Pub Date : 2024-10-01DOI: 10.1016/j.fluid.2024.114243
Elsa Moggia
This article focuses on the predictive potentialities of the Quasi-Random Lattice (QRL) model, developed for describing the activity behaviour of electrolytic solutions, and elaborates strategies for their improvement.
First, the study critically discusses the computational-experimental procedure (previously published) for determining the QRL parameterization, whose convergence within few iterations is counterbalanced by known experimental issues concerning, in particular, the mean activity coefficient. An alternative procedure is proposed, that makes use of osmotic data at medium-high concentrations, so as to make QRL more interesting from a practical point of view.
Second, the study explores the applicability of the model beyond the concentration ranges earlier considered. To this purpose, the solution density is evaluated in detail. Its thermodynamic relationship with the mean activity coefficient yields a parametric Abel Equation of the Second Kind valid in the medium-high range of concentrations. A further density equation is formulated, useful in the low-medium range, based on a classical power-series combined with appropriate analytical constraints to improve estimation and prediction methods.
QRL theory, methods and procedures are applied to binary aqueous solutions at 25°C.
{"title":"Predictive potentialities of the Quasi-Random Lattice model for electrolyte solutions, discussion and improvement strategies","authors":"Elsa Moggia","doi":"10.1016/j.fluid.2024.114243","DOIUrl":"10.1016/j.fluid.2024.114243","url":null,"abstract":"<div><div>This article focuses on the predictive potentialities of the Quasi-Random Lattice (QRL) model, developed for describing the activity behaviour of electrolytic solutions, and elaborates strategies for their improvement.</div><div>First, the study critically discusses the computational-experimental procedure (previously published) for determining the QRL parameterization, whose convergence within few iterations is counterbalanced by known experimental issues concerning, in particular, the mean activity coefficient. An alternative procedure is proposed, that makes use of osmotic data at medium-high concentrations, so as to make QRL more interesting from a practical point of view.</div><div>Second, the study explores the applicability of the model beyond the concentration ranges earlier considered. To this purpose, the solution density is evaluated in detail. Its thermodynamic relationship with the mean activity coefficient yields a parametric Abel Equation of the Second Kind valid in the medium-high range of concentrations. A further density equation is formulated, useful in the low-medium range, based on a classical power-series combined with appropriate analytical constraints to improve estimation and prediction methods.</div><div>QRL theory, methods and procedures are applied to binary aqueous solutions at 25°C.</div></div>","PeriodicalId":12170,"journal":{"name":"Fluid Phase Equilibria","volume":"588 ","pages":"Article 114243"},"PeriodicalIF":2.8,"publicationDate":"2024-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142418262","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-09-30DOI: 10.1016/j.fluid.2024.114242
Hui Shi , Jiazuo Wei , Tiantian Xu , Yulei Guan , Jingjun Liu
Glycerol carbonate, a high-value derivative of glycerol, finds extensive applications in the cosmetics, pharmaceuticals, and food industries, as well as in plasticizers and battery electrolytes. This study assessed the feasibility of extracting glycerol carbonate from glycerol using three solvents: 2-pentanone, cyclohexanone, and 4-methyl-2-pentanone. The extraction performance of these solvents was evaluated through liquid-liquid equilibrium (LLE) measurements at atmospheric pressure and temperatures of 303.2 K, 313.2 K, and 323.2 K. Although 4-methyl-2-pentanone exhibited high extraction selectivity, the distribution coefficient of glycerol carbonate in it was less than one. Conversely, while cyclohexanone provided a high distribution coefficient, its extraction selectivity was low. In contrast, 2-pentanone demonstrated a relatively balanced extraction selectivity and capacity. The Non-Random Two-Liquid (NRTL) model was used as an activity model in the equilibrium data correlation, and the corresponding binary interaction parameters were estimated. The regressed parameters of the NRTL model successfully reproduced the phase equilibrium trends observed for all systems investigated, facilitating process design and solvent screening for glycerol carbonate extraction from glycerol.
