Classification of calorimeters

Calorimetry is the basic experimental method employed in thennochemistry and thennal physics which enables the measurement of the difference in the energy U or enthalpy //of a system as a result of some process being done on the system. The instrument that is used to measure this energy or enthalpy difference (At/ or AH) is called a calorimeter. In the first section the relationships between the thennodynamic fiinctions and calorunetry are established. The second section gives a general classification of calorimeters in tenns of the principle of operation. The third section describes selected calorimeters used to measure thennodynamic properties such as heat capacity, enthalpies of phase change, reaction, solution and adsorption. 

There are also other criteria for the classification of calorimeters. They can also be divided according to the aim for which they are used, i.e. 

These authors were aware of the difficulty of establishing a comprehensive classification of calorimeters In every classification there are certain calorimeters which do not clearly belong to a particular category.The Calvet calorimeter, for instance, can be used eidier isothermally with electric compensation... or in an isoperibol manner involving the measurement of a local temperature difference. Moreover, a number of existing calorimeters remain outside our classification. One example is a calorimeter involving a compensation of the thermal effect other than by thermoelectric means or by phase transition. But such devices can be easily included in our classification by analogy. ... 

Classification of calorimeters Methods of determination of heat effects... 

Various classifications of calorimeters have been presented [75-83]. The classification given here [84] is based on the assumption that the calorimeter is a dynamic object in which heat is generated. Calorimeters are graded by applying the criteria of the temperature conditions under which the measurement was made. As an initial basis for further considerations, the Fourier - Kirchhoff equation (Eq. (1.29)) has been used in the following form ... 

The classification of calorimeters presented above conforms with that given in 1930 by Lange and Miszczenko [1], who distinguished four groups of calorimeters ... 

The present theory of calorimetry is a result of the authors own work. Its essential feature is the simultaneous application of the relationship and notions specific to heat transfer theory and control theory. The present theory has been used to develop a classification of calorimeters, to discuss selected methods of determining thermal effects and thermokinetics, and to describe the processes proceeding in calorimeters of various types. Calorimeters have been assumed to constitute linear systems. This assumption allowed the principle of superposition to be used to analyze several constraints acting simultaneously in and on the calorimeter. 

The thermal and dynamic properties that are distinguished are used as a basis for the classification of calorimeters. The methods applied to determine the total heat effects and thermokinetics are presented. For analysis of the courses of heat effects, the equation of dynamics is formulated. This equation is demonstrated to be of value for an analysis of various thermal transformations occurring in calorimeters. 

The operating conditions described can be used as major characteristics for the classification of calorimeters. 

After some comments on the classification of calorimeters, we shall embark in this chapter upon a discussion of the instrumentation of calorimetry in greater detail and depth. The examples presented were selected so as to make the respective operation principle as clear as possible. No attempt was made to describe the newest instrument of a given type on the contrary, in many cases, a number of simple, classical calorimeters were chosen instead. However, efforts were made to cover the currently available types of commercial instruments as fully as possible. 

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