| 1. |
- Osmanbegovic, Nahla, et al.
(författare)
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Experimental and CFD study on influence of viscosity on layer melt crystallization
- 2022
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Ingår i: Separation and Purification Technology. - : Elsevier BV. - 1383-5866 .- 1873-3794. ; 284
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Tidskriftsartikel (refereegranskat)abstract
- In the present work, the influence of solution viscosity on growth kinetics and purification efficiency in layer melt crystallization was investigated. Melt crystallization experiments were conducted for three different types of aqueous sucrose solution as they are ideal solutions and a relatively wide viscosity range can be investigated with a moderate change of freezing points. The aqueous 10 wt%, 23 wt%, and 30 wt% sucrose solutions have a dynamic viscosity value of 2.01 mPas, 4.74 mPas, and 7.21 mPas at their respective freezing points of −0.63 °C, −1.78 °C, and −2.64 °C. The solution temperature distribution was predicted by computational fluid dynamics (CFD) simulations run in COMSOL Multiphysics 5.6 software. Experimental results showed that a higher solution viscosity caused a higher crystal layer impurity and lower crystal yields in static layer melt crystallization. The cooling process of different solutions predicted by a CFD heat transfer study showed that the supersaturation region is wider for less concentrated solutions as cooling proceeds more rapidly. Hence, the temperature gradients obtained follow the boundary layer theory, i.e., the thinner the boundary layer, the faster the heat transfer.
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| 2. |
- Alopaeus, Ville
(författare)
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Modeling surfactant and drop size dynamics in polydisperse liquid-liquid systems with population balances
- 2022
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Ingår i: Chemical Engineering Science. - : Elsevier BV. - 0009-2509 .- 1873-4405. ; 248
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Tidskriftsartikel (refereegranskat)abstract
- A population balance framework based on high order moment conserving method of classes is extended to capture surfactant dynamics and its effect on drop size distributions. The proposed method is flexible for incorporating various closure models for drop breakage and coalescence, mass transfer, and physical equilibria between dispersed and continuous phase as well as for adsorption to the interface. The method is first schematically explained and derived in a generic form, and then appropriate closure models are discussed. The model is accurate and fast and can be implemented in process models, parameter optimization algorithms, and computational fluid dynamics software due to its high accuracy with limited number of additional variables.
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| 3. |
- Baird, Zachariah Steven, et al.
(författare)
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Densities, Viscosities, and Thermal Conductivities of the Ionic Liquid 7-Methyl-1,5,7-triazabicyclo[4.4.0]dec-5-enium Acetate and Its Mixtures with Water
- 2020
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Ingår i: International journal of thermophysics. - : Springer Science and Business Media LLC. - 0195-928X .- 1572-9567. ; 41:12
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Tidskriftsartikel (refereegranskat)abstract
- 7-Methyl-1,5,7-triazabicyclo[4.4.0]dec-5-enium acetate (mTBD acetate) is a protic ionic liquid that is being investigated for use in industrial processes, such as for producing textiles from cellulose. To aid in designing such processes, we have measured the densities, viscosities, and thermal conductivities of mTBD acetate and aqueous mixtures containing mTBD acetate. We also investigated how excess amounts of mTBD or acetic acid affect the density, and found that in general an excess of either component decreases the density. However, when no water is present, the sample with excess acetic acid actually has a slightly higher density than when there is an equimolar amount of acid and base. The maximum density occurs when some water is present (around 30–40 mol%). We also modeled the density data using the ePC-SAFT equation of state and provide simple correlations for calculating the viscosity and thermal conductivity of these mixtures.
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| 4. |
- Baird, Zachariah Steven, et al.