{"title":"Determination and correlation of liquid-liquid equilibrium data for the extraction of glycerol carbonate from glycerol using 2-pentanone, cyclohexanone, and 4-methyl-2-pentanone","authors":"Hui Shi , Jiazuo Wei , Tiantian Xu , Yulei Guan , Jingjun Liu","doi":"10.1016/j.fluid.2024.114242","DOIUrl":"10.1016/j.fluid.2024.114242","url":null,"abstract":"<div><div>Glycerol carbonate, a high-value derivative of glycerol, finds extensive applications in the cosmetics, pharmaceuticals, and food industries, as well as in plasticizers and battery electrolytes. This study assessed the feasibility of extracting glycerol carbonate from glycerol using three solvents: 2-pentanone, cyclohexanone, and 4-methyl-2-pentanone. The extraction performance of these solvents was evaluated through liquid-liquid equilibrium (LLE) measurements at atmospheric pressure and temperatures of 303.2 K, 313.2 K, and 323.2 K. Although 4-methyl-2-pentanone exhibited high extraction selectivity, the distribution coefficient of glycerol carbonate in it was less than one. Conversely, while cyclohexanone provided a high distribution coefficient, its extraction selectivity was low. In contrast, 2-pentanone demonstrated a relatively balanced extraction selectivity and capacity. The Non-Random Two-Liquid (NRTL) model was used as an activity model in the equilibrium data correlation, and the corresponding binary interaction parameters were estimated. The regressed parameters of the NRTL model successfully reproduced the phase equilibrium trends observed for all systems investigated, facilitating process design and solvent screening for glycerol carbonate extraction from glycerol.</div></div>","PeriodicalId":12170,"journal":{"name":"Fluid Phase Equilibria","volume":"588 ","pages":"Article 114242"},"PeriodicalIF":2.8,"publicationDate":"2024-09-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142418264","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-09-28DOI: 10.1016/j.fluid.2024.114239
Kian Shariati , Sona Raeissi , Cor.J. Peters
Alkane mixture phase equilibria is required for a range of industrial applications, most particularly for the petroleum industries. Mixtures containing light and heavy normal alkanes are of even further significance due to their non-ideal thermodynamic behavior. In this work, for the first time, the ternary system of C1 + C10 + C28 was investigated experimentally to obtain bubble point pressures at various concentrations and temperatures ranging from 373 up to 445 K. The synthetic method of phase equilibrium measurements was utilized, which is known to have high accuracy. The resulting bubble points for the mixtures ranged in pressure from about 3 MPa up to 6 MPa. The data indicated that methane concentrations had the greatest impact, not only on the magnitude of the bubble point pressure, but also on the slope of its temperature trend. The relative concentrations of n-decane and n-octacosane had far less impact on the bubble point curves. The results were also modelled using the Peng–Robinson equation of state, and it was found that this equation has the capability to predict the data with an AARD% of 5.1 %. When temperature-independent binary interaction parameters were optimized to the data, the AARD% reduced to 2.4 %. Although the components vary greatly in size, perhaps the success of the Peng–Robinson equation of state for this mixture could be attributed to the fact that it was developed for hydrocarbon mixtures, and so, a reason for its popularity in the petroleum industries, alongside its simplicity and ease of use.
