2_01_25_Duhaneyb_TM

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Apr 3, 2024

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Date: 21 February 2024 To: Colin Selleck, ME 391 Instructor From: Brandon Duhaney, 2_01_ 25 Subject: Temperature Measurement Introduction Thermistors, RTDs (Resistance Temperature Detectors), and thermocouples are essential temperature sensing devices used across a wide range of industries and applications. Thermistors rely on the principle of electrical resistance varying with temperature, offering high sensitivity and precise measurements. RTDs present a linear relationship between resistance and temperature. Which provides a high accuracy measurement and stability when recording the data. Thermocouples, on the other hand, generate a voltage which is proportional to the temperature. Thermocouples also offer great durability and a wide temperature range when recording the data. While thermistors are proficient in sensitivity when recording data, RTDs offer excellent accuracy, while thermocouples on the other hand provide durability and versatility. Each type of temperature sensor is chosen based on what is needed during the experiment, such as temperature range, accuracy, and environmental conditions, making them essential tools in temperature measurement for various industries. Experimental Procedure Equipment required for Experiment.  Glass mercury-free thermometer (used as calibration reference)  RTD (Resistance Temperature Detector)  Thermistor (a semiconductor resistance device)  Type J Thermocouple (constantan/iron, red & white color code)  Thermocouple Code Chart  Resistor  400 ml beaker  1000 ml beaker  Hot plate  Probe fixture, terminal strip.  Ice  Water 1) First 400 mL of Ice was added to 1000 mL and then water was added to make 750 mL of the ice bath until a temperature of 2 degrees Celsius was yielded. 2) The 1000 mL beaker was then placed on the hot plate turned off and the three electrical sensors, thermocouple, RTD and thermistor were suspended over the beaker into the ice

bath using the probe fixture making sure to not touch the glass. Next, calibration measurements were made until all three sensors were calibrated properly. 3) The hot plate was then turned on to medium heat and then once the ice bath began to melt the temperature was recorded in increments of 10◦C up to 90◦C. Experimental Data Temp ◦C V(tc) mVDC RTD kΩ (ts)kΩ 0 0.08 0.101 6.04 10 0.25 0.104 4.04 20 0.68 0.108 2.87 30 1.3 0.114 1.67 40 1.18 0.117 1.17 50 2.35 0.121 0.78 60 2.86 0.125 0.554 70 3.39 0.129 0.395 80 3.89 0.132 0.298 90 4.39 0.136 0.227 Table 1:Temperature Measurements 0 10 20 30 40 50 60 70 80 90 100 0 0.5 1 1.5 2 2.5 3 3.5 4 4.5 5 f(x) = 0.05 x − 0.24 R² = 0.98 Thermocouple Temperature V(tc) mVDC Figure 1:Thermocouple Temperature Measurement

0 10 20 30 40 50 60 70 80 90 100 0.1 0.11 0.12 0.13 0.14 f(x) = 0 x + 0.1 R² = 1 RTD Temperature kΩ Figure 2: RTD Temperature Measurement 0 10 20 30 40 50 60 70 80 90 100 0 1 2 3 4 5 6 7 f(x) = − 0.06 x + 4.39 R² = 0.8 Thermistor Axis Title Axis Title Figure 3: Thermistor Temperature Measurement Analysis For the Thermocouple, the temperature stayed mostly constant except for one data point in which the measurement decreased from 30 degrees to 40 degrees. From the trendline it is visible that the values measured in the experiment remained very close to the expected values and from the equations below the sensitivity and coefficients can be calculated ( 1 ) Y = 0.0507 x − 2.449

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( 2 ) R 2 = 0.9768 Equations 1 and 2 above show that the slope of the thermocouple data is 0.0507x and the y- intercept or the sensitivity of the instrument is 2.449. For the RTD the temperature and measurements and the rate they increase is constant the whole time. There is slight deviation from the trendline, and it is visible that the values measured in the experiment remained very close to the expected values and from the equations below the sensitivity and coefficients can be calculated. ( 3 ) Y = 0.0004 x − 0.1008 ( 4 ) R 2 = 0.9959 Equations 3 and 4 above show that the slope of the thermocouple data is 0.0004x and the y- intercept or the sensitivity of the instrument is 0.1008. For the Thermistor, the temperature and measurements are significantly different from the expected value. There is significant deviation from the trendline, and it is visible that the values measured in the experiment were not very close to the expected values. The trendline shows a constant decline while the data calculated decreased exponentially. ( 5 ) Y =− 0.0573 x + 4.3851 ( 6 ) R 2 = 0.8015 Equation 5 and 6 above shows that the slope of the thermocouple data is -0.0573x and the y- intercept or the sensitivity of the instrument is 4.3851. Of the three instruments the RTD had the least sensitivity at .1008 then next is the thermocouple at 2.449 and the thermistor last at 4.385. Conclusion Overall, the experiment went very well. There could have been slight error in making the ice bath and the temperature of the bath itself which may have caused the random dips in some of the measurements. Out of the three instruments the RTD having the least sensitivity directly led to the data being more accurate and closer to the expected values, which explains why the thermistor values were so different form the expected values and produced a different curve.

References [1] Brightspace Material [2] [Online] https://www.mathworks.com/help/daq/acquire-temperature-data-from-a- thermocouple.html [3] Beckwith, Mechanical Measurements, 6th ed., Pearson/Prentice Hall, 2007