Quarter ending 22802

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Oklahoma State University Geothermal Smart Bridge
Quarterly Progress Report

• Quarter ending 2/28/02
• Task 4.3.1.3 - Integrated Control Strategies
• Stone/Spitler/Elliott

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Accomplishments

• Alternative controller (SC2) implemented and
  tested on the model bridge
• Bridge deck wetness sensor deployed and tested on
  model bridge
• Revisions for SC2 identified
• Strategy for adapting SC2 identified

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SC2 Algorithm

• The ON/OFF controller is engaged during the
  threat of a freezing wet bridge deck surface.
  (TRUE message)
• Once the threat of a wet bridge deck surface has
  passed, the ON/OFF controller is allowed to
  disengage. (FALSE message)
• The ON/OFF controller does not disengage until
  the bridge deck surface is dry.
• If the bridge deck surface is wet and the deck
  temperature falls near freezing, the ON/OFF
  controller is engaged.

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Controller structure
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Controller Triggering
Trigger Event
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Issues Identified with SC2

• Use of 4 C trigger ranges for temperature and use
  of high dew-point at freezing are much too
  conservative
• Changed temperature trigger finally to 1 C
• Eliminated dew-point trigger, gt 98 RH may be
  useful
• More reliable network needed
• Simpler connections (now 5 step process, 3
  secure)
• Secure shell issues

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Reliable Network Required
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Issues Identified with SC2

• Use of 4 C trigger ranges for temperature and use
  of high dew-point at freezing are much too
  conservative
• Changed temperature trigger finally to 1 C
• Eliminated dew-point trigger, gt 98 RH may be
  useful
• More reliable network needed
• Simpler connections (now 5 step process, 3
  secure)
• Secure shell issues

• Assumption that ON/OFF controller at bridge could
  operate slightly above freezing without turning
  heat-pump ON Invalid
• More accurate triggering of ON/OFF controller
  needed
• 2 hr Delay in receiving RUC forecast critical

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Controller Adaptivity

• Primary issue in adapting controller to different
  bridges is thermal model
• Avoid focus on improving NOAAs forecast
• Have ready access to local thermal model inputs
  and outputs in the controller
• Need to predict deck freezing event to within
  approximately 1 hr.
• Critical variables are temperature and solar
  radiation
• Solar radiation currently predicted with a
  theoretical model.
• Need current local solar radiation to improve
  theoretical estimate

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Plans for Next Quarter

• SC2 will be revised and tested via simulation
  during the following quarter.
• Alternative communications strategies will be
  developed
• Strategies for adapting the bridge deck thermal
  model will be examined