{"title":"Vapor-liquid equilibria of the ternary system of methane + n-decane + n-octacosane at high pressures","authors":"Kian Shariati , Sona Raeissi , Cor.J. Peters","doi":"10.1016/j.fluid.2024.114239","DOIUrl":"10.1016/j.fluid.2024.114239","url":null,"abstract":"<div><div>Alkane mixture phase equilibria is required for a range of industrial applications, most particularly for the petroleum industries. Mixtures containing light and heavy normal alkanes are of even further significance due to their non-ideal thermodynamic behavior. In this work, for the first time, the ternary system of C<sub>1</sub> + C<sub>10</sub> + C<sub>28</sub> was investigated experimentally to obtain bubble point pressures at various concentrations and temperatures ranging from 373 up to 445 K. The synthetic method of phase equilibrium measurements was utilized, which is known to have high accuracy. The resulting bubble points for the mixtures ranged in pressure from about 3 MPa up to 6 MPa. The data indicated that methane concentrations had the greatest impact, not only on the magnitude of the bubble point pressure, but also on the slope of its temperature trend. The relative concentrations of n-decane and n-octacosane had far less impact on the bubble point curves. The results were also modelled using the Peng–Robinson equation of state, and it was found that this equation has the capability to predict the data with an AARD% of 5.1 %. When temperature-independent binary interaction parameters were optimized to the data, the AARD% reduced to 2.4 %. Although the components vary greatly in size, perhaps the success of the Peng–Robinson equation of state for this mixture could be attributed to the fact that it was developed for hydrocarbon mixtures, and so, a reason for its popularity in the petroleum industries, alongside its simplicity and ease of use.</div></div>","PeriodicalId":12170,"journal":{"name":"Fluid Phase Equilibria","volume":"589 ","pages":"Article 114239"},"PeriodicalIF":2.8,"publicationDate":"2024-09-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142431977","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
In this work, we investigated the phase equilibria and the kinetics of palmitic acid hydrodeoxygenation over Pt/C to produce liquid hydrocarbons as drop-in biofuels. To describe the reaction mixture in detail, the binary interaction parameters of water/hydrogen, water/palmitic acid, water/n-hexadecane, and water/hexadecan-1-ol were estimated for a group contribution model based on the PC-SAFT equation of state using experimental solubility data taken from literature. Kinetic modeling using a power law model based on concentrations, a power law model based on fugacities, and a coupled VLE/power-law model were conducted to evaluate the effects of considering the non-ideality and the phase equilibria of the system. Under the operational conditions studied, the power law model based on concentrations was deemed more suitable to describe the process since it provided a faster implementation and similar outcomes compared to the fugacity-based and the VLE coupled models.
{"title":"Kinetic modeling of palmitic acid hydrodeoxygenation incorporating phase-equilibria predictions from the GC-PC-SAFT equation of state","authors":"Mariana Afonso Pinto Pedroza , Iuri Soter Viana Segtovich , Mônica Antunes Pereira da Silva","doi":"10.1016/j.fluid.2024.114236","DOIUrl":"10.1016/j.fluid.2024.114236","url":null,"abstract":"<div><div>In this work, we investigated the phase equilibria and the kinetics of palmitic acid hydrodeoxygenation over Pt/C to produce liquid hydrocarbons as drop-in biofuels. To describe the reaction mixture in detail, the binary interaction parameters of water/hydrogen, water/palmitic acid, water/n-hexadecane, and water/hexadecan-1-ol were estimated for a group contribution model based on the PC-SAFT equation of state using experimental solubility data taken from literature. Kinetic modeling using a power law model based on concentrations, a power law model based on fugacities, and a coupled VLE/power-law model were conducted to evaluate the effects of considering the non-ideality and the phase equilibria of the system. Under the operational conditions studied, the power law model based on concentrations was deemed more suitable to describe the process since it provided a faster implementation and similar outcomes compared to the fugacity-based and the VLE coupled models.</div></div>","PeriodicalId":12170,"journal":{"name":"Fluid Phase Equilibria","volume":"588 ","pages":"Article 114236"},"PeriodicalIF":2.8,"publicationDate":"2024-09-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142418261","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-09-24DOI: 10.1016/j.fluid.2024.114238
Wonhyeong Lee , Jeongwoo Lee , Kwangbum Kim , Yun-Ho Ahn , Jae W. Lee
The increasing greenhouse gas (GHG) emissions from industrial activities have driven the development of efficient and environmentally safe GHG capture technologies. Clathrate hydrates, primarily composed of water, have attracted significant attention for their potential in GHG capture due to their ability to manage large emissions and their environmental advantages over materials like amine-based sorbents and metal-organic frameworks. This study investigates the hydrate-based capture of SF6 and N2O, two potent GHGs, to develop an effective GHG capture process. Phase equilibrium measurements demonstrate that binary SF6-N2O hydrates can form under moderate thermodynamic conditions, even with a small proportion of SF6, highlighting the feasibility of using hydrate-based methods to capture GHG mixtures. Furthermore, the formation of binary SF6-N2O hydrates enhances GHG volumetric storage capacity compared to pure SF6 hydrates. The guest compositions calculated for each binary SF6-N2O hydrate phase, along with spectroscopic analyses (Powder X-Ray Diffraction and Raman spectroscopy), confirm that the high GHG uptake in binary hydrates results from N2O molecules occupying the small cages of structure II hydrates, which are inaccessible to the larger SF6 molecules. These findings suggest that both the small and large cages of sII hydrates can be practically utilized for efficient capture of GHG mixture (SF6 and N2O) under mild conditions, thereby increasing the storage density of GHGs within the hydrate structure.
