1 Nicole Reed Department of Energy and Mineral Engineering EGEE 520 Penn State University April 29, 2008 COMSOL Modeling of Liquid Flow Through a Fixed-Bed Packed Reactor for Adsorptive Desulfurization

Desulfurization approaches require severe conditions and are not suitable for fuel cell applications Selective Adsorption (SARS) is achieved at ambient pressure and temperature without hydrogen Hydrodesulfurization (HDS) –High Temp ( °C) –High Pressure of H 2 (30-40 bar)

A fixed-bed continuous flow system measures the performance of adsorbents for various fuels Fuel HPLC Pump (X ppm S) Fixed-bed reactor 23 Fuel samples collected at regular intervals g Samples weighed 1 Amount of Treated Fuel C = C 0

This study focuses on liquid fuel flow through a packed bed Fuel Diesel Fuel Density = 800 kg/m 3 Flow Rate = 0.05 ml/min  m/s Fixed-bed reactor Volume = 2.49 mL Length = 0.15 m Width = m Packed Bed: Activated Carbon Porosity(ε) = 0.6 (experimental) Permeability(κ) = 1.88x m 2

5 Darcy’s Law describes flow through porous medium in terms of head gradients Darcy’s Law: TermMeaningUnits qDarcy Fluxm/s QDischargem 3 /s KHydraulic conductivitym/s kPermeabilitym2m2 µAbsolute viscosityNs/m 2 ρDensitykg/m 3 hheadm νKinematic viscositym 2 /s

6 Boundary Conditions r = m Insulation BC h = 0.15 m 2-D Axial Symmetry Inflow/Outflow = m/s QuantityValueUnitDescription ρ0.8kg/m 3 Density κ1.88x m2m2 Permeability µ.0024Pa·sDynamic Viscosity f0kg/(m 3 ·s)Source Term

7 Solution Inflow = m/s ΔP = atm Outflow = m/s ΔP = atm

8 Validation Darcy’s Law Column Length From COMSOL Solution: Maximum Pressure - Minimum Pressure = Pressure Drop – = atm

9 Parametric Study How does particle size and fuel flow rate affect the pressure drop? Particle Size  Permeability Fuel flow rate  Velocity CaseFlow RateVelocityParticle SizePermeabilityMaxMinP DROP E E E E E E E E E E E E E E E E E E , 0.20, and 1.0 ml/min 50, 5, and 0.5 microns

10 Summary COMSOL can effectively model packed bed reactors with the following parameters: –Adsorbent: porosity, particle size, density –Fuel: flow rate, density Particle size and fuel flow rate affect pressure drop across small reactors COMSOL can be used to find limits for scale-up models and other reactor designs THANK YOU!