J = 6~y~l . r~~ m N = 6~y k / m Q r rs R = capillary radius, cm. t t, T = V,' + Qt u = velocity of center of free bubble away from tip after force balance bubble formation i s complete, cm./sec. u, = velocity of gas through capillary, cm./sec. u, = velocity of bubble center during expansion, cm./sec. uh = velocity of residual bubble, cm./sec. V = bubble volume, cc. V F = final bubble volume, cc. V,' = force balance bubble volume, cc. x = distance covered by base of bubble, cm. y = surface tension of liquid, dynes/cm. p = viscosity of liquid, poises = mass of bubble, g. = volumetric flow rate of gas, cc./sec. = radius of bubble, cm. = radius of "force balance bubble," cm. = time variable used to define stage of detachment, sec. = time of detachment after bubble formation due to force M = Q ( P L -P~) 8/m balance is complete, sec. p s = gas density, g./cc. p , = liquid density, g./cc.Experimental data for the gas-particle heat transfer coefficient in packed beds a t Reynolds numbers between 2 and 100 were determined using a model which takes into account axial dispersion of heat in the gas phase and axial conduction in the solid phase. Beds of copper, lead, and glass were used with particle sizes ranging from 0.0198 to 0.080 inch. Dynamic thermal conductivities of the solid phase in the direction of flow were measured simultaneously.