(författare)
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Vapor-Liquid Equilibrium of Ionic Liquid 7-Methyl-1,5,7-triazabicyclo[4.4.0]dec-5-enium Acetate and Its Mixtures with Water
- 2020
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Ingår i: Journal of Chemical and Engineering Data. - : American Chemical Society (ACS). - 0021-9568 .- 1520-5134. ; 65:5, s. 2405-2421
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Tidskriftsartikel (refereegranskat)abstract
- Ionic liquids have the potential to be used forextracting valuable chemicals from raw materials. These processesoften involve water, and after extraction, the water or otherchemicals must be removed from the ionic liquid, so it can bereused. To help in designing such processes, we present data onthe vapor−liquid equilibrium of the system containing protic ionicliquid 7-methyl-1,5,7-triazabicyclo[4.4.0]dec-5-enium acetate,water, acetic acid, and 7-methyl-1,5,7-triazabicyclo[4.4.0]dec-5-ene. Earlier studies have only focused on mixtures of water and anionic liquid with a stoichiometric ratio of the ions. Here, we alsoinvestigated mixtures containing an excess of the acid or basecomponent because in real systems with protic ionic liquids, theamount of acid and base in the mixture can vary. We modeled thedata using both the ePC-SAFT and NRTL models, and we compared the performance of different modeling strategies. We alsoexperimentally determined the vapor composition for a few of the samples, but none of the modeling strategies tested couldaccurately predict the concentration of the acid and base components in the vapor phase.
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| 5. |
- Bijok, Nicolaus, et al.
(författare)
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Chip scale modelling of the kraft pulping process by considering the heterogeneous nature of the lignocellulosic feedstock
- 2023
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Ingår i: Chemical engineering research & design. - : Elsevier BV. - 0263-8762 .- 1744-3563. ; 193, s. 13-27
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Tidskriftsartikel (refereegranskat)abstract
- This article focuses on a multiscale modelling approach to describe the delignification of softwood during the kraft pulping process. A framework for modelling the lignocellulosic feedstock on a fibre scale which considered the fundamental chemical components of wood as a distributed variable is re-assessed and extended to include chip-level phenomena such as diffusion limitations and initial component distributions within a softwood chip mixture. A new description of the wood chip is presented using a finite volume discretisation along one spatial dimension by simultaneously considering the anisotropic structural differences of the wood. Additionally, based on literature data, a distinction between the softwood chips' early- and latewood regions with their differences in densities and chemical composition is suggested. The presented model framework uses published sub-models for kinetics, diffusion etc. The validation and estimation of the remaining parameters are conducted from experimental data that quantifies the kappa number distribution of individual softwood fibres after kraft pulping. The investigation hypothesises a Gaussian distribution for the initial chemical component distribution within wood chips from a well-defined region. In contrast, a Log-normal distribution is used to describe the initial chemical distribution within a softwood chip mixture. The established sub-models for the kraft pulping process's kinetics and mass transfer phenomena could not predict the experimental data satisfactorily. However, modifying the sub-models by including a change in lignin reactivity and a temperature dependency of the lignin reactivity decline during the delignification progress could predict the essence of the observed experimental kappa number distribution.
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| 6. |
- Bijok, Nicolaus, et al.
(författare)
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Modelling the kraft pulping process on a fibre scale by considering the intrinsic heterogeneous nature of the lignocellulosic feedstock
- 2022
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Ingår i: Chemical Engineering Journal. - : Elsevier BV. - 1385-8947 .- 1873-3212. ; 438
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Tidskriftsartikel (refereegranskat)abstract
- Renewable raw materials such as lignocellulose are inherently complex and demanding in chemical processing compared to petroleum-based feedstocks. This article addresses the challenge of developing a general model framework for modelling lignocellulosic feedstock on a fibre scale, considering its inherent heterogeneous nature in terms of the fundamental chemical component distribution in addition to its anisotropic structural properties. The presented model is tested and validated for the well-established kraft pulping process. Simulations and parameter estimation are carried out to investigate the kappa number distribution of softwood fibres during kraft pulping by using experimental data from the literature showing non-uniform delignification. A moving grid discretisation method for the distributed concentration variables is used to predict the reaction of the wood solids. The results suggest that an inherent fundamental chemical component distribution can be hypothesised as one source of the non-uniform delignification. The model indicates that a Gaussian distribution can be assumed for the initial lignin concentration within softwood. In addition, an investigation of the lignin kinetics suggests that the reactivity of lignin during kraft pulping decreases as the delignification progresses.