{"title":"Thermodynamic phase equilibria of binary SF6–N2O hydrates and their structural analysis for the hydrate-based greenhouse gas capture","authors":"Wonhyeong Lee , Jeongwoo Lee , Kwangbum Kim , Yun-Ho Ahn , Jae W. Lee","doi":"10.1016/j.fluid.2024.114238","DOIUrl":"10.1016/j.fluid.2024.114238","url":null,"abstract":"<div><div>The increasing greenhouse gas (GHG) emissions from industrial activities have driven the development of efficient and environmentally safe GHG capture technologies. Clathrate hydrates, primarily composed of water, have attracted significant attention for their potential in GHG capture due to their ability to manage large emissions and their environmental advantages over materials like amine-based sorbents and metal-organic frameworks. This study investigates the hydrate-based capture of SF<sub>6</sub> and N<sub>2</sub>O, two potent GHGs, to develop an effective GHG capture process. Phase equilibrium measurements demonstrate that binary SF<sub>6</sub>-N<sub>2</sub>O hydrates can form under moderate thermodynamic conditions, even with a small proportion of SF<sub>6</sub>, highlighting the feasibility of using hydrate-based methods to capture GHG mixtures. Furthermore, the formation of binary SF<sub>6</sub>-N<sub>2</sub>O hydrates enhances GHG volumetric storage capacity compared to pure SF<sub>6</sub> hydrates. The guest compositions calculated for each binary SF<sub>6</sub>-N<sub>2</sub>O hydrate phase, along with spectroscopic analyses (Powder X-Ray Diffraction and Raman spectroscopy), confirm that the high GHG uptake in binary hydrates results from N<sub>2</sub>O molecules occupying the small cages of structure II hydrates, which are inaccessible to the larger SF<sub>6</sub> molecules. These findings suggest that both the small and large cages of sII hydrates can be practically utilized for efficient capture of GHG mixture (SF<sub>6</sub> and N<sub>2</sub>O) under mild conditions, thereby increasing the storage density of GHGs within the hydrate structure.</div></div>","PeriodicalId":12170,"journal":{"name":"Fluid Phase Equilibria","volume":"588 ","pages":"Article 114238"},"PeriodicalIF":2.8,"publicationDate":"2024-09-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142418265","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-09-24DOI: 10.1016/j.fluid.2024.114240
Allan Paolo L. Almajose , Maria Lourdes P. Dalida
This study presents a novel three-parameter equation of state (EOS) wherein attraction parameter polynomial coefficients are optimized to enhance predictive capabilities. The performance of the proposed EOS is systematically compared with established models including Peng-Robinson, Patel-Teja, and Twu-Coon-Cunningham equations. Through comprehensive evaluation, it is demonstrated that the proposed EOS exhibits superior accuracy in vapor pressure and latent enthalpy predictions, while maintaining comparable precision in liquid density estimations. Notably, the fugacity expression of the proposed EOS closely resembles that of a two-parameter equation, resulting in significantly reduced computational overhead. Additionally, a comprehensive table of equation of state parameters for all four equations is available in an online repository, facilitating easy implementation and comparison. Furthermore, a reliable generalized polynomial correlation is provided for the proposed EOS parameters against the true compressibility factor and acentric factor, leveraging data accessibility and enhancing its applicability and versatility. These findings underscore the potential of the optimized attraction parameter polynomial coefficients approach in advancing the accuracy and efficiency of EOS modeling, thereby offering promising avenues for diverse applications in thermodynamics and process engineering.
