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This work reports the results of an investigation on industrial requirements for thermodynamic and transport properties carried out by the Working Party on Thermodynamic and Transport properties () of the European Federation of Chemical Engineering, EFCE (). A carefully designed questionnaire was sent to a number of key technical people in companies in the oil and gas, chemicals, and pharmaceutical/biotechnology sectors. Twenty-eight companies have provided answers which formed the basis for the analysis presented here. A number of previous reviews, specifically addressed to or written by industrial colleagues, are discussed initially. This provides the context of the survey and material with which the results of the survey can be compared. The results of the survey have been divided into the themes: data, models, systems, properties, education, and collaboration. The main results are as follows. There is (still) an acute need for accurate, reliable, and thermodynamically consistent experimental data. Quality is more important than quantity. Similarly, there is a great need for reliable predictive, rather than correlative, models covering a wide range of compositions, temperatures, and pressures and capable of predicting primary (phase equilibrium) and secondary (enthalpy, heat capacity, etc.) properties. It is clear that the ideal of a single model covering all requirements is not achievable, but there is a consensus that this ideal should still provide the direction for future development. The use of new methods, such as SAFT, is increasing, but they are not yet in position to replace traditional methods such as cubic equations of state (especially in oil and gas industry) and the UNIFAC group contribution approach. A common problem with novel methods is lack of standardization, reference data, and correct and transparent implementations, especially in commercially available simulation programs. The survey indicates a great variety of systems where further work is required. For instance, for electrolyte systems better models are needed, capable of describing all types of phase behavior and mixtures with other types of components. There is also a lack of data and methods for larger complex molecules. Compared with the previous reviews, complex mixtures containing carbon dioxide associated with a wide range of applications, such as capture, transport, and storage are becoming interesting to a number of survey participants. Despite the academic success of molecular simulation techniques, the survey does not indicate great interest in it or its future development. Algorithms appear to be a neglected area, but improvements are still needed especially for multiphase reactive systems (simultaneous chemical and physical equilibrium). Education in thermodynamics is perceived as key, for the future application of thermodynamics in the industry. A number of suggestions for improvement were made at all three levels (undergraduate, postgraduate, and professional development) indicating that the education is correctly percei...

Smoluchowski's equation for rapid coagulation is used to describe the kinetics of gelation, in which the coagulation kernel Kij models the bonding mechanism. For different classes of kernels we derive criteria for the occurrence of gelation, and obtain critical exponents in the pre-and postgelation stage in terms of the model parameters; we calculate bounds on the time of gelation to, and give an exact postgelation solution for the model K,j = (/j)'~ (~0 > 1/2) and Kq = a i+j

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The cubic-plus-association (CPA) equation of state (EoS) is applied in this study to binary aqueous mixtures containing hydrocarbons. The CPA EoS combines the Soave−Redlich−Kwong (SRK) cubic equation of state for the physical part and perturbation theory for the chemical (association) part. Rigorous expressions for the contribution of the association term to the pressure and to the chemical potential, which do not include any derivatives of the mole fraction of molecules i not bonded at site A (X A i ), are presented. Three different association models for water have been considered depending on the number of hydrogen bonding sites per water molecule:  the two-, three-, and four-site models. Successful correlation of both vapor pressures and saturated liquid volumes is obtained with all three models. However, satisfactory correlation results of the mutual solubilities of water/aliphatic hydrocarbon systems are obtained only with the four-site model using a single interaction parameter (k ij ) in the attractive term of the EoS. A generalized expression of k ij as a function of the molecular weight of the members of the homologous series is presented, something that allows CPA to be used as a predictive tool. Very satisfactory prediction results are obtained, comparable to the correlation ones of the SAFT EoS for the water solubility in the hydrocarbon-rich phase and orders of magnitude better for the hydrocarbon solubility in the water-rich phase. Satisfactory predictions are also obtained for the vapor-phase compositions and the three-phase equilibrium pressures.

Abstract. The exact solution (size distribution ck(t) and moments M , ( t ) ) of Smoluchowski's coagulation equation (S-model) and of a modified equation (F-model) with a coagulation rate K,, = ij for i-and j-clusters is obtained for arbitrary Ck(0) in the sol ( t < I,) and gel ( I > [ , ) phases, where tc is the gel point. The behaviour of c k ( t ) and M,(t) is given for k -+CO, t -+ CO and t + I,. The critical exponents, critical amplitudes and scaling function that characterise the singularities near the non-equilibrium phase transition are calculated.For short-range c k ( 0 ) (i.e. all M ,

If the excess Gibbs free-energy function for re-component mixtures depends on composition only through a limited number, K, of linear functions (scalar products), then the set of two-phase equilibrium equations and the equations of the stability test can be reduced to a set of only K + 1 equations; the Newton-Raphson correction equations can be reduced from a system of re linear equations to one of size, K + 1, and the spinodal curve can be evaluated from the criterion of positive semidefiniteness for a (K + l)-dimensional quadratic form. Applications include examples ranging from mixtures of hydrocarbons with L non-hydrocarbons (K = 2L + 2) to polymer mixtures. In a number of special cases, the simplications have been exploited by other authors, among other things to save computer time and storage. The present work shows the mathematical structure behind these examples and generalizes these to a well-defined class of models.