| 1. |
- Ji, Linan, et al.
(författare)
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An overview of the progress of new working pairs in absorption heat pumps
- 2023
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Ingår i: Energy Reports. - : Elsevier Ltd. - 2352-4847. ; 9, s. 703-729
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Forskningsöversikt (refereegranskat)abstract
- Absorption heat pumps have emerged as a potential tool to address the energy crisis because of their ability to utilize low-grade heat. The performance of an absorption heat pump largely depends on the efficiency of the working pair to operate at the source temperature. The commercialized working pairs H2O/LiBr and NH3/H2O linger with operational and economic issues. Several binary/ternary combinations were tested among water, ammonia, salt, alcohols, hydrocarbons, and ionic liquids (ILs) in quest of the potential working pairs. The last decade has witnessed a stupendous surge in IL-based working pairs because of their several advantageous properties over the traditional solvents. The present review encompasses the research progress on various working pairs, in particular, their properties, modeling and correlation results, and coefficient of performance (COP) values.
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| 2. |
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| 3. |
- Ji, Xiaoyan, et al.
(författare)
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Thermodynamic and dynamic investigation for CO2 storage in deep saline aquifers
- 2011
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Ingår i: Proceedings of the World Renewable Energy Congress 2011 (WREC 2011). - Linköping : Linköping University Electronic Press.
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Konferensbidrag (refereegranskat)abstract
- Thermodynamic and dynamic investigations are needed to study the sequestration capacity, CO2 leakage, and environmental impacts. The results of the phase equilibrium and densities for CO2-sequestration related subsystems obtained from the proposed thermodynamic model on the basis of statistical associating fluid theory equation of state were summarized. Based on the equilibrium thermodynamics, preliminary kinetics results were also illustrated with chemical potential gradient as the driving force. The proposed thermodynamic model is promising to represent phase equilibrium and thermodynamic properties for CO2-sequestration related systems, i.e. CO2-(H2S)-H2O-ions (such as Na+, K+, Ca2+, Mg2+, Cl-, CO32-), and the implementation of thermodynamic model into kinetics model to adjust the non-ideality of species is vital because of the high pressure for the investigation of the sequestration process.
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| 4. |
- Ji, Yuanhui, et al.
(författare)
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Coupling mass transfer with mineral reactions to investigate CO2 sequestration in saline aquifers with non-equilibrium thermodynamics
- 2011
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Ingår i: Proceedings of the World Renewable Energy Congress 2011 (WREC 2011). - : Linköping University Electronic Press.
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Konferensbidrag (refereegranskat)abstract
- The coupling behaviors of mass transfer of aqueous CO2 with mineral reactions of aqueous CO2 with rock anorthite are investigated by chemical potential gradient and concentration gradient models, respectively. SAFT1-RPM is used to calculate the fugacity of CO2 in brine. The effective diffusion coefficients of CO2 are obtained based on the experimental kinetic data reported in literature. The calculation results by the two models and for two cases (mass transfer only and coupling mass transfer with mineral reaction) are compared. The results show that there are considerable discrepancies for the concentration distribution with distance by the concentration gradient and chemical potential gradient models, which implies the importance of consideration of the non-ideality. And the concentrations of aqueous CO2 at different distances by the concentration gradient model are higher and further than that by the chemical potential gradient model. The mineral reaction plays a considerable role for the CO2 geological sequestration when the time scale reaches 10 years for the anorthite case.
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| 5. |
- Ji, YuanHui, et al.
(författare)
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Modeling mass transfer of CO2 in brine at high pressures by chemical potential gradient
- 2013
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Ingår i: Science China Chemistry. - : Springer Science and Business Media LLC. - 1674-7291 .- 1869-1870. ; 56:6, s. 821-830
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Tidskriftsartikel (refereegranskat)abstract
- To investigate long-term CO2 behavior in geological formations and quantification of possible CO2 leaks, it is crucial to investigate the potential mobility of CO2 dissolved in brines over a wide range of spatial and temporal scales and density distributions in geological media. In this work, the mass transfer of aqueous CO2 in brines has been investigated by means of a chemical potential gradient model based on non-equilibrium thermodynamics in which the statistical associating fluid theory equation of state was used to calculate the fugacity coefficient of CO2 in brine. The investigation shows that the interfacial concentration of aqueous CO2 and the corresponding density both increase with increasing pressure and decreasing temperature; the effective diffusion coefficients decrease initially and then increase with increasing pressure; and the density of the CO2-disolved brines increases with decreasing CO2 pressure in the CO2 dissolution process. The aqueous CO2 concentration profiles obtained by the chemical potential gradient model are considerably different from those obtained by the concentration gradient model, which shows the importance of considering non-ideality, especially when the pressure is high.
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| 6. |
- Ji, Yuanhui, et al.
(författare)
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Modeling of specific structure crystallization coupling with dissolution
- 2010
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Ingår i: Frontiers of Chemical Science and Engineering. - : Springer Science and Business Media LLC. - 1673-7369. ; 4:1, s. 52-56
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Tidskriftsartikel (refereegranskat)abstract
- In this paper, the research framework for specific structure crystallization modeling has been proposed in which four steps are required in order to investigate the rigorous crystallization modeling by thermodynamics. The first is the activity coefficient model of the solution, the second is Solid-Liquid equilibrium, the third and fourth are the dissolution and crystallization kinetics modeling, respectively. Our investigations show that the mechanisms of complex structure formation and microphase transition can be analyzed by combining the dissolution and crystallization kinetics modeling. Moreover, the formation mechanism of the porous KCl has been analyzed, which may provide a reference for the porous structure formation in the advanced material synthesis
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| 7. |
- Ji, Yuanhui, et al.
(författare)
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Modeling the transport of CO2 in porous media with aqueous solutions by Gibbs free energy gradient
- 2010
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- The concentration of CO2 in atmosphere has been increasing greatly because of the fossil fuel combustion, which leads to a significant climate changes. CO2 is one of the most important greenhouse gases being responsible for about 64% of the enhanced "greenhouse effect" [1], and the disposal of anthropogenic CO2 has become an important issue of worldwide concern. Geological sequestration, generally refers to the injection of CO2 into deep geological formations such as deep saline aquifers, depleted hydrocarbon reservoirs or deep coalbeds, is attracting great attention [2] because of the large capacity and long residence time [3]. To predict the sequestration potential, to study the long-term behavior of CO2, and to estimate the potential for CO2 leakage in the geologic reservoirs, it is necessary to study the transport rate of CO2 in porous media with aqueous solutions. In the present work, the transport rate of CO2 in porous media with aqueous solutions is described and predicted by the Gibbs free energy gradient modeling based on linear nonequilibrium thermodynamics, and the Statistical Associating Fluid Theory equation of state is used to calculate the Gibbs free energy of the components in the investigated systems. The effects of temperature and pressure are analyzed.
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| 8. |
- Ji, Yuanhui, et al.
(författare)
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Modelling of mass transfer coupling with crystallization kinetics in microscale
- 2010
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Ingår i: Chemical Engineering Science. - : Elsevier BV. - 0009-2509 .- 1873-4405. ; 65:9, s. 2649-2655
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Tidskriftsartikel (refereegranskat)abstract
- Microstructure technologies have attracted interests in chemistry, chemical engineering, and biotechnology. To investigate the mass transfer of ions and crystallization of crystals in microscale and then to explain the formation mechanism of the porous structure materials, a microscale mathematical model for mass transfer processes coupling with local reactions is proposed in which the chemical potential gradient Δμ is used as the driving force to avoid the discontinuity of the kinetics equations in the micro-channels. Meanwhile, the dissolution kinetics of KCl at 298.15 K is measured to determine the dissolution rate constant kd and the average area of crystals Ac. The investigation for the fractional crystallization process of carnallite shows that the calculated mixing time versus channel width agree with the Einstein diffusion equation, which validates that the model can be used to describe the ion diffusion very well. Meanwhile, to have an accurate Δμ of KCl, in the channel width of or narrower than 2.0×10-6 m, it is enough to consider the diffusion only, while in the channel width of or wider than 2.0×10-5 m, diffusion should be coupled with reaction. The investigation also shows the vital of the consideration of the ionic activity coefficient for the investigated systems in micron scales. Moreover, the new formation mechanism of the porous structures in the inorganic material fabrication will be proposed from the process simulation for the synthesis of porous KCl, which will provide a reference for the porous structure formation in the advanced inorganic material synthesis.
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| 9. |
- Ji, Yuanhui, et al.
