Pub Date : 2026-01-23DOI: 10.1016/j.supflu.2026.106915
Yung-Chun Yang , Hsu-Chen Wang , Chie-Shaan Su , Chieh-Ming Hsieh
The solubility of pharmaceutical compounds in supercritical carbon dioxide (scCO2) is crucial for process development. In this study, the solubility of levofloxacin and metacetamol was measured using a high-pressure semi-flow apparatus at 313.2 K, 323.2 K, and 333.2 K, over a pressure range of 12 MPa to 24 MPa for levofloxacin and 12 MPa to 22 MPa for metacetamol. Solubilities (in mole fraction) ranged from 1.51 × 10−7 to 2.71 × 10−6 for levofloxacin and from 8.00 × 10−7 to 7.32 × 10−6 for metacetamol. Semi-empirical correlations proposed by Chrastil, Mendez-Santiago & Teja, Kumar & Johnston, and Bartle reproduced the data with average absolute relative deviations (AARD-y) of 2.89–3.90 % for levofloxacin and 2.64–6.73 % for metacetamol. Two thermodynamic models based on the Peng-Robinson equation of state (PR EOS), PR+VDW and PR+MHV1 +Wilson, were also used to correlate the data, giving AARD values of 8.53 % and 23.6 % for levofloxacin, and 4.53 % and 8.21 % for metacetamol, respectively. In addition, the PR EOS was combined with COSMO-SAC through the MHV1 mixing rule to enable solubility prediction without adjusting system-specific parameters. This predictive framework yielded average logarithmic deviation (ALD-y) values of 0.229 for levofloxacin and 0.169 for metacetamol, corresponding to AARDs of 39.5 % and 48.7 %.
{"title":"Measurement and prediction of levofloxacin and metacetamol solubility in supercritical carbon dioxide","authors":"Yung-Chun Yang , Hsu-Chen Wang , Chie-Shaan Su , Chieh-Ming Hsieh","doi":"10.1016/j.supflu.2026.106915","DOIUrl":"10.1016/j.supflu.2026.106915","url":null,"abstract":"<div><div>The solubility of pharmaceutical compounds in supercritical carbon dioxide (scCO<sub>2</sub>) is crucial for process development. In this study, the solubility of levofloxacin and metacetamol was measured using a high-pressure semi-flow apparatus at 313.2 K, 323.2 K, and 333.2 K, over a pressure range of 12 MPa to 24 MPa for levofloxacin and 12 MPa to 22 MPa for metacetamol. Solubilities (in mole fraction) ranged from 1.51 × 10<sup>−7</sup> to 2.71 × 10<sup>−6</sup> for levofloxacin and from 8.00 × 10<sup>−7</sup> to 7.32 × 10<sup>−6</sup> for metacetamol. Semi-empirical correlations proposed by Chrastil, Mendez-Santiago & Teja, Kumar & Johnston, and Bartle reproduced the data with average absolute relative deviations (AARD-<em>y</em>) of 2.89–3.90 % for levofloxacin and 2.64–6.73 % for metacetamol. Two thermodynamic models based on the Peng-Robinson equation of state (PR EOS), PR+VDW and PR+MHV1 +Wilson, were also used to correlate the data, giving AARD values of 8.53 % and 23.6 % for levofloxacin, and 4.53 % and 8.21 % for metacetamol, respectively. In addition, the PR EOS was combined with COSMO-SAC through the MHV1 mixing rule to enable solubility prediction without adjusting system-specific parameters. This predictive framework yielded average logarithmic deviation (ALD-<em>y</em>) values of 0.229 for levofloxacin and 0.169 for metacetamol, corresponding to AARDs of 39.5 % and 48.7 %.</div></div>","PeriodicalId":17078,"journal":{"name":"Journal of Supercritical Fluids","volume":"232 ","pages":"Article 106915"},"PeriodicalIF":4.4,"publicationDate":"2026-01-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146033094","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-01-21DOI: 10.1016/j.supflu.2026.106904
Houdong Shi , Bingguo Zhu , Qing Zhang
This study proposes a novel non-uniform variable cross-section zigzag printed circuit heat exchanger (UZPCHE) to address the demand for high-performance and compact heat exchangers in the precooler of the supercritical CO2 Brayton cycle (SCO2-BC). Three geometric parameters including the variable diameter (d1) and the inner and outer chord lengths (L1 and L2) of the turning region are selected as design variables, with the Nusselt number (Nu), friction factor (f), and compactness performance (Q/V) as optimization objectives. A quadratic response surface model (RSM) is established using the Box–Behnken design, and grey relational analysis (GRA) is employed to elucidate the influence degree of geometric parameters on thermal–hydraulic performance. Subsequently, a multi-objective optimization framework integrating the non-dominated sorting genetic algorithm II (NSGA-II) and the technique for order preference by similarity to ideal solution (TOPSIS) is applied to derive the optimal compromise design. The results indicate that the developed RSM exhibits high predictive accuracy. The d1 is identified as the dominant parameter, contributing approximately 38 % to the objective functions. The optimized non-uniform variable-cross-section printed circuit heat exchanger (UZPCHE, d1 = 1.2 mm, L1 = 2.5 mm, L2 = 2.7 mm) exhibits superior thermohydraulic performance (PEC=1.173) compared to the traditional zigzag printed circuit heat exchanger (TZPCHE), wavy channel printed circuit heat exchanger (WAPCHE), and straight channel printed circuit heat exchanger (STPCHE). Furthermore, the optimized UZPCHE reduces the maximum equivalent stress in the solid region compared to the TZPCHE. These findings provide valuable insights for the structural optimization of printed circuit heat exchangers in supercritical CO2 power systems.
