Publications
87 results found
Kirmse CJW, Oyewunmi, Taleb A, et al., 2016, A two-phase single-reciprocating-piston heat conversion engine: Non-linear dynamic modelling, Applied Energy, Vol: 186, Pages: 359-375, ISSN: 0306-2619
A non-linear dynamic framework is presented for the modelling of a novel two-phase heat engine termed ‘Up-THERM’, which features a single solid moving-part (piston). When applied across the device, a constant temperature difference between an external (low- to medium-grade) heat source and an external heat sink is converted into sustained and persistent oscillations of pressure and volumetric fluid displacement. These oscillations are transformed in a load arrangement into a unidirectional flow from which power is extracted by a hydraulic motor. The Up-THERM engine is modelled using a system of first-order differential equations that describe the dominant thermal/fluid processes in each component of the device. For certain components where the deviations from a linear approximation are non-negligible (gas spring in the displacer cylinder, check valves and piston valve, and heat exchangers), a non-linear description is employed. A comparison between the linear and non-linear descriptions of the gas spring at the top of the displacer cylinder reveals that the non-linear description results in more realistic predictions of the oscillation frequency compared to experimental data from a similar device. Furthermore, the shape of the temperature profile over the heat-exchanger surfaces is modelled as following a hyperbolic tangent function, based on findings from an experimental investigation. Following the validation of these important device components, a parametric study is performed on the Up-THERM engine model with the aforementioned non-linear component descriptions, aimed at investigating the effects of important geometric parameters and of the heat-source temperature on key performance indicators, namely the oscillation frequency, power output and exergy efficiency of the engine. The results indicate that the geometric design of the displacer cylinder, including the height of the gas spring at the top of the cylinder, and the heat-source temperature hav
Kirmse CJW, Oyewunmi OA, Haslam AJ, et al., 2016, Comparison of a novel organic-fluid thermofluidic heat converter and an organic Rankine cycle heat engine, Energies, Vol: 9, ISSN: 1996-1073
The Up-THERM heat converter is an unsteady, two-phase thermofluidic oscillator that employs an organic working fluid, which is currently being considered as a prime-mover in small- to medium-scale combined heat and power (CHP) applications. In this paper, the Up-THERM heat converter is compared to a basic (sub-critical, non-regenerative) organic Rankine cycle (ORC) heat engine with respect to their power outputs, thermal efficiencies and exergy efficiencies, as well as their capital and specific costs. The study focuses on a pre-specified Up-THERM design in a selected application, a heat-source temperature range from 210 °C to 500 °C and five different working fluids (three n-alkanes and two refrigerants). A modeling methodology is developed that allows the above thermo-economic performance indicators to be estimated for the two power-generation systems. For the chosen applications, the power output of the ORC engine is generally higher than that of the Up-THERM heat converter. However, the capital costs of the Up-THERM heat converter are lower than those of the ORC engine. Although the specific costs (£/kW) of the ORC engine are lower than those of the Up-THERM converter at low heat-source temperatures, the two systems become progressively comparable at higher temperatures, with the Up-THERM heat converter attaining a considerably lower specific cost at the highest heat-source temperatures considered.
Oyewunmi OA, Kirmse CJW, Haslam AJ, et al., 2016, Working-fluid selection and performance investigation of a two-phase single-reciprocating-piston heat-conversion engine, Applied Energy, Vol: 186, Pages: 376-395, ISSN: 0306-2619
We employ a validated first-order lumped dynamic model of the Up-THERM converter, a two-phase unsteadyheat-engine that belongs to a class of innovative devices known as thermofluidic oscillators, which containfewer moving parts than conventional engines and represent an attractive alternative for remote or off-gridpower generation as well as waste-heat recovery. We investigate the performance the Up-THERM withrespect to working-fluid selection for its prospective applications. An examination of relevant working-fluidthermodynamic properties reveals that the saturation pressure and vapour-phase density of the fluid play importantroles in determining the performance of the Up-THERM – the device delivers a higher power outputat high saturation pressures and has higher exergy efficiencies at low vapour-phase densities. Furthermore,working fluids with low critical temperatures, high critical pressures and exhibiting high values of reducedpressures and temperatures result in designs with high power outputs. For a nominal Up-THERM designcorresponding to a target application with a heat-source temperature of 360 ◦C, water is compared withforty-five other pure working fluids. When maximizing the power output, R113 is identified as the optimalfluid, followed by i-hexane. Fluids such as siloxanes and heavier hydrocarbons are found to maximize theexergy and thermal efficiencies. The ability of the Up-THERM to convert heat over a range of heat-sourcetemperatures is also investigated, and it is found that the device can deliver in excess of 10 kW when utilizingthermal energy at temperatures above 200 ◦C. Of all the working fluids considered here, ammonia, R245ca,R32, propene and butane feature prominently as optimal and versatile fluids delivering high power over awide range of heat-source temperatures.