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| 7. |
- Dahal, Roshi, et al.
(författare)
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Liquid – liquid equilibria in binary and ternary systems of phenol + hydrocarbons (n–dodecane or n–hexadecane) and water + phenol + hydrocarbons (n–dodecane or n–hexadecane) at temperatures between 298K and 353K
- 2022
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Ingår i: Fluid Phase Equilibria. - : Elsevier BV. - 0378-3812 .- 1879-0224. ; 556
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Tidskriftsartikel (refereegranskat)abstract
- This study reports liquid–liquid equilibrium (LLE) and liquid–liquid–liquid equilibrium (LLLE) data for binary (phenol + n-dodecane, or n-hexadecane) and ternary (water + phenol + n-dodecane, or n-hexadecane) systems measured under atmospheric pressure. The compositions of coexisting phases were determined with analytical and cloud point methods at temperatures 298 K – 353 K. The Non–Random Two–Liquid (NRTL) excess Gibbs energy model was employed to correlate the measured systems. The binary interaction parameters were regressed using analytical LLE and cloud point data. In addition, the parameters were also calculated using the binary LLE data combined with the isothermal vapor–liquid data from the literature applying the NRTL–RK (Redlich–Kwong) property method. The average absolute deviations in liquid mole fraction obtained with the NRTL model (using six adjusted parameters) for the LLE and VLE experimental data were 0.006 and 0.014 respectively. The phase equilibria of binary phenol + hydrocarbon (n-dodecane or n-hexadecane) systems were modeled at the temperature range of 313 K – 573 K.
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| 8. |
- Dahal, Roshi, et al.
(författare)
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Vapor- liquid equilibrium for the n-dodecane + phenol and n-hexadecane + phenol systems at 523 K and 573 K
- 2021
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Ingår i: Fluid Phase Equilibria. - : Elsevier BV. - 0378-3812 .- 1879-0224. ; 537
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Tidskriftsartikel (refereegranskat)abstract
- A continuous flow apparatus was applied to measure the phase equilibrium at 523 K and 573 K. The performance of the apparatus was analysed with the determination of vapor pressures of water at the temperatures (T = 453 K and 473 K). The measured water vapor pressures deviated from the literature values less than 1 %. Vapor pressures of n-dodecane, n-hexadecane and phenol were measured at the temperatures (T = 523–623 K) and, the bubble point pressures of n-dodecane + phenol and n-hexadecane + phenol were measured at the temperatures (T = 523 K and 573 K). The measured vapor pressures of the pure components were compared with the literature values. Relative vapor pressure deviated from the literature value less than 2 % for all the measured vapor pressures. The measured vapor pressures value in this work agreed well with the literature, which indicates that the measurement apparatus and the method can produce good-quality data. The measured bubble point pressures for the n-dodecane + phenol and n-hexadecane + phenol systems were modeled with Peng-Robinson and Perturbed-Chain Statistical Associating Fluid Theory (PC-SAFT) equations of state and Non-random Two-liquid (NRTL) activity coefficient model. The measured systems were at first modeled with Peng-Robinson and Perturbed-Chain Statistical Associating Fluid Theory (PC-SAFT) equations of state without binary interaction parameters. Additionally, the parameters were regressed to optimize the performance of the models. The NRTL activity coefficient model described the behaviour of the measured and the literature data better than the equations of state. Furthermore, the Peng-Robinson equation of state resulted in better predictions than PC-SAFT equation of state even without binary interaction parameters regression. Both equations of state modeled the phase equilibrium behaviour of the system well. The n-dodecane + phenol system showed azeotropic behaviour.
