Calorimetry high pressure

It should become clear from this review that calorimetry, (high pressure) DTA, and DSC give relevant, reproducible data that are of great importance in many fields of food technology, because this information characterizes the food globally. From the basics of food technology it is easy to understand that calorimetric techniques help in quality control, improvement of food characteristics, development of new operations, and process safety [127-134]. 

To our knowledge, the question of the standard state corrections in DSC experiments has never been addressed. These corrections may in general be negligible, because most studies only involve condensed phases and are performed at pressures not too far from atmospheric. This may not be the case if, for example, a decomposition reaction of a solid compound that generates a gas is studied in a hermetically closed crucible, or high pressures are applied to the sample and reference cells. The strategies for the calculation of standard state corrections in calorimetric experiments have been illustrated in chapter 7 for combustion calorimetry. 

Charlu T. V., Newton R. C., and Kleppa O. J. (1978). Enthalpy of formation of lime silicates by high temperature calorimetry, with discussion of high pressure phase equilibrium. Geochim. Cosmochim. Acta, 42 367-375. 

Le Parlouer, P. Dalmazzone, C. Herzhaft, B. Rousseau, L. Mathonat, C. (2004). Characterisation of gas hydrates formation using a new high pressure MICRO-DSC. J. Thermal Analysis Calorimetry, 78, 165-172. 

Urszula Domahska has been professor. Faculty of Chemistry, Warsaw University of Technology since February 1995. She has been the Head of the Physical Chemistry Division since September 1991 and vice director of the Institute of Fundamental Chemistry (1988-1990). She had long-term scientific visits as visiting professor Laboratoire De Thermodynamique Ft D Analyse Chimique, University of Metz, France University of Turku, Finland Faculty of Science, Department of Chemistry, University of Natal, South Africa Department of Chemical Engineering, Louisiana State University, United States. Her interests have included such areas of physical chemistry as thermodynamics, especially thermodynamics of phase equilibria, VLE, LLE, SLE, high-pressure SLE, separation science, calorimetry, correlation and prediction of physical-chemical properties, and ionic liquids. She is a member of the Polish Chemical Society member of the Polish Association of Calorimetry and Thermal Analysis member of lUPAC Commission on Solubility member of International Association of Chemical Thermodynamics and scientific advisor at the Journal of Chemical Engineering Data. 

Calorific Values of Explosives, Calorific value is defined by Weissberger (Ref 3) as the heat evolved when the substance is exploded in the absence of oxygen except for what it contains itself . This quantity is practically the same as the heat evolved when the substance is exploded under normal operating conditions (such as in bore holes or in shells). Experimental techniques differ somewhat from chose employed in ordinary combustion calorimetry. The bombs employed in calorific value techniques are smaller in capacity and possess very thick walls to withstand high pressures. For example the bomb described in Ref 2 is of 124cc capacity. It was developed at Woolwich Arsenal and modified by Taylor et al. 

High-pressure differential scanning calorimetry (Handa, 1986d Le Parlouer et al., 2004 Palermo et al., 2005) Yes P, T Yes Hydrate phase vs. time Typically up to 5800 psi, 230 to 400 K 7 isS, heat capacities, heat of dissociation. Emulsion stability and hydrate agglomeration... 

In the CSM laboratory, Rueff et al. (1988) used a Perkin-Elmer differential scanning calorimeter (DSC-2), with sample containers modified for high pressure, to obtain methane hydrate heat capacity (245-259 K) and heat of dissociation (285 K), which were accurate to within 20%. Rueff (1985) was able to analyze his data to account for the portion of the sample that was ice, in an extension of work done earlier (Rueff and Sloan, 1985) to measure the thermal properties of hydrates in sediments. At Rice University, Lievois (1987) developed a twin-cell heat flux calorimeter and made AH measurements at 278.15 and 283.15 K to within 2.6%. More recently, at CSM a method was developed using the Setaram high pressure (heat-flux) micro-DSC VII (Gupta, 2007) to determine the heat capacity and heats of dissociation of methane hydrate at 277-283 K and at pressures of 5-20 MPa to within 2%. See Section 6.3.2 for gas hydrate heat capacity and heats of dissociation data. Figure 6.6 shows a schematic of the heat flux DSC system. In heat flux DSC, the heat flow necessary to achieve a zero temperature difference between the reference and sample cells is measured through the thermocouples linked to each of the cells. For more details on the principles of calorimetry the reader is referred to Hohne et al. (2003) and Brown (1998). 