(författare)
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Progress in the study on the phase equilibria of the CO2-H2O and CO2-H2O-NaCl systems
- 2007
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Ingår i: Chinese Journal of Chemical Engineering. - 1004-9541 .- 2210-321X. ; 15:3, s. 439-448
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Tidskriftsartikel (refereegranskat)abstract
- To study the feasibility of CO2 geological sequestration, it is needed to understand the complicated multiple-phase equilibrium and the densities of aqueous solution with CO2 and multi-ions under wide geological conditions (273.15-473.15 K, 0-60 MPa), which are also essential for designing separation equipments in chemical or oil-related industries. For this purpose, studies on the relevant phase equilibria and densities are reviewed and analyzed and the method to improve or modify the existing model is suggested in order to obtain more reliable predictions in a wide temperature and pressure range. Besides, three different models (the electrolyte non random two-liquid (ELECNRTL), the electrolyte NRTL combining with Helgeson model (ENRTL-HG), Pitzer activity coefficient model combining with Helgeson model (PITZ-HG)) are used to calculate the vapor-liquid phase equilibrium of CO2-H2O and CO2-H2O-NaCl systems. For CO2-H2O system, the calculation results agree with the experimental data very well at low and medium pressure (0-20 MPa), but there are great discrepancies above 20 MPa. For the water content at 473.15 K, the calculated results agree with the experimental data quite well. For the CO2-H2O-NaCl system, the PITZ-HG model show better results than ELECNRTL and ENRTL-HG models at the NaCl concentration of 0.52 mol•L-1. Bur for the NaCl concentration of 3.997 mol•L-1, using the ELECNRTL and ENRTL-HG models gives better results than using the PITZ-HG model. It is shown that available experimental data and the thermodynamic calculations can satisfy the needs of the calculation of the sequestration capacity in the temperature and pressure range for disposal of CO2 in deep saline aquifers. More experimental data and more accurate thermodynamic calculations are needed in high temperature and pressure ranges (above 398.15 K and 31.5 MPa).
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| 10. |
- Ji, Yuanhui, et al.
(författare)
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Thermodynamic analysis on the mineralization of trace organic contaminants with oxidants in advanced oxidation processes
- 2009
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Ingår i: Industrial & Engineering Chemistry Research. - : American Chemical Society (ACS). - 0888-5885 .- 1520-5045. ; 48:23, s. 10728-10733
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Tidskriftsartikel (refereegranskat)abstract
- There is a growing demand for the efficient treatment of organic polluted wastewaters by advanced oxidation processes (AOPs) which calls for the determination of the mineralization order of ease for the organic contaminants with oxidants. The mineralization abilities of organic contaminants in AOPs are investigated in this work. Photocatalytic experiments for three representative organic contaminants are carried out, and their corresponding reaction rates are determined experimentally. Meanwhile, molar Gibbs free energy changes Delta(r)G(m)degrees for the reactions of 31 organic contaminants (10 chlorinated hydrocarbons, four brominated hydrocarbons, I I aromatic hydrocarbons and their derivatives, three chloroacetic acid, and three chloroacetyl chloride) with oxidants of (OH)-O-center dot, H2O2, O-center dot(-), O-3, and O-2 are calculated, and the mineralization order of ease is determined theoretically on the basis of Delta(r)G(m)degrees. The agreement of the theoretical and experimental mineralization abilities for most of the organic contaminants investigated implies the reliability of the determination of the mineralization ability from the magnitude of Delta(r)G(m)degrees for the mineralization of trace organic contaminants. Results also show that for most of the organic contaminants studied, the mineralization abilities are (OH)-O-center dot > H2O2 > O-center dot(-) > O-3 > O-2, and the mineralization ability of the organic contaminants depends on not only the oxidants but also the structure and properties of the organic contaminants themselves, and the degradation reaction products.
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| 11. |
- Ji, Yuanhui, et al.
(författare)
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Thermodynamic study on the reactivity of trace organic contaminant with the hydroxyl radicals in waters by advanced oxidation processes
- 2009
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Ingår i: Fluid Phase Equilibria. - : Elsevier BV. - 0378-3812 .- 1879-0224. ; 277:1, s. 15-19
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Tidskriftsartikel (refereegranskat)abstract
- This paper is to investigate the degradation abilities of various chlorinated aliphatics, benzene and its derivatives in order to treat organic polluted wastewaters efficiently by advanced oxidation processes (AOPs). A thermodynamic method is proposed to calculate the standard molar Gibbs energy of formation for aqueous organic species. Using the method proposed, the standard molar Gibbs energies of formation for 31 aqueous organic species are obtained. Moreover, the molar Gibbs energy change of reaction Δr Gm0 for the organic species with hydroxyl radicals is calculated from the standard molar Gibbs energy of formation for aqueous organic species to determine the degradation order of ease for the organic species. New photocatalytic experiments are carried out for the model verification. The calculation results of the model agree with the available and new experimental results. This work shows that the thermodynamics of the degradation reaction for the organic pollutants in AOPs can find the corresponding relationships with the degradation reaction rate by experimental measurements. The work in this paper represents a success of thermodynamics for the application in environmental area.
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| 12. |
- Lu, XiaoHua, et al.
(författare)
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Methodology of non-equilibrium thermodynamics for kinetics research of CO2 capture by ionic liquids
- 2012
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Ingår i: Science in China Series B. - : Springer Science and Business Media LLC. - 1674-7291 .- 1869-1870. ; 55:6, s. 1079-1091
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Forskningsöversikt (refereegranskat)abstract
- In this paper, the methodology of non-equilibrium thermodynamics is introduced for kinetics research of CO 2 capture by ionic liquids, and the following three key scientific problems are proposed to apply the methodology in kinetics research of CO 2 capture by ionic liquids: reliable thermodynamic models, interfacial transport rate description and accurate experimental flux. The obtaining of accurate experimental flux requires reliable experimental kinetics data and the effective transport area in the CO 2 capture process by ionic liquids. Research advances in the three key scientific problems are reviewed systematically and further work is analyzed. Finally, perspectives of non-equilibrium thermodynamic research of the kinetics of CO 2 capture by ionic liquids are proposed.
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| 13. |
- Shen, Gulou, et al.
(författare)
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Partition and selectivity of electrolytes in cylindrical nanopores with heterogeneous surface charge
- 2021
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Ingår i: Journal of Molecular Liquids. - : Elsevier. - 0167-7322 .- 1873-3166. ; 340
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Tidskriftsartikel (refereegranskat)abstract
- In this work, ion partitioning and selectivity in cylindrical nanopores with heterogeneous surface charges at equilibrium with reservoirs are investigated by a two-dimensional (2D) classical density functional theory (DFT). We present an efficient numerical method for the large 2D system in which the fast Hankel transform and fast Fourier transform are used to calculate convolution integrals, and a hybrid method of Picard iteration and Anderson mixing is used to solve the Euler-Lagrange equations. The performance of the 2D DFT is tested by calculating the profiles of a model electrolyte in long homogeneous cylindrical nanopores. The profiles from the 2D DFT model matches well with those from a 1D DFT, and the computing time of the hybrid iteration algorithm is six times shorter than that of pure Picard iteration. We apply the model to electrolytes in cylindrical nanopores with heterogeneous surface charges. It is found that the ion adsorption and selectivity are strongly affected by the surface charge pattern, the magnitude of the surface charge, the size of charged domains on the surface, and the pore size.
