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Definitions and the First Law of Thermodynamics
Published in Marc J. Assael, Geoffrey C. Maitland, Thomas Maskow, Urs von Stockar, William A. Wakeham, Stefan Will, Commonly Asked Questions in Thermodynamics, 2022
Marc J. Assael, Geoffrey C. Maitland, Thomas Maskow, Urs von Stockar, William A. Wakeham, Stefan Will
However, more practical (secondary) thermometers are more commonly encountered. They include mercury-in-glass thermometers, which exploit the thermal expansion of mercury, platinum resistance thermometers, which exploit the resistivity change of platinum with temperature, thermocouples or thermistors. The last three require the measurement of a resistance or voltage rather than direct visual observation. All of these devices require calibration against a primary thermometer or a set of accepted standard reference points so that the temperature they report can be related to the thermodynamic temperature. The choice of instrument is determined by the precision required in the temperature and the range in which it is required. The interpretation of the resistivity of platinum in terms of thermodynamic temperature is achieved by the use of the International Temperature Scale of 1990 (ITS-90) (Preston-Thomas 1990; Nicholas 2003, BIPM 2019).
Understanding the Role of Existing Technology in the Fight Against COVID-19
Published in Ram Shringar Raw, Vishal Jain, Sanjoy Das, Meenakshi Sharma, Pandemic Detection and Analysis Through Smart Computing Technologies, 2022
The working principle of an IR thermometer is based on the black body radiations. All bodies with mass emit heat energy in the IR region. The IR thermometer detects the heat energy (IR electromagnetic radiations) emitted by an object and compares it with the IR radiations coming from the surrounding environment. The difference between the two incoming radiations gives a measure of the temperature. According to Stefan-Boltzmann’s law, the power radiated by a body is proportional to the fourth power of temperature. The main components of an IR thermometer comprise a lens and a detector. The lens focuses the incoming radiations onto the detector, which converts the radiations into electrical energy. The detector used in the IR thermometer is a thermopile. A thermopile consists of several thermocouples connected in series. The thermopile absorbs the IR radiations, which heats up one set of the thermocouple junctions. The other junctions are maintained at a reference temperature. The difference in the heat energy (or temperature) between the two layers of thermopile generates an electrical signal. An output voltage is generated which is proportional to the temperature difference, and thus gives the required temperature reading. The total process of temperature measurement takes a few seconds, thus making IR thermometers much faster than conventional medical thermometers. The schematic diagram showing the working of an IR thermometer is shown in Figure 2.1(a).
Instrumentation and Measurement
Published in Dale R. Patrick, Stephen W. Fardo, Ray E. Richardson, Brian W. Fardo, Energy Conservation Guidebook, 2020
Dale R. Patrick, Stephen W. Fardo, Ray E. Richardson, Brian W. Fardo
A rather recent development to the RTD family of temperature-measuring instruments is the portable digital thermometer. Figure 10-7 shows a representative digital thermometer that will measure temperatures over the range –50 to 900°F (–45.5 to 482.2°C). When the instrument is equipped with a platinum RTD probe its accuracy is 0.1°F or 0.05°C.
Experimental analysis for thermo-physical properties of phase change materials during accelerated thermal cycling
Published in Australian Journal of Mechanical Engineering, 2022
Onkar A. Babar, Vinkel K. Arora, Prabhat K. Nema
Uncertainty analysis was used to account error encountered during experimental analysis. It is actual measure of amount of deviations observed in measured values of quantity of interest relative to its true value. Uncertainty in performance of instruments depends upon uncertainties in the independent variables measured by that instrument and was determined as suggested in (Holman 2004). Digital thermometer had accuracy of ±0.1°C. Whereas, weighing balance possessed accuracy of ±0.1 g. Uncertainties in the measurement of temperatures were 0.01414. Uncertainty in the measurement of the mass of the PCM; was 0.51. The uncertainty values observed during experiments in case of performance of instruments were very small, so all readings obtained during measurements in this study were within acceptable range.
Thermal efficiency enhancement using a ceramic coating on the cylinder liner and the piston head of the IC engine
Published in International Journal of Ambient Energy, 2021
P. Anand, D. Rajesh, M. Shunmugasundaram, I. Saranraj
An infrared thermometer is a thermometer which infers temperature from a portion of the thermal radiation sometimes called blackbody radiation emitted by the object being measured. They are sometimes called laser thermometers if a laser is used to help aim the thermometer, or non-contact thermometers or temperature guns, to describe the device’s ability to measure temperature from a distance. By knowing the amount of infrared energy emitted by the object and its emissivity, the object’s temperature can often be determined. Infrared thermometers are a subset of devices known as ‘thermal radiation thermometers’. Sometimes, especially near ambient temperatures, false readings will be obtained indicating the incorrect temperature (Suzuki et al. 1986). This is most often due to other thermal radiation reflected from the object being measured, but having its source elsewhere, like a hotter wall or other object nearby – even the person holding the thermometer can be an error source in some cases. It can also be due to an incorrect emissivity on the emissivity control or a combination of the two possibilities.
Drying of onion shreds in corrugated electric and solar-conduction dryers: Techno-economic evaluation and quality degradation kinetics
Published in Drying Technology, 2023
Srinivasan Savitha, Snehasis Chakraborty, Bhaskar N. Thorat
Temperature profile of the SCD plate was prepared by recording the temperature at various points on the tray, on the sample, and between the samples (gaps) using an infrared gun (Stanley, IR Thermometer STHT77365). An infrared gun emits infrared light and focusses on the object surface and detects the radiation coming from the surface. Its detector translates the electrical energy generated into temperature reading. The thermometer could measure in the range of −38 °C to 520 °C with an accuracy of the thermometer was 2% ± 0.1 °C.