Kirmse CJW, Oyewunmi OA, Haslam AJ, et al., 2016, A thermo-economic assessment and comparison of the Up-THERM heat converter and an organic Rankine cycle engine, Heat Powered Cycles Conference 2016
In this paper we present a thermodynamic and economic comparison of a recently proposed two-phasethermofluidic oscillator known as the Up-THERM heat converter and the more established organic Rankine cycle(ORC) engine, when converting heat at temperatures below 150 °C using the refrigerant R-227ea as the workingfluid. The Up-THERM heat converter is being considered as a possible prime mover for small- to medium-scalecombined heat and power (CHP) applications. Using suitable thermodynamic models of both systems, it is foundthat the power output and thermal efficiencies of a pre-specified Up-THERM design are generally lower thanthose of an equivalent ORC engine. The Up-THERM, however, also demonstrates higher exergy efficiencies andis associated with lower capital costs, as expected owing to its simple construction and use of fewer and morebasic components. Interestingly, the specific costs (per rated kW) of the ORC engine are lower than those of theUp-THERM converter at lower heat source temperatures, specifically below 130 °C, whereas the Up-THERMbecomes a more cost effective alternative (in terms of the specific cost) to the ORC engine at higher temperatures.
Kirmse CJW, Oyewunmi OA, Haslam A, et al., 2016, A THERMO-ECONOMIC COMPARISON OF THE UP-THERM HEAT CONVERTER AND AN ORGANIC RANKINE CYCLE HEAT ENGINE, 12th International Conference on Heat Transfer, Fluid Mechanics and Thermodynamics
In this paper we compare a recently proposed two-phase thermofluidicoscillator device termed ‘Up-THERM’ to a basic(sub-critical, non-regenerative) equivalent organic Rankine cycle(ORC) engine. In the Up-THERM heat converter, a constanttemperature difference imposed by an external heat source andsink leads to periodic evaporation and condensation of the workingfluid, which gives rise to sustained oscillations of pressureand volumetric displacement. These oscillations are convertedin a load arrangement into a unidirectional flow, which passesthrough a hydraulic motor that extracts useful work from the device.A pre-specified Up-THERM design is being considered in aselected application with two n-alkanes, n-hexane and n-heptane,as potential working fluids. One aim of this work is to evaluatethe potential of this proposed design. The thermodynamic comparisonshows that the ORC engine outperforms the Up-THERMheat converter in terms of power output and thermal efficiency,as expected. An economic comparison, however, reveals that thecapital costs of the Up-THERM are lower than those of the ORCengine. Nevertheless, the specific costs (per unit power) favourthe ORC engine due to its higher power output. Some aspects ofthe proposed Up-THERM design are identified for improvement
Brechtelsbauer C, Haslam A, Shah U, et al., 2016, Measuring vapour pressure with an isoteniscope - a hands-on introduction to thermodynamic concepts, Journal of Chemical Education, Vol: 93, Pages: 920-926, ISSN: 1938-1328
Characterization of the vapor pressure of a volatile liquid or azeotropic mixture, and its fluid phase diagram, can be achieved with an isoteniscope and an industrial grade digital pressure sensor using the experimental method reported in this study. We describe vapor-pressure measurements of acetone and n-hexane and their azeotrope, and how the data can be used to calculate thermodynamic properties of the test liquids, such as the molar heat of vaporization. This hands-on experience allows students to appreciate important thermodynamic concepts such as phase equilibrium, preparing them for more advanced studies of the subject.