本研究提出了一种新颖的三参数状态方程（EOS），其中对吸引参数多项式系数进行了优化，以提高预测能力。将所提出的状态方程的性能与彭-罗宾逊方程、帕特尔-特加方程和特武-库恩-坎宁安方程等已有模型进行了系统比较。通过综合评估，证明了所提出的 EOS 在蒸气压和潜焓预测方面具有更高的精度，同时在液体密度估算方面也保持了相当的精度。值得注意的是，拟议 EOS 的逸度表达式与双参数方程的逸度表达式非常相似，从而大大降低了计算开销。此外，所有四个方程的状态方程参数综合表都可在在线资料库中找到，便于实施和比较。此外，还提供了可靠的广义多项式相关性，用于将所提出的状态方程参数与真实的压缩系数和中心系数进行比较，从而充分利用数据的可获取性，提高其适用性和通用性。这些发现强调了优化吸引参数多项式系数方法在提高 EOS 建模的准确性和效率方面的潜力，从而为热力学和过程工程中的各种应用提供了前景广阔的途径。
{"title":"Prediction of pure and mixture thermodynamic properties and phase equilibria using an optimized equation of state – part 1: Parameter estimation","authors":"Allan Paolo L. Almajose , Maria Lourdes P. Dalida","doi":"10.1016/j.fluid.2024.114240","DOIUrl":"10.1016/j.fluid.2024.114240","url":null,"abstract":"<div><div>This study presents a novel three-parameter equation of state (EOS) wherein attraction parameter polynomial coefficients are optimized to enhance predictive capabilities. The performance of the proposed EOS is systematically compared with established models including Peng-Robinson, Patel-Teja, and Twu-Coon-Cunningham equations. Through comprehensive evaluation, it is demonstrated that the proposed EOS exhibits superior accuracy in vapor pressure and latent enthalpy predictions, while maintaining comparable precision in liquid density estimations. Notably, the fugacity expression of the proposed EOS closely resembles that of a two-parameter equation, resulting in significantly reduced computational overhead. Additionally, a comprehensive table of equation of state parameters for all four equations is available in an online repository, facilitating easy implementation and comparison. Furthermore, a reliable generalized polynomial correlation is provided for the proposed EOS parameters against the true compressibility factor and acentric factor, leveraging data accessibility and enhancing its applicability and versatility. These findings underscore the potential of the optimized attraction parameter polynomial coefficients approach in advancing the accuracy and efficiency of EOS modeling, thereby offering promising avenues for diverse applications in thermodynamics and process engineering.</div></div>","PeriodicalId":12170,"journal":{"name":"Fluid Phase Equilibria","volume":"588 ","pages":"Article 114240"},"PeriodicalIF":2.8,"publicationDate":"2024-09-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142418260","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-09-21DOI: 10.1016/j.fluid.2024.114237
Nian Li , Xuehui Wang , Shenghan Jin , Neng Gao , Guangming Chen
In this work, the interfacial property of surface tension has been observed to be quasi-universally linked to a dimensionless calorimetric parameter (DCP) for saturated simple liquids. This parameter, derived from thermodynamic calorimetric properties and exclusively influenced by molecular interactions, holds promise for predicting interfacial property and displaying universal behavior. Similar to the excess entropy scaling, empirical evidence indicates linear relations between interfacial properties with the DCP, when appropriate scaling is applied. Based on this observation, formulas for calculating these properties through DCP has been be developed. For fluids with strong molecular interactions, we have also identified their deviations from universality and have proposed a new DCP based modification strategy. These new DCP-based models were evaluated and validated by comparing them with experimental data for 19 pure fluids from different molecular structure catalogues. The average absolute deviations (AADs) were within 2.04 %.
