TEMPERATURE MEASUREMENT. GROUP 3 Noah Beauchamp Kyle Camacho Jack Connolly Curtis Yu

Transcription

1 TEMPERATURE MEASUREMENT GROUP 3 Noah Beauchamp Kyle Camacho Jack Connolly Curtis Yu Thermodynamics I Section January 2018

2 Group 3 Page: 2 Abstract The Temperature Measurement lab involved using a Armfield TH-1 to heat and measure a vessel of water. From this process a variety of measurements were taken every 5 degrees celsius starting at the ambient temperature of degrees celcius, all the way to 100 degrees celsius. At every interval six measurements were taken, these being reference temperature, IND reading, thermocouple, thermistor, liquid-in-glass thermometer, and vapor pressure thermometer. It was concluded that the thermocouple is the most accurate measuring device. Introduction Temperature is defined as the internal energy of a system. It determines if heat energy is transferred between bodies that make contact at different temperatures. Should two bodies have the same temperature, no heat energy is transferred because these bodies are in equilibrium. One can measure temperature by using a temperature sensitive probe, which reaches thermal equilibrium with the body that is to be measured and then noting whether this value changes over time. In this experiment, the temperature of water is measured over time using six different methods. Since the temperature is being measured in water, it is important that a stirrer be used to continuously mix the water which insures a uniform temperature throughout. The primary objective of this lab was to become familiarized with the operation and interface of the Armfield TH-1 temperature measurement apparatus. Secondary objectives include investigating the thermoelectric properties of several temperature

3 Group 3 Page: 3 measuring devices including a platinum resistance device, a thermocouple, and a thermistor. This also incorporates an investigation of the effect of temperature on a liquid-in-glass device and a bi-metal thermometer. Tertiary objectives include learning the accuracy of each device that was used to measure. Experimental procedure To begin this experiment, turn on the main power to the Armfield TH-1 Temperature measurement and calibration system on by flipping the switch on the orange panel. Take an initial reading for each of the sensors. These readings on the measurement system would be the PT100 REF temperature, the PT100 IND reading, the Thermocouple Reading, and the Thermistor Reading. Then take the liquid in glass thermometer reading from the liquid in glass thermometer to the side and the Vapor pressure thermometer reading from the built in vapor pressure thermometer. After these readings have been taken, turn on the heater and stirrer setting both to their maximum power. As the temperature rises, take the readings from each sensor at 5 degrees Celsius intervals, starting from the initial reading all the way up to 100 degrees Celsius. When the water has reached boiling point, reduce the heating power while maintaining the process of the water boiling, this should make the reference PT100 output display a steady readout. After this happens, hold the temperature and observe if there are any further changes in any of the sensor readings, making sure the water level doesn t drop below the bottom mark on the sight glass. When all this is finished, switch everything off. Now that the table is finished, take the results gathered and plot a graph for each of the sensor readings.

4 Group 3 Page: 4 The graph generated for the type K thermocouple should be a temperature readout using the table. The graph may need linear interpolation. Once this is done, compare the thermocouple temperatures with the REF PT100 readings. The graph for the thermistor should be generated using the same table, but comparing the thermistor temperatures with the REF PT100. Finally generate a zero-error scatter plot using the REF PT100 series along the x-axis and a duplicate series of REF PT100 along the y-axis. Once this is done, plot the temperature reading of the thermocouple, the thermistor, the vapor-pressure thermometer, and the liquid in glass thermometer, respectively along the y-axis, using the x-axis with the REF PT100 data. Diagrams

5 Group 3 Page: 5 Results Data Collection Target Temperature PT100 Reference Temperature PT100 Industrial Reading (Ω) Thermocouple Reading (µv) Thermistor Reading (Ω) Liquid-In-Glas s Temperature Vapor Pressure Thermomete r Temperature

6 Group 3 Page: 6 Thermocouple Thermistor PT100 Reference Temperatu re Thermocoup le Reading (µv) Temperat ure Conversio n Percent Error from Ref. Temp. (%) Thermisto r Reading (Ω) Temperat ure Conversio n Percent Error from Ref. Temp. (%)