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| 14. |
- Wu, Nanhua
(författare)
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Molecular Thermodynamic Models for Nano-Micro Fluid/Solid Interfaces
- 2020
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Introducing materials with large interfaces to enhance process performance has become a feature of advanced chemical engineering, where the research focus has been changed from the traditional ideal isotropic fluid in the bulk phase to the highly non-ideal anisotropic confined fluid on the nano-micro interfaces, owing to the strong and asymmetric interactions between the complex fluids (supported metal nanoparticles, ionic liquids, proteins, etc.) and the sophisticated solid-surface (roughness, electrostatic effects, chemical heterogeneities, etc.). The traditional theories cannot be used to accurately describe the properties of the fluids at the complex solid-surfaces, due to the lack of considering molecular interactions between the fluid and solid-surface, and establishing new models is essential.In this thesis, a generalized interfacial molecular thermodynamic model was proposed with the consideration of molecular interactions between the fluid and solid-surface. Firstly, the original and surface-energy modified Gibbs-Thomson equations were analyzed to calculate the melting points of mono noble metals and compared with the literature data, highlighting the importance of developing new models with the consideration of the interfacial effect. An empirical model was proposed to represent the interfacial effect for calculating the melting points of mono noble metals. Then, the mono noble metal nanoparticle supported at the flat solid-surface was chosen as the “model” system to develop a generalized model, and the developed model was extended to the supported alloy systems. The CO2 absorption capacity (or solubility) of the ionic liquids immobilized on the porous solid materials (substrates) was further investigated with the developed model. The main results were summarized as follows:To develop models for representing the melting points of mono noble metal nanoparticles, the original and surface-energy modified Gibbs-Thomson equations were analyzed and then further modified empirically considering the effect of substrate. The results revealed that the original Gibbs–Thomson equation is invalid for the particles with radii smaller than 10 nm, and the performance of the surface-energy modified equation was improved but further modification by considering the interfacial effect is necessary for the particles smller than 5 nm in radius. The empirical model with the interfacial effect further improved the model performance, and the adjustable parameters can be predicted quantitatively from the thermodynamic properties of the metal and substrate. Additionally, the micro-wetting parameter αw can be used to qualitatively study the overall impact of the substrate on the melting point depression.Combined with the analysis of the corresponding state theory, a generalized molecular thermodynamic model was developed. It was found that, the developed generalized model can provide accurate results of melting points with deviations within ± 15 K. The developed model was used to predict the melting point of Pt nanoparticles on the substrates of TiO2 and carbon (C), and the results showed that Pt on TiO2 was more stable than that on C, being consistent with the newly measured experimental results.The generalized model was further parameterized based on the analysis of the interfacial tensions and molar volumes of Al-Si3N4, Pb-Si, Bi-C, and In-C, and the model showed the deviation was within ± 36 K. The model with fully generalized parameters was extended to the supported alloy nanoparticles to illustrate their stabilities, where the common catalysts, Pd-Au alloy nanoparticles supported on different substrates, developed for H2O2 reaction, were chosen as the examples. The model prediction displayed that the Pd-Au alloy nanoparticles supported on C/TiO2 (molar ratio: 0.01) with the mass proportion Pd5Au1 (i.e., mass ratio of 5:1) is more stable than the mono noble metals. Furthermore, the model prediction indicated that the supported alloy nanoparticles are more stable than the supported Pd.The generalized model was also successfully extended to study the CO2 absorption capacity in the immobilized ionic liquids, where the Gibbs free energy of CO2 in the immobilized ionic liquids was modeled from both macro- and micro-analyses. The theoretical investigations revealed that the substrate has a crucial effect on the gas solubility in the ionic liquid immobilized on the substrates, and the performance of the model with the consideration of surface-energy and interfacial effects was further verified with the newly determined experimental data.
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| 15. |
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| 16. |
- Zhang, Zhibo, et al.
(författare)
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Encapsulation of multiple enzymes in a metal–organic framework with enhanced electro-enzymatic reduction of CO2 to methanol
- 2021
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Ingår i: Green Chemistry. - : Royal Society of Chemistry. - 1463-9262 .- 1463-9270. ; 23:6, s. 2362-2371
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Tidskriftsartikel (refereegranskat)abstract
- Efficient enzymatic conversion of CO2 to methanol is limited by low CO2 solubility in water (33 mM), and the high-cost of the cofactor (NADH) hinders the potential large-scale application of CO2 enzymatic conversion. In this study, a bioelectrocatalytic system was established for tackling both these issues, and in this system enzymes were embedded in the metal–organic framework ZIF-8 via in situ encapsulation to increase the substrate (CO2) concentration and pre-concentrate NADH, and a Rh complex-grafted electrode was developed for regenerating NADH in a sustainable manner. The results showed that after encapsulation of enzymes in ZIF-8, the methanol concentration increased from 0.061 to 0.320 mM (5 fold) in three hours. Furthermore, after coupling with electrocatalytic NADH regeneration, the methanol concentration further increased to 0.742 mM (12 fold) compared to a free enzyme system. Overall, methanol was produced at a rate of 822 μmol g−1 h−1.
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| 17. |
- Ali, Asad, et al.
(författare)
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Emerging strategies and developments in oxygen reduction reaction using high-performance platinum-based electrocatalysts
- 2024
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Ingår i: Nano Reseach. - : Tsinghua University Press. - 1998-0124 .- 1998-0000. ; 17:5, s. 3516-3532
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Forskningsöversikt (refereegranskat)abstract
- The global practical implementation of proton exchange membrane fuel cells (PEMFCs) heavily relies on the advancement of highly effective platinum (Pt)-based electrocatalysts for the oxygen reduction reaction (ORR). To achieve high ORR performance, electrocatalysts with highly accessible reactive surfaces are needed to promote the uncovering of active positions for easy mass transportation. In this critical review, we introduce different approaches for the emerging development of effective ORR electrocatalysts, which offer high activity and durability. The strategies, including morphological engineering, geometric configuration modification via supporting materials, alloys regulation, core-shell, and confinement engineering of single atom electrocatalysts (SAEs), are discussed in line with the goals and requirements of ORR performance enhancement. We review the ongoing development of Pt electrocatalysts based on the syntheses, nanoarchitecture, electrochemical performances, and stability. We eventually explore the obstacles and research directions on further developing more effective electrocatalysts.
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| 18. |
- Ali, Asad, et al.
(författare)
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Gram-scale production of in-situ generated iron carbide nanoparticles encapsulated via nitrogen and phosphorous co-doped bamboo-like carbon nanotubes for oxygen evolution reaction
- 2023
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Ingår i: Materials Science for Energy Technologies. - : Elsevier. - 2589-2991. ; 6, s. 301-309
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Tidskriftsartikel (refereegranskat)abstract
- Optimizing electrocatalytic activity and recognizing the most reactive sites for oxygen evolution reaction (OER) electrocatalysts are valuable to the order of renewable power. In this research article, we explored an innovative in-situ annealing technique for constructing iron carbide nanoparticles (Fe3C NPs) encapsulated via nitrogen and phosphorous doped bamboo-shape carbon nanotubes (NP-CNTs) for OER. Interestingly, the constructed Fe3C NPs@NP-CNT-800 composite exhibited remarkable electrochemical operation and offered a stable current density of 10 mA/cm2 at a lower overpotential (280 mV) in an alkaline solution. Furthermore, an innovative Fe3C NPs@N,P-CNT-800 hybrid surpassed the standard RuO2 electrocatalyst in terms of OER performance and showed negligible degradation in chronoamperometric (21 h) and chronopotentiometry (3000 cycles) analyses. The remarkable performance and stability are ascribed to the Fe3C NPs, novel tubular bamboo-like morphology of its carbon materials, and heteroatom doping, which contribute to the electrochemical interfaces, large surface area, active catalytic sites, and rapid charge transfer kinetics.
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| 19. |
- An, Rong, et al.
(författare)
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Atomic force microscopy probing interactions and microstructures of ionic liquids at solid surfaces
- 2022
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Ingår i: Nanoscale. - : Royal Society of Chemistry. - 2040-3364 .- 2040-3372. ; :14, s. 11098-11128
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Forskningsöversikt (refereegranskat)abstract
- Ionic liquids (ILs) are room temperature molten salts that possess preeminent physicochemical properties and have shown great potential in many applications. However, the use of ILs in surface-dependent processes, e.g. energy storage, is hindered by the lack of a systematic understanding of the IL interfacial microstructure. ILs on the solid surface display rich ordering, arising from coulombic, van der Waals, solvophobic interactions, etc., all giving near-surface ILs distinct microstructures. Therefore, it is highly important to clarify the interactions of ILs with solid surfaces at the nanoscale to understand the microstructure and mechanism, providing quantitative structure–property relationships. Atomic force microscopy (AFM) opens a surface-sensitive way to probe the interaction force of ILs with solid surfaces in the layers from sub-nanometers to micrometers. Herein, this review showcases the recent progress of AFM in probing interactions and microstructures of ILs at solid interfaces, and the influence of IL characteristics, surface properties and external stimuli is thereafter discussed. Finally, a summary and perspectives are established, in which, the necessities of the quantification of IL–solid interactions at the molecular level, the development of in situ techniques closely coupled with AFM for probing IL–solid interfaces, and the combination of experiments and simulations are argued.
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| 20. |
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| 21. |
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| 22. |
- An, Rong, et al.