{"title":"Quasi-universally modeling of interfacial properties for saturated liquids using a dimensionless calorimetric parameter","authors":"Nian Li , Xuehui Wang , Shenghan Jin , Neng Gao , Guangming Chen","doi":"10.1016/j.fluid.2024.114237","DOIUrl":"10.1016/j.fluid.2024.114237","url":null,"abstract":"<div><div>In this work, the interfacial property of surface tension has been observed to be quasi-universally linked to a dimensionless calorimetric parameter (DCP) for saturated simple liquids. This parameter, derived from thermodynamic calorimetric properties and exclusively influenced by molecular interactions, holds promise for predicting interfacial property and displaying universal behavior. Similar to the excess entropy scaling, empirical evidence indicates linear relations between interfacial properties with the DCP, when appropriate scaling is applied. Based on this observation, formulas for calculating these properties through DCP has been be developed. For fluids with strong molecular interactions, we have also identified their deviations from universality and have proposed a new DCP based modification strategy. These new DCP-based models were evaluated and validated by comparing them with experimental data for 19 pure fluids from different molecular structure catalogues. The average absolute deviations (AADs) were within 2.04 %.</div></div>","PeriodicalId":12170,"journal":{"name":"Fluid Phase Equilibria","volume":"588 ","pages":"Article 114237"},"PeriodicalIF":2.8,"publicationDate":"2024-09-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142314133","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Understanding the thermal stability of gas hydrate in complex marine geological environment is of importance to hydrate-based carbon sequestration. In this work, the factors affecting the equilibrium of CO2 hydrate in ocean sediments, including quartz sands, inorganic salts and gas impurities were quantitatively measured in a temperature range from 273 to 283 K and a phase equilibrium model of hydrate was established. To reveal the distribution in pore structure, the micro-morphologies of hydrate-bearing sediments were measured by cryo-SEM. Results showed that reduction of initial water saturation, addition of NaCl and CH4 were found to have inhibitory effect on CO2 hydrate equilibrium. Initial water saturation reduced the equilibrium temperature by the capillary pressure, but only 0.3–0.7 K temperature depression was observed as the water saturation reduced to 5 %. About 5.7 K in the average temperature depression was found by the addition of 10 wt% NaCl and 24 mol% CH4. NaCl and CH4 influenced the hydrate equilibrium by changing the water activity and chemical potential of hydrate water lattice. SEM images showed that the hydrate formed in pores of quartz sand had porous surface and coated the sand particles like a layer of cells which are 5–20 μm in diameter, suggesting the hydrate layer exists between the liquid and gas phase. Based on the van der Waals-Platteeuw model, a hydrate equilibrium model was developed. The model provided a good prediction of the hydrate equilibrium in the presence of quartz sand, NaCl and CH4 with an averaged deviation of ±4.2 %, which had the potential to be applicated in more complexed ocean sedimentary environment.
{"title":"Effect of particle size, water saturation, inorganic salt and methane on the phase equilibrium of CO2 hydrates in sediments","authors":"Xuebing Zhou , Shuanshi Fan , Chenlu Xu , Huiyun Wen , Evgeny Chuvilin , Deqing Liang","doi":"10.1016/j.fluid.2024.114234","DOIUrl":"10.1016/j.fluid.2024.114234","url":null,"abstract":"<div><div>Understanding the thermal stability of gas hydrate in complex marine geological environment is of importance to hydrate-based carbon sequestration. In this work, the factors affecting the equilibrium of CO<sub>2</sub> hydrate in ocean sediments, including quartz sands, inorganic salts and gas impurities were quantitatively measured in a temperature range from 273 to 283 K and a phase equilibrium model of hydrate was established. To reveal the distribution in pore structure, the micro-morphologies of hydrate-bearing sediments were measured by cryo-SEM. Results showed that reduction of initial water saturation, addition of NaCl and CH<sub>4</sub> were found to have inhibitory effect on CO<sub>2</sub> hydrate equilibrium. Initial water saturation reduced the equilibrium temperature by the capillary pressure, but only 0.3–0.7 K temperature depression was observed as the water saturation reduced to 