| 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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