(631b) New Universal Pressure Drop Correlation for Structured Adsorbents with Parallel Channels of Any Cross-Sectional Shape

A 1D axial pressure drop correlation was developed for structured adsorbents with parallel channels of any cross-sectional shape. It is based on the Darcy-Weisbach (DW) equation, which includes both laminar and inertial contributions to the pressure drop. This 1D correlation is contrasted against the correlations of both Shah and London,¹ and Muzychka and Yovanovich,² and against in house experimental results. The new correlation is proposed for pressure drop determination in structured adsorbents with parallel channels of any cross-sectional shape, and it was built based on a new, recently published,³ non-experimental methodology that uses 3D Navier–Stokes (NS) computational fluid dynamics (CFD). To resolve the 1D-DW correlation, expressed in terms of a Darcy friction factor involving just two fitting parameters, f₁ and f₂, an analytic expression derived from the differential 1D-DW model was regressed simultaneously with all the 3D-NS model results for four channel cross-sectional shapes (equilateral triangle, isosceles triangle, square, and rectangle) with air at 1 atm and 25 ^oC. Then predictions from the differential 1D-DW correlation, now solved numerically in COMSOL, were contrasted against those from the bench-scale experiments using two structured adsorbents at 0.5, 1 and 3 atm of CO₂ and He in addition to air at 25 ^oC. These bench-scale experiments included a Catacel structured adsorbent with parallel triangular channels and a Gore structured adsorbent with parallel trapezoidal channels. A wide range of velocities, pressures, channel dimensions and gas molecular weights were explored. The 1D-DW correlation showed good agreement with experiment for all outlet pressures and all three gases and better prediction than the two alternative correlations indicated above. These results indicated the 1D-DW correlation could be used with confidence in an adsorption process simulator to predict the pressure drop in a structured adsorbent with parallel channels of any cross-sectional shape.

1. Shah, R .K., London, A. L., Laminar Flow Forced Convection in Ducts: A Source Book for Compact Heat Exchanger Analytical Data.” Chapter VIII, pgs 223 – 246, Academic Press (1978).
2. Muzychka, Y. S. and M. M. Yovanovich. Pressure Drop in Laminar Developing Flow in Noncircular Ducts: A Scaling and Modeling Approach, Journal of Fluids Engineering 131, 111105-1 – 111105-11 (2009).
3. Mohammadi, N., Sanders, R. T., Holland, C. E., Ebner, A. D. and James A. Ritter, Non‑Experimental Methodology for Developing Pressure Drop Correlations for Structured Adsorbents with Parallel Channels, Adsorption 29, 29 – 43 (2023).