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| 9. |
- Fearon, O, et al.
(författare)
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Detailed Modeling of Kraft Pulping Chemistry. Delignification
- 2020
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Ingår i: Industrial and Engineering Chemistry Research. - : American Chemical Society (ACS). - 0888-5885 .- 1520-5045. ; 59:29, s. 12977-12985
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Tidskriftsartikel (refereegranskat)abstract
- This work introduces a phenomena-based model for delignification in the kraft pulping process. The solubilization of lignin is described as a set of chemical reactions representing the entire chemistry of lignin degradation as well as dissolution of the degraded lignin. For modeling, reaction mechanisms and reactions kinetics derived mainly from the literature were used. Each reaction was simulated separately and then combined for the overall degradation. The model was validated with experimental results from pine wood meal pulping under a wide range of reaction parameters. The experimental data presented a good fit with the model. With the aid of the model, the structure and the amount of wood components, in fibers and black liquor, can be determined at any pulping stage. Several engineering parameters can be computed from the detailed chemical composition of liquor and wood or chemical pulp. These include, e.g., kappa number, brightness, yield, active alkali, effective alkali, sulfidity, and higher heating value.
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| 10. |
- Fearon, O, et al.
(författare)
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Detailed modeling of the kraft pulping chemistry: carbohydrate reactions
- 2020
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Ingår i: AIChE Journal. - : John Wiley & Sons. - 0001-1541 .- 1547-5905. ; :16252
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Tidskriftsartikel (refereegranskat)abstract
- The article introduces a detailed model for carbohydrate chemistry in kraft pulping. This article is continuation to the modeling work carried out for hot water extraction and chemical pulp bleaching. The model includes galactoglucomannan, xylan, and cellulose acid–base equilibria, in addition to peeling, stopping, and alkaline hydrolysis reactions of the same carbohydrates, as well as hexenuronic acid formation and degradation reactions. The Arrhenius parameters were applied from the literature or regressed against experimental data in the present study. The model is very successful in predicting the experimental data of carbohydrate reactions during kraft pulping. Many features of the pulping-related model can be applied to specific fractionation chemistry considerations. The detailed knowledge on carbohydrates composition at any stage of pulping gives possibility for further development of biorefinery cases based on kraft pulping, such as biofuel and chemicals production.
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| 11. |
- González Escobedo, José Luis, et al.
(författare)
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Hydrodeoxygenation Model Compounds γ-Heptalactone and γ-Nonalactone : Density from 293 to 473 K and H2 Solubility from 479 to 582 K
- 2020
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Ingår i: Journal of Chemical and Engineering Data. - : American Chemical Society (ACS). - 0021-9568 .- 1520-5134. ; 65:5, s. 2764-2773
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Tidskriftsartikel (refereegranskat)abstract
- Determining the H2 solubility in model compounds that represent lignocellulose derivatives is valuable for the study of upgrading processes such as hydrodeoxygenation. In this work, γ-heptalactone and γ-nonalactone are studied as model compounds at conditions relevant to hydrodeoxygenation. The solubility of H2 in the lactones was determined in the range of 479 to 582 K and 3 to 10 MPa. The solubility measurements were performed in a continuous flow setup based on the visual observation of the bubble point. Furthermore, the densities of the lactones were measured in order to provide the necessary data for the solubility calculations. The density measurements were performed from 293 to 373 K and from 0.16 to 9.9 MPa in a vibrating tube density meter. Using the measurements, a model of the density as a function of temperature and pressure was developed, obtaining average relative deviations on the order of 0.1%. Similarly, the Peng-Robinson equation of state with the Boston-Mathias modification was used to predict the H2 solubility in the lactones. A temperature-dependent model of the symmetric binary parameter of the equation of state was regressed from the data in order to improve the predictions.
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| 12. |
- Gorji, Ali Ebrahimpoor, et al.
