One-dimensional steady-state thermal model for rotary kilns used in the manufacture of cement

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Exact on-event expressions for discrete potential systems

The properties of systems composed of atoms interacting though discrete potentials are dictated by a series of events which occur between pairs of atoms. There are only four basic event types for pairwise discrete potentials and the square-well/shoulder systems studied here exhibit them all. Closed analytical expressions are derived for the on-event kinetic energy distribution functions for an atom, which are distinct from the Maxwell-Boltzmann distribution function. Exact expressions are derived that directly relate the pressure and temperature of equilibrium discrete potential systems to the rates of each type of event. The pressure can be determined from knowledge of only the rate of core and bounce events. The temperature is given by the ratio of the number of bounce events to the number of disassociation/association events. All these expressions are validated with event-driven molecular dynamics simulations and agree with the data within the statistical precision of the simulations

Carbon footprint of calcium sulfoaluminate clinker production

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Stable algorithm for event detection in event-driven particle dynamics : logical states

Acknowledgments: The authors gratefully acknowledge the support of the German Research Foundation (DFG) through the Cluster of Excellence ‘Engineering of Advanced Materials’ at the University of Erlangen-Nuremberg and through Grant Po 472/25.Peer reviewedPostprin

Using the Zeno line to assess and refine molecular models

The Zeno line is the locus of points on the temperature-density plane where the compressibility factor of the fluid is equal to one. It has been observed to be straight for a broad variety of real fluids, although the underlying reasons for this are still unclear. In this work, a detailed study of the Zeno line and its relation to the vapor-liquid coexistence curve is performed for two simple model pair-potential fluids: attractive square-well fluids with varying well-widths λ, and Mie n-6 fluids with different repulsive exponents n. Interestingly, the Zeno lines of these fluids are curved, regardless of the value of λ or n. We find that for square-well fluids, λ ≈ 1:8 presents a Zeno line which is the most linear over the largest temperature range. For Mie n-6 fluids, we find that the straightest Zeno line occurs for n between 8 and 10. Additionally, the square-well and Mie fluids with the straightest Zeno line showed the closest quantitative agreement with the vapor-liquid coexistence curve for experimental fluids that follow the principle of corresponding states (e.g., argon, xenon, krypton, methane, nitrogen, and oxygen). These results suggest that the Zeno line can provide a useful additional feature, in complement to other properties such as the phase envelope, to evaluate molecular models

Tethered-particle model : the calculation of free energies for hard-sphere systems

Two methods for computing the entropy of hard-sphere systems using a spherical tether model are explored, which allow the efficient use of event-driven molecular-dynamics simulations. An intuitive derivation is given, which relates the rate of particle collisions, either between two particles or between a particle and its respective tether, to an associated hypersurface area, which bounds the system's accessible configurational phase space. Integrating the particle-particle collision rates with respect to the sphere diameter (or, equivalently, density) or the particle-tether collision rates with respect to the tether length then directly determines the volume of accessible phase space and, therefore, the system entropy. The approach is general and can be used for any system composed of particles interacting with discrete potentials in fluid, solid, or glassy states. The entropies calculated for the liquid and crystalline hard-sphere states using these methods are found to agree closely with the current best estimates in the literature, demonstrating the accuracy of the approach

Thermodynamic and dynamical properties of the hard sphere system revisited by molecular dynamics simulation

Acknowledgements Some of the MD calculations were performed at the Poznan Supercomputing and Networking Center (PCSS). DMH would like to thank Dr. T. Crane (Department of Physics, Royal Holloway, University of London, UK) for helpful software support.Peer reviewedPostprin

From Atoms to Colloids: Does the Frenkel Line Exist in Discontinuous Potentials?

The Frenkel line has been proposed as a crossover in the fluid region of phase diagrams between a "non-rigid" and a "rigid" fluid. It is generally described as a crossover in the dynamical properties of a material, and as such has been described theoretically using a very different set of markers from those with which is it investigated experimentally. In this study, we have performed extensive calculations using two simple yet fundamentally different model systems: hard spheres and square well potentials. The former has only hardcore repulsion, while the latter also includes a simple model of attraction. We computed and analysed a series of physical properties used previously in simulations and experimental measurements, and discuss critically their correlations and validity as to being able to uniquely and coherently locate the Frenkel in discontinuous potentials

Production of belite calcium sulfoaluminate cement using sulfur as a fuel and as a source of clinker sulfur trioxide : pilot kiln trial

The authors gratefully acknowledge the financial support provided by the Gulf Organization for Research and Development (GORD), Qatar, through research grant number ENG016RGG11757. The authors would also like to acknowledge Thomas Matschei and Guanshu Li for the stimulating and fruitful discussions concerning the development of this work. The continuous support prior to, during and after the pilot kiln trial from Vadym Kuznietsov and the entire team at IBU-tec is also greatly appreciated.Peer reviewedPublisher PD