Nobody downloaded yet

Thermocouple and thermistor - Essay Example

Comments (0) Cite this document
Awareness of heat and attempting to measure the intensity can be traced to ancient history in the development of humankind. The initial success in measuring heat or temperature was based on the phenomenon of thermal expansion…
Download full paperFile format: .doc, available for editing
GRAB THE BEST PAPER91.2% of users find it useful
Thermocouple and thermistor
Read TextPreview

Extract of sample
"Thermocouple and thermistor"

Download file to see previous pages Awareness of heat and attempting to measure the intensity can be traced to ancient history in the development of humankind. The initial success in measuring heat or temperature was based on the phenomenon of thermal expansion. It has remained one of the simplest methods and the most popular means for temperature sensing and is the basis of the liquid-in-glass thermometers that find applications ranging from home to the science laboratories. (1). Advances in the field of science required more accurate thermal sensing then was possible with the best liquid-in-glass thermometers, which led to development of thermal sensing devices using different methods. The range of modern thermal sensing devices includes thermoelectric, resistive, semi-conductive, optical, acoustic, and piezo-electric detectors. (1). Thermoelectric and resistive devices are based on the transmission of a fraction of the quantity thermal energy of the object to a contact sensor that has the ability to convert the heat energy into an electric signal that can be used for measuring the temperature of the object. However, there arises an error issue in this method that requires the sensor to be placed on or in the object. The error issue pertains to the sensor, irrespective of its size, disturbing the point of contact or the measurement site, and thereby causing inaccuracy in the measurement of the temperature. These inaccuracies are applicable to any method of sensing, be it conductive, convective, or radiative. A key goal in engineering has been to minimize these inaccuracies in temperature measurements through appropriate design of the sensors and use of correct measurement techniques. (1). 2. Principle and Design of the Thermocouple Thermocouples are based on the discovery by Thomas Johann Seebeck of thermoelectric currents during his studies of electromagnetic effects using bismuth-copper and bismuth-antimony circuits. The observation of Seebeck in 1821 that small currents flow in circuits made up of two different conductors, when their junctions are maintained at dissimilar temperatures is called the Seebeck Effect and is the principle on which thermocouples are founded. (2). In case one junction of a circuit consisting of dissimilar metals is maintained at a hotter temperature than the other junction, an electro-motive force (emf) is generated, which is in proportion to the difference in temperature between the hot junction or the measuring junction and the cold junction or the reference junction. The emf produced in this condition is called the Seebeck emf, which is measured in millivolts, and the pair of conductors that make up the thermoelectric circuit is called the thermocouple. (2). Measuring of the Seebeck emf can be effected either through a closed circuit current or an open circuit current. The Seebeck voltage constitutes the net conversion of thermal energy to electric energy, which is seen in the electric current generated. There are two factors on which the direction and magnitude of the Seebeck voltage is dependent, and they are the temperatures of the two junctions and the materials that constituter the thermo couple. When the temperature of the references junction is available, it is possible to measure the temperature of the measuring junction through an accurate measurement of the Seebeck emf generated by the thermocouple. There are three possible emf-measuring instruments that can be used for this purpose, namely deflection meters, digital voltmeters, and potentiometers. Digital voltmeters and potentiometers are the preferred emf-measuring instruments, because of their higher accuracy. (2). There are four main types of thermocouple junctions. These are exposed or bare-wire junction, grounded junction, ungrounded or isolated junction, and reduced diameter junction. In the exposed or bare-wire junction the sheath and insulating material are removed causing exposure of the thermocouple wires and are joined to create a measuring junction. This type of ...Download file to see next pagesRead More
Cite this document
  • APA
  • MLA
(“Thermocouple and thermistor Essay Example | Topics and Well Written Essays - 2500 words”, n.d.)
Retrieved from
(Thermocouple and Thermistor Essay Example | Topics and Well Written Essays - 2500 Words)
“Thermocouple and Thermistor Essay Example | Topics and Well Written Essays - 2500 Words”, n.d.
  • Cited: 0 times
Comments (0)
Click to create a comment or rate a document
Re-write lab
...? Tin Melting Experiment 3-8-11 Group 6 Summary This experiment was conducted to identify the melting point of pure Tin. In order to find that, a ceramic crucible that contained Tin was heated in the furnace up to 400C. 400C is considerably above the estimated melting point of pure Tin. To keep the sample from getting oxidized, nitrogen was introduced into the furnace while it was made sure, that no oxygen entered it. Tin’s melting point was virtually determined through its transition from solid to molten state. Tin was then shifted into a coffee can. Sand was already there in the can. A thermocouple sheath made of stainless steel was also introduced into it exactly quarter of an inch above the crucible’s base. The...
2 Pages(500 words)Lab Report
Lab Report
...? Tin Melting Experiment Summary: The basic reason of conducting this experiment was to find out the melting point of pure Tin. In order to do that, a ceramic crubicle containing pure Tin was heated in a furnace up to the temperature of 400C. This temperature is above the anticipated melting point of pure Tin. Meanwhile, nitrogen was made to enter the furnace keeping oxygen out so as to keep the sample from oxidizing. When the Tin reached the melting point (as determined visually), the sample of pure Tin was put into a coffee can that was filled with sand. A stainless steel thermocouple sheath was placed into the container at a distance of ? inch from the bottom of the crucible and it was isolated with the help of a glass...
2 Pages(500 words)Lab Report
Magnetic Resonance Imaging (MRI)
