1. SmartBridge Control Group n Outline –Current Functionality < Working Control System Simulator –Control System Overview –Mesonet Weather Station Integration –Interface to HVACSIM+ Bridge Model –Layered Control Concept –Simulation –Current Tasks

2. Control System Overview Objective - No Ice on Bridge!

3. Layered Control Concept n Multiple Independent Feedforward Controllers < Parallel operation < Worst case scenario rules –Dynamic Layer Configurations < Cold weather usually moves NW to SE (in OK) < Additional layers added to catch unusual weather < Layers configured based on history, current conditions

4. Mesonet Weather Station Integration n Archived Data for 1993-1999 –Ten stations –15-minute data Air Temp. (1.5,9 m)Wind Speed (10,2 m) RainfallSolar Rad. (Shortwave) %Relative HumidityWind Direction Max. Wind GustPressure Sample of Mesonet Data

5. Mesonet Weather Sites

6. HVACSIM+ Model Integration n Bridge Response Time –Iterative with HVACSIM+ model < Utilizes Mesonet Weather Data < On/Off Heat Pump Response < 33.5 o F target average bridge deck temperature < No Ice on Bridge - Conservative Approach

7. Simulation n Use archived weather data and HVACSIM+ –~60 sec. computer time per run < Controller - ~5 sec. < HVACSIM+ Model - ~15 to 75 sec. –~60 hrs. computer time per winter n System evaluation < Bridge on-time < Ground loop temperatures

8. Current Tasks n NWS Weather Station Integration –Use to validate, enhance Mesonet data n Radar-based Weather Front Prediction –Locate front and project path, speed –Rough estimate of precipitation n Bridge Model Enhancements –Variable Flow Rate n Evaluate Other Bridge Systems –Virginia / Oregon

9. Tunable User Parameters n Parameters –Danger Temp < Minimum desired average bridge deck temp. –Approach Temp < Weather station warning temperature –Warn Time < Length of time future weather is extrapolated –Layer Threshold < # of warnings required to start heat pump