wetteroth, Chem. Engr. Prog., 49, 141 (1953)] Gkp(D)2/3=1.77((1)dGM~)0.44 where kp is the mass transfer coefficient (moles per (length) 2 time pressure), G is total convective flux (moles per (length) 2 time pressure), d is particle diameter, and is bed porosity. You are studying 0.1cm particles of coal burning in a bed with =0.42 fluidized by air at 1,250C. The air flux at 1.7 atm is 380lb/ft2hr. What is the film or unstirred-layer thickness around these particles? (H. Beesley)