...thermistor or thermocouple-based techniques (Shellock, 2012). For emergency situations, a ventilator and other devices for first aid care should also present to provide increased air saturation. Currently, the mechanical switches, microprocessors and other components of ventilators are made up of ferrous material. Thus, it may be used only at a certain distance away from the MRI, or securely attached to the floor to prevent missile effects (Shellock, 2012). PATIENT PREPARATION FOR SEDATION History taking and physical examination should be conducted in order to anticipate conditions that the patient may be at risk of having after sedation. Nothing per orem should also be implemented six to two hours...
7 Pages(1750 words)Essay
Remote temperature sensor proportion to the temperature. Digital temperature sensor: they sense the temperature of the surrounding and generate an electrical signal that is then converted to a digital value through electronic devices (maxim, 2001). 1.1.3 Calibration of sensors The most common temperature sensors include thermocouples, RTD and Thermistor. In all these sensors the temperature changes affect the voltage generated or the resistance of sensors. Thus the temperature voltage relationship is utilized in these sensors. To avoid errors in measurements calibration of the sensors must be done to ensure that the reading output by the sensors in terms of the voltage correspond to a given temperature. Calibration...
24 Pages(6000 words)Essay
Electronic Devices
...and temperature dependent resistors, we can change the behavior of the circuit. The temperature dependent one can be replaced by light dependent resistors. The circuit consists of a Wheatstone bridge with an Op-amp used to detect when the bridge is balanced. One leg of the bridge contains temperature dependent resistor or a Thermister. It has negative temperature co-efficient. Other leg has potentiometer which is set at a value equal to resistance of thermistor at the critical temperature. At normal temperature (below critical) thermistor resistance is greater than potentiometer resistance thus creating an unbalanced condition that drives the op-amp to its low saturated output level. As the...
11 Pages(2750 words)Essay
Integrated Technology Systems
...temperatures or moderate Reference junction compensation is required They are to be tested in order to verify performance in controlled conditions for critical applications Thermocouple temperature sensors are suitable for both soil and air temperature recording due to their rapid temperature response and accuracy. In addition, they are easy to calibrate. 2.2 Resistive Devices Thermistor is temperature sensor that proportionally changes its resistance in relation to temperature changes. Thermistors are of two types: negative temperature coefficient (NTC) and positive temperature coefficient (PTC). PTCs have positive change in resistance with temperature rise, while NTCs have negative...
9 Pages(2250 words)Assignment
...making them more reliable than Thermocouples and the Temperature resistant detectors. Thermistors are classified according to the attachment of electrodes to the ceramic encapsulation as Negative temperature coefficient and positive temperature coefficient. I. Negative temperature coefficient thermistors Materials used to make Negative temperature coefficient thermistors include rods, plates, pressed disc and cast chips of semiconductors. The temperature impacts the resistance negatively to increase the number of charge carriers to conduct more current and the relationship is shown by an exponential curve. They have higher temperature sensitivity than other temperature...
10 Pages(2500 words)Assignment
A Review of the Main Temperature Sensors for Control System and Summary of the Typical Sensors for Measurement of Rainfall
... A Review of the Main Temperature Sensors for Control System and Summary of the Typical Sensors for Measurement of Rainfall Question 1 A review of the main temperature sensors for control systems (Resistance Temperature Detectors, RTD, Thermocouples, Thermistors) outlining the characteristics of each type and providing explanations and examples of the types of systems they are most suited. Introduction Many people virtually ignore the importance of temperature sensors in various thermal systems. Bharathi and Vasantharajan (2008) and Nieuwenhove and Vermeeren (2004) affirm that temperature measurement can be achieved using various forms of sensing mechanisms. Temperature measurement systems consist...
10 Pages(2500 words)Assignment
HNC Summer School Project Briefing (Mechanical Engineering)
...operation. Mainly, when the machine is under operation and the temperature increment beyond expected limit, the automatic system through its sensors will be able detect the change in temperature and automatically activates the coolants to propel in order to decrease the temperature. The project outline and describes the design and the working principles of an automatic cooling system. The design of a cooling system will encompass the use of sensors to control the temperature change as well as the use of a thermistor. Primarily, a thermistor is a kind of resistor whose resistance varies or fluctuates due to temperature change. The thermistor consists of a sensitive material which is able...
24 Pages(6000 words)Essay
Control System Project for A Car Wash System
...signal, which is a function of the input signal and has to be related by a specific sensitivity parameter. The sensors can be self-generating or modulating (Langereis, 1999). Self-Generating Sensors (thermocouple sensors) Self-generating sensors convert energy for a particular domain to another. The output signal in this case turns out to be zero since the signal itself is the only energy applied. For this reason, the sensor is referred to as self-generating transducer. Self-generating transducers have no output and hence there is no offset as depicted in figure 1 below (Langereis, 1999). This aspect constitute to the reason for choosing the thermocouple sensors. Only the slope need to be known. Figure...
3 Pages(750 words)Assignment
sponsored ads
We use cookies to create the best experience for you. Keep on browsing if you are OK with that, or find out how to manage cookies.
Let us find you another Essay on topic Thermocouple and thermistor for FREE!
logo footer
Contact us:
Contact Us Now
FREE Mobile Apps:
  • StudentShare App Store
  • StudentShare Google play
  • About StudentShare
  • Testimonials
  • FAQ
  • Blog
  • Free Essays
  • New Essays
  • Essays
  • Miscellaneous
  • The Newest Essay Topics
  • Index samples by all dates
Join us:
Contact Us