Quarter ending 113101

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Oklahoma State University Geothermal Smart Bridge
Quarterly Progress Report

• Quarter ending 11/31/01
• Task 4.3.1.3 - Integrated Control Strategies
• Stone/Spitler/Elliott

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Accomplishments

• Alternative controller (SC2) developed for the
  model bridge
• Bridge deck wetness sensor developed
• Preliminary communications infra-structure plan
  for Smart Bridge control systems developed

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Issues driving development of alternative
controller

• The model bridge heating system uses a single
  heat-pump and is configured for an ON/OFF
  controller.
• The minimum OFF time after the model bridge
  heat-pump has been engaged is 5 to 20 minutes.
  This severely limits modulation of heat into the
  bridge by controlling length of ON cycles.
• The existing simulated MPC controller optimizes
  heating time by manipulating loop temperature
  into the deck and is not easily modified to
  control the model bridge.
• Typical warm-up time to 0 0C for the bridge deck
  is 6-12 hours which is approximately best
  forecast lead time.
• The existing MPC controller does not handle the
  situation where there is no precipitation, the
  deck is wet, and the deck surface cools below
  freezing.
• A controller that implements ON/OFF action with
  dead-band has been implemented successfully
  (Smith et. al.) on the model bridge.

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SC2 Concept

• Based on icing prevention through
• Bridge deck wetness prediction
• Bridge deck wetness sensing
• Bridge deck temperature control.
• Uses NWS RUC product
• Detect threat of a wet bridge surface
• Precipitation
• Dew events
• Up to 12 hours lead-time.
• Existing ON/OFF controller for temperature
  control.
• leaf wetness type sensors for deck wetness
  sensing.

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SC2 Algorithm

• The ON/OFF controller is engaged during the
  threat of a wet bridge deck surface.
• Once the threat of a wet bridge deck surface has
  passed, the ON/OFF controller is allowed to
  disengage.
• 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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Smartbridge Control System Communications Elements
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Smartbridge control system tasks and information
flow
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Plans for Next Quarter

• SC2 will be implemented on the model bridge and
  monitored during the following quarter.
• Bridge deck wetness sensor will be tested and
  performance validated.
• A strategy will be identified for implementing
  adaptivity for the Smart Bridge controller.