Pressure drop and liquid holdup in trickle flow reactors: Improved Ergun constants and slip correlations for the slit model

The original and extended Holub phenomenological models for pressure drop a nd liquid holdup in trickle flow regime systematically under-predicted fric tional pressure drops at elevated pressure and at high gas throughputs. On the basis of an extensive historic trickle flow regime database and Ergun b ed constants (over 4000 measurements from 34 references between 1959 and 19 98), state-of-the-art correlations for shear and velocity slip factors and Ergun single-phase flow bed constants (Blake-Kozeny-Carman and Burke-Plumme r bed parameters) were developed. The correlations involved combination of feed-forward neural networks and dimensional analysis. The shear and veloci ty slip factors were expressed as a function of the six most expressive dim ensionless groups (Re-L, Re-G, Fr-L, We(L), X-L, St(L)), whereas Blake-Koze ny-Carman and Burke-Plummer bed parameters were correlated to particle equi valent diameter, sphericity factor, bed porosity, and column diameter. Thes e correlations fed into Holub's phenomenological model improved noticeably the prediction of frictional pressure drop and liquid holdup in trickle flo w reactors.