Measurement of Temperatures

A bottle of excellent chianti holds 750. mL. What is its volume in quarts  

Milk is often purchased by the half gallon. Determine the number of liters equal to this amount. 

The temperature of a system can be expressed by several different scales. Three commonly used temperature scales are Celsius (pronounced se//-see-t s), Kelvin (also called absolute), and Fahrenheit. The unit of temperature on the Celsius and Fahrenheit scales is called a degree, but the size of the Celsius and the Fahrenheit degree is not the same. 

Comparison of Celsius, Kelvin, and Fahrenheit temperature scales. 

The symbol for the Celsius and Fahrenheit degrees is and it is placed as a superscript after the number and before the symbol for the scale. Thus, 10.0°C means 10.0 degrees Celsius. The degree sign is not used with Kelvin temperatures  

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The luminometer index (ASTM D 1740) is a characteristic that is becoming less frequently used. It is determined using the standard lamp mentioned above, except that the lamp is equipped with thermocouples allowing measurement of temperatures corresponding to different flame heights, and a photo-electric cell to evaluate the luminosity. The jet fuel under test is compared to two pure hydrocarbons tetraline and iso-octane to which are attributed the indices 0 and 100, respectively. The values often observed in commercial products usually vary between 40 and 70 the official specification is around 45 for TRO. 

Optical metiiods, in both bulb and beam expermrents, have been employed to detemiine tlie relative populations of individual internal quantum states of products of chemical reactions. Most connnonly, such methods employ a transition to an excited electronic, rather than vibrational, level of tlie molecule. Molecular electronic transitions occur in the visible and ultraviolet, and detection of emission in these spectral regions can be accomplished much more sensitively than in the infrared, where vibrational transitions occur. In addition to their use in the study of collisional reaction dynamics, laser spectroscopic methods have been widely applied for the measurement of temperature and species concentrations in many different kinds of reaction media, including combustion media [31] and atmospheric chemistry [32]. 

The measuring of temperature rise permits monitoring efficiency for a fixed pressure ratio and suction temperature. Efficiencies should always exceed 0.6, and 1.00 is approachable in reciprocating devices. Their better efficiency needs to be balanced against their greater cost, greater maintenance, and lower capacity. 

Two alloys containing tungsten are commercially available. The first, containing about 3 wt % rhenium, is used for heating filaments. The rhenium contributes improved resistance to thermal and mechanical shock. The second alloy contains about 25 wt % rhenium. This latter alloy is sold as sheet, rod, and heavy wire and may be fabricated for various uses. An important use of these rhenium alloys is in the constmction of thermocouples. Various combinations, 3 wt % Re—97 wt % W, or 25 wt % Re—75 wt % W, are usehil for measurement of temperatures to 2500°C (see Temperaturemeasurement). 

Several types of secondary pyrometer are available. In addition to those that measure by varying lamp current, some pyrometers maintain the lamp at constant current but interpose a wedge of graduated neutral density, whose position is a measure of temperature. Also, automatic pyrometers are available in which the eye is replaced by a detector and the measuring element is operated by a servo. In general, the accuracy of the automatic pyrometer is somewhat less than that achieved manually by a skilled operator. 

For continuously rated machines, readings should be taken at intervals of one hour or less. For non-continuously rated machines, readings should be taken at intervals consistent with the time rating of the machine. The temperature rise test should continue until there is a variation of 1°C or less between the two consecutive measurements of temperature. 

Rosenberg, Z., and Partom, Y. (1984), Direct Measurement of Temperature in Shock Loaded Polymethlmetacrylate with Very Thin Copper Thermisters, in Shock... 

Detailed measurements of temperature, humidity, airflow, or other parameters are more appropriate to a later stage of profile development. However, chemical smoke can be used to observe airflow patterns and pressure relationships between special use areas or other identified pollutant sources and surrounding rooms. Odors in inappropriate locations may indicate that ventilation system components require adjustment or repair. 

An evaluation of the HVAC system may include limited measurements of temperature, humidity, air flow, as well as smoke tube observations. Complex investigations may require more extensive or sophisticated measurements of the same variables (e.g., repeated COj measurements taken at the same location under different operating conditions, continuous temperature and relative humidity measurements recorded with a data logger). 

Thermocouple An instrument for the measurement of temperature consisting of two wires of different metals joined at each end. An electrical electromotive force is generated, the magnitude of which allows the temperature to be measured. 

Besides readings of Earth s surface temperatures taken with standard glass thermometers, direct readings of atmospheric temperatures have been taken with satellites and weather balloons. In addition to direct measurements of Earth s recent temperatures, proxy measurements of temperatures from farther in the past can be derived from borehole temperature measurements, from historical and physical evidence regarding the e xtent and mass of land and sea ice, and from the bleaching of coral reefs. 