(författare)
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Ti–Si–Zr–Zn Nanometallic Glass Substrate with a Tunable Zinc Composition for Surface-Enhanced Raman Scattering of Cytochrome c
- 2023
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Ingår i: ACS Applied Materials and Interfaces. - : American Chemical Society (ACS). - 1944-8244 .- 1944-8252. ; 15:21, s. 25275-25284
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Tidskriftsartikel (refereegranskat)abstract
- As a remarkably powerful analytical technique, surface-enhanced Raman scattering (SERS) continues to find applications from molecular biology and chemistry to environmental and food sciences. In search of reliable and affordable SERS substrates, the development has moved from noble metals to other diverse types of structures, e.g., nano-engineered semiconductor materials, but the cost of the enhancement factors (EF) substantially decreasing. In this work, we employ biocompatible thin films of Ti–Si–Zr–Zn nanometallic glasses as the SERS substrates, while tuning the Zn composition. Aided by quartz crystal microbalance, we find that the composition of 4.3% Zn (Ti–Si–Zr–Zn4.3) gives an ultrasensitive detection of Cytochrome c (Cyt c) with an EF of 1.38 × 104, 10-fold higher than the previously reported EF in the semiconducting metal oxide nanomaterials, such as TiO2, and even comparable to the reported noble-metal-assisted semiconducting tungsten oxide hydrate. Ti–Si–Zr–Zn4.3 exhibits a stronger adhesion force toward Cyt c, which ensures the strong binding of Cyt c to the surface, facilitating the Cyt c adsorption onto the surface and thus enhancing the SERS signal. The high separation efficiency of photoinduced electrons and holes in Ti–Si–Zr–Zn4.3 is also acknowledged for promoting the SERS activity.
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| 23. |
- Bao, Ningzhong, et al.
(författare)
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Thermodynamic modeling and experimental verification for ion-exchange synthesis of K2O·6TiO2 and TiO2 fibers from K2O·4TiO2
- 2002
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Ingår i: Fluid Phase Equilibria. - 0378-3812 .- 1879-0224. ; 193, s. 229-243
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Tidskriftsartikel (refereegranskat)abstract
- A thermodynamic model was established to determine ion-exchange conditions for the synthesis of potassium hexatitanate (K2O·6TiO2) and titanium dioxide (TiO2) from potassium tetratitanate (K2O·4TiO2) fiber. In the proposed model equilibrium species in the solid phase and corresponding ion-exchange equilibrium constants at 298.15 K were determined from the experimental data of Sasaki et al. [Inorg. Chem. 24 (1985) 2265]. In order to verify the proposed model, prediction results were compared with experimental data determined in literature and those measured in this work. The comparison shows a good agreement. Based on this, the proposed model was also used to predict more extensive suitable conditions for the synthesis of K2O·6TiO2 and TiO2.
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| 24. |
- Bülow, M., et al.
(författare)
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Incorporating a concentration-dependent dielectric constant into ePC-SAFT. An application to binary mixtures containing ionic liquids
- 2019
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Ingår i: Fluid Phase Equilibria. - : Elsevier. - 0378-3812 .- 1879-0224. ; 492, s. 26-33
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Tidskriftsartikel (refereegranskat)abstract
- Primitive thermodynamic models for electrolyte solutions require the dielectric constant ε. This property strongly depends on the concentration of the electrolytes in the mixture. Neglecting this dependency might be reasonable for modeling solutions at low electrolyte concentrations. However, in solutions containing ionic liquids (ILs) and especially for the calculation of liquid-liquid equilibria (LLE) of systems with ILs, liquid phases often contain high IL concentrations. At such conditions, neglecting the influence of concentration on ε is an oversimplification. In this work, an approach to account for the concentration-dependent dielectric constant within the Debye-Hückel theory was implemented into electrolyte Perturbed-Chain Statistical Associating Fluid Theory (original ePC-SAFT). This new approach was then applied to model LLE of binary mixtures containing water and commonly used hydrophobic ILs. These common ILs are comprised of the IL-cations [C n mim] + , [C n py] + , [C n mpy] + , [C n mpyr] + , [C 4 m 4 py] + and the IL-anions [BF 4 ] - , [NTf 2 ] - , [PF 6 ] - , [TFO] - . The LLE of binary mixtures water + IL were modeled at ambient pressure and different temperatures with the new ePC-SAFT and with the original ePC-SAFT [Ji et al. DOI: 10.1016/j.fluid.2012.05.029] without the concentration-dependent ε. Overall, the new approach within ePC-SAFT shows superior modeling as well as correlation capability compared to original ePC-SAFT, which was concluded by comparing both models with LLE data from literature.
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| 25. |
- Cao, Jian, et al.
(författare)
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Heterogeneous consecutive reaction kinetics of direct oxidation of H2 to H2O2: Effect and regulation of confined mass transfer
- 2023
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Ingår i: Chemical Engineering Journal. - : Elsevier. - 1385-8947 .- 1873-3212. ; 455
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Tidskriftsartikel (refereegranskat)abstract
- Porous catalysts in heterogeneous reactions have played an important role in the modern chemical industry, but it is still challenging to quantitatively describe mass transfer and surface reaction behaviors of reactants in nano-confined space. Direct synthesis of hydrogen peroxide (H2O2) is considered as an attractive alternative to anthraquinone oxidation process, while the confined mass transfer of H2O2 in porous catalysts limits the reactivity. In this work, taking the consecutive reaction of H2O2 synthesis as an example, a quantitative method in modeling the effects of confined mass transfer on the reactivity was studied. More specifically, calorimetry was developed to characterize the confined structures of porous carbon experimentally, the linear nonequilibrium thermodynamics and the statistical mechanics method were further combined. Then, the heterogeneous consecutive reaction kinetics and the Thiele modulus influenced by confined mass transfer were modeled. Consequently, regulation strategies were proposed with the help of theoretical models. The optimized catalyst with biological skeleton carbon support and 0.5 wt% palladium loading shows an excellent catalytic performance. Lastly, for the mesoscience in heterogeneous reaction, the resistance was explored as a quantitative descriptor to compromise in the competition between mass transfer and surface reaction. The mesoscale structures were considered as the dynamic spatiotemporal distribution of substance concentrations, and the resistance minimization multi-scale (RMMS) model was proposed.
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| 26. |
- Carvalho, Lara, et al.
(författare)
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Alkali enhanced biomass gasification with in situ S capture and a novel syngas cleaning : Part 2: Techno-economic analysis
- 2018
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Ingår i: Energy. - : Elsevier. - 0360-5442 .- 1873-6785. ; 165:Part B, s. 471-482
-
Tidskriftsartikel (refereegranskat)abstract
- Previous research has shown that alkali addition has operational advantages in entrained flow biomass gasification and allows for capture of up to 90% of the biomass sulfur in the slag phase. The resultant low-sulfur content syngas can create new possibilities for syngas cleaning processes. The aim was to assess the techno-economic performance of biofuel production via gasification of alkali impregnated biomass using a novel gas cleaning systemcomprised of (i) entrained flow catalytic gasification with in situ sulfur removal, (ii) further sulfur removal using a zinc bed, (iii) tar removal using a carbon filter, and (iv) CO2 reductionwith zeolite membranes, in comparison to the expensive acid gas removal system (Rectisol technology). The results show that alkali impregnation increases methanol productionallowing for selling prices similar to biofuel production from non-impregnated biomass. It was concluded that the methanol production using the novel cleaning system is comparable to the Rectisol technology in terms of energy efficiency, while showing an economic advantagederived from a methanol selling price reduction of 2–6 €/MWh. The results showed a high level of robustness to changes related to prices and operation. Methanol selling prices could be further reduced by choosing low sulfur content feedstocks.
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| 27. |
- Chen, Jingjing, et al.
(författare)
-
A high efficient heat exchanger with twisted geometries for biogas process with manure slurry
- 2020
-
Ingår i: Applied Energy. - : Elsevier. - 0306-2619 .- 1872-9118. ; 279
-
Tidskriftsartikel (refereegranskat)abstract
- Heat-transfer enhancement in manure slurry is crucial for increasing the efficiency and production of biogas during anaerobic digestion in biogas plants. In this study, a novel heat exchanger with an optimal twisted geometry was developed based on the numerical screening of the twisted tubes with equilateral polygons, and experiments were conducted to validate the numerical results. It was observed that the SST k-ω model is more efficient than other turbulence models in representing the heat transfer performance of the twisted tubes, and the numerical model with a thermostatic wall can be used to reliably screen the twisted geometries. The twisted hexagonal tube has the optimal geometry, with enhancement capability of up to 1.4 times compared to that of the circular tube. The formation of high continuity regions with relatively strong heat-transfer rates along the heat-exchange wall is the main reason for the high performance during heat transfer. The external heating process was integrated in a full-scale biogas plant, and the model and algorithm were developed and validated with additional experiments to describe the overall performance of both conventional and screened optimal geometries under different conditions. It was observed that a profit equivalent to 39% of total production for a large-scale biogas plant can be achieved owing to energy conservation in external heating with the twisted hexagonal tubes.
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| 28. |
- Chen, Jingjing, et al.