Chow YTF, Eriksen DK, Galindo A, et al., 2016, Interfacial tensions of systems comprising water, carbon dioxide and diluent gases at high pressures: experimental measurements and modelling with SAFT-VR Mie and square-gradient theory, Fluid Phase Equilibria, Vol: 407, Pages: 159-176, ISSN: 0378-3812
Experimental interfacial tensions of the systems (H<inf>2</inf>O+CO<inf>2</inf>), (H<inf>2</inf>O+N<inf>2</inf>), (H<inf>2</inf>O+Ar), (H<inf>2</inf>O+CO<inf>2</inf> +N<inf>2</inf>) and (H<inf>2</inf>O+CO<inf>2</inf> +Ar) are compared with calculations based on the statistical associating fluid theory for variable range potentials of the Mie form (SAFT-VR Mie) in combination with the square-gradient theory (SGT). Comparisons are made at temperatures from (298 to 473)K and at pressures up to 60MPa. Experimental data for the systems (H<inf>2</inf>O+CO<inf>2</inf>), (H<inf>2</inf>O+N<inf>2</inf>) and (H<inf>2</inf>O+CO<inf>2</inf> +N<inf>2</inf>) are taken from the literature. For the (H<inf>2</inf>O+Ar) and (H<inf>2</inf>O+CO<inf>2</inf> +Ar) systems, we report new experimental interfacial-tension data at temperatures of (298.15-473.15)K and pressures from (2 to 50)MPa, measured by the pendant-drop method. The expanded uncertainties at 95% confidence are 0.05K for temperature, 70kPa for pressure, 0.016× γ for interfacial tension in the binary (Ar+H<inf>2</inf>O) system and 0.018× γ for interfacial tension in the ternary (CO<inf>2</inf> +Ar+H<inf>2</inf>O) system.The parameters in the SAFT-VR Mie equation of state are estimated entirely from phase-equilibrium data for the pure components and binary mixtures. For pure water, the SGT influence parameter is determined from vapour-liquid surface-tension data, as is common practice. Since the other components are supercritical over most or the entire temperature range under consideration, their pure-component influence parameters are regressed by comparison with the binary interfacial-tension data. A geometric-mean combining rule
Oyewunmi OA, Taleb A, Haslam A, et al., 2015, On the use of SAFT-VR Mie for assessing large-glide fluorocarbon working-fluid mixtures in organic rankine cycles, Applied Energy, Vol: 163, Pages: 263-282, ISSN: 1872-9118
By employing the SAFT-VR Mie equation of state, molecular-based models are developed from which the thermodynamic properties of pure (i.e., single-component) organic fluids and their mixtures are calculated. This approach can enable the selection of optimal working fluids in organic Rankine cycle (ORC) applications, even in cases for which experimental data relating to mixture properties are not available. After developing models for perfluoroalkane (n-C4F10 + n-C10F22) mixtures, and validating these against available experimental data, SAFT-VR Mie is shown to predict accurately both the single-phase and saturation properties of these fluids. In particular, second-derivative properties (e.g., specific heat capacities), which are less reliably calculated by cubic equations of state (EoS), are accurately described using SAFT-VR Mie, thereby enabling an accurate prediction of important working-fluid properties such as the specific entropy. The property data are then used in thermodynamic cycle analyses for the evaluation of ORC performance and cost. The approach is applied to a specific case study in which a sub-critical, non-regenerative ORC system recovers and converts waste-heat from a refinery flue-gas stream with fixed, predefined conditions. Results are compared with those obtained when employing analogue alkane mixtures (n-C4H10 + n-C10H22) for which sufficient thermodynamic property data exist. When unlimited quantities of cooling water are utilized, pure perfluorobutane (and pure butane) cycles exhibit higher power outputs and higher thermal efficiencies compared to mixtures with perfluorodecane (or decane), respectively. The effect of the composition of a working-fluid mixture in the aforementioned performance indicators is non-trivial. Only at low evaporator pressures (< 10 bar) do the investigated mixtures perform better than the pure fluids. A basic cost analysis reveals that systems with pure perfluorobutane (and butane) fluids are associated with rela
