Special Calorimeters

Special calorimeter (UFA to assess combustion in under-ventilated conditions and evaluate tendency for dripping and char strength by performing experiments in vertical orientation)... 

There are some special calorimeters, or accessories for special applications, on the market ... 

The pressure perturbation calorimeter, a very special calorimeter accessory offered by MicroCal, measures differential heat change in a biopolymer solution, when the pressure above the solution is changed. This method is suitable for research on biopolymer solutions the interaction of biopolymers with the solvent is often highly sensitive to pressure changes. The measured heat, compared with that of the pure solvent, provides information about the interaction change with changed pressure. 

The cement calorimeter MC CAL - another very special calorimeter from C3 Prozess- und Analysentechnik - vas developed to study the hardening behavior of different cement blends with the help of the heat flow rate-time function. 

Calorimeter. The P-decay energy of tritium is very precisely known (9). The thermal energy generated by the decay can thus be used with a specially designed calorimeter to measure the quantity of tritium in a system of known heat capacity. 

The heat of combustion of solids or liquids is usually measured in a device known as an oxygen bomb calorimeter. Such a device operates at a constant volume between states 1 and 2, and its heat loss is measured by means of the temperature rise to a surrounding water-bath. This is schematically shown in Figure 2.2. The combustion volume is charged with oxygen and a special fuel is added to ensure complete combustion of the fuel to be measured. Since the process is at constant volume (V), we have... 

However, we believe that we have also been able to diagnose true cationic polymerisations of styrene, but only under special conditions in calorimeter experiments with relatively large quantities of perchloric acid, especially at low temperature, down to -90 °C, it was found that when the phial of acid was broken in such a way that the mixing of acid with the solution was relatively slow, the solution turned yellow for a fraction of a second, near the broken phial, and there was an abnormally fast polymerisation which settled down after a few seconds to the rate appropriate to the pseudocationic reaction. The rate of these very fast reactions was much greater than could be accounted for by the high local concentration of acid if the reactions had been of the normal pseudocationic type, and we believe them to betray the transient presence of, and polymerisation by, true ions. 

Many of the reactions that chemists study are reactions that occur at constant pressure. During the discussion of the coffee-cup calorimeter, the heat change at constant temperature was defined as qp. Because this constant-pressure situation is so common in chemistry, a special thermodynamic term is used to describe this energy enthalpy. The enthalpy change, AH, is equal to the heat gained or lost by the system under constant-pressure conditions. The following sign conventions apply ... 

Electrical calibration has the advantage of being more flexible. It can afford s0 through equation 7.23 ifitisdone on the reference calorimeter proper. Flowever, it can also be performed on the initial or final state of the actual experiment leading to (e0 + ecl) or (e0 + ecf), respectively. Twenty or 30 years ago the electrical calibration required very expensive instrumentation that was not readily available except in very specialized places, such as the national standards laboratories. Although the very accurate electronic instrumentation that is available today at moderate prices may change the situation, most users of combustion calorimetry still prefer to calibrate their apparatus with benzoic acid. 

R. S. Jessup. Heat of Combustion of Benzoic Acid with Special Reference to the Standardization of Bomb Calorimeters. J. Res. Nat. Bur. Stand. 1942, 29, 247-270. 

The Sikarex safety calorimeter system and its application to determine the course of adiabatic self-heating processes, starting temperatures for self-heating reactions, time to explosion, kinetic data, and simulation of real processes, are discussed with examples [1], The Sedex (sensitive detection of exothermic processes) calorimeter uses a special oven to heat a variety of containers with sophisticated control and detection equipment, which permits several samples to be examined simultaneously [2]. The bench-scale heat-flow calorimeter is designed to provide data specifically oriented towards processing safety requirements, and a new computerised design... 

Researchers have used a specially designed calorimeter, called a human calorimeter, to monitor the heat that is produced by metabolic reactions in humans. Research the human calorimeters that are used to study metabolic reactions. What are the design features of these calorimeters What factors do researchers need to take into account Why are the experiments with human calorimeters important Design an investigation that incorporates the results of your research. 

As was already mentioned, experimental determinations of heat of explosion and of heat of detonation are conducted in steel or special alloy cylindrical vessels of strong construction, known as "constant volume explosion bomb calorimeters and as "detonation calorimeters . To the brief description of such calorimeters (bombs), which is given in Vol 2 of Encycl, p Cll-R, the following may be added ... 

This Annex describes the special requirements for adiabatic calorimeters which are suitable for obtaining runaway chemical reaction data for relief system sizing. Methods for obtaining the data required for relief system sizing and for determining the system type for relief sizing (see 4.2) are then described. 

Calorimeters of Historical and Special Interest Around 1760 Black realized that heat applied to melting ice facilitates the transition from the solid to the liquid stale at a constant temperature. For the first time, the distinction between the concepts of temperature and heat was made. The mass of ice that melted, multiplied by the heal of fusion, gives the quantity of heal. Others, including Bunsen, Lavoisier, and Laplace, devised calorimeters based upon this principle involving a phase transition. The heat capacity of solids and liquids, as well as combustion heats and the production of heat by animals were measured with these caloritnelers. 

Calorimeters can determine the heat content of their samples by (1) direct burning, (2) calculation from composition, and (3) special designs. Their operation can be continuous, cyclic, or portable. Their errors range from 0.5 to 2% full scale (FS). 

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