(författare)
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Designing heat exchanger for enhancing heat transfer of slurries in biogas plants
- 2019
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Ingår i: Innovative Solutions for Energy Transitions. - : Elsevier. ; , s. 1288-1293
-
Konferensbidrag (refereegranskat)abstract
- Heat transfer geometries with enhanced performance for the slurries with high viscosity can improve the net raw biogas production in bio-methane process. In this study, the rheological properties of different slurries were tested, correlated and implemented to computational fluid dynamics (CFD). CFD was then used to screen a new geometry based on the twisted tube combined with mechanism study, and experimental testing was conducted for verification. It shows that the twisted hexagonal tube (THT) has the highest performance. The mechanism for enhancing the heat transfer with THT was mainly due to the effective shear rate. Furthermore, the waste-heat recovery with the THT heat exchanger in biogas production was estimated quantitatively and compared with the normal heat exchanger and scraped-surface heat exchanger (SSHE). Compared to the normal heat exchanger, for THT, the increase of net raw biogas production δNRBP can be up to 17%, while it is only up to 8.53% for SSHE. Besides, the external heating up processes with THT and normal heat exchanger were studied to estimate the heating time for different temperature fluctuations and power requirements of boiler. It is found that the process with THT can save 25-38% heating time for the anaerobic reactor compared to the normal heat exchanger. Therefore, designed THT heat exchanger is promising, and the developed methods can also be beneficial for studying other heat transfer processes.
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| 29. |
- Chen, Jingjing, et al.
(författare)
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Heat-transfer enhancement for corn straw slurry from biogas plants by twisted hexagonal tubes
- 2020
-
Ingår i: Applied Energy. - : Elsevier. - 0306-2619 .- 1872-9118. ; 262
-
Tidskriftsartikel (refereegranskat)abstract
- Heat-transfer geometries that enhance heat transfer performance for slurries increase the net raw biogas production in the bio-methane process. In this study, the precise temperature-dependent rheologies of corn straw slurry with 6 and 8% total solid were determined, collected, and modeled to conduct a numerical simulation via CFD, the first instance of such research. Subsequently, the reliability of the numerical results was verified with heat-transfer experiments. The heat-transfer performances of the circular, twisted square and twisted hexagonal tubes were estimated numerically, ultimately showing that the twisted hexagonal tube performed optimally with an enhancement factor of up to 2.0 in the turbulent region, compared to the circular tube. Based on the numerical results, the mechanism of heat-transfer enhancement was revealed, showing balanced radial mixing and the near-wall shear effect that leads to a strong and continuous shear rate under a considerable radial-flow intensity. An engineering equation was obtained for the performance evaluation, and the waste-heat recovery from corn straw slurry was analyzed, showing the twisted hexagonal tube can increase the net raw biogas production by up to 17.0% compared to the circular tube.
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| 30. |
- Chen, Jingjing
(författare)
-
Heat-transfer Enhancement for Slurries from Biogas Plants− Properties, processes, and thermal systems
- 2022
-
Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Biomethane production from renewable residues with anaerobic digestion gains increasing attention as a crucial alternative to petroleum fuels. It has been vigorously developed, but the large amounts of subsidy from the government indicate that the process efficiency needs to be further improved. For biomethane production, on the one hand, a great amount of heat needs to be used for heating the feeding slurry, sanitation of slurry, and maintaining the temperature in the large-scale reactors. On the other hand, a large amount of thermophilic effluent slurries brings a huge amount of waste heat, which can be recovered. This makes it important to study how to increase production by improving the thermal efficiency of biogas plants with novel heat exchangers. The working fluids in the biogas plants are the non-Newtonian and high-viscous slurries, and the conventional heat exchangers in biogas plants always show much lower performance compared to those in other industries. Normally, the slurries in the biogas plant consist of different substrates, including straw, manure, food waste, municipal sludge, and their mixtures, and various factors such as the amount and type of solids, particle size, shear rate, and temperature impact the rheological properties of the slurries, which makes the complexity in the rheological properties and the difficulty in developing novel heat exchangers.The development of heat exchangers calls for the rheological properties of slurries. However, to the best of our knowledge, only the rheology of manure slurry was systematically determined and modeled considering the effect of temperature. The lack of the rheological properties of slurries further hinders the design and development of novel geometries to enhance the heat transfer of the slurries. Correspondingly, the quantitative contribution and potential of the waste-heat recovery from the slurries to production using the enhanced geometry remain unclear. In this thesis work, to design novel geometry with heat-transfer enhancement for different slurries and determine its potential in thermal cycles in the full-scale biogas plants, firstly, the temperature-dependent rheological properties of the slurries, including the corn straw, food waste, and mixed slurries, were tested and modeled. It was found that these slurries possess strong shear-thinning behavior, the temperature has a significant impact on their dynamic viscosity, and the power-law model combined with the Arrhenius equation can describe the rheology well. Subsequently, with the reliable models of the rheological properties as the key input, Computational Fluid Dynamics simulations were conducted to screen different twisted geometries, determine the heat-transfer performance, and reveal the mechanism of the heat-transfer enhancement. Lab- and pilot-scale experiments were also conducted to validate the numerical results. The twisted hexagonal tubes show a positive enhancement factor up to 2.6 compared to normal heat exchangers in a wide range of operating conditions. The continuous and strong near-wall shear effect is the intrinsic reason for achieving a significant heat-transfer enhancement in the twisted hexagonal tubes. Moreover, the generalized engineering equations for predicting the effective shear rate and heat-transfer performance with measurable parameters were established and verified with both numerical and experimental results. Finally, the twisted-hexagonal-tube heat exchange was integrated with complete thermal cycles, including waste-heat recovery and external heating processes in the biogas plant, and the potential of increased production and profits were modeled and analyzed combined with the practical operating conditions in a full-scale biogas plant. It was found that for the waste-heat recovery using the twisted hexagonal tubes, the net raw biogas production can increase by up to 17.0 %, and for the external heating process, the increased profit equivalent to 39 % of total production can be achieved owing to energy conservation in external heating using the twisted-hexagonal-tube heat exchangers for a full-scale biogas plant.
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| 31. |
- Chen, Jingjing, et al.
(författare)
-
Heat-transfer Enhancement with Pulsating Flow in Twisted Hexagonal Tube for Manure Slurry from Biogas Plants
- 2020
-
Ingår i: Proceedings of 12th International Conference on Applied Energy. - : Applied Energy Innovation Institute (AEii).
-
Konferensbidrag (refereegranskat)abstract
- Biogas is one of the most crucial renewable energy and achieving high-efficient heat exchangers is the key to improve its production. In this study, the effect of pulsating flow on heat transfer in a twisted hexagonal tube with manure slurry was investigated for the first time by using computational fluid dynamics CFD. The performances of pulsating flows were simulated under different conditions, including the inlet velocity, frequency, and amplitude of pulsating flow in the twisted hexagonal tube with different torques. Pressure drops at different frequencies were further investigated. Moreover, the mechanism of heat-transfer enhancement was revealed with the evolution of the heat-transfer coefficient over time. It was found the pulsating flow achieves an 18.9% enhancement at low torque.
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| 32. |
- Chen, Jingjing, et al.
(författare)
-
Heat-transfer performance of twisted tubes for highly viscous food waste slurry from biogas plants
- 2022
-
Ingår i: Biotechnology for Biofuels and Bioproducts. - : Springer Nature. - 2731-3654. ; 15
-
Tidskriftsartikel (refereegranskat)abstract
- Background: The use of food waste as feedstock shows high production of biogas via anaerobic digestion, but requires efficient heat transfer in food waste slurry at heating and cooling processes. The lack of rheological properties hampered the research on the heat-transfer process for food waste slurry. Referentially, the twisted hexagonal and elliptical rubes have been proved as the optimal enhanced geometry for heat transfer of medium viscous slurries with non-Newtonian behavior and Newtonian fluids, respectively. It remains unknown whether improvements can be achieved by using twisted geometries in combination with food waste slurry in processes including heating and cooling.Results: Food waste slurry was observed to exhibit highly viscous, significant temperature-dependence, and strongly shear-thinning rheological characteristics. Experiments confirmed the heat-transfer enhancement of twisted hexagonal tubes for food waste slurry and validated the computational fluid dynamics-based simulations with an average deviation of 14.2%. Twisted hexagonal tubes were observed to be more effective at low-temperature differences and possess an enhancement factor of up to 2.75; while twisted elliptical tubes only exhibited limited heat-transfer enhancement at high Reynolds numbers. The heat-transfer enhancement achieved by twisted hexagonal tubes was attributed to the low dynamic viscosity in the boundary layer induced by the strong and continuous shear effect near the walls of the tube.Conclusions: This study determined the rheological properties of food waste slurry, confirmed the heat-transfer enhancement of the twisted hexagonal tubes experimentally and numerically, and revealed the mechanism of heat-transfer enhancement based on shear rate distributions.
