Gas calorimetry

A NEW ON-LINE TECHNIQUE FOR NATURAL GAS CALORIMETRY TABLE VII. COMPOSITION OF NATURAL GAS SAMPLE... 

C. G. Hyde and M. W. Jones, Gas Calorimetry, Ernest Benn, London, 1960. 

The commercial value of fuels in general and fuel gases in particular depends on the amount of energy contained in a given amount of fuel. Traditionally, this amount of energy per unit amount, the calorific value, has been determined by gas calorimetry (Hyde and Jones, 1960). In recent times, gas chromatography... 

An excellent example of work of this type is given by the investigations of Benson and co-workers [127, 128]. They found, for example, a value of = 276 ergs/cm for sodium chloride. Accurate calorimetry is required since there is only a few calories per mole difference between the heats of solution of coarse and finely divided material. The surface area of the latter may be determined by means of the BET gas adsorption method (see Section XVII-5). 

Solution calorimetry covers the measurement of the energy changes that occur when a compound or a mixture (solid, liquid or gas) is mixed, dissolved or adsorbed in a solvent or a solution. In addition it includes the measurement of the heat capacity of the resultant solution. Solution calorimeters are usually subdivided by the method in which the components are mixed, namely, batch, titration and flow. 

Solution Polymers. Acryflc solution polymers are usually characterized by their composition, solids content, viscosity, molecular weight, glass-transition temperature, and solvent. The compositions of acryflc polymers are most readily determined by physicochemical methods such as spectroscopy, pyrolytic gas—liquid chromatography, and refractive index measurements (97,158). The solids content of acryflc polymers is determined by dilution followed by solvent evaporation to constant weight. Viscosities are most conveniently determined with a Brookfield viscometer, molecular weight by intrinsic viscosity (158), and glass-transition temperature by calorimetry. 

Ozone can be analyzed by titrimetry, direct and colorimetric spectrometry, amperometry, oxidation—reduction potential (ORP), chemiluminescence, calorimetry, thermal conductivity, and isothermal pressure change on decomposition. The last three methods ate not frequently employed. Proper measurement of ozone in water requites an awareness of its reactivity, instabiUty, volatility, and the potential effect of interfering substances. To eliminate interferences, ozone sometimes is sparged out of solution by using an inert gas for analysis in the gas phase or on reabsorption in a clean solution. Historically, the most common analytical procedure has been the iodometric method in which gaseous ozone is absorbed by aqueous KI. 

What are the consequences What is the maximum pressure Vapor pressure of solvent as a function of temperature Gas evolution Differential Thermal Analysis (DTA) / Differential Scanning Calorimetry (DSC) Dewar flask experiments... 

In recent years, fluorine bomb calorimetry has been used effectively. A number of substances that will not burn in oxygen will burn in fluorine gas. The heat resulting from this fluorine reaction can be used to calculate AfH°m. For example, Murray and 0 Hare have reacted GeS2 with fluorine and measured ArH°. The reaction is... 

Bomb calorimetry Use of oxygen and an inert gas enables the heat of combustion and the heat of decomposition to be evaluated respectively. 

In an earlier study calorimetry achieved this objective for the compositional boundaries between two and three phases (2). Such boundaries are encountered both in "middle-phase microemulsion systems" of low tension flooding, and as the "gas, oil, and water" of multi-contact miscible EOR systems (LZ). The three-phase problem presents by far the most severe experimental and interpretational difficulties. Hence, the earlier results have encouraged us to continue the development of calorimetry for the measurement of phase compositions and excess enthalpies of conjugate phases in amphiphilic EOR systems. 

Finally, experimental procedures differing from that described in the preceding examples could also be employed for studying catalytic reactions by means of heat-flow calorimetry. In order to assess, at least qualitatively, but rapidly, the decay of the activity of a catalyst in the course of its action, the reaction mixture could be, for instance, either diluted in a carrier gas and fed continuously to the catalyst placed in the calorimeter, or injected as successive slugs in the stream of carrier gas. Calorimetric and kinetic data could therefore be recorded simultaneously, at least in favorable cases, by using flow or pulse reactors equipped with heat-flow calorimeters in place of the usual furnaces. 

The versatility and accuracy of the oxygen consumption method in heat release measurement was demonstrated. The critical measurements include flow rates and species concentrations. Some assumptions need to be invoked about (a) heat release per unit oxygen consumed and (b) chemical expansion factor, when flow rate into the system is not known. Errors in these assumptions are acceptable. As shown, the oxygen consumption method can be applied successfully in a fire endurance test to obtain heat release rates. Heat release rates can be useful for evaluating the performance of assemblies and can provide measures of heat contribution by the assemblies. The implementation of the heat release rate measurement in fire endurance testing depends on the design of the furnace. If the furnace has a stack or duct system in which gas flow and species concentrations can be measured, the calorimetry method is feasible. The information obtained can be useful in understanding the fire environment in which assemblies are tested. 

The most accurate clinical tool for estimating energy requirements is indirect calorimetry or metabolic gas monitoring. This noninvasive proce-... 

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