Temperature and Response time measurement
In this experiment, a Resistive Thermal Device (RTD) and thermocouple were calibrated for first order measurement. Then, the response times of the RTD and thermocouple sensors were calculated. After performing this experiment, it was found that the time constants for the RTD were found to be -78.7 for cold to hot and 17.39 for hot to cold. The time constants for the thermocouple were found to be 3.519 for cold to hot and 2.64 for hot to cold. The rise times for the RTD were found to be 7.39 for cold to hot, and 7.9 for hot to cold. The rise times for the thermocouple were found to be 1.14 for cold to hot, and 1.27 for hot to ...view middle of the document...
The other beaker was kept on an electric heater to keep the water inside boiling. The RTD measurements were taken first. The RTD sensor was put in the beaker of boiling water and allowed to heat up. When the RTD sensor was close to 100 degrees Celsius, it was quickly switched over to the beaker of ice water. The results were then recorded from the display screen. Then, RTD sensor was quickly switched moved from the cold beaker back to the boiling beaker. The results for this temperature change were recorded as well. After this trial was concluded, the process was repeated a second time.
For the second part of the experiment, temperature measurements were taken using the thermocouple. The same procedure that was used for the RTD was used for the thermocouple, but the thermocouple’s temperature reading switched much faster. The data from the thermocouple was sent directly to Microsoft Excel.
The goals for this experiment were to calibrate the RTD and thermocouple and to calculate the response time of the RTD and thermocouple sensors. For data analysis, Microsoft Excel was used to organize data and create plots. The data from the calibration of the RTD and thermocouple was plotted so it would be easier to compare the two. These plots can be seen in Figures 1-4.
Fig. 1 Temperature vs. Time for RTD (Hot to Cold)
Fig. 2 Temperature vs. Time for RTD (Cold to Hot)
Fig. 3 Temperature vs. Time for Thermocouple (Hot to Cold)
Fig. 4 Temperature vs. Time for Thermocouple (Cold to Hot)
It can be seen that the response time for the thermocouple is a lot faster than that of the RTD. The thermocouple only needs a second or two to measure the temperature of its surroundings. The RTD on the other hand is much slower yet more precise with measuring the temperature change of the sensor with time. Since it takes longer to measure, it provides more data points and allows for a nice curve. The thermocouple is hard to find a curve for since there are only a few relevant data points due to its fast reponse time.
After creating these plots, the response time had to be calculated. The response time was calculated using the equation
y=log((T(t) - T∞)/(To - T∞) (1)
Plots were then constructed for the RTD and thermocouple with this function on the y-axis and time on the x-axis. This allowed for linear plots, which can be seen in Figures 5-8.
Fig. 5 Y vs. Time for RTD (Cold to Hot)
Fig. 6 Y vs. Time for RTD (Hot to Cold)
Fig. 7 Y vs. Time for Thermocouple (Hot to Cold)
Fig. 8 Y vs. Time for Thermocouple (Cold to Hot)
The slopes of the linear best fit line of these plots is equal to -1/τ. Therefore, the time constant, τ, could easily be calculated. For cold to hot, the time constant was calculated to be -78.7 for the RTD and 3.519 for the thermocouple. The -78.7 seems to be...