5 %. About 5.7 K in the average temperature depression was found by the addition of 10 wt% NaCl and 24 mol% CH<sub>4</sub>. NaCl and CH<sub>4</sub> influenced the hydrate equilibrium by changing the water activity and chemical potential of hydrate water lattice. SEM images showed that the hydrate formed in pores of quartz sand had porous surface and coated the sand particles like a layer of cells which are 5–20 μm in diameter, suggesting the hydrate layer exists between the liquid and gas phase. Based on the van der Waals-Platteeuw model, a hydrate equilibrium model was developed. The model provided a good prediction of the hydrate equilibrium in the presence of quartz sand, NaCl and CH<sub>4</sub> with an averaged deviation of ±4.2 %, which had the potential to be applicated in more complexed ocean sedimentary environment.</div></div>","PeriodicalId":12170,"journal":{"name":"Fluid Phase Equilibria","volume":"588 ","pages":"Article 114234"},"PeriodicalIF":2.8,"publicationDate":"2024-09-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142314132","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-09-20DOI: 10.1016/j.fluid.2024.114233
Stijn H.M. van Leuken , Judith J. van Gorp , Rolf A.T.M. van Benthem , Mark Vis , Remco Tuinier
Essential properties of plastics, such as longevity and mechanical strength, depend on their water absorption capacity. In particular, the water uptake of polycondensates, like polyamides, strongly depends on their composition. To enhance physical characteristics, formulations of polyamide mixtures can be devised. Here, we present dynamic vapor sorption measurements, propose a theoretical approach to predict moisture uptake by aliphatic polyamide mixtures, and compare theoretical and experimental results. Experimental moisture uptake is determined for a wide range of relative humidities, using the weight difference of 10-15 mg samples measured with a specificity of . Our experimental results show that moisture uptake depends on composition and environmental humidity. Our theoretical model considers these dependencies in an extension of Flory–Huggins theory, and demonstrates semi-quantitative predictions of moisture absorption in various mixtures of PA 46, PA 48, PA 412, PA 418, and PA 436. The largest deviations are observed for the PA 46/PA 418 mixture, in which the measured moisture uptake is higher than the computed wt%. With a newly defined effective amide-concentration, the moisture uptake as a function of concentration can be predicted using a single master curve for different polyamide combinations. The absorption of water in a homogeneous polyamide mixture is found to be lower than in mixtures in which (micro-)phase separated domains are formed. The theory predicts up to 43% less moisture uptake in a homogeneous, 50/50 PA 46/PA 436 mixture compared to a phase separated mixture. Additionally, moisture uptake is marginally influenced by the volume of these domains and interfacial areas. The predictions regarding total miscibility and water absorption closely align with the experimental results obtained through dynamic vapor sorption measurements of moisture uptake. The proposed theoretical framework holds the potential to significantly contribute to the development of polyamides with optimized and more desirable properties.
塑料的基本特性（如使用寿命和机械强度）取决于其吸水性。特别是聚酰胺等聚缩聚物的吸水性在很大程度上取决于其成分。为了提高物理特性，可以设计聚酰胺混合物配方。在此，我们介绍了动态蒸汽吸附测量方法，提出了预测脂肪族聚酰胺混合物吸湿性的理论方法，并对理论和实验结果进行了比较。实验吸湿率是在很宽的相对湿度范围内，利用 10-15 毫克样品的重量差来测定的，其特异性为 0.1 微克。实验结果表明，吸湿性取决于成分和环境湿度。我们的理论模型在扩展 Flory-Huggins 理论时考虑了这些依赖性，并对 PA 46、PA 48、PA 412、PA 418 和 PA 436 的各种混合物的吸湿性进行了半定量预测。PA 46/PA 418 混合物的偏差最大，其中测量的吸湿率高于计算的 wt%。有了新定义的有效酰胺浓度，就可以用一条主曲线来预测不同聚酰胺组合的吸湿率与浓度的关系。研究发现，均质聚酰胺混合物的吸水率低于形成（微）相分离畴的混合物。根据理论预测，与相分离混合物相比，均质、50/50 PA 46/PA 436 混合物的吸湿率最高可降低 43%。此外，吸湿性受这些畴的体积和界面面积的影响很小。关于总混溶性和吸水性的预测与通过动态吸湿蒸汽测量获得的实验结果非常吻合。所提出的理论框架有望为开发具有优化和更理想特性的聚酰胺做出重大贡献。