This study was run in a laboratory bench-scale unit with 0.75-in. reactor tubes. The catalysts were sized to 10 X 12 mesh and diluted nine-to-one with Si02 in order to spread the reaction out through the bed and to permit measurement of temperature profiles, the profile being an... 

The measurement of temperature is achieved by making use of two experimental facts ... 

Two scales used in die measuring of temperatures are Fahrenheit (F) and Celsius (C) (also known as centigrade). On the Fahrenheit scale, die freezing point of water is 32° F and die boiling point of water is 212° F. On die Celsius scale, 0° C is the freezing point of water and 100° C is die boiling point of water. 

Glass transition temperature (Tg), measured by means of dynamic mechanical analysis (DMA) of E-plastomers has been measured in binary blends of iPP and E-plastomer. These studies indicate some depression in the Tg in the binary, but incompatible, blends compared to the Tg of the corresponding neat E-plastomer. This is attributed to thermally induced internal stress resulting from differential volume contraction of the two phases during cooling from the melt. The temperature dependence of the specific volume of the blend components was determined by PVT measurement of temperatures between 30°C and 270°C and extrapolated to the elastomer Tg at —50°C. 

Figure 7.2.12 shows scatter plots of instantaneous measurements of temperature and CH4 mole fraction obtained at a height of 5 mm and at several radial locations, which are color-coded in the figure. The foremost observable characteristics are that there are no samples richer than 0.2 in the mixture fraction (1.0 being pure fuel) and that many samples remain at room temperature even within the limits of flammability. Many... 

Seebeck used antimony and copper wires and found the current to be affected by the measuring instrument (ammeter). But, he also found that the voltage generated (EMF) was directly proportional to the difference in temperature of the two junctions. Peltier, in 1834, then demonstrated that if a current was induced in the circuit of 7.1.3., it generated heat at the junctions. In other words, the SEEBECK EFFECT was found to be reversible. Further work led to the development of the thermocouple, which today remains the primary method for measurement of temperature. Nowadays, we know that the SEEBECK EFFECT arises because of a difference in the electronic band structure of the two metals at the junction. This is illustrated as follows ... 

For example, the final heat treatment temperatures In the manufacture will produce different electrochemical properties, even with the same surface treatments (2-4) since the structure and electrical property of glassy carbon depends on the temperature, as Indicated by the single crystal TEM patterns and by measurement of temperature dependent conductivity (5-6). On the other hand. It Is also well established that the electrochemical properties of carbon-based electrodes are markedly affected by surface treatments. 

Another early fiber optic refractive "sensor" was the one for measurement of temperature and salinity variations of sea water31. The sensing region consisted of a partly uncovered light guide. It detects salinity variations in water of known temperature, and temperature variations in water of known salinity with an accuracy of +/- 2 g/L and 1 °C, respectively, at NaCl concentrations of 300 g/L. 

Ivanov V.N., Ivanov S.V., Kel baHkhanov B.F., Klimova L.G., Trubnikov B.N., Chemyi V.V., Elisashvili D.T., Measurement of temperature and salinity variations of water with a fiber-optical sensor, Fizika Atmosfery i Okeana 1985 21 555. 

This first family of laboratory equipment was no more commercial since the closing down of the Prolabo French company. The support is made by CEM [45]. However, we describe these system because many laboratories use these devices [46]. The Synthewave 402 and 1000 are systems devoted to laboratory synthesis [47, 48]. They are constituted by a closed rectangular waveguide section playing the role of cavity. The magnitude of microwave power available is 300 W. They can use cylindrical tubes with several diameters. A condenser could be connected to the tube. The originality of this setup is to allow measurements of temperature by an infrared pyrom-... 

The validation of CFD codes by comparison to reliable experiments is of the highest importance. Especially promising is the use of MRI methods to non-invasively provide flow fields and dispersion data. Major challenges will be to extend MRI and similar methods such as LDV and particle tracking to a wider range of conditions, and to develop noninvasive measurements of temperature to improve verification of heat transfer simulations. 

Schellenz et al. [ 1.133] confirmed that the assumption of an infinite plate in Eq. (12) is a reasonable approximation, even for drying of products in vials. They show by the measurement of temperature profiles and by X-ray photos during drying of a 5 % mannitol solution, 23 mm filling height, that the sublimation front retreats mostly from the top parallel to the bottom. The heat transfer from glass vials deforms the flat surface only to some extent close to the wall. 

Willemer, H. Measurements of temperature, ice evaporation rates and residual moisture content in freeze-drying. Developments in Biological Standardization, Vol. 74, p. 123-136. Acting Editors Joan C. May, F. Brown, S. Karger AG, CH-4009 Basel (Switzerland), 1992... 

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