(författare)
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Toward solvent screening in the extractive desulfurization using ionic liquids : QSPR modeling and experimental validations
- 2021
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Ingår i: Fuel. - : Elsevier BV. - 0016-2361 .- 1873-7153. ; 302
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Tidskriftsartikel (refereegranskat)abstract
- In the present study, the effects of different structures of the involved compounds (such as cation, anion, and hydrocarbon) in the ternary systems on the distribution coefficient of the thiophene between ionic liquid and hydrocarbon-rich phases have been studied using Quantitative Structure-Property Relationship (QSPR). By a comprehensive literature survey, the experimental data of the distribution of thiophene for 84 different ternary systems with 763 data points have been collected. The data set includes 14, 10, and 10 different cation, anion, and hydrocarbon structures, respectively. A general QSPR model has been developed to evaluate the simultaneous effect of the hydrocarbon structure, the cation structure, and the anion structure on the thiophene distribution between the hydrocarbon and ionic liquid-rich phases. The selected molecular descriptor in this model was simple descriptor of the number of carbon atom (nC) for the cation structure, the number of nitrogen atom (nN) for the anion structure, and “Pol” for the hydrocarbon structure. The outcome of the internal validation, the external validation, and the statistical evaluation of the final QSPR models (R2 = 0.91, %AARD = 17.28) confirmed the acceptable prediction capability. The Liquid-Liquid Equilibrium (LLE) data has also been generated using the QSPR approach for a vast number of non-studied ternary systems for the first time. The LLE data of four different ternary systems ([C2MIM][EtSO4] (1) - Thiophene (2) - Cyclohexane, Methyl cyclohexane, n-Nonane, n-Decane (3)) was measured experimentally. The comparison of the measured experimental data and the predicted data using the developed QSPR model confirmed the validity of the QSPR developed model, again.
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| 13. |
- Jama, Mohamed Ali, et al.
(författare)
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Analytical time-stepping solution of the discretized population balance equation
- 2020
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Ingår i: Computers and Chemical Engineering. - : Elsevier BV. - 0098-1354 .- 1873-4375. ; 135
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Tidskriftsartikel (refereegranskat)abstract
- The prediction of the particle-size distribution (PSD) of the particulate systems in chemical engineering is very important in a variety of different contexts, such as parameter identification, troubleshooting, process control, design, product quality, production economics etc. The time evolution of the PSD can be evaluated by means of the population balance equation (PBE), which is a complex integro-differential equation, whose solution in practical cases always requires sophisticated numerical methods that may be computationally tedious. In this work, we propose a novel technique that tackles this issue by using an analytical time-stepping procedure (ATS) to resolve the PSD time dependency. The ATS is an explicit time integrator, taking advantage of the linear or almost linear time dependency of the discretized population balance equation. Thus, linear approximation of the source term is a precondition for the ATS simulations. The presented technique is compared with a standard variable step time integrator (MATLAB ODE15s stiff solver), for practical examples e.g. emulsion, aging cellulose process, cooling crystallization, reactive dissolution, and liquid-liquid extraction. The results show that this advancing in time procedure is accurate for all tested practical examples, allowing reproducing the same results given by standard time integrators in a fraction of the computational time.
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| 14. |
- Schlapp-Hackl, Inge, et al.