针对超临界CO2布雷顿循环（SCO2-BC）预冷器对高性能紧凑型换热器的需求，提出了一种新型非均匀可变截面之字印刷电路换热器（UZPCHE）。选取车体变径（d1）和内外弦长（L1和L2） 3个几何参数作为设计变量，以努塞尔数（Nu）、摩擦系数(f)和紧致性能（Q/V）为优化目标。采用Box-Behnken设计方法建立了二次响应面模型（RSM），并采用灰色关联分析（GRA）分析几何参数对热工性能的影响程度。随后，将非支配排序遗传算法II （NSGA-II）与理想解相似性排序偏好技术（TOPSIS）相结合，建立了多目标优化框架，推导出最优妥协设计。结果表明，该方法具有较高的预测精度。d1被确定为主导参数，对目标函数的贡献约为38% %。优化后的非均匀变截面印刷电路换热器（UZPCHE, d1 = 1.2 mm, L1 = 2.5 mm, L2 = 2.7 mm）与传统的之字形印刷电路换热器（TZPCHE）、波浪形印刷电路换热器（WAPCHE）和直线型印刷电路换热器（STPCHE）相比，具有更好的热液性能（PEC=1.173）。此外，与TZPCHE相比，优化后的UZPCHE降低了固体区的最大等效应力。这些发现为超临界CO2电力系统中印刷电路热交换器的结构优化提供了有价值的见解。
{"title":"Multi-objective optimization of a novel non-uniform variable cross-section zigzag printed circuit heat exchanger for supercritical CO2 Brayton Cycle","authors":"Houdong Shi , Bingguo Zhu , Qing Zhang","doi":"10.1016/j.supflu.2026.106904","DOIUrl":"10.1016/j.supflu.2026.106904","url":null,"abstract":"<div><div>This study proposes a novel non-uniform variable cross-section zigzag printed circuit heat exchanger (UZPCHE) to address the demand for high-performance and compact heat exchangers in the precooler of the supercritical CO<sub>2</sub> Brayton cycle (SCO<sub>2</sub>-BC). Three geometric parameters including the variable diameter (<em>d</em>1) and the inner and outer chord lengths (<em>L</em>1 and <em>L</em>2) of the turning region are selected as design variables, with the Nusselt number (<em>Nu</em>), friction factor (<em>f</em>), and compactness performance (<em>Q/V</em>) as optimization objectives. A quadratic response surface model (RSM) is established using the Box–Behnken design, and grey relational analysis (GRA) is employed to elucidate the influence degree of geometric parameters on thermal–hydraulic performance. Subsequently, a multi-objective optimization framework integrating the non-dominated sorting genetic algorithm II (NSGA-II) and the technique for order preference by similarity to ideal solution (TOPSIS) is applied to derive the optimal compromise design. The results indicate that the developed RSM exhibits high predictive accuracy. The <em>d</em>1 is identified as the dominant parameter, contributing approximately 38 % to the objective functions. The optimized non-uniform variable-cross-section printed circuit heat exchanger (UZPCHE, <em>d</em>1 = 1.2 mm, <em>L</em>1 = 2.5 mm, <em>L</em>2 = 2.7 mm) exhibits superior thermohydraulic performance (PEC=1.173) compared to the traditional zigzag printed circuit heat exchanger (TZPCHE), wavy channel printed circuit heat exchanger (WAPCHE), and straight channel printed circuit heat exchanger (STPCHE). Furthermore, the optimized UZPCHE reduces the maximum equivalent stress in the solid region compared to the TZPCHE. These findings provide valuable insights for the structural optimization of printed circuit heat exchangers in supercritical CO<sub>2</sub> power systems.</div></div>","PeriodicalId":17078,"journal":{"name":"Journal of Supercritical Fluids","volume":"232 ","pages":"Article 106904"},"PeriodicalIF":4.4,"publicationDate":"2026-01-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146014436","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-01-21DOI: 10.1016/j.supflu.2026.106903
Zhaoyang Yuan , Xuanang Zhang , Jintao He , Yonghao Zhang , Jie Yu , Zhen Wang , Lingfeng Shi , Hua Tian , Gequn Shu
The integration of a lead-bismuth fast reactor (LFR) with a transcritical CO2 (T-CO2) power cycle represents a promising offshore nuclear energy solution. Although prior research has advanced the primary and secondary circuits separately, their dynamic interactions under tightly coupled conditions remain insufficiently explored. This work establishes a dynamic system model to investigate bidirectional disturbance propagation and load-following coordination between the two circuits. Results indicate that reducing reactor power by 5 % and 10 % decreases secondary circuit output by 13.8 % and 28.4 %, respectively. Variations in secondary circuit parameters, such as pump speed and cold source temperature, alter the CO2 mass flow rate and evaporator heat transfer, leading to temperature changes in the primary coolant. Through inherent temperature feedback, the reactor autonomously adjusts its power, demonstrating strong closed-loop coupling. Notably, pump speed has a greater influence on secondary circuit output than cold source temperature, contributing approximately 5.6 % more to the output work variation. During load following, adjusting only reactor power lowers both turbine inlet temperature and system efficiency. In contrast, coordinated adjustment of reactor power and secondary circuit flow maintains a more stable thermal state while adapting to load changes, improving average thermal efficiency by 2.1 % compared to the reactor-only strategy. This study clarifies key thermophysical coupling mechanisms in the LFR–T-CO2 system and provides a valuable reference for the coordinated control of marine nuclear power systems under dynamic operating conditions.
