Temperature change, very small, measurement

Temperature measurement is almost invariably made using thermocouples . The latter must be constructed from fine wire °and have a fast response such that even a very small temperature change may be measured precisely. ... 

The third is infrared radiation pyrometer with an optical fiber (Hosokawa et al. 2010). This method is useful to measure the rotary cutting tool because it makes possible to measure the temperature of very small area which temperature changes very quickly. Tool temperature at the flank face of cutting tool is measured using a fiber-coupled two-color pyrometer in ADRT. The fundamental system of this pyrometer is shown in Fig. 9. Chalcogenide glass fiber-A is embedded in the workpiece, and the incidence face of the fiber is inserted into a small hole... 

B2.4.2). The slope of the line gives AH, and the intercept at 1/J= 0 is related to A imimolecular reaction, such as many cases of exchange, might be expected to have a very small entropy change on gomg to the transition state. However, several systems have shown significant entropy contributions—entropy can make up more than 10% of the barrier. It is therefore important to measure the rates over as wide a range of temperatures as possible to obtain reliable thennodynamic data on the transition state. 

Since heat exchange between the calorimeter vessel and the heat sink is not hindered in a heat-flow calorimeter, the temperature changes produced by the thermal phenomenon under investigation are usually very small (less than 10 4 degree in a Calvet microcalorimeter, for instance) (23). For most practical purposes, measurements in a heat-flow calorimeter may be considered as performed under isothermal conditions. 

For metering very small quantities, the volume of the bulb must be known accurately. The amount of material in it can be controlled very closely by changing the temperature of the compound in the reservoir, provided that its vapour pressure curve is known. By using the vapour of ice, it was possible to measure out ca. 10 mole of water (ca. 2 x 10" g), (Biddulph, Plesch and Rutherford, 1965). 

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