Jover J, Galindo A, Jackson G, et al., 2015, Fluid-fluid coexistence in an athermal colloid-polymer mixture: thermodynamic perturbation theory and continuum molecular-dynamics simulation, MOLECULAR PHYSICS, Vol: 113, Pages: 2608-2628, ISSN: 0026-8976
Jover J, Galindo A, Jackson G, et al., 2015, Fluid-fluid coexistence in an athermal colloid-polymer mixture: thermodynamic perturbation theory and continuum molecular-dynamics simulation (vol 113, pg 2608, 2015), MOLECULAR PHYSICS, Vol: 113, ISSN: 0026-8976
Kirmse C, Oyewunmi OA, Haslam AJ, et al., 2015, A two-phase single-reciprocating-piston heat conversion engine, 11th International Conference on Heat Transfer, Fluid Mechanics and Thermodynamics (HEFAT2015)
This paper considers an energy-conversion heat-engineconcept termed ‘Up-THERM’. This machine is capable ofconverting low- to medium-grade heat to useful positivedisplacementwork through the periodic evaporation andcondensation of a working fluid in an enclosed space. Thesealternating phase-change processes drive sustained oscillations ofthermodynamic properties (pressure, temperature, volume) as theworking fluid undergoes an unsteady thermodynamic heatenginecycle. The resulting oscillatory flow of the working fluidis converted into a unidirectional flow in a hydraulic loadarrangement where power can be extracted from the machine.The engine is described with lumped dynamic modelsconstructed using electrical analogies founded on previouslydeveloped thermoacoustic and thermofluidic principles, whichare extended here to include a description of the phase-changeheat-transfer processes. For some sub-components of the engine,such as the gas spring, valves and the temperature profile in theheat exchangers, deviations from the linear theory are nonnegligible.These are modelled using non-linear descriptions. Inparticular, the results of linear and non-linear descriptions of thegas spring are compared using three important performanceindicators — efficiency, power output and frequency.The non-linear description of the gas spring results in morerealisticpredictions of the oscillation frequency compared todirect measurements on an experimental prototype of a similarengine. Owing to its mode of operation and lack of moving parts,the Up-THERM engine does offer a much simpler and morecost-efficient solution than alternative engines for heat recoveryand solar applications. The results from this work suggest thatthis technology can be a competitive alternative in terms of costper unit power in low-power, small-scale applications, especiallyin remote, off-grid settings, for example in developing countrieswhere minimising upfront costs is crucial.
Oyewunmi OA, Haslam AJ, Markides CN, 2015, Towards the computer-aided molecular design of organic rankine cycle systems with advanced fluid theories, SusTEM 2015 International Conference, Pages: 180-189
Organic Rankine cycle (ORC) power-generation systems are increasingly being deployed for heat recovery and conversion from geothermal reservoirs and in several industrial settings. Using a case study of an exhaust flue-gas stream, an ORC power output in excess of 20 MW is predicted at thermal efficiencies ranging between 5% and 15%. The considerable influence on cycle performance of the choice of the working fluid is illustrated with alkane and perfluoroalkane systems modelled using the SAFT-VR Mie equation of state (EoS); in general, the more-volatile pure components (n-butane or n-perfluorobutane) are preferred although some mixtures perform better at restricted cycle conditions.The development of computer-aided molecular design (CAMD) platforms for ORC systems requires both cycle and working-fluid models to be incorporated into a single framework, for the purposes of whole-system design and optimization. Using pure alkanes and their mixtures as a case study, we test the suitability of the recent group-contribution SAFT- Mie EoS method for describing the thermodynamic properties of working fluids relevant to the analysis of ORC systems. The theory is shown to predict accurately the relevant properties of these fluids, thereby suggesting that this SAFT-based CAMD approach is a promising approach towards working-fluid design of ORC power systems.
