1. Power Control System for a Concrete Durability Test Cabinet – Phase 2 Jacob Jameson Madhav Kothapalli Thomas Persinger Andrew Versluys

2. Planning System Concept and Requirements

3. Problem Statement The National Concrete Pavement Technology Center uses a system to perform temperature tests on concrete samples. ◦ The temperature test consists of 300 cycles between 0º and 40º F (±3ºF error). ◦ The client wants the system to be monitored and controlled with a program created by LabVIEW. ◦ There is existing hardware and software in place, but it does not achieve consistent results.

4. Need Statement Design control method to fix the existing system to run the tests consistently. ◦ Clean up the temperature sensors ◦ Re-write the software

5. Concept Sketch – Test Cabinet

6. System Description LabVIEW Program ◦ Accessible by remote desktop ◦ Sends commands to temperature controller Temperature Sensors ◦ Old system analog thermostat ◦ High temperature shut-off ◦ Circle graph recorder. ◦ New system thermocouple measuring the internal temperature of the concrete specimens within the cabinet. System Processes ◦ Measured temperature approaches 0 º, System activates a relay that shuts off the compressor and turns on the heater. ◦ Measured temperature approaches 40 º, System activates a relay that shuts off the heater and turns on the compressor. ◦ Cycle continues until the user ends it.

7. System Block Diagram

8. Operating Environment The system will operate in an indoor laboratory. This lab works with concrete so there is a chance of dust getting into the system. Water is poured into the system before running the freeze/thaw test, so the system must be sealed.

9. User Interface Records the data from the tests Allows the user to analyze data in graphical form Allows the user to change the freeze-thaw controls manually Accessible by remote desktop

10. Functional Requirements The freezing-thawing apparatus shall have automatic controls which are able to continuously reproduce cycles from 0±3°F to 40±3°F. The heat-cool cycle shall take between 2-5 hours. The exchange between heater and compressor phases shall not exceed 10 minutes.

11. Non Functional Requirements All of the electrical components shall be housed in a waterproof enclosure. The system shall not cause any fire hazards or electrical shocks. The user interface shall show a temperature vs. time graph of the current test.

12. Market/Literature Survey System Manufacturers ◦ Humboldt Manufacturing ◦ ScienTemp ◦ Schleibinger Buying a new system replacement is not an option because of the high cost.

13. Deliverables Computerized system ◦ Automatically controls the freeze-thaw cycle of the test cabinet ◦ Automatic system error adjustments ◦ Accurate temperature sensing User interface ◦ Allows users to input and analyze data ◦ Allows users to change the freeze-thaw controls manually System manual for reference

14. Work Breakdown Schedule Project Design ◦ Develop New Control System in LabVIEW ◦ Simulated Testing and LabVIEW Program Revision ◦ LabVIEW Interface Implementation and Testing ◦ Implement New LabVIEW Program ◦ Test New LabVIEW Program ◦ LabVIEW Program Revision and Error Correction ◦ Documentation of Results Develop User Manual Final Report and Presentation Project Poster

15. Design System analysis and specifications

16. System Requirements Automatic controls Error handling Meet test requirements

17. Initial System Analysis Positive ◦ Reproduces cycles between 0 and 40 degrees ◦ Heating and cooling cycles between 2 to 4 hours Negative ◦ Large overshoot and oscillations on heating cycle due to heater strength. ◦ The temperature does not stay between 0 and 40 after many cycles.

18. Functional Decomposition

19. Input/output Specification Input Output Thermocouple DELTA Controller Computer DELTA Controller Cycle Relay LabVIEW Excel Heater Compressor

20. Temperature Sensor Thermocouple T-type. Sends the reading to the temperature controller.

21. Delta Temperature Controller Used as an A-D converter Uses RS-485 Communication

22. RS232/485 Converter Communication module that sends temperature readings between the Delta controller and the computer.

23. User Interface Specification Temperature Based Control Parameters ◦ Controls heater and compressor based on user-defined temperature range ◦ Range can be changed while the system is running ◦ Data may be recorded to an Excel file

24. User Interface Specification

26. Software Specification Communications ◦ Establish temperature controller connection ◦ Retrieve current temperature and pass on ◦ Signal heating/cooling switch Filtering ◦ Low-pass filter, possibly rolling average Logic ◦ Determine set points via temperature and time based variables Output ◦ Display temperature vs. time on screen and to Excel file, use existing

27. Testing System Tests and Results

28. System Testing Accurate data collection ◦ Thermocouple testing Overall system stability and behavior ◦ Step response testing Overall response to input ◦ Natural response testing Extent of control issues ◦ Full cycle testing

29. Thermocouple Testing

30. Step Response Testing Test each operational mode ◦ Room temperature to 0°F ◦ Room temperature to 40°F ◦ 0°F to 40°F ◦ 40°F to 0°F Goals ◦ Identify transients and phase changes ◦ Determine rise and fall times

31. Step Response: Room to 0°F Cooling time ◦ 250 minutes Phase change ◦ 60 minutes Steady state ◦ Oscillatory ◦ 35 minute period ◦ 6.5°F amplitude Undershoot ◦ 1°F

32. Step Response: Room to 40°F Cooling time ◦ 120 minutes Steady state ◦ Oscillatory ◦ 65 minute period ◦ 7.5°F amplitude Undershoot ◦ 1.7°F

33. Step Response: 0°F to 40°F Heating time ◦ 82 minutes Phase Change ◦ 15 minutes Steady state ◦ Oscillatory ◦ 45 minute period ◦ 6.6°F amplitude Overshoot ◦ Transient: 20.8°F ◦ Steady state: 4.5°F

34. Step Response: 40°F to 0°F Cooling time ◦ 170 minutes Phase Change ◦ 60 minutes Steady state ◦ Oscillatory ◦ 40 minute period ◦ 7°F amplitude Undershoot ◦ 1.8°F

35. Natural Response Testing Frozen state time constant ◦ 13:08:07 Liquid state time constant ◦ 38:44:00

36. Full Cycle Testing Peak info ◦ Average: 44.67°F ◦ Standard deviation: 2.45°F Trough info ◦ Average: -0.5°F ◦ Standard deviation: 0.394°F

37. Conclusions and Recommendations How do we plan to fix this system?

38. Possible Sources of Error A. Thermocouple B. LabVIEW Software C. System Water D. Compressor Power

39. Option A. Replace Thermocouple Get a more reliable welded stainless steel sensor

40. Option B. Create New LabVIEW Program Keep: Communications module User Interface Graphing Capability Rewrite: Logic and Filtering

41. Option C. Regulate Water in System Full cycle tests show water has effect on system

42. Option D. Upgrade Compressor Heater is able to pass through phase change must faster than compressor

43. Questions?