Carbon dioxide thermodynamic diagrams

The carbon dioxide phase diagram (see Figure 7.8) has three phases gaseous, liquid, and solid. The triple point (pressure 5.1 atm, temperature -56.7 °C) is defined as the temperature and pressure where three phases (gas, liquid, and solid) can exist simultaneously in thermodynamic equilibrium. 

Some values of physical properties of CO2 appear in Table 1. An excellent pressure—enthalpy diagram (a large Mohier diagram) over 260 to 773 K and 70—20,000 kPa (10—2,900 psi) is available (1). The thermodynamic properties of saturated carbon dioxide vapor and Hquid from 178 to the critical point,... 

Available data on the thermodynamic and transport properties of carbon dioxide have been reviewed and tables compiled giving specific volume, enthalpy, and entropy values for carbon dioxide at temperatures from 255 K to 1088 K and at pressures from atmospheric to 27,600 kPa (4,000 psia). Diagrams of compressibiHty factor, specific heat at constant pressure, specific heat at constant volume, specific heat ratio, velocity of sound in carbon dioxide, viscosity, and thermal conductivity have also been prepared (5). 

If we compare the experimentally established phase diagrams, for the substances iodine (I2) and carbon dioxide (CO2), with the form we have predicted by logical use and development of the thermodynamics discussed so far we see that our conjectures... 

On the basis of thermodynamic constants obtained for hydroxide compounds of iron with different aging time and also of experimental data, the physicochemical character of the diagenetic transformations of iron sediments of various compositions (oxide, silicate, carbonate, sulfide) can be traced. The results obtained are represented graphically in the form of stability diagrams of iron compounds as a function of variations in the main parameters governing the physicochemical character of the environment of diagenesis—pH, Eh, activity of iron and dissolved forms of sulfur and carbon dioxide. 

The thermodynamic data of carbon dioxide and other fluids are compiled in International Thermodynamic Tables of the Fluid State published by the International Union of Pure and Applied Chemistry (lUPAC) [28] in the form of tables and equations of state. Thermodynamic data and equations of state are also provided by Journal of Physical and Chemical Reference Data for argon [29], nitrogen [29], oxygen [29], carbon dioxide [30], methane [31], ethane [31], propane [31], butane [31, 32], isobutene [31, 32], ethylene [29] and methanol [33]. Fluid Phase Equilibria , Journal of Supercritical Fluids and Chemical Engineering Science are also good sources of thermodynamic and thermochemical data of SCFs. Data for phase diagrams. 

Din was the editor of a series of books designed to provide reliable thermodynamic data for industrially important gases. Temperature-entropy diagrams were chosen as the most generally useful graphical presentations and these are supplemented by tables of entropy, enthalpy, volume, heat capacity at constant pressure and at constant volume, and Joule-Thomson coefficients. Unfortunately, there is no consistency in the choice of units, although the thermochemical calorie is employed. The report on each substance (i.e. ammonia, carbon dioxide, carbon monoxide, air, argon, acetylene, ethylene, and propane) consists of a brief introduction, a survey of experimental data, a description of methods used for the thermodynamic calculations, and a set of tables. 

Substances considered in a compilation of the thermodynamic properties of refrigerants include hydrogen, parahydrogen, helium, neon, nitrogen, air, oxygen, argon, carbon dioxide, hydrocarbons (e.g. methane, ethane, propane, butane, isobutane, ethylene, and propene), and fluoro-and fluoro-chloro-hydrocarbons. Properties listed include those for the liquid and saturated vapour, superheated vapour, and unsaturated vapour. In addition, pressure-enthalpy, and in some instances pressure-entropy, diagrams are provided. 

Figure 1.7 Pressure/composition diagrams for carbon dioxide/squalane system. (Data of Liphard and Schneider (1975) J. Chem. Thermodynam. 1 805.)...

Figure A3.2 Thermodynamics diagrams for carbon dioxide (a) pressure—temperature and...

The diagram for carbon in Fig. 83 displays a very small domain of stability. It is thermodynamically possible for carbons to be easily oxidized to carbon dioxide, carbonic acid, and carbonates. Reduction of carbon may lead to the formation of methane, methyl alcohol and other organic substances. However, the energetically possible reactions are strongly irreversible [2] and do not occur under normal conditions of pressure and temperature. Schmidt [24] reported a corrosive destruction of carbon electrodes when a critical potential was exceeded during the reduction of O2. The carbon electrodes were not impregnated with metallic electrocatalysts. The critical potential depended upon the extent to which an oxygen layer was present (compare section 5 in chapter VIII). 

GCMC simulations have also been used to explore the favorable thermodynamic conditions for exchanging carbon dioxide and methane in the S-I clathrate hydrates. Of practical interest is the need to find a feasible thermodynamic pathway in the phase diagram consisting of methane, carbon... 

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