7 Group 3 Page: 7 Liquid In Glass Thermometer Vapor Pressure Thermometer PT100 Reference Temperature Liquid-In-Glass Temperature Percent Error from Ref. Temp. (%) Vapor Pressure Thermometer Temperature Percent Error from Ref. Temp. (%)

8 Group 3 Page: 8 Discussion of Results A source of error for the thermocouple and thermistor is that it would be the difficulty to maintain a specific temperature due to the way the equipment heated the water. It was also difficult to take data consistently on the same heat due to the fluctuation of the heat even when the heater is turned off at the 5 degree intervals. The liquid in glass thermometer and vapor pressure thermometer error could be from the angle in which the thermometer was seen as well as the lack of precision on the

9 Group 3 Page: 9 equipment, considering it only counted by every 2 degrees. Also both thermometers were influenced by the temperature outside the system of the temperature of the room. The maximum percent error for each equipment would be: Liquid-in-Glass: 7.18% Vapor Pressure: 4.79% Thermocouple: 0.96% Thermistor: 2.41% The average percent error for each device would be: Liquid-in-Glass: 1.31% Vapor Pressure: 2.57% Thermocouple:.87% Thermistor: 1.41% PT100 - A PT100 is a Platinum Resistance Thermometer (PRT). This means that as temperature changes, the resistance of a small platinum element changes. This resistance can be approximately linearized to temperature: at 0 C, the resistance of the element is 100 Ω, and at 100 C, the resistance is Ω. THe furthest deviation from this line approximation is only 0.4 C. These sensors can broaden their temperature range to measure from -250 to 800 to be very versatile and fairly accurate, usually about ±0.3 C [1].

10 Group 3 Page: 10 Thermistor - A thermistor or thermally sensitive resistor is a type of semiconductor. A semiconductor works by having a higher resistance than that of whatever substance it is measuring. Increasing the temperature of the measured substance decreases its resistance and subsequently allows for a temperature measurement based off of the resistance of the system. Liquid-in-glass Thermometer - A Thermometer in which the liquid inside expands when it is heated. The volume inside the tube increases and rises, and the liquid expands much more than the glass. This allows this tool for measurement to be not as accurate due to the fact that it could be influenced by temperatures outside the system [2]. Vapor-Pressure Thermometer - A Thermometer in which the variable saturated vapor pressure of a volatile liquid is used as a measure of the temperature and which thus has the advantage over some other types of thermometers of being free from errors due to bulb expansion - Merriam-Webster dictionary. This version of measuring a system is more accurate than the liquid in the glass due to the fact that this form of measurement takes the pressure within the system [5]. Thermocouple - According to Omega Engineering [4], a thermocouple consists of two dissimilar metals joined at both ends, when one end is heated, there is a continuous current which flows through the thermoelectric current. So, when the junction of the two metals is heated, or cooled, a voltage is produced relates back to the temperature. Thermocouples

11 Group 3 Page: 11 are robust measuring devices capable of a wide variety of temperature measurements from -250 F F based on the model needed. Conclusions The thermocouple is the most accurate device for measuring temperature as it had both the lowest maximum percent error and the lowest average percent error. The liquid in glass thermometer is the second most accurate, however, outlying measurements skewed the percentage of error a little. The thermistor is a fairly accurate measuring tool as well, with low percentages of error that are consistent. Finally, the vapor pressure is the least accurate of the tools used with a percentage of error that is between 1% and 4% for almost every measurement taken. This data is useful for when one needs to choose how accurate their measuring device needs to be for future experiments, should more than one kind of device suffice. References [1] PT100 platinum resistance thermometers, Pico Technology. [Online]. Available: ers. [Accessed: 21-Jan-2018]. [2] Standard Grade Bitesize Physics - The use of thermometers : Revision, Page 2, BBC. [Online]. Available: sion/2/. [Accessed: 15-Jan-2018].

12 Group 3 Page: 12 [3] Thermistor, Omega Engineering. [Online]. Available: [Accessed: 15-Jan-2018]. [4] Thermocouples, Omega Engineering. [Online]. Available: [Accessed: 15-Jan-2018]. [5] Vapor-pressure Thermometer, Merriam-Webster. [Online]. Available: [Accessed: 15-Jan-2018].