TEMPERATURE_MEASUREMENT_eee5

TEMPERATURE_MEASUREMENT_eee5 - TEMPERATURE MEASUREMENT...

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TEMPERATURE MEASUREMENT OBJECTIVE The objective of this experiment is to conduct temperature measurement tests in order to demonstrate the use of thermocouples for high temperature measurements. APPARATUS Vertical tube furnace Thermocouple calibration cell Thermocouple Potentiometer Mercury in glass thermometer SAMPLE We used Tin(Sn) but we do not know its exact composition. THEORY In engineering applications and modern experimental studies temperature measurement is an important topic because in many cases accuracy of these temperature measurements determine the total error of the experiments.Most of the time we look for the way to measure temperature that yields: Accuracy and speed of response required by the application
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Acceptable initial investment Low maintenence cost Long life and stability of calibration All methods of temperature measurement can be divided into two groups: 1)Indirect methods(contactless) for instance optical methods.(I mainly talk about it in the questions part). 2)Direct methods (contact methods).Here are some possibilities for this method: Thermometers.It can be alcohol(-40 ° C,+80 ° C) or mercury(-5 ° C,+350 ° C) Resistance wire termometers Temperature sensors Thermocouples In our experiment we mainly deal with thermocouples so we have to define it.A thermocouple is a system composed of two homogenous metal wires dissimilar in chemical composition that are soldered ,fused or welded together at one end forming a closed circuit when the free ends are connected to an indicating instrument which is mostly a potentiometer. Thermocouples are available in different combinations of metals or calibrations. The most common calibrations are J, K, T and E. There are also high temperature calibrations R, S, C and GB. Here are the properties of mostly used ones(of coarse there are other kinds of thermocouples for specific purposes.):
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RESULTS AND DISCUSSIONS For our particular aim we need to draw temperature vs time graph.To do this correctly of course we have to make necessary corrections considering the room temperature as we learn in our experiment.We take our sample at 250° C and cool it to nearly 211° C ;by the way we write the data seen in computer in every 30 seconds.After making our graph(temperature vs time) we have found the melting point of Sn by measuring the thermo- emf between the thermocouple ends. We have found the melting point of Sn is about 226 ° C but the melting point of pure Sn is 232 ° C. This shows that our sample is not pure.In our particular case we do not observe undercooling but it can be undercooling in some cases as we are learned in our experiment so at this point of my report I want to give information about the undercooling. Undercooling is a very useful process in many cases. If done right, the temperature of
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This note was uploaded on 12/27/2011 for the course MATH 286 taught by Professor Adad during the Spring '11 term at Middle East Technical University.

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TEMPERATURE_MEASUREMENT_eee5 - TEMPERATURE MEASUREMENT...

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