Static calorimeters

Duplicate measurements of heat production rate (P) on human obliquus internus muscle using two different calorimeters static and perfusion instrument. Source reference 75. 

Combustion or bomb calorimetry is used primary to derive enthalpy of fonuation values and measurements are usually made at 298.15 K. Bomb calorimeters can be subdivided into tluee types (1) static, where the bomb or entire calorimeter (together with the bomb) remains motionless during the experiment (2) rotating-... 

The calculation of other bond enthalpy terms, such as E (Ge—Ge), E (Ge—O), E (Ge—N) and E(Ge—S), can be made from data in Table 1. However, due to the above-mentioned controversy involving most of the data obtained with static-bomb combustion calorimeters, we refrain from tabulating those terms. 

Most static-bomb calorimeters used are of the isoperibol type, such as the one in figure 7.1. Here, the bomb A is a pressure vessel of 300 cm3 internal volume. Combustion bombs are usually made of stainless steel and frequently have an internal platinum lining to prevent corrosion. In a typical high-precision experiment, the platinum ignition wire B connects the two electrodes C, which are affixed to the bomb head. A cotton thread fuse D (other materials such as polyethene are also used), of known energy of combustion, is weighed to a precision of 10-5 — 10-6 g and tied to the platinum wire. A pellet E of the compound... 

Figure 7.1 Scheme of a macro static-bomb isoperibol combustion calorimeter (see text). 

As indicated, only elemental iodine is found in the combustion products of organoiodine compounds [61,62,67]. The iodine formed in a static bomb is mostly in the crystalline state, but some is present in the aqueous and in the gaseous phases. The thermal corrections for dissolution and sublimation are very small and, therefore, static-bomb calorimeters may be used to study organoiodine compounds. However, to avoid the uncertainty in the final state due to the distribution... 

The calorific value is the heat produced by the combustion of a unit quantity of coal in a bomb calorimeter with oxygen and under a specified set of conditions (ASTM D-121 ASTM D-2015 ASTM D-3286 ISO 1928). For the analysis of coal, the calorific value is determined in a bomb calorimeter either by a static (isothermal) method or by an adiabatic method, with a correction made if net calorific value is of interest. The unit is calories per gram, which may be converted to the alternate units (1.0 kcal/kg = 1.8 Btu/lb = 4.187 kJ/kg). 

The cone calorimeter,71 which is a dynamic flow-through fire test, can also be used to assess smoke obscuration. The rankings tend to be quite different from those found with the static smoke chamber and are much more realistic. Several empirical parameters have been proposed to make this compensation for incomplete sample consumption, including one called the smoke factor (SmkFct), determined in small-scale RHR calorimeters.188 It combines the two aspects mentioned earlier the light obscuration (as the total smoke released) and the peak RHR. 

The sensitivity, S, is the static calibration constant of the calorimeter and is usually expressed in... 

The determination of the constants S and t constitutes the static and dynamic calibration of the calorimeter. The calibration of the calorimeter may be done by means of a known thermal effect produced during suitable conditions inside the cell, for example. Joule effect calibration (2, 4, 41). 

The enthalpy of formation of Se02(cr) is obtained from the three accepted measurements of the heat of combustion of Se(trigonal) listed in Table V-22 (references to earlier experimental results or selected values in compilations can be found in [62GAT]). Selenium reacts only partly with oxygen in the bomb calorimeter unless mixed with a combustion aid. Benzoic acid was used for this purpose and the heat evolved by the combustion aid was about 50% in the static bomb and about 90% in the rotating bomb experiments. 

For thermal analyses by the static method, a precise adiabatic calorimeter is required. Although many adiabatic calorimeters have been described in the literature, Glasgow et al. (18) have described a calorimeter which was used to determine the purity of benzene and other substances in the temperature range 10-300K. The calorimeter is illustrated schematically in Figure 10.4. 

The scanning because the criterion used is the mode of operation, it makes sense, at first sight, to make a special family with the calorimeters used in the temperature scanning mode. However this only considers a single aspect of the mode of operation (namely, the mode of heating), whereas many other aspect could be considered (mode of introduction of the sample, mode of initiation of the phenomenon studied, open or closed system, static or dynamic experiment. ..). One may therefore wonder whether calorimeters 4 to 6 should not be simply considered as sub-groups of the first three ... 

Between 1881 and 1905, Berthelot and co-workers developed the first combustion calorimeter, precursor of the modem calorimeters with static bomb [27-30]. 

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