Properties thermophysical

The thermophysical properties of a foam heat capacity and thermal conductivity, depend on the total liquid content and its distribution in the foam. The bubbles shape and distribution of liquid between borders, films and vertexes also affect thermal conductivity. By definition the bulk heat capacity CV (at p - const) equals 

The quantity of heat supplied to the foam to increase its temperature by At, assuming C = const, is 

From Eqs. (8.60) and (8.61) it is possible to derive the foam expansion ratio from the heat capacity of the foam and the heat capacities of its constituents, liquid and gas phases 

Foams from Triton-X-100 solutions (10 3 mol dm 3), containing NaCl (0.4 mol dm 3) were studied. The foam volume was 40 cm3. Foam expansion ratio was regulated by changing either the time for foam drying or the pressure Ap in the solution, contacting the porous plates. Conductometric measurements of foam expansion ratio were performed for comparison. 

Experimental results, relating the heat capacity and expansion ratio of a foam 

Knowledge of the values of these properties is essential in obtaining numerical results in the other two areas. Our objective here will be twofold  

evaluation of the thermodynamic - i.e. derived - properties internal energy, enthalpy, entropy, etc., from data on the measurable ones pressure, volume, temperature, and heat capacities and 

Starting with a combination of the first and second laws we will develop the necessary framework of equations that can be used, in combination with physical property data, in the determination of thermodynamic properties. Because the available in the typical case data cover a limited range of pressure and temperature, the obtained values are not the absolute ones, but relative to some arbitrarily chosen reference state. 

The entropy and enthalpy values in the Steam Tables, for example, have been developed using these equations, combined with extensive experimental pressure-volume-temperature PVT) and ideal gas heat capacity data. The given values, however, are relative to zero values for saturated water at 273.16 K. 

Estimation of Thermophysical Properties On the other hand, considering  

This completes our description of the Aspen H YSYS Petroleum Refining model. In subsequent sections, we discuss issues of thermophysical properties, fractionation and feed lumping. These issues are not specific to a simulation program and apply generally to any model of a reforming process. 

The requirements for thermophysical properties depend on the kinetic lumping chosen for the process. Typically, the reactor model requires only the heat capacity and molecular weight The fractionation section may require a correlation to predict JC-values or critical parameters when an equation of state is used. One approach is to use one set of lumps for the reactor model and another set for the fractionation. However, this approach may cause problems when recycling material back into the reactor and makes producing an integrated model difficult If possible, we suggest the use of uniform lumps across the reactor and fractionation models. 

If the reactor lumps resemble real measured products (e.g., A8), then it is sufficient to use the known properties of one of the compounds comprising the lump as the properties of the lump. The kinetic lumps in this work resemble real lumps, so we use known compound properties. If this information is not available, we can use Riazi s correlations [42] to estimate the relevant critical properties for 

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From the analytical results, it is possible to generate a model of the mixture consisting of an number of constituents that are either pure components or petroleum fractions, according to the schematic in Figure 4.1. The real or simulated results of the atmospheric TBP are an obligatory path between the experimental results and the generation of bases for calculation of thermodynamic and thermophysical properties for different cuts. 

Calculation of thermophysical properties of gases relies on the principle of corresponding states. Viscosity and conductivity are expressed as the sum of the ideal gas property and a function of the reduced density ... 

Riazi, M.R. (1979), "Prediction of thermophysical properties of petroleum fractions". Ph. D. Thesis, Dpt of Chem. Eng., The Pennsylvania State University, PA. 

This database provides thermophysical property data (phase equilibrium data, critical data, transport properties, surface tensions, electrolyte data) for about 21 000 pure compounds and 101 000 mixtures. DETHERM, with its 4.2 million data sets, is produced by Dechema, FIZ Chcmic (Berlin, Germany) and DDBST GmhH (Oldenburg. Germany). Definitions of the more than SOO properties available in the database can be found in NUMERIGUIDE (sec Section 5.18). 

Heatshield thickness and weight requirements are determined using a thermal prediction model based on measured thermophysical properties. The models typically include transient heat conduction, surface ablation, and charring in a heatshield having multiple sublayers such as bond, insulation, and substmcture. These models can then be employed for any specific heating environment to determine material thickness requirements and to identify the lightest heatshield materials. 

N. B. Vargafdk, Tables on the Thermophysical Properties of Eiquids and Gases,]ohxi Wiley Sons, Inc., New York, 1975. 

Food processing operations can be optimi2ed according to the principles used for other chemical processes if the composition, thermophysical properties, and stmcture of the food is known. However, the complex chemical composition and physical stmctures of most foods can make process optimi2ation difficult. Moreover, the quaUty of a processed product may depend more on consumer sensory responses than on measurable chemical or physical attributes. 

Data Book, Vol. 2, Thermophysical Properties Research Center, Purdue University, W. Lafayette, Ind., 1964, Chapt. 1. 

R. D. McCarty and R. B. Stuart, in S. Gratch, ed.,Mdvances In Thermophysical Properties atTxtreme Temperatures and Pressures, American Society of Mechanical Engineers, New York, 1965, pp. 84—97. 

R. D. McCarty, Hydrogen Technological Survey—Thermophysical Properties, NASA SP-3089, U.S. Government Printing Office, Washington, D.C., 1975, pp. 518-519. 

Thermophysical Properties of Matter, Vol. 4, Thermal Expansion, Plenum Publishing Corp., New York, 1970. 

An area that has used chemical stmctures for predictive purposes quite successfully is the estimation of thermophysical properties of compounds. There has been an extensive compilation of estimation methods (81), and prediction of physical properties has been automated using these techniques (82). More recendy, the use of group contribution techniques to design new molecules that have specified properties has been described (83). This approach to compound design is being used to develop replacement materials for chloroduorocarbons. 

Specific Heat and Other Thermophysical Properties of Water Substance. 2-313... 

Thermophysical Properties of Selected Nonmetallic Solid Substances. 

TABLE 2-244 Thermophysical Properties of Saturated Carbon Tetrachloride... 

TABLE 2-289 Thermophysical Properties of Nitrogen (R728) at Atmospheric Pressure... 

TABLE 2-330 Thermophysical Properties of Compressed Gaseous Refrigerant 134a... 

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