The Beach House ACM Cooling Enclosure

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The Beach House ACM Cooling Enclosure
Eric Jacobs Doug Robertson Jakub Vidim Emily
Marshall
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Introduction

• X-43AMA is a human occupied, high powered
  (5,000mph) jet
• Aerodynamic Control Module (ACM) controls flight
  stability of the X-43AMA
• If overheated the ACM will become unstable and it
  will cause the X-43AMA to crash

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Specifications

• ACM temperature must not exceed 85C at 25 Watts
• Cooling system enclosure must not exceed 180mm
  wide by 150 mm high by 180mm long
• Two fans with a power of 12 Volts can be used
• Looking for the best heat transfer coefficient

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Control Volume Around Module
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ACM and Fan Diagrams
Aerodynamic Control Module
Fan
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Cooling Systems

• Three different designs were discussed Basic
  Model, The Beach House, and a Funnel Design
• Star-CD was used to understand the cooling method
  of each distinct design
• Looking for good turbulent air flow
• High velocity of air flow near and around the
  module

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Box Design

• Velocity was not as high as we would have liked
• Simple, not very effective
• No turbulent air flow

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Funnel Design
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The Beach House

• Star-CD showed the best heat flow through the
  model
• Two fans blowing over the top of the model on an
  angle
• Module and fans raised for heat escape below and
  around module

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Construction

• Building material foam board
• Max critical physical dimensions
• 55o roof pitch
• Ability to easily alter enclosure heights

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Trials Performed

• Both fans operational
• ? h 81.54 5.96 W/m2K
• One fan operational
• ? h 71.12 4.73 W/m2K
• 2 modifications with 2 fans
• ? h1 72.58 4.45 W/m2K
• ? h2 70.40 4.40 W/m2K

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Steady State Temperatures
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Convection Coefficients
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Uncertainty

• Uncertainty due to
• Temperature ( T is largest contributing
  factor)
• Electric Power (PiV)
• Q conduction shape factor 2
• Q convection Electric Power - Q conduction

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CosmosWorks testing

• To get the idea how hot the actual chip in the
  module gets
• Detailed model of the ACM was built in SolidWorks
• Validity of the CosmosWorks model was tested by
  running the thermal analysis with the same h and
  obtaining the same result

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Actual CosmosWorks model

• Boundary conditions on the model
• Chip was powered by 25W
• Ambient temperature on surfaces with convection
  T298K
• Back of the PCB (Plastic Circuit Board) had a
  free convection boundary with h100W/m2K
• Sides of the PCB had no convection
• All other surfaces had a convection boundary with
  h81.54W/m2K

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Analysis and Results

• We ran the CosmosWorks analysis four times with
  different size of mesh, from very coarse to very
  fine
• The results from all runs converged to the value
  obtained in the finest mesh
• Chip temperature T85.59C with finest mesh

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Temperature distribution inside the ACM
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Analysis with uncertainty

• h81.545.96 W/m2K
• Analysis at h87.5 W/m2K and h75.58W/m2K

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Conclusion Does our design satisfy the specs?
Answer No to our approval. Solution Increase
the convection coefficient
through practical methods
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Why a Heat Sink?

• Theory How does it help cool?
• - Extended Surface - Increase surface area for
  convection HT
• Simple addition both construction and cooling
  efficiency

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Temperature Distribution with Heat Sink
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ACM model with Heat Sink

• We ran the analysis on the same model building
  a SolidWorks model of heat sink and running the
  analysis would be almost impossible
• The higher h255.67W/m2K greatly improves the
  chip temperature
• Tchip64.54C which easily meets the
  specifications

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Finally a Solution

• The addition of a Heat Sink proved to be an
  effective method to efficiently cool the ACM
  Module

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porteusb_at_union.edu
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Uncertainty
?
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