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| 33. |
- Chen, Jingjing, et al.
(författare)
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Mechanism of waste-heat recovery from slurry by scraped-surface heat exchanger
- 2017
-
Ingår i: Applied Energy. - : Elsevier. - 0306-2619 .- 1872-9118. ; 207, s. 146-155
-
Tidskriftsartikel (refereegranskat)abstract
- Waste-heat recovery from discharged slurries can improve the net raw biogas production in the bio-methane process in order to meet the demand for a next-generation of anaerobic digestion. In this study, a numerical model of a scraped-surface heat exchanger was proposed with the consideration of the complete and precise rheological behaviour of the slurry of animal manure for the first time for achieving highly efficient waste-heat recovery. The rheological model results were verified with new experimental data measured in this work. Subsequently, the convective heat-transfer coefficient of the scraped-surface heat exchanger was calculated numerically with the proposed numerical model, and the performance was determined. Then, the contributions of waste-heat recovery from the slurry to the biogas production using a general shell-and-tube heat exchanger and the scraped-surface heat exchanger were calculated quantitatively and compared. For the case of scraped-surface heat exchanger, the increase of net raw biogas production can be up to 8.53%, which indicates that there is a great potential to increase the net raw biogas production in the bio-methane process using a scraped-surface heat exchanger with low-cost equipment and a compactible structure.
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| 34. |
- Chen, Jingjing, et al.
(författare)
-
Mechanism Study of Heat Transfer Enhancement Using Twisted Hexagonal Tube with Slurry from Biogas Plant
- 2017
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Ingår i: Energy Procedia. - : Elsevier. - 1876-6102. ; 142, s. 880-885
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Tidskriftsartikel (refereegranskat)abstract
- Waste-heat recovery from discharged slurries is important to improve the biogas production efficiency but still remains challenge duo to the special properties of slurries in anaerobic digestion process. In this work, numerical study was carried out to investigate the flow field, and heat transfer performance of slurry from biogas plant in the twisted hexagonal and other twisted tubes was simulated with computer fluid dynamic (CFD) for the first time. The numerical method was validated with experimental data from the literature. The heat transfer performance and flow resistance of twisted hexagon tube were calculated and compared with other types of twisted tubes. The enhancement factor of the twisted hexagonal tube reached to 2 and kept optimum at turbulence flow region compared to the twisted tubes with square and elliptical cross section. Meanwhile, the mechanism of heat transfer enhancement with different twisted tubes was further studied, and the optimal field synergy and minimum local circulation flow near the wall are the main reasons for the high performance and low flow resistance of the twisted hexagonal tube.
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| 35. |
- Chen, Jingjing, et al.
(författare)
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Mechanism Study of Waste Heat Recovery from Slurry by Surface Scraped Heat Exchanger
- 2017
-
Ingår i: Energy Procedia. - : Elsevier. - 1876-6102. ; 105, s. 1109-1115
-
Tidskriftsartikel (refereegranskat)abstract
- Waste-heat recovery from discharged slurries can improve the net raw biogas production in bio-methane process in order to meet the demand of a new generation of anaerobic digestion. In order to achieve a high efficient waste-heat recovery, in this work, a mathematical model of waste-heat recovery process with surface scraped heat exchanger (SSHE) was proposed with the consideration of the shear rate and temperature-dependent rheological behaviour. The convective heat transfer performance of SSHE was calculated numerically where slurry was considered. The contribution of waste heat recovery from the slurry to biogas production by SSHE and general shell-and-tube heat exchanger (STHE) were firstly calculated quantitatively, and the increase of net raw biogas production could be over 13.5% by SSHE with need of heat exchange area less than a quarter of STHE's, which showed a great potential to increase the net raw biogas production in bio-methane process with low equipment investments and more compactible structure.
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| 36. |
- Chen, Jingjing, et al.
(författare)
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Slippage on Porous Spherical Superhydrophobic Surface Revolutionizes Heat Transfer of Non-Newtonian Fluid
- 2022
-
Ingår i: Advanced Materials Interfaces. - : John Wiley & Sons. - 2196-7350. ; 9:34
-
Tidskriftsartikel (refereegranskat)abstract
- In this study, a new strategy to achieve high-efficient heat transfer for non-Newtonian fluids with slippage using a stably prepared superhydrophobic coating is presented. A superhydrophobic coating is prepared on the inner surface of a sleeve at specific shear stress. The slippage and heat-transfer processes of the typical non-Newtonian fluid–1% carboxymethyl cellulose solutions on the superhydrophobic coating are investigated simultaneously. A novel porous spherical type of superhydrophobic coating with a contact angle of 168° is obtained. It is found that the shear stress in electrodeposition is a key parameter to control the morphology and wetting ability of the superhydrophobic coating. The slip length and enhancement factor of heat transfer for the non-Newtonian fluid on the coating are found in a range of 20–900 µm and 1.47 experimentally. A new parameter is proposed as Reynolds number Re divided by the dimensionless slip length ls* (Re/ls*) for the heat-transfer enhancement with slippage, which can be used as the guide for designing coating and selecting the operating conditions. The Re/ls* is <4, which can enhance the heat transfer via the slippage.
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| 37. |
- Chen, Yifeng
(författare)
-
CO2 separation using ionic liquid-based absorbents : thermodynamics and kinetics
- 2020
-
Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Ionic liquids (ILs) have shown great potential to be used as absorbents for CO2 separation owing to their unique properties such as immeasurably low vapour pressure, high thermal stability, high CO2 affinity, and tunable structure. A huge amount of researches have been carried out, and most of them focused on developing novel ILs for CO2 separation. However, high viscosity will impede the IL-based absorbents for the large-scale applications in CO2 separation.The goal of this thesis was to develop IL-based hybrid green absorbents (i.e. choline-2-pyrrolidine-carboxylic acid/polyethylene glycol/H2O ([Cho][Pro]/PEG200/H2O) and 1-hexyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide/titanium dioxide /PEG200 ([Hmim][Tf2N]/TiO2/PEG200)) for CO2 separation, in which H2O and/or PEG200 were used as co-solvents to adjust the viscosity. A systematic study was conducted from pure to multi-component systems convering experimental measurements and theoretical modeling of thermdynmaics and kinetics, and thus the effects of co-solvents on properties, phase equilibria, and kinetics were also analyzed.To provide reliable and systematic properties and study the effect of H2O, the properties of PEG200 and PEG200/H2O were surveyed, evaluated, and correlated. The density and viscosity of [Cho][Pro]/PEG200/H2O were measured and correlated, and the excess mole volume and excess Gibbs energy of activation were estimated to understand the molecular structure and interactions between [Cho][Pro]/PEG200 and H2O. The results showed that H2O and PEG200 could decrease the viscosity of the hybrid absorbent significantly, and H2O interacted strongly with [Cho][Pro]/PEG200.To obtain reliable and systematic gas solibilities and analyze the effect of H2O, the solubilities of pure CO2, CH4, and N2 in PEG200 were surveyed, measured, evaluated, and described with theoretical models. The CO2, CH4, and N2 solubilities in PEG200/H2O were measured and described with the Redlich-Kwong Nonrandom-Two-Liquid (RK-NRTL) model. The CO2 solubilities in [Cho][Pro]/PEG200 and [Cho][Pro]/H2O were also surveyed, measured, evaluated, and described using the RK-NRTL model. Furthermore, CO2 solubility in the hybrid absorbent was predicted with the model and compared with the new experimental results. The further investigation showed that the formation of carbomate dominated the entire CO2 absorption process by [Cho][Pro]/PEG200/H2O, and the presence of H2O resulted in the formation of bicarbonate.To study the kinetics systematically combined with the effect of H2O, the liquid-side mass-transfer coefficients (kL) of [Cho][Pro]/PEG200/H2O were obtained from the CO2 diffusion coefficients () and the kL values in PEG200/H2O, in which was calculated from the density and viscosity of the hybrid absorbents, while the kL values in PEG200/H2O were measured experimentally. The reaction rate constant of CO2 in the hybrid absorbents was also estimated.Based on the systematic studies from experimental measurement and modeling, it showed that 30 wt%[Cho][Pro]/H2O + PEG200 could be promising for CO2 separation with the consideration of both thermodynamic and kinetic properties. In addition, the hybrid absorbent also showed the good recyclability.To use the confinement as the other strategy for further developing IL-based technology, the CO2 solubility in [Hmim][Tf2N]/TiO2/PEG200 with different ratios of [Hmim][Tf2N]/TiO2 was measured, and the Henry’s constant and absorption enthalpy of CO2 in the hybrid absorbent were calculated. The CO2 solubility in the hybrid absorbent was described with the Henry's law, the contribution of the confinement effect on the CO2 solubility was quantified, and the relationship between the roughness of TiO2 and molecular parameters was established. The results showed that the mass ratio of [Hmim][NTf2]/TiO2 in the hybrid absorbent should be lower than 5.72 %, where the contribution of confinement occupied around 20 % of the total CO2 absorption capacity in [Hmim][NTf2]/T500/PEG200. 2.88 wt%[Hmim][NTf2]/T500 + PEG200 could be promising for CO2 separation on aspects of CO2 capacity and absorption enthplay, and further study will be conducted on the properties and CO2 absorption kinetics.