Dufal S, Lafitte T, Galindo A, et al., 2015, Developing intermolecular-potential models for use with the SAFT-VRMie equation of state, AIChE Journal, Vol: 61, Pages: 2891-2912, ISSN: 0001-1541
A major advance in the statistical associating fluid theory (SAFT) for potentials of variable range (SAFT-VR) has recently been made with the incorporation of the Mie (generalized Lennard–Jones [LJ]) interaction between the segments comprising the molecules in the fluid (Lafitte et al. J. Chem. Phys. 2013;139:154504). The Mie potential offers greater versatility in allowing one to describe the softness/hardness of the repulsive interactions and the range of the attractions, which govern fine details of the fluid-phase equilibria and thermodynamic derivative properties of the system. In our current work, the SAFT-VR Mie equation of state is employed to develop models for a number of prototypical fluids, including some of direct relevance to the oil and gas industry: methane, carbon dioxide and other light gases, alkanes, alkyl benzenes, and perfluorinated compounds. A complication with the use of more-generic force fields such as the Mie potential is the additional number of parameters that have to be considered to specify the interactions between the model molecules, leading to a degree of degeneracy in the parameter space. A formal methodology to isolate intermolecular-potential models and assess the adequacy of the description of the thermodynamic properties in terms of the complex parameter space is developed. Fluid-phase equilibrium properties (the vapor pressure and saturated-liquid density) are chosen as the target properties in the refinement of the force fields; the predictive capability for other properties such as the enthalpy of vaporization, single-phase density, speed of sound, isobaric heat capacity, and Joule–Thomson coefficient, is appraised. It is found that an overall improvement of the representations of the thermophysical properties of the fluids is obtained using the more-generic Mie form of interaction; in all but the simplest of fluids, one finds that the LJ interaction is not the most appropriate.
Dufal S, Lafitte T, Haslam AJ, et al., 2015, The A in SAFT: developing the contribution of association to the Helmholtz free energy within a Wertheim TPT1 treatment of generic Mie fluids, Molecular Physics, Vol: 113, Pages: 948-984, ISSN: 1362-3028
An accurate representation of molecular association is a vital ingredient of advanced equations of state (EOSs), providing a description of thermodynamic properties of complex fluids where hydrogen bonding plays an important role. The combination of the first-order thermodynamic perturbation theory (TPT1) of Wertheim for associating systems with an accurate description of the structural and thermodynamic properties of the monomer fluid forms the basis of the statistical associating fluid theory (SAFT) family of EOSs. The contribution of association to the free energy in SAFT and related EOSs is very sensitive to the nature of intermolecular potential used to describe the monomers and, crucially, to the accuracy of the representation of the thermodynamic and structural properties. Here we develop an accurate description of the association contribution for use within the recently developed SAFT-VR Mie framework for chain molecules formed from segments interacting through a Mie potential [T. Lafitte, A. Apostolakou, C. Avendaño, A, Galindo, C. S. Adjiman, E. A. Müller, and G. Jackson, J. Chem. Phys. 139, 154504 (2013)]. As the Mie interaction represents a soft-core potential model, a method similar to that adopted for the Lennard-Jones potential [E. A. Müller and K. E. Gubbins, Ind. Eng. Chem. Res. 34, 3662 (1995)] is employed to describe the association contribution to the Helmholtz free energy. The radial distribution function (RDF) of the Mie fluid (which is required for the evaluation of the integral at the heart of the association term) is determined for a broad range of thermodynamic conditions (temperatures and densities) using the reference hyper-netted chain (RHNC) integral-equation theory. The numerical data for the association kernel of Mie fluids with different association geometries are then correlated for a range of thermodynamic states to obtain a general expression for the association contribution which can be applied for varying values
Kirmse C, Taleb AJ, Oyewunmi OA, et al., 2015, Performance comparison of a novel thermofluidic organic-fluid heat converter and an organic rankine cycle heat engine, 3rd International Seminar on ORC Power Systems (ASME ORC 2015)
The Up-THERM engine is a novel two-phase heat engine with a single moving part–a vertical solidpiston–that relies on the phase change of a suitable working fluid to produce a reciprocating displacementand sustained thermodynamic oscillations of pressure and flow rate that can be converted to useful work.A model of the Up-THERM engine is developed via lumped dynamic descriptions of the various enginesub-components and electrical analogies founded on previously developed thermoacoustic principles.These are extended here to include a description of phase change and non-linear descriptions of selectedprocesses. The predicted first and second law efficiencies and the power output of a particular Up-THERM engine design aimed for operation in a specified CHP application with heat source and sinktemperatures of 360 ○C and 10 ○C, are compared theoretically to those of equivalent sub-critical, nonregenerativeorganic Rankine cycle (ORC) engines. Five alkanes (from n-pentane to n-nonane) are beingconsidered as possible working fluids for the aforementioned Up-THERM application, and these arealso used for the accompanying ORC thermodynamic analyses. Owing to its mode of operation, lackof moving parts and dynamic seals, the Up-THERM engine promises a simpler and more cost-effectivesolution than an ORC engine, although the Up-THERM is expected to be less efficient than its ORCcounterpart. These expectations are confirmed in the present work, with the Up-THERM engine showinglower efficiencies and power outputs than equivalent ORC engines, but which actually approach ORCperformance at low temperatures. Therefore, it is suggested that the Up-THERM can be a competitivealternative in terms of cost per unit power in low-power/temperature applications, especially in remote,off-grid settings, such as in developing countries where minimising upfront costs is crucial.
