Mass transfer between bubbles and the dense phasein gas fluidized beds

Mass transfer between a bubble and the dense phase in gas fluidized beds of Group A and Group B particles was proposed based on previous experimental results and literature data.The mass transfer coefficient between bubbles and the dense phase was determined by k;= 0.21d;.A theoretical analysis of the mass transfer coefficient between a bubble and the dense phase using diffusion equations showed that the mass transfer coefficient between a bubble and the dense phase is k;∝ε;（Du;/d;）;in both three- and two-dimensional fluidized beds.An effective diffusion coefficient in gas fluidized beds was introduced and correlated with bubble size as De = 13.3d;7 for Group A and Group B particles.The mass transfer coefficient k;can then be expressed as k;= 0.492ε;(u;d;);for bubbles in a three-dimensional bed and k;= 0.576ε;(u;d;);for bubbles in a two-dimensional bed.