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| 38. |
- Chen, Yifeng, et al.
(författare)
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CO2 absorption using a hybrid 1-hexyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide/titanium dioxide/polyethylene glycol absorbent
- 2021
-
Ingår i: Fluid Phase Equilibria. - : Elsevier. - 0378-3812 .- 1879-0224. ; 538
-
Tidskriftsartikel (refereegranskat)abstract
- Developing novel hybrid ionic liquid/porous material/co-solvent absorbents with the confinement effect is essential for CO2 separation. In this study, CO2 solubilities in 1-hexyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide/titanium dioxide/polyethylene glycol ([Hmim][Tf2N]/TiO2-PEG200) with different ratios of [Hmim][Tf2N]/TiO2 and various roughnesses of TiO2 (P25 and T500) were measured and described with the Henry's law. Furthermore, the contribution of the confinement effect on the CO2 solubility was quantified, and the relationship between the surface roughness and molecular parameters was established for predicting its contribution to the confinement effect. In addition, the hybrid absorbent was recycled by a multi-cycle experiment. The results show that the contribution of confinement effect on CO2 absorption capacity (on mass basis) and Gibbs free energy occupy around 24.5 % and 8.12 % in [Hmim][NTf2]/T500-PEG200 (w[Hmim][NTf2]/T500 = 2.88 wt%) at 308.2 K, respectively. The surface roughness can double the confinement effect. Based on the CO2 absorption capacity and enthalpy, [Hmim][NTf2]/T500-PEG200 (w[Hmim][NTf2]/T500 = 2.88 wt%) is a promising hybrid absorbent for CO2 separation.
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| 39. |
- Chen, Yifeng, et al.
(författare)
-
CO2 separation using a hybrid choline-2-pyrrolidine-carboxylic acid/polyethylene glycol/water absorbent
- 2020
-
Ingår i: Applied Energy. - : Elsevier. - 0306-2619 .- 1872-9118. ; 257
-
Tidskriftsartikel (refereegranskat)abstract
- Developing novel hybrid absorbents is essential for CO2 separation. In this study, the density and viscosity of a hybrid absorbent (choline-2-pyrrolidine-carboxylic acid/polyethylene glycol/water ([Cho][Pro]/PEG200/H2O)) were measured experimentally, and its CO2 solubility was also determined. The excess mole volume and excess Gibbs energy of activation of the hybrid absorbent were further estimated to understand the molecular structure and interactions between [Cho][Pro]/PEG200 and H2O. The CO2 solubilities in [Cho][Pro]/PEG200 and [Cho][Pro]/H2O were analyzed and described using the Redlich–Kwong non-random-two-liquid (RK-NRTL) model. Furthermore, the CO2 solubility in the hybrid absorbent was predicted using the RK-NRTL model and was compared with the new experimental results for verification. The effect of H2O on the CO2 absorption performance was further analyzed. The performance and cost of the hybrid absorbent were compared with those of other commercialized CO2 absorbents. In addition, the recyclability of the hybrid absorbent for CO2 separation was studied. The results of this study indicated that the hybrid absorbent could be promising for CO2 separation.
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| 40. |
- Chen, Yifeng, et al.
(författare)
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Developing aqueous porous carbons for biogas upgrading
- 2024
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Ingår i: Separation and Purification Technology. - : Elsevier B.V.. - 1383-5866 .- 1873-3794. ; 329
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Tidskriftsartikel (refereegranskat)abstract
- Developing novel sorbents is essential for biogas upgrading. In this study, mixed sorbents of aqueous porous carbons were developed to separate CO2 from the biogas, where the porous carbon with the developed micropore structure was identified as the most desirable constituent. Both thermodynamics and kinetics were studied experimentally, and Henry’s constant (KH) and the liquid-side mass-transfer coefficient (kL) of CO2 in the mixed sorbent as well as the selectivity of CO2/CH4 were obtained accordingly. Furthermore, the CO2 separation performance was evaluated with a proposed index, and the cost of biogas upgrading using the mixed sorbent was estimated and compared. The results showed that the porous carbon with the developed micropore structure led to better performance on KH and kL of CO2 in the mixed sorbent, and the mixed sorbent with 3.03 wt% porous carbon exhibited the best CO2 separation performance, reducing 36.2 % in cost compared to the current technologies.
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| 41. |
- Chen, Yifeng, et al.
(författare)
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Developing hybrid 1-hexyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide/titanium dioxide/water absorbent for CO2 separation
- 2022
-
Ingår i: Applied Energy. - : Elsevier Ltd. - 0306-2619 .- 1872-9118. ; 326
-
Tidskriftsartikel (refereegranskat)abstract
- The development of novel absorbents is essential for improving CO2 separation technology. In this study, 1-hexyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide/titanium dioxide/water ([Hmim][NTf2]/TiO2-H2O) was developed to separate CO2, where the thermodynamic and kinetic experiments were conducted, and Henry's constant and the liquid-side mass-transfer coefficient were determined accordingly. Furthermore, CO2 separation performance in a bubble tower was validated. A previously proposed index named “absorption ability” (AA) was used to predict and compare the experimental results. Additionally, the cost of biogas upgrading (i.e., CO2 removal for biogas purification) using [Hmim][NTf2]/TiO2-H2O was estimated. The results showed that for the developed [Hmim][NTf2]/TiO2-based technology, the average CO2 mass-transfer rate was increased by 20.0% compared with the current commercialized technology, and the contributions from the thermodynamic and kinetic aspects were 2.5% and 17.5%, respectively. The cost of biogas upgrading was 16.6% lower. In addition, AA successfully predicted the performance of CO2 separation technologies, achieving an average relative deviation of 8.1%.
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| 42. |
- Chen, Yifeng, et al.
(författare)
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Kinetics study and performance comparison of CO2 separation using aqueous choline-amino acid solutions
- 2021
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Ingår i: Separation and Purification Technology. - : Elsevier. - 1383-5866 .- 1873-3794. ; 261
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Tidskriftsartikel (refereegranskat)abstract
- The thermodynamic and kinetic properties of CO2 in aqueous choline-amino acids ([Cho][AA]s) are important information to demonstrate their performance. In this study, the apparent kinetic properties of CO2 in the five aqueous [Cho][AA]s, including the liquid-side mass-transfer coefficients, enhancement factor, and reaction rate constant, were systematically studied. Furthermore, a new ‘‘absorption ability’’ (AA) index was proposed, combining the apparent kinetic properties determined in this study and thermodynamic properties determined in our previous study. The CO2 separation performance using aqueous [Cho][AA]s was evaluated based on the AA and CO2 desorption enthalpy values. The results show that 30 wt% aqueous choline-serine is a promising absorbent for CO2 separation, and it is comparable to aqueous monoethanolamine.
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| 43. |
- Chen, Yifeng, et al.
(författare)
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Kinetics study and performance evaluation of a hybrid choline-glycine/polyethylene glycol/water absorbent for CO2 separation
- 2023
-
Ingår i: Separation and Purification Technology. - : Elsevier B.V.. - 1383-5866 .- 1873-3794. ; 304
-
Tidskriftsartikel (refereegranskat)abstract
- Thermodynamic and kinetic properties of absorbents are beneficial in evaluating their CO2 separation performance. In this study, the kinetic properties of CO2 in a hybrid choline-glycine/polyethylene glycol/water absorbent, including the liquid-side mass-transfer coefficient, enhancement factor, and reaction rate constant, were systematically determined through experimental measurements and data processing. Furthermore, an index referred to as “absorbility” was proposed to combine the kinetic properties determined in this study with the thermodynamic properties obtained in our previous study to evaluate the CO2 separation performance. Additionally, the regeneration performance of the hybrid absorbent was also conducted. The results show that the performance of the hybrid absorbent (30 wt% [Cho][Gly] + 10 wt% PEG200 + 60 wt% H2O) is comparable to that of aqueous monoethanolamine, and is thus promising for CO2 separation, considering its low regeneration temperature and low environmental impact.
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| 44. |
- Chen, Yifeng, et al.
