Temperature Definitions

The modern absolute temperature definition, suggested by W. Thomson, is based on Carnot cycle A scale whose definition does not depend on a specific substance is called absolute ... 

As a result of these new testing methods the following terminology for ignition temperature definitions has been proposed ... 

Since the rates in Table 13 have been determined at different temperatures, the features discussed here are based on estimated extrapolations to the same temperature. Definitive conclusions will have to await more detailed experimental results. 

For example, Schmidt et al. (1985) developed 12 kinetic models for the metabolism of organic chemicals that are not supporting bacterial growth. Assignment of the appropriate kinetic model requires measurement of sufficient experimental points on the disappearance curve. Often insufficient data points are collected to assign a kinetic model, especially with screening studies. Temperature definitely has an impact on the biodegradation kinet- 2000 CRC Press LLC... 

Name, Symbol kelvin, K-(temperature) Definition The kelvin is the fraction 1/273.16 of the thermodynamic temperature of the triple point of water. The kelvin is a unit of thermodynamic temperature (T). The word (or symbol) degree is not used with kelvin. The Celsius (formerly centigrade) temperature is also used. Celsius temperature (symbol f) is defined by the equation t = T — T0, where T0 equals 273.15 K. A degree Celsius (°C) is thus equal to one kelvin. 

All of the temperature definitions discussed so far are founded on mathematical representations of physically proved laws. In chemical engineering, particularly in its application to process chemistry, the prime objective is not to determine a theoretical temperature with known limits of precision, but to obtain some value that can be repeatedly reproduced and that gives reproducible process results. Such temperatures can be as diverse as the means available to measure them. Two or three such temperatures have reached the point of common usage, and are discussed in Section III, D. 

The above criterion, which has been proposed by Gierman (2) is based on the argument that the temperature required for a given conversion in the test reactor should not exceed the theoretical one by more than 1 °C, which can be considered to be within the accuracy of temperature definition in practice. A similar, but more conservative criterion has been proposed earlier by Mears (5) based on a maximum increase of 5% in bed length or catalyst volume to effect the same conversion as in an ideal reactor. In the criterion of Mears, the coefficient 8 in Equation 1 should be replaced by 20. 

For large (pilot plant) laboratory reactors, on the other hand, the adiabatic mode of operation is generally preferable since natural heat losses play a lesser role and heat removal or supply through the bed is more difficult. In the following part the accuracy of temperature definition in both modes of operation will be analyzed. 

The first term in the denominator is the non-dimensional bulk temperature definition,... 

Sprinkle a little water on the external surface of the process unit or the gas duct. If it boils off immediately, the temperamre is more than 100 °C. Now draw a line on the surface with a piece of solid sulphur—if it melts immediately, the temperature is more than 120° if it ignites, it is 250 °C. If a line is drawn with a piece of lead melts, then it is 330 °C. Such surface temperatures definitely indicate damage of internal refractory lining (melting point of tin is 232 °C and zinc is 419.4 °C. These can also be used). 

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