Jover JF, Mueller EA, Haslam AJ, et al., 2015, Aspects of Asphaltene Aggregation Obtained from Coarse-Grained Molecular Modeling, ENERGY & FUELS, Vol: 29, Pages: 556-566, ISSN: 0887-0624
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- Citations: 21
Coletti F, Crittenden BD, Haslam AJ, et al., 2015, Modeling of Fouling from Molecular to Plant Scale, CRUDE OIL FOULING: DEPOSIT CHARACTERIZATION, MEASUREMENTS, AND MODELING, Editors: Coletti, Hewitt, Publisher: GULF PROFESSIONAL PUBL, Pages: 179-320, ISBN: 978-0-12-801256-7
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- Citations: 7
Jimenez Serratos MG, Haslam AJ, Jackson G, et al., 2014, 5. Modeling of Fouling from Molecular to Plant Scale5.2 Thermodynamic and Molecular Modeling, Crude Oil Fouling Deposit Characterization, Measurements, and Modeling, Editors: Coletti, Hewitt, Publisher: Gulf Professional Publishing, ISBN: 9780128013595
With production from unconventional rigs continuing to escalate and refineries grappling with the challenges of shale and heavier oil feedstocks, petroleum engineers and refinery managers must ensure that equipment used with today’s crude ...
Jimenez Serratos MG, Haslam AJ, Jackson G, et al., 2014, 5. Modeling of Fouling from Molecular to Plant Scale5.2 Thermodynamic and Molecular Modeling, Crude Oil Fouling Deposit Characterization, Measurements, and Modeling, Editors: coletti, Hewitt, Publisher: Gulf Professional Publishing, ISBN: 9780128013595
With production from unconventional rigs continuing to escalate and refineries grappling with the challenges of shale and heavier oil feedstocks, petroleum engineers and refinery managers must ensure that equipment used with today’s crude ...
Oyewunmi OA, Taleb AI, Haslam AJ, et al., 2014, An assessment of working-fluid mixtures using SAFT-VR Mie for use in organic Rankine cycle systems for waste-heat recovery, Computational Thermal Sciences, Vol: 6, Pages: 301-316, ISSN: 1940-2503
© 2014 by Begell House, Inc. Working-fluid mixtures offer an improved thermal match to heat source streams in organic Rankine cycles (ORCs) over pure (single) fluids. In the present work we investigate the selection of working-fluid mixtures and component mixing ratios for an ORC system from a thermodynamic and economic point of view. A mathematical model of a subcritical, nonregenerative ORC is constructed. We employ the SAFT-VR Mie equation of state, a state-of-the-art version of the statistical associating fluid theory (SAFT), to predict the thermodynamic state properties and phase behavior of the fluid mixtures. The effect of the working-fluid mixture selection on the efficiency and power output from the cycle is investigated, as is its effect on the sizes of the various components of the ORC engine. This is done in order to appreciate the role that the fluid mixtures have on the investment/capital costs attributed to the installation of such a unit, intended for waste-heat recovery and conversion to power. Results of an ORC using a binary decane–butane mixture as the working fluid demonstrate a significant improvement in the cost per unit power output compared to the two pure fluid components. Specifically, the added costs of the four main ORC system components (pump, expander, and two heat exchangers) were found to be as low as 120–130 £/kW, 20–30% lower compared to the pure fluids.