(författare)
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Mass-transfer kinetics of CO2 in a hybrid choline-2-pyrrolidine-carboxylic acid/polyethylene glycol/water absorbent
- 2021
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Ingår i: Journal of Molecular Liquids. - : Elsevier. - 0167-7322 .- 1873-3166. ; 336
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Tidskriftsartikel (refereegranskat)abstract
- Understanding the mass-transfer kinetics of CO2 in novel hybrid absorbents with physical and chemical contributions is essential for process design and evaluation. In this study, the liquid-side mass-transfer coefficients (kL) and second-order reaction rate constants (k2) of CO2 in hybrid absorbents (namely, choline-2-pyrrolidine-carboxylic acid salt/polyethylene glycol/water ([Cho][Pro]/PEG200/H2O)) were determined. The kL values for the hybrid absorbents were obtained from the CO2 diffusion coefficients (DCO2) and the kL values in PEG200/H2O. The DCO2 value was calculated from the density and viscosity of the hybrid absorbents, whereas the kL values in PEG200/H2O were measured experimentally. The k2 values of CO2 in the hybrid absorbents were estimated according to the reaction mechanism, the enhancement factor, and the kL values, and compared with those of other commercialized absorbents. The results showed that 30 wt% [Cho][Pro]+70 wt% H2O had the highest kL and k2 values at atmospheric pressure, whereas the values of kL and k2 of CO2 in 30 wt% [Cho][Pro]/H2O+PEG200 were comparable to those in diethanolamine aqueous and amino-functionalized ILs. The hybrid absorbent of [Cho][Pro]/PEG200/H2O could be promising for CO2 separation considering its thermodynamic and kinetic properties.
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| 45. |
- Chen, Yifeng, et al.
(författare)
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Novel Solvent for CO2 Capture
- 2019
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Ingår i: Energy Procedia. - : Elsevier. - 1876-6102. ; 158, s. 5124-5129
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Tidskriftsartikel (refereegranskat)abstract
- To develop novel solvent for CO2 capture, CO2 absorption performance using the aqueous of polyethylene glycol 200 (PEG200) and choline-2-pyrrolidinecarboxylic acid ([Cho][Pro]) was studied and evaluated systematically in this work, in which the critical properties of PEG200 were estimated with group contribution method, and other thermo-physical properties were determined experimentally or taken from literatures directly and then correlated with empirical equations. The CO2 solubility in PEG200 was measured and represented with the Henry’s law and Poynting correction, while the measured CO2 solubility in PEG200/H2O was correlated with RK-NRTL model. [Cho][Pro] was used as the chemical ingredient to enhance the absorption capacity and rate of CO2 in [Cho][Pro]/PEG200/H2O, and the corresponding properties and CO2 solubility were studied. The kinetic parameters, such as enhancement factor (E), reaction rate constant (k), and activation energy (Ea) of CO2 in [Cho][Pro]/PEG200/H2O were estimated from the new experimental data measured in this work and compared with the commercialized aqueous MEA solution. The process simulation and pilot-testing based on [Cho][Pro]/PEG200/H2O will be performed in the future.
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| 46. |
- Chen, Yifeng, et al.
(författare)
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Thermodynamic Study for Gas Absorption in Choline-2-pyrrolidine-carboxylic Acid + Polyethylene Glycol
- 2016
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Ingår i: Journal of Chemical and Engineering Data. - : American Chemical Society (ACS). - 0021-9568 .- 1520-5134. ; 61:10, s. 3428-3437
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Tidskriftsartikel (refereegranskat)abstract
- The solubility of pure CO2, CH4, and N2 in the mixture of choline-2-pyrrolidine carboxylic acid ([Cho][Pro]) and polyethylene glycol (PEG200) (mass ratio = 1:2) was measured experimentally at temperatures from 308.15 to 338.15 K and pressures up to 28 bar, in which [Cho][Pro] is an ionic liquid and PEG200 is a cosolvent with the purpose to decrease the viscosity. It was found that [Cho][Pro]/PEG200 showed a good selectivity for CO2/CH4 and CO2/N2 separation. The measured experimental data points from this work and others were further used to estimate the thermodynamic properties including the Henry's law constants for the gases in [Cho][Pro]/PEG200, the equilibrium constant for the reaction between CO2 and [Cho][Pro], the CO2 absorption enthalpy in [Cho][Pro]/PEG200, and so forth. The consistent results of the CO2 absorption enthalpy at infinite dilution prove the reliability of the thermodynamic properties obtained in this work. The thermodynamic properties of [Cho][Pro]/PEG200 were further compared with other three typical absorbents, and the absorption enthalpy is nearly half of that for 30 wt % MEA aqueous solution. At the same time, the theoretical amount of absorbents needed for [Cho][Pro]/PEG200 is much lower than that of H2O scrubbing. This shows that [Cho][Pro]/PEG200 is a promising absorbent
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| 47. |
- Chen, Yifeng, et al.
(författare)
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Thermodynamic study on aqueous polyethylene glycol 200 solution and performance assessment for CO2 separation
- 2020
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Ingår i: Fluid Phase Equilibria. - : Elsevier. - 0378-3812 .- 1879-0224. ; 504
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Tidskriftsartikel (refereegranskat)abstract
- To develop polyethylene glycol 200 (PEG200) and aqueous PEG200 solutions (PEG200/H2O) as solvents for CO2 separation, in this study, the available thermo-physical properties of PEG200 and PEG200/H2O measured experimentally were surveyed, evaluated, and correlated with empirical equations. The solubility of CO2 in PEG200 was also surveyed, evaluated and described with the Henry's law with the Poynting correction, while the solubilities of CH4 and N2 in PEG200 were determined experimentally and then described with the Henry's law. The CO2, CH4 and N2 solubilities in PEG200/H2O were measured and described with the Redlich–Kwong Nonrandom-Two-Liquid (RK-NRTL) model. In addition, the performances of PEG200, PEG200/H2O and other commercialized physical solvents for CO2 separation were discussed based on the properties, and the biogas upgrading was chosen as the example to quantitatively evaluate the performances of PEG200 and PEG200/H2O with process simulation and compared with the high pressure water scrubbing (HPWS). It shows that the total energy usage and the amount of recirculated solvent for biogas upgrading can decrease by 9.1% and 26.5%, respectively, when H2O is replaced by PEG200 completely.
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| 48. |
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| 49. |
- Dai, Fei, et al.
(författare)
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Recent Progress on Hydrogen-Rich Syngas Production from Coal Gasification
- 2023
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Ingår i: Processes. - : MDPI. - 2227-9717. ; 11:6
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Tidskriftsartikel (refereegranskat)abstract
- Coal gasification is recognized as the core technology of clean coal utilization that exhibits significant advantages in hydrogen-rich syngas production and CO2 emission reduction. This review briefly discusses the recent research progress on various coal gasification techniques, including conventional coal gasification (fixed bed, fluidized bed, and entrained bed gasification) and relatively new coal gasification (supercritical water gasification, plasma gasification, chemical-looping gasification, and decoupling gasification) in terms of their gasifiers, process parameters (such as coal type, temperature, pressure, gasification agents, catalysts, etc.), advantages, and challenges. The capacity and potential of hydrogen production through different coal gasification technologies are also systematically analyzed. In this regard, the decoupling gasification technology based on pyrolysis, coal char–CO2 gasification, and CO shift reaction shows remarkable features in improving comprehensive utilization of coal, low-energy capture and conversion of CO2, as well as efficient hydrogen production. As the key unit of decoupling gasification, this work also reviews recent research advances (2019–2023) in coal char–CO2 gasification, the influence of different factors such as coal type, gasification agent composition, temperature, pressure, particle size, and catalyst on the char–CO2 gasification performance are studied, and its reaction kinetics are also outlined. This review serves as guidance for further excavating the potential of gasification technology in promoting clean fuel production and mitigating greenhouse gas emissions.
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| 50. |
- Dai, Zhengxing, et al.
(författare)
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Melting points of ionic liquids: Review and evaluation
- 2024
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Forskningsöversikt (refereegranskat)abstract
- The melting points of ionic liquids (ILs) reported since 2020 were surveyed, collected, and reviewed, which were further combined with the previous data to provide a database with 3129 ILs ranging from 177.15 to 645.9 K in melting points. In addition, the factors that affect the melting point of ILs from macro, micro, and thermodynamic perspectives were summarized and analyzed. Then the development of the quantitative structure-property relationship (QSPR), group contribution method (GCM), and conductor-like screening model for realistic solvents (COSMO-RS) for predicting the melting points of ILs were reviewed and further analyzed. Combined with the evaluation together with the preliminary study conducted in this work, it shows that COSMO-RS is more promising and possible to further improve its performance, and a framework was thus proposed.
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