INTRODUCTION Heat effects accompany changes in temperature@ pressure@ phase@ and chemical nature. Enthalpies@ heat capacities@ heat capacity ratios@ and entropies of the substances involved are required to predict the magnitude of these heat effects. These properties (particularly heat capacity) are also used frequently in correlations of other physical properties and design parameters such as thermal conductivity and the Prandtl number. Methods for predicting these important thermal properties are presented in this chapter for pure hydrocarbons and their mixtures@ both for defined and undefined composition. This chapter was prepared for use primarily with nonreacting systems. The enthalpy basis does not include heat of formation data@ so the enthalpies of products and reactants cannot be subtracted to give the heat of reaction. Further@ the figures and procedures are all designed to give thermal properties on a per-kilogram basis@ whereas a molar basis would be more convenient for reacting systems. The approach taken here is the most convenient for the thermal calculations that are common in the petroleum industry. The effect of temperature on the enthalpy@ heat capacity@ and entropy of pure hydrocarbons and their defined mixtures is determined from data for the pure substances in the ideal gas state. Extensive tabulations for hydrocarbons have been prepared in API Research Project 44 (2). It is impractical to reproduce all these data in this chapter@ so coverage is given only for approximately 130 of the most common hydrocarbons. Throughout this chapter@ procedures for both desk and digital computer calculations are presented in a parallel structure. The complete desk method is presented first@ followed by the corresponding computer method. No computer program listings are presented; only the pertinent equations are given. Both the desk and computer methods are based on the theorem of corresponding states. The methods are internally consistent for density and all the thermodynamic properties. In most cases@ values for tables and graphs used in the desk methods were generated from the corresponding computer method. Unfortunately@ neither is consistent with the vapor-liquid equilibrium predictions of Chap. 8. Both are comparable in accuracy when compared with the existing data.
API 998 VOLUME II-1976 history
1976API 998 VOLUME II-1976 Technical Data Book-Petroleum Refining Volume II Chapters 7-9 (METRIC; First Edition; Volume II)