Schreckenberg JMA, Dufal S, Haslam AJ, et al., 2014, Modelling of the thermodynamic and solvation properties of electrolyte solutions with the statistical associating fluid theory for potentials of variable range, Molecular Physics: An International Journal at the Interface Between Chemistry and Physics, Vol: 112, Pages: 2339-2364, ISSN: 0026-8976
An improved formulation of the extension of the statistical associating fluid theory for potentials of variable range to electrolytes (SAFT-VRE) is presented, incorporating a representation for the dielectric constant of the solution that takes into account the temperature, density and composition of the solvent. The proposed approach provides an excellent correlation of the dielectric-constant data available for a number of solvents including water, representative alcohols and carbon dioxide, and it is shown that the methodology can be used to treat mixed-solvent electrolyte solutions. Models for strong electrolytes of the metal-halide family are considered here. The salts are treated as fully dissociated and ion-specific interaction parameters are presented. Vapour pressure, density, and mean ionic activity coefficient data are used to determine the ion–ion and solvent–ion parameters, and mixed-salt electrolyte solutions (brines) are then treated predictively. We find that the resulting intermolecular potential models follow physical trends in terms of energies and ion sizes with a close relationship observed with well-established ionic diameters. A good description is obtained for the densities, mean ionic activity coefficients, and vapour pressures of the electrolyte solutions studied. The theory is also seen to provide excellent predictions of the osmotic coefficient and of the depression of the freezing temperature, and provides a qualitative estimate of the solvation free energy. The vapour pressure of aqueous brines is predicted accurately, as is the density of these solutions, although not at the highest pressures considered. Calculations for the vapour–liquid and liquid–liquid equilibria of salts in water+methanol and water+n-butan-1-ol are presented. In addition, it is shown that the salting-out of carbon dioxide in sodium chloride solutions is captured well using a predictive model.
Forte E, Haslam AJ, Jackson G, et al., 2014, Effective coarse-grained solid-fluid potentials and their application to model adsorption of fluids on heterogeneous surfaces, PHYSICAL CHEMISTRY CHEMICAL PHYSICS, Vol: 16, Pages: 19165-19180, ISSN: 1463-9076
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- Citations: 32
Horton RM, Haslam AJ, Galindo A, et al., 2013, New methods for calculating the free energy of charged defects in solid electrolytes, JOURNAL OF PHYSICS-CONDENSED MATTER, Vol: 25, ISSN: 0953-8984
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- Citations: 2
Dominguez H, Haslam AJ, Jackson G, et al., 2013, Modelling and understanding of the vapour-liquid and liquid-liquid interfacial properties for the binary mixture of <i>n</i>-heptane and perfluoro-<i>n</i>-hexane, JOURNAL OF MOLECULAR LIQUIDS, Vol: 185, Pages: 36-43, ISSN: 0167-7322
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- Citations: 9
Oyewunmi OA, Taleb A, Haslam A, et al., 2013, An assessment of working-fluid mixtures in organic Rankine cycles for waste-heat recovery using SAFT-VR., 2nd International Seminar on ORC Power Systems (ASME ORC 2013)
Jover J, Haslam AJ, Galindo A, et al., 2012, Pseudo hard-sphere potential for use in continuous molecular-dynamics simulation of spherical and chain molecules, JOURNAL OF CHEMICAL PHYSICS, Vol: 137, ISSN: 0021-9606
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- Citations: 80
Franco-Melgar M, Haslam AJ, Jackson G, 2012, A generalisation of the Onsager trial function approach: Describing nematic liquid crystals with an algebraic equation of state (vol 106, pg 649, 2008), MOLECULAR PHYSICS, Vol: 110, Pages: 3107-3107, ISSN: 0026-8976
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- Citations: 4
Dufal S, Galindo A, Jackson G, et al., 2012, Modelling the effect of methanol, glycol inhibitors and electrolytes on the equilibrium stability of hydrates with the SAFT-VR approach, MOLECULAR PHYSICS, Vol: 110, Pages: 1223-1240, ISSN: 0026-8976
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- Citations: 23
Artola P-A, Pereira FE, Adjiman CS, et al., 2011, Understanding the fluid phase behaviour of crude oil: Asphaltene precipitation, FLUID PHASE EQUILIBRIA, Vol: 306, Pages: 129-136, ISSN: 0378-3812
Brumby PE, Haslam AJ, de Miguel E, et al., 2011, Subtleties in the calculation of the pressure and pressure tensor of anisotropic particles from volume-perturbation methods and the apparent asymmetry of the compressive and expansive contributions, MOLECULAR PHYSICS, Vol: 109, Pages: 169-189, ISSN: 0026-8976
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- Citations: 26
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