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ECE5320 Mechatronics Thermocouples

ECE5320 Mechatronics Thermocouples. Prepared by: Leonardo Alfonseca Dept. of Electrical and Computer Engineering Utah State University. 3/11/2010. Outline. Reference list To explore further Major applications Working principle Types of thermocouples Voltage/Temperature response curve

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ECE5320 Mechatronics Thermocouples

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  1. ECE5320 MechatronicsThermocouples Prepared by: Leonardo Alfonseca Dept. of Electrical and Computer Engineering Utah State University 3/11/2010

  2. Outline • Reference list • To explore further • Major applications • Working principle • Types of thermocouples • Voltage/Temperature response curve • Practical Circuits • Selecting a thermocouple • Appendix ECE5320 Mechatronics. Assignment#1 Survey on sensors and actuators

  3. Reference list • [1] http://tcomega.com/temperature/Z/pdf/z021-032.pdf • [2] http://en.wikipedia.org/wiki/Thermocouple#Types • [3] http://web.cecs.pdx.edu/~gerry/epub/pdf/thermocouple.pdf ECE5320 Mechatronics. Assignment#1 Survey on sensors and actuators

  4. To explore further • Practical Thermocouple temperature measurements • http://www.dataforth.com/catalog/pdf/an107.pdf • Heat-balance equation for a disk-thermocouple system in an isotropic medium • Journal of Engineering Physics and Thermophysics ECE5320 Mechatronics. Assignment#1 Survey on sensors and actuators

  5. Major applications • Temperature measurement in industry • When the range of temperature is wide and the accuracy is not an issue thermocouples are of great interest. http://haryana.gov.in/Industry/industry1.jpg ECE5320 Mechatronics. Assignment#1 Survey on sensors and actuators

  6. Major applications • Steel Industry • For the correct temperature control in the process of making steel • Heating safety • For daily use appliances such oven and hot water, the safety is of use is guarantee using a heat control • Manufacturing Area • Some process require control in welding of plastic and the amount of heat used, since precision is not an important issue thermocouples are widely used • Radioisotope Thermoelectric • These are generation plants that use thermocouples to generate electricity with temperature ECE5320 Mechatronics. Assignment#1 Survey on sensors and actuators

  7. Working Principle • The principle is based upon the use of a joint of two different metals; this metals generate electric power in relationship with the temperature. ECE5320 Mechatronics. Assignment#1 Survey on sensors and actuators

  8. Basic Working Principle ECE5320 Mechatronics. Assignment#1 Survey on sensors and actuators

  9. Basic Working Principle • Where: • Tref represents the reference temperature • T represents the interest point temperature • represents the seebeck coefficient from the two metals ECE5320 Mechatronics. Assignment#1 Survey on sensors and actuators

  10. Types of thermocouples The thermocouple types depends on the materials used to generate the power out of the different temperature • The types of thermocouples are directed depending on the following elements: • Temperature range • Chemical resistance of the thermocouple • Abrasion and vibration resistance • Installation requirements Simple diagram of IR a thermometer [4]. ECE5320 Mechatronics. Assignment#1 Survey on sensors and actuators

  11. Types of Thermocouples In industry we have some standard types of thermocouples and the types are as follows: • Type K • Alloy of chromel-alumel • Sensitivity:  41 µV/°C • Temperature range: −200 °C to +1250 °C ECE5320 Mechatronics. Assignment#1 Survey on sensors and actuators

  12. Type E • Alloy chromel-constantan • Sensitivity: 68 µV/°C • Temperature range: −200 °C to +900 °C • Type J • Alloy iron-constantan • Sensitivity: 55 µV/°C • Temperature range: −40 to +750 °C ECE5320 Mechatronics. Assignment#1 Survey on sensors and actuators

  13. Type N • Alloy Nicrosil-Nisil • Sensitivity: 39 µV/°C at 900 °C • Temperature range: exceeding 1200 °C • Type T • Alloy cooper-constantan • Sensitivity: 43 µV/°C • Temperature range: −200 to 350 °C There are other types of thermocouples but not covered here ECE5320 Mechatronics. Assignment#1 Survey on sensors and actuators

  14. Thermocouple mV/Temperature curve ECE5320 Mechatronics. Assignment#1 Survey on sensors and actuators

  15. Practical Thermocouple circuits • Iced-bath Reference Junction ECE5320 Mechatronics. Assignment#1 Survey on sensors and actuators

  16. Thermocouple System with a Known Arbitrary reference point ECE5320 Mechatronics. Assignment#1 Survey on sensors and actuators

  17. Criteria for Thermocouple Selection • Temperature range • Environment of operation • Physical Space limitations • Response Time ECE5320 Mechatronics. Assignment#1 Survey on sensors and actuators

  18. Appendix Percentage of material per thermocouple type: ECE5320 Mechatronics. Assignment#1 Survey on sensors and actuators

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