(författare)
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Application-Related Consideration of the Thermal Stability of [mTBDH][OAc] Compared to Amidine-Based Ionic Liquids in the Presence of Various Amounts of Water
- 2022
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Ingår i: Industrial & Engineering Chemistry Research. - : American Chemical Society (ACS). - 0888-5885 .- 1520-5045. ; 61:1, s. 259-268
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Tidskriftsartikel (refereegranskat)abstract
- The hydrolysis kinetics of 7-methyl-1,5,7triazabicyclo[4.4.0]dec-5-enium acetate [mTBDH][OAc] was investigated in a comprehensive study by the utilization of the well-known Schlenk technique to achieve a better understanding of its stability for dry-jet wet spinning applications (e.g., Ioncell) and due to the course of operation for recovery methods like fractional distillation. Decomposition behavior as a function of temperature, time, acid-base stoichiometry, and water content was extensively analyzed and characterized by nuclear magnetic resonance spectroscopy (NMR), capillary electrophoresis (CE), and thermogravimetric analysis (TGA). Furthermore, kinetic models were formulated for the prediction of the stability and the results were compared with the closely related amidine-based analogues 1,5diazabicyclo[4.3.0]non-5-enium acetate [DBNH][OAc] and 1,8-diazabicyclo[5.4.0]undec-7-enium acetate [DBUH][OAc].
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| 15. |
- Touronen, J, et al.
(författare)
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Application of GaInSn Liquid Metal Alloy Replacing Mercury in a Phase Equilibrium Cell: Vapor Pressures of Toluene, Hexylbenzene, and 2-Ethylnaphthalene
- 2020
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Ingår i: Journal of Chemical and Engineering Data. - : American Chemical Society (ACS). - 0021-9568 .- 1520-5134. ; 65:7, s. 3270-3276
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Tidskriftsartikel (refereegranskat)abstract
- Mercury has been applied as a sealing and pressure transmission fluid in many experimental phase equilibrium studies employing the synthetic visual method as well as a moving piston in analytical isobaric and/or isothermal methods. However, mercury is highly toxic and therefore its use is restricted by authorities such as those of the European Union. A new apparatus employing nontoxic GaInSn liquid metal alloy as a sealing, moving piston, and pressure transmission fluid for phase equilibrium measurements with a nonvisual variable volume method is presented. The vapor pressures of toluene, hexylbenzene, and 2-ethylnaphtalene are provided within the applied temperature range of 400-620 K. New values for the parameters of the DIPPR 101 and Wagner equations, and PC-SAFT equation of state were regressed. The results demonstrate that GaInSn can be used in phase equilibrium cells as a very convenient substitute for mercury, especially at high temperatures.
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| 16. |
- Vuorinen, V., et al.
(författare)
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Modelling aerosol transport and virus exposure with numerical simulations in relation to SARS-CoV-2 transmission by inhalation indoors
- 2020
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Ingår i: Safety Science. - : Elsevier BV. - 0925-7535. ; 130
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Tidskriftsartikel (refereegranskat)abstract
- We provide research findings on the physics of aerosol and droplet dispersion relevant to the hypothesized aerosol transmission of SARS-CoV-2 during the current pandemic. We utilize physics-based modeling at different levels of complexity, along with previous literature on coronaviruses, to investigate the possibility of airborne transmission. The previous literature, our 0D-3D simulations by various physics-based models, and theoretical calculations, indicate that the typical size range of speech and cough originated droplets (d⩽20μm) allows lingering in the air for O(1h) so that they could be inhaled. Consistent with the previous literature, numerical evidence on the rapid drying process of even large droplets, up to sizes O(100μm), into droplet nuclei/aerosols is provided. Based on the literature and the public media sources, we provide evidence that the individuals, who have been tested positive on COVID-19, could have been exposed to aerosols/droplet nuclei by inhaling them in significant numbers e.g. O(100). By 3D scale-resolving computational fluid dynamics (CFD) simulations, we give various examples on the transport and dilution of aerosols (d⩽20μm) over distances O(10m) in generic environments. We study susceptible and infected individuals in generic public places by Monte-Carlo modelling. The developed model takes into account the locally varying aerosol concentration levels which the susceptible accumulate via inhalation. The introduced concept, ’exposure time’ to virus containing aerosols is proposed to complement the traditional ’safety distance’ thinking. We show that the exposure time to inhale O(100) aerosols could range from O(1s) to O(1min) or even to O(1h) depending on the situation. The Monte-Carlo simulations, along with the theory, provide clear quantitative insight to the exposure time in different public indoor environments.
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