{"title":"Study on the dynamic response mechanisms of a lead-bismuth fast reactor coupled with a transcritical CO2 power cycle","authors":"Zhaoyang Yuan , Xuanang Zhang , Jintao He , Yonghao Zhang , Jie Yu , Zhen Wang , Lingfeng Shi , Hua Tian , Gequn Shu","doi":"10.1016/j.supflu.2026.106903","DOIUrl":"10.1016/j.supflu.2026.106903","url":null,"abstract":"<div><div>The integration of a lead-bismuth fast reactor (LFR) with a transcritical CO<sub>2</sub> (T-CO<sub>2</sub>) power cycle represents a promising offshore nuclear energy solution. Although prior research has advanced the primary and secondary circuits separately, their dynamic interactions under tightly coupled conditions remain insufficiently explored. This work establishes a dynamic system model to investigate bidirectional disturbance propagation and load-following coordination between the two circuits. Results indicate that reducing reactor power by 5 % and 10 % decreases secondary circuit output by 13.8 % and 28.4 %, respectively. Variations in secondary circuit parameters, such as pump speed and cold source temperature, alter the CO<sub>2</sub> mass flow rate and evaporator heat transfer, leading to temperature changes in the primary coolant. Through inherent temperature feedback, the reactor autonomously adjusts its power, demonstrating strong closed-loop coupling. Notably, pump speed has a greater influence on secondary circuit output than cold source temperature, contributing approximately 5.6 % more to the output work variation. During load following, adjusting only reactor power lowers both turbine inlet temperature and system efficiency. In contrast, coordinated adjustment of reactor power and secondary circuit flow maintains a more stable thermal state while adapting to load changes, improving average thermal efficiency by 2.1 % compared to the reactor-only strategy. This study clarifies key thermophysical coupling mechanisms in the LFR–T-CO<sub>2</sub> system and provides a valuable reference for the coordinated control of marine nuclear power systems under dynamic operating conditions.</div></div>","PeriodicalId":17078,"journal":{"name":"Journal of Supercritical Fluids","volume":"232 ","pages":"Article 106903"},"PeriodicalIF":4.4,"publicationDate":"2026-01-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146014435","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-01-20DOI: 10.1016/j.supflu.2026.106899
Yun Chang , Yung-Chun Yang , Chieh-Ming Hsieh , Chie-Shaan Su
Pirfenidone is an orally active antifibrotic agent for the treatment of idiopathic pulmonary fibrosis. For designing effective pulmonary drug delivery, microparticle production with controlled particle size is crucial. To select the appropriate supercritical process to meet the goal of particle design of pirfenidone, the solubility of pirfenidone in supercritical carbon dioxide (CO2) was measured at 313 K to 333 K and 10 MPa to 22 MPa, yielding dissolved mole fractions between 3.90 × 10⁻5 and 1.77 × 10⁻3. The measured solubility data were also correlated using four semi-empirical models, with the Chrastil equation providing the best fit. Due to its high solubility, the rapid expansion of supercritical solutions (RESS) was selected for microparticle generation. The effects of extraction temperature, extraction pressure, pre-expansion temperature, and spray distance were investigated. Under the appropriate screening conditions, pirfenidone microparticles with a mean size of 2.5 μm, which fall within the size range suitable for pulmonary drug delivery, were produced. In addition, solid-state characterizations, including PXRD, DSC, and FTIR, confirmed that the crystalline form, thermal behavior, and spectroscopic properties of pirfenidone remained consistent before and after RESS processing. These results demