Contacting Schemes for Liquid-Liquid Systems

Transcription

1 Contacting Schemes for Liquid-Liquid Systems T Contactor simple T contactor Multi-layer contactor short length scales for fast transfer more difficult to fabricate Acknowledgement Tamara Floyd, MIT multi-layer contactor

2 Microreactor for Liquid Phase Chemistry Integrated Heat Exchangers and Temperature Sensors Heat Exchanger 300µm air gap cooling fluid reaction mixture U = 1500 W/m 2 C Example: acid base mixing and reaction Optical fiber Visible spectroscopy Thin-Film Temperature Sensor

3 Top View CFD Velocity Profiles A symmetry line A Mixing and Reacting Channel 90 µm 2-D approximation valid in this region 90 µm A A Initial Condition: 0.1 ml/min flow rate in each of the 10 inlet channels

4 Top View CFD Mixing Profiles Cross-Sections A A symmetry line A A B B channel bottom B B CC DD C C D D Initial condition: A=0.0 and A=1.0 for alternating channels

5 Distribution Effects Conditions equal total flow rates equal power concentration at ~10 ms after focusing 10% mixed 80% mixed 100% mixed Distribution of the fluid among the channels greatly influences mixing

6 Ehrfeld IMM Mixer MITMIT-ICE ICESpring Spring 01 01

7 Micro Fixed-Bed Reactor Design - Matt Losey MIT Liquid Inlets Thermocouple Wells Catalyst Section Exit Port Gas Inlets 625 µm Catalyst Restrainer 500 µm MIT- MIT-ICE ICE 200 Spring Spring µm Volume = 4µL Reactor Weight = 0.7 g 200 µm

8 Silicon Microfabrication Silicon Substrate, 500um thick 1. Etch topside reaction channels 2. Etch backside ports 3. Repeat and fusion bond 4. Metalize Pyrex glass wafer 5. Anodically bond the two wafers 1.5cm

9 Pressure Drop for Microfluidic Packed-Beds Correlations such as Ergun s equation or Leva s correlation for pressure drop in packed beds (Re <10): 2 P µ Q ( 1 ε) 2 3 L D p A s ε 100 P 1 = P 2 (For Constant τ) Pressure (PSIG) Activated Carbon(53-74um) Glass Spheres(53-74um) Leva Correlation* Flow Rate Ethanol (ml/min.) Measured pressure drop agrees with correlation Depends strongly on: void fraction, shape and distribution of particles, loading procedure

10 Multi-Channel Packed-Bed Reactor 10 Channels 40 µl Volume 1.5 cm 0.06 cm

11 Chip design for gas-liquid mixing Gas Inlet Manifold Liquid Inlet Manifold Integrated Packed-Bed Catalyst Reactor Channels contain contain staggered arrays powdered of 50µm catalysts diameter cylinders to promote mixing 625 µm 200 µm

12 Integrated Catalyst Supports 50 µm diameter posts 2000 posts per channel Void fraction defined (65%) S/V = 300 cm 2 /cm 3 (10 cm 2 /cm 3 for a bubble column reactor) 25µm 100µm

13 Microstructured Packing and Pressure Drop Two-phase Pressure (MPA) Microstructured Packing Stable Interface Dispersed Flow Ethanol/Air Toluene/Air Liquid Flow Rate(mL/min.) Pressure (MPA) Particulate (50µm) Packing Leva Correlation* Activated Carbon(53-74um) Glass Spheres(53-74um) Flow Rate Ethanol (ml/min.) Equivalent P at 10X throughput For packed beds, P depends strongly on: void fraction, shape and distribution of particles P L µ Q ( 1 ε) 2 3 D p A s ε 2