Bou-Diab, L., Lerena, P. and Stoessel, F. (2000) A tool for process development. Safety investigations with high-pressure reaction calorimetry. Chemical Plants and Processing, 2, 90 1. 

Raemy, A. and Ottaway, M. (1991) The use of high pressure DTA, heat flow and adiabatic calorimetry to study exothermic reactions. Journal of Thermal Analysis, 37, 1965-71. 

Sharma, B. K., and Stipanovic, A. J. 2003. Development of a New Oxidation Stability Test Method for Lubricating Oils Using High-Pressure Differential Scanning Calorimetry. Thermochim. Acta, 402,1-18. 

Fig. 9.5. Specific molar volumes of the folded (Vf) and unfolded (Vu) states of Snase as derived from densitometric measurements [15] (crosses, diamonds), pressure perturbation calorimetry [16] (open square), and spectroscopic high-pressure unfolding experiments [14] (filled squares). Dashed lines correspond to extrapolations...

The energy expenditure of an animal or human may also be determined by the method of direct calorimetry. Direct calorimetry requires the use of an insulated room, chamber, or suit for the human or animal. The enclosure contains a water jacket. The water passes from one end of the jacket to the other, maintaining the room, chamber, or suit at a constant temperature. The temperature of the water leaving the jacket is used to calculate the energy expended by the subject. The principles behind the use of the chamber are identical to those behind the use of the bomb calorimeter. The major difference is that in bomb calorimetry combustion is catalyzed by a small spark. In addition, in the bomb calorimeter oxygen is present at a high pressure to facilitate combustion. With direct calorimetry, combustion is catalyzed by enzymes. This combustion proceeds more slowly than that catalyzed by a spark, and the temperature of the subject does not increase much over the normal resting body temperature with the various activities. 

Lyon (5) proposed that A H may be affected by vacancy concentration, which varies from 14 to 15% (5) in samples of stoichiometric B-TiO obtained at normal pressure. Samples with vacancy concentrations dow to 0% have been prepared (6) at high pressure. PVT data (6) allowed calculation (5) of values of A H for Ti0(B, 0% vacancies) + TiO(B, 14% vacancies). These values, if valid, suggest that A H should be quite different for vacancy-free B-TiO and significantly different even for the normal range of vacancy concentrations. Ideal ordered a-TiO, containing 1/6 or 16.7% vacancies, should involve additional changes in volume ( ) and AjH . In summary, the discrepancy in a H may arise from sample differences - phase, composition and vacancy concentration - or from bias in the reaction calorimetry. 

Ohtaka O, Yaman a T, Kume S, Ito E, Navrotsky A (1991) Stability of monoclinic and orthorhombic zirconia studies by high-pressure phase equilibria and calorimetry. J Am Ceram Soc 74 505-509... 

Figure 12.2 High-pressure liquid intrusion calorimetry setup for the determination of energies of wetting for nonwetting systems. (Adapted from [39].)...

Fluorine bomb calorimetry is a development from the early 1960s. Before that time, reliable enthalpy data concerning fluorides were very scarce, principally because fluorine gas is so very reactive. Fluorine bomb calorimetry was extended to high-pressure (up to 15 atm of fluorine) metal combustion bombs by Hubbard and co-workers [2] at the Argonne National Laboratory (ANL) in the United States in 1961. The technique has been developed over the past 30 years, and is now comparable in precision and accuracy to the other types of calorimetry. Enthalpies of formation have been determined from direct fluorination experiments. 

ASTM D 5885 Standard Test Method for Oxidative Induction Time of Polyolefin Geosynthetics by High-Pressure Differential Scanning Calorimetry Principally, this is the same test as the above and is performed using a DSC, except now with a high-pressure cell that can sustain a pressure of 5500 kPa. The test is designed for highly stabilized materials. It is applicable only to materials whose... 

Chandra, D., et al.. Vanadium Hydrides at Low and High Pressure, Final Report to Tritium Science and Engineering Group, 2006, Los Alamos National Laboratory. Luo, W.R, Clewley, J.D. and Flanagan, T.B., Thermodynamics and isotope effects of the vanadium-hydrogen system using differential heat conduction calorimetry. Journal of Chemical Physics, 1990, 93(9) p. 6710-6722. 

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