Calorimeter design

A liquid serves as the calorimetric medium in which the reaction vessel is placed and facilitates the transfer of energy from the reaction. The liquid is part of the calorimeter (vessel) proper. The vessel may be isolated from the jacket (isoperibole or adiabatic), or may be in good themial contact (lieat-flow type) depending upon the principle of operation used in the calorimeter design. 

Various books and chapters in books are devoted to calorimeter design and specific applications of calorimetry. For several decades the Connnission on Themiodynamics of the International Union of Pure and... 

Figure Bl.27.9. High-temperature heat-leak calorimeter. (Reproduced by pemiission from Cliristensen J J and Izatt R M 1984 An isothemial flow calorimeter designed for high-temperature, high-pressure operation...

Figure 7.9 Scheme of the aneroid dynamic combustion calorimeter designed by Adams, Carson, and Laye [77], A jacket B jacket lid C motor that drives the rotation of calorimetric system D rotation system E bomb (which is also the calorimeter proper) F channels to accommodate the temperature sensor, which is a copper wire resistance wound around the bomb G crucible H electrode I gas valve. Adapted from [77]. 

The RSST calorimeter (see Annex 2) is a pseudo-adiabatic, low thermal inertia calorimeter, intended for screening purposes. It can identify the system type and measure adiabatic rate of temperature-rise and rate of gas generation by the reacting mixture. It is therefore well-suited to the task of selecting the overall worst case scenario from a small number of candidates. Alternatively, a calorimeter designed to obtain relief system sizing data may be used for this purpose (see Annex 2). 

Most calorimeters described above rely on a measurement of temperature (heat-Flow Calorimeters). The Tian182-Calvet183 calorimeters (some with a twin calorimeter design) use a thermopile (instead of a thermocouple) to measure heat flow directly (Fig. 11.78). 

Calorimeter. A differential calorimeter, operating at 25.0 °C under near-isothermal conditions, was used for all heat measurements. Similar calorimeters, designed for determining heats of ion exchange in zeolites, have been described previously (5, 6, 14, 15). The calorimeter was calibrated by measuring the heat of solution of potassium chloride in water. The ratio of the area under the curve traced by the recorder pen to the heat produced was 1.50 dz 0.04 cm per calorie. No heat could be detected when an empty evacuated bulb was broken under water. 

Miniaturization is especially advantageous in an era when compounds with extraordinarily interesting structural and thermochemical properties are being synthesized but only in very small amounts. Because the first principle of all calorimetry is that the sample must be well defined and pure (or at least have a small amount of known impurity), microcalorimetry permits use of a wider range of contemporary purification techniques, especially preparative gas chromatography, than traditional calorimetry. There is, of course, no reason to suppose that the evolutionary process of hydrogen calorimeter design cannot be continued to produce smaller, safer, and possibly more accurate instruments. 

This result was measured in an early version of a new calorimeter design and is not preferred. Hydrogenation was carried out in cyclohexane. An error making the measured value about 1.7 kcal mol 1 less exothermic than the true value is likely. 

Constant-Volume Calorimetry In the coffee-cup calorimeter, we assume all the heat is gained by the water, but some must be gained by the stirrer, thermometer, and so forth. For more precise work, as in constant-volume calorimetry, the heat capacity of the entire calorimeter must be known. One type of constant-volume apparatus is the bomb calorimeter, designed to measure very precisely the heat released in a combustion reaction. As Sample Problem 6.5 will show, this need for greater precision requires that we know (or determine) the heat capacity of the calorimeter. 

FIGURE 212. Ice calorimeter, designed by Lavoisier and the famous mathematician Laplace. Heat was defined in units of ice melted. The idea that metabolism was similar to combustion derived from the knowledge that oxygen was required, carbon dioxide and water produced and heat generated by animals. Thus, Lavoisier realized that combustion, calcination and metabolism were all related in the sense that each involved combination with oxygen. 

The ice calorimeter, designed by Pierre Simon de Laplace, was first employed by Lavoisier during winter, 1782/83. Heat from the reaction vessel was measured by the quantity of ice in the surrounding metal jacket that melted and was collected as water. Lavoisier and Laplace measured the heat given off by many chemical processes, including the combustion of charcoal. They also measured the heat produced by a living guinea pig. 

Because of the profusion of calorimeter designs there is no agreed system of classification. Hemminger and Hohne have suggested a method based on three criteria ... 

Any calorimeter designed for cryogenic work is subject to thermal contraction of one or both of the insulation boundary surfaces. For the calorimeter at hand, the geometric modification due to thermal expansion and contraction was calculated using data of Corruc-cini and Gniewek [ ]. Calculations show that an error as high as 4.6% can be introduced into the results unless the expansion and contraction phenomena are taken into account in evaluation of the data [ ]. 

During his professional career, he made significant contributions in several fields including precision calorimeter design and construction, determination of thermodynamic data for ligand interactions with protons and cations, compilation of thermodynamic data, and organization of international symposia. He was coorganizer of the first Symposium on Macrocyclic Chemistry. This Symposium is now held on an annual basis. 

The author wishes to thank M. M. Fulk and R. H. Kropschot of the NBS-CEL for supplying the basic calorimeter design and for consultation on several occasions. H. Teicher and M. J. Scott of this laboratory have given continual counsel and assistance, and D. P. Ames and G. Brautigam have suggested the techniques adapted for infrared transmission measurements. 

Answer by author We used only one calorimeter design, which had a 1 in. separation between the hot and cold surfaces. 

One of the first scarming adiabatic calorimeters designed in the past was the DASM IM microcalorimeter [107], used to determine the apparent molar heat capacity and conformational changes of proteins and nucleic acids. Measurements are performed in the temperature interval from 10 to 100°C, the shield heating rate can vary from 0.1 deg-min to 2 deg-min", and the sensitivity of the instmment is 4-10 cal-deg". A... 

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