Hydrocarbons specific heats

For non-polar components like hydrocarbons, the results are very satisfactory for calculations of vapor pressure, density, enthalpy, and specific, heat and reasonably close for viscosity and conductivity provided that is greater than 0.10. 

Progressive chlorination of a hydrocarbon molecule yields a succession of Hquids and/or soHds of increasing nonflammability, density, and viscosity, as well as improved solubiUty for a large number of inorganic and organic materials. Other physical properties such as specific heat, dielectric constant, and water solubihty decrease with increasing chlorine content. 

For hydrocarbon vapors, values for P,/P, can be obtained from Figure 11, which is sufficiently accurate under all conditions for PR valve calculations. The ratio of specific heats, K, for a particular substance, varies with pressure and... 

The specific heat of natural gas and hydrocarbon liquids can be calculated using procedures described later in this text (see pp. 41 and 42). 

The specific heat of hydrocarbon vapors and liquids is given by Figures 2-13 and 2-14. 

Figure 2-14. Specific heats of hydrocarbon vapors. (From Holcomb and Brown, /no. Eng. Chem., 34, 595, 1942 reprinted from Process Heat Transfer, Kern, McGraw-Hill Co., 1950.)...

For gases with specific heat ratios of approximately 1.4, the critical pressure ratio is approximately 0.5. For hydrocarbon service, this means that if the back-pressure on the relief valve is greater than 50% of the set pressure, then the capacity of the valve will be reduced. In other words, if the pressure in the relief piping at the valve outlet is greater than half (he set pressure, then a larger relief valve will be required to handle the same amount of fluid. 

Gases and Vapors Hydrocarbons Reference Symbols i Chemical Formula Mol. Wt. 1r> 1/7 I a Mol. Wt. Critical Conditions Boiling Point (F) 14,7 Psia Specific Volume Cu ft/lb 14.7 Psia 81 60F (Z Facior Accounted For) Latent Heat of Vaporization (Btu/lb 14.7 Psia) Specific heat Constant Pressure (Cp 60F) Specific heat Constant Volume Specific heat ratio K = Cp/Cv... 

A hydrocarbon oil of density 950 kg/m3 and specific heat capacity 2.5 kJ/kg K is cooled in a heat exchanger from 363 to 313 K by water flowing countercurrently. The temperature of the water rises from 293 to 323 K. If the flowrate of the hydrocarbon is 0.56 kg/s, what is the required flowrate of water ... 

We can now estimate the order of magnitude of the acoustic growth rate expected for this mechanism. Consider a lean hydrocarbon-air flame. Si 0.3 m/s. The ratio of the specific heats of the mixture is C /C = 1.4. 

A gas well contains hydrocarbon gases with an average molecular weight of 24, which can be assumed to be an ideal gas with a specific heat ratio of 1.3. The pressure and temperature at the top of the well are 250 psig and 70°F, respectively. The gas is being produced at a slow rate, so conditions in the well can be considered to be isentropic. 

Cyclopentadiene in a hydrocarbon mixture is to be 75% dimerized in a three stage CSTR. Feed rate is 16000 kg/hr containing 16 wt% CPD which is equivalent to C0 = 1.74 gmol/liter. Specific heat of the mixture is 550 cal/kg-K, density is 0.8 kg/liter and heat of reaction is AHr = -9000 cal/... 

In deriving the constraints, it was assumed that all passes are identical and that the two sides are identical. In addition, it was assumed that the heat transfer coefficients for the sides are related to the heat transfer coefficients for the passes. Effects such as the heat of reaction were not considered separately, but were lumped into an effective specific heat for the hydrocarbons. 

A hydrocarbon mixture with molecular weight 44.23 is raised from 41°F and 20.1 psia to 100.5 psia at the rate of 2400 lb mol/hr. Its specific heat ratio is k = 1.135 and its inlet and outlet compressibilities are estimated as z, =0.97 and z2 = 0.93. A size of compressor will be selected from Table 7.6 and its expected performance will be calculated ... 

Specific heats are extremely important engineering quantities in refinery practice because they are used in all calculations on heating and cooling petroleum products. Many measurements have been made on various hydrocarbon... 

For thermodynamic calculation of equilibria useful in petroleum science, combustion data of extreme accuracy are required because the heats of formation of water and carbon dioxide are large in comparison with those in the hydrocarbons. Great accuracy is also required of the specific heat data for the calculation of free energy or entropy. Much care must be exercised in selecting values from the literature for these purposes, since many of those available were determined before the development of modem calorimetric techniques. 

In the older organic chemistry it was assumed that a free rotation was possible about a single C—C bond because, for example, there exist no isolatable isomers of 1,2 dichloroethane. Accurate measurements of the specific heat of ethane at low temperatures and likewise the difference between determinations and calculations of equilibria of hydrocarbons have, however, shown that there is no question of a free rotation rotation is indeed possible but there is a potential barrier of about 3 kcal/mole which has to be surmounted. The state of lowest energy is that in which the two methyl groups, or the methyl and the CH2 group, are alternate. In 1, 2 dichloroethane etc. there appear to be two positions of (relatively) minimum energy, the trans position and an oblique position which lies 1.2 kcal higher than the former. 

Until 1939, she continued her research on the specific heats and heats of crystallisation of a number of homologous series, including hydrocarbons, fatty acids, methyl and ethyl esters, and amides. The work was of importance in relation to the cause of the alternation in melting points of the homologous series. Her experimental work ceased at the beginning of the Second World War, when her duties as Librarian and Secretary took up all of her time. In addition, she was an ambulance driver during the air raids. She died on 17 December 1952. 

Values given for gases ai y to such substances as air, nitrogen, carbon dioxide, light hydrocarbon mixtures (no condensation), ttc. Because of die hi diermal cwductivides and specific heats of hydrogen and helhim, gas... 

---