{"title":"Water absorption in aliphatic polyamide mixtures","authors":"Stijn H.M. van Leuken , Judith J. van Gorp , Rolf A.T.M. van Benthem , Mark Vis , Remco Tuinier","doi":"10.1016/j.fluid.2024.114233","DOIUrl":"10.1016/j.fluid.2024.114233","url":null,"abstract":"<div><div>Essential properties of plastics, such as longevity and mechanical strength, depend on their water absorption capacity. In particular, the water uptake of polycondensates, like polyamides, strongly depends on their composition. To enhance physical characteristics, formulations of polyamide mixtures can be devised. Here, we present dynamic vapor sorption measurements, propose a theoretical approach to predict moisture uptake by aliphatic polyamide mixtures, and compare theoretical and experimental results. Experimental moisture uptake is determined for a wide range of relative humidities, using the weight difference of 10-15 mg samples measured with a specificity of <span><math><mrow><mn>0</mn><mo>.</mo><mn>1</mn><mspace></mspace><mi>μ</mi><mi>g</mi></mrow></math></span>. Our experimental results show that moisture uptake depends on composition and environmental humidity. Our theoretical model considers these dependencies in an extension of Flory–Huggins theory, and demonstrates semi-quantitative predictions of moisture absorption in various mixtures of PA 46, PA 48, PA 412, PA 418, and PA 436. The largest deviations are observed for the PA 46/PA 418 mixture, in which the measured moisture uptake is higher than the computed wt%. With a newly defined effective amide-concentration, the moisture uptake as a function of concentration can be predicted using a single master curve for different polyamide combinations. The absorption of water in a homogeneous polyamide mixture is found to be lower than in mixtures in which (micro-)phase separated domains are formed. The theory predicts up to 43% less moisture uptake in a homogeneous, 50/50 PA 46/PA 436 mixture compared to a phase separated mixture. Additionally, moisture uptake is marginally influenced by the volume of these domains and interfacial areas. The predictions regarding total miscibility and water absorption closely align with the experimental results obtained through dynamic vapor sorption measurements of moisture uptake. The proposed theoretical framework holds the potential to significantly contribute to the development of polyamides with optimized and more desirable properties.</div></div>","PeriodicalId":12170,"journal":{"name":"Fluid Phase Equilibria","volume":"588 ","pages":"Article 114233"},"PeriodicalIF":2.8,"publicationDate":"2024-09-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142356866","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
We investigate the phase behavior of associating fluids inside heterogeneous slit pores. Two distinct phase transitions are observed for connected pores of two slit widths for both hard and attractive walls. In the case of the hard wall, the wider pore undergoes the vapor-liquid transition earlier than the narrower pore due to its weaker confinement and increased fluid interactions. In the case of an attractive pore surface, the narrower pore undergoes the vapor-liquid transition earlier than the wider pore. This can be attributed to the enhanced surface interactions in the narrower pore, which promote the condensation of the fluid phase. The x-density profile of the systems reveals that the interfacial fluid molecules play an essential role in early/delayed phase transition in the respective pores of the heterogeneous systems.
我们研究了异质狭缝孔隙内关联流体的相行为。在硬壁和吸引壁两种狭缝宽度的连通孔隙中观察到两种截然不同的相变。在硬壁的情况下，较宽的孔隙比较窄的孔隙更早发生汽液转换，原因是较窄小的孔隙的封闭性较弱，流体间的相互作用增加。在孔隙表面有吸引力的情况下，较窄的孔隙比较宽的孔隙更早发生汽液转换。这可能是由于较窄孔隙中的表面相互作用增强，促进了流体相的凝结。系统的 x 密度曲线显示，界面流体分子在异质系统各自孔隙的早期/延迟相变中起着至关重要的作用。
{"title":"Effect of nanopore network connectivity on the phase behavior of confined associating fluids","authors":"Sashanka Sekhar Mandal , Sudhir Kumar Singh , Sandip Khan","doi":"10.1016/j.fluid.2024.114235","DOIUrl":"10.1016/j.fluid.2024.114235","url":null,"abstract":"<div><div>We investigate the phase behavior of associating fluids inside heterogeneous slit pores. Two distinct phase transitions are observed for connected pores of two slit widths for both hard and attractive walls. In the case of the hard wall, the wider pore undergoes the vapor-liquid transition earlier than the narrower pore due to its weaker confinement and increased fluid interactions. In the case of an attractive pore surface, the narrower pore undergoes the vapor-liquid transition earlier than the wider pore. This can be attributed to the enhanced surface interactions in the narrower pore, which promote the condensation of the fluid phase. The x-density profile of the systems reveals that the interfacial fluid molecules play an essential role in early/delayed phase transition in the respective pores of the heterogeneous systems.</div></div>","PeriodicalId":12170,"journal":{"name":"Fluid Phase Equilibria","volume":"588 ","pages":"Article 114235"},"PeriodicalIF":2.8,"publicationDate":"2024-09-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142322360","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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