Design of a Portable Catalytic Stripper for RealTime Aerosol Measurements

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Design of a Portable Catalytic Stripper for
Real-Time Aerosol Measurements

• Team Members (Presentation Order) Simon
  Spottiswoode
• Lang Ho
• Andrew Kukowski
• Mohd Izzat Mohd Thiyahuddin
• Nate Geffre

Advisers Professor David Kittelson Dr. Winthrop
Watts Adam Ragatz
Special thanks to Johnson Matthey for providing
catalysts and technical assistance.
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Outline

• Introduction
• Problem Definition Background
• Mission
• Customer Needs and Design Specification
• Customer Needs, Design Specs, System Components
• System Particle Losses
• Heater and Insulation
• Catalyst Flow
• Heat Exchanger
• Cooling System
• Project Timeline

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Problem Definition

• Diesel Particulate Matter (DPM) is a potential
  occupational carcinogen and poses a health risk
  to areas with Diesel traffic
• Schools, Fire Stations, Airport Terminals,
  Loading Docks, etc.
• There is no portable, real-time aerosol
  instrument capable of measuring DPM.
• Volatile organic compounds (VOCs) and
  nanoparticles present in DPM suppress the
  response of measurement devices, such as the
  Photoelectric Aerosol Sensor (PAS)

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Diesel Particulate Matter (DPM)

• DPM is composed of a carbonaceous core surrounded
  by adsorbed hydrocarbons, sulfates, and trace
  metals.
• DPM exposure is regulated in underground mines by
  estimating Elemental Carbon (EC) concentrations
• A Catalytic Stripper (CS) can be used to improve
  the response of aerosol measurement devices,
  such as the PAS, however a portable CS is not
  available

Jones, T.J., Kittelson, D.B., W. Watts
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Mission

• Design a portable mini-catalytic stripper that
  will remove volatile material and sulfates from
  DPM to improve the response of aerosol
  instruments.
• Specific Goals
• 99 removal of VOCs and sulfates
• Minimize particle losses (less than 30 particle
  loss by mass)
• Uniform flow in catalyst
• Portable
• Minimize power consumption
• Battery operated

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Primary Design Goals
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Mechanisms of Particle Loss

• Inertial Impaction
• Occurs at size selective inlet and streamline
  bends
• Brownian Diffusion
• Significant for small particles in catalyst
• Gravitational Settling
• Negligible for particle size range of interest
• Thermophoresis
• Occurs for all particles during cooling

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Particle Penetration
Thermophoresis
100
Impaction,
Diffusion
Settling
Penetration ()
10
100
1000
Particle Diameter, nm
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Particle Loss Considerations

• Loss Minimization
• Elimination or Proper Sizing of Pipe Bends
  (Impaction)
• Reduction of Catalyst Length (Diffusion)
• Uniform Flow Temperature Gradient
  (Thermophoresis)
• Theoretical Estimation - MATLAB
• Compute Losses for Particles Sized Between 10 and
  1000 nm
• Laboratory Testing
• Measure Actual Losses in System Using HEPA Filter

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System Schematic
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Heater Considerations

• Air Heated to 300C
• Voltile Material Released
• Air Heated Uniformly
• All Particles Reach 300C
• Light-Weight

Star Wound Heater (Previous Design)
Heater
Flat Coiled Heater
Pictures from http//www.watlow.com
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Heater Selection
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Insulation

• Evacuated Chamber with Conductive Resistant
  Insulation

Conductive Insulation
Evacuated Chamber
Catalyst
Regenerative Heating/ Cooling Section
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Future Heating Considerations

• Acquiring Heater
• Where can a DC heater be obtained?
• Testing Heater Effectiveness
• Does it provide enough heat to deal with
  volatiles?
• Wiring the Heater
• How will the wiring feed into the system?
• Testing Heat Loss and Comparing to Theoretical
• Heat loss is calculated at 12 watts, is that
  accurate?
• Managing Packaging
• What kind(s) of insulation will be most
  compatible with our packaging?

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Catalyst Flow Considerations

• Uniform Flow Through Catalyst
• Ensures all channels are effective in removing
  volatiles
• Particle Loss
• Brownian Diffusion
• Mass Transfer
• How well are volatiles removed?
• Pressure Drop
• Higher pressure drop helps diffuse the flow
  across all channels

Catalyst
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Flow Through Single Tube of Catalyst
Bored Catalyst Pro-E Model
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Pressure Drop Through Single Catalyst Channel
Where
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Future Catalyst Flow Considerations

• Perform CFD Simulation of Air Flow Through the
  Catalyst (ANSYS)
• Calculate Particle and Heat Losses
• Test in Lab to Determine Catalyst Performance and
  Particle Losses
• Potential Problems
• Complexity of CFD simulation
• Distributing Even Flow Through Channels

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Regenerative Heat Recovery Considerations

• Heating the flow before the Catalytic Stripper
  requires significant amount of power in the
  instrument.
• Previous instrument does not employ regenerative
  heating to recover exhaust heat.
• Heat exchanger is the primary cooling before
  secondary cooling of the flow in the cooling
  section.
• Recycling the heat from the outflow to inflow,
  reduces required heating power.
• Less Power Consumed
• Longer Battery Life

Regenerative Heating System
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Heat Exchanger Design

• The Heat Exchanger is integrated into the layout
  of the Catalytic Stripper.
• Principle Counterflow Heat Exchanger.
• Calculations indicate that the rate of energy
  needed to heat the air is 5.5 Watts. With this
  design, up to 18 of that heat could be
  recovered.

Source Heat Transfer Book, Lienhard 3rd Edition
Source Heat Transfer Book, Lienhard 3rd Edition
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Future Regenerative Heat Recovery Considerations

• Select conductive materials dimensions for
  optimal heat recovery.
• Addressing heat transfer issue due to laminar
  flow
• Entrance Region
• Entrance length effect
• Developing Laminar Flow

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Cooling System Considerations

• The aerosol sample temperature must meet the
  requirements of the sensor for example the PAS
  (0-80 C).
• Minimize particle losses, with no changes in
  aerosol physical and chemical composition.
• The system must be small in size, less than 15
  of total package volume.
• The system must require little or no power to
  operate (lt 2 Watts).

Cooling System
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Cooling Design Selection Process
Heat Pipes
Finned- Tubing
http//www.alibaba.com/
Hhtp//www.cdrinfo.com/
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Heat Pipe vs Finned-Tube Cooling

• Heat Pipe
• Operates on Principles of Evaporation and
  Condensation
• Heat is pulled away from tubing via fluid
  evaporation inside the heat pipe, condenses on
  cooled heat sink and process is repeated
• Sample Flow Pipe is attached to Heat Pipes and
  Cooled
• Low Power Consumption, but Large Space
  Requirements
• Finned-Tube
• Hot sample is run through copper finned tubing
  and cooled by an external fan
• Easy to Construct and Minimal Size Requirements
• Mountable on exterior of device to prevent dust
  and debris from entering the case and harming
  electronics
• Small Fan Required to Move Air Over Fins

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Future Cooling Considerations

• Construct prototypes of both designs for testing
  in a lab environment
• Calculate heat removal from each system using
  formulas and experimental measurements
• Choose Final Design for Prototype Based on Tested
  Performance
• Determine the method of application that will
  prevent product shell from having air leakage
• Shell must remain air-tight to ensure that
  electronics will not be damaged in mine
  environments

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Project Timeline
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Goal Review

• Must Remove Volatiles/Nanoparticles
• Portable
• Uniform Flow in Catalyst
• Reduction in Power Consumption

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QUESTIONS???
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Equations for Heat Exchanger
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Flow Through Single Tube of Catalyst
Single Catalyst Channel
X
X
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Calculated Catalyst Pressure Drop
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Particle Equations

• Particle Mobility

• Diffusivity

• Thermophoretic Force