MONTANA STATE UNIVERSITY  
DEPARTMENT OF MECHANICAL ENGINEERING                                

ETME 360 Spring 2014
Measurements and Instrumentation Laboratory                                                    R. Larson

EXERCISE 4: 
Temperature Measurement using Multiple Thermocouples

Description: In this exercise, students write and utilize a data acquisition system program to investigate low-rate sampling of temperatures, using thermocouples.  An instrumented aluminum rod test specimen with an array of  Type E, Type T or Type J thermocouples is subjected to a step temperature change at one end of the rod, and the temperature  response of all thermocouples is recorded.

References:
ETME360 Lecture, ETME360 Lab Demonstration
A. Wheeler & A Ganji, Introduction to Engineering Experimentation, Chapters 3, 4, and 9.  

Discussion:
This laboratory experiment introduces multi-channel measurement of temperature samples at a relatively low sampling rate. It utilizes the on-board temperature compensation (CJC) feature of the NI9213 Compact DAQ modules.

Equipment:
Endocal Constant Temperature Circulating Bath units
Instrumented 6061-T6 Aluminum rod equipped with an array of Type T, Type J, or Type E Thermocouples. (Color coded for type and polarity.)
Digital thermometer                      
PC with LabVIEW program
National Instruments Compact DAQ Data Acquisition System, with NI9213 Thermocouple modules

Procedure Part 1: LABVIEW programming  and Data Acquisition System Setup

Programming details should address the following bullets: Your program should -

Install the NI9213 card into the compact DAQ chassis, and connect power and USB cords. Start LabVIEW, and use the DAQ Assistant to program measurement of five channels of temperature data. Install your thermocouple bare wire into the front of the NI9213 Thermocouple modules, noting correct channel number terminal location & polarity for the thermocouple type on the particular test specimen chosen.

Procedure Part 2: Testing
 

Review your data (use Excel, Notepad, Easyplot, etc.) to ensure that data was saved correctly. Ensure that your data was saved to a known, accessible file location such as a removable drive, floppy disk or common network drive for subsequent data reduction.

Results:

1.  Use a program such as EXCEL to plot your temperature readings versus time for the duration of the test

2.    Clearly define the time required for the specimen to reach steady temperatures.

3.  Investigate what other parameters/procedures would be need to permit calculation of the thermal conductivity of the specimen.

4.   Specifically note and discuss any issues, problems, discrepancies, sources of error, etc. Be sure to discuss BIAS error that is sometimes present with our DAQ systems.

6.    Prepare and submit  a laboratory report in the usual format. Include a data sheet containing all typical items except the acquired data. (This data was already displayed in the plots specified in #1 above.) Be sure to include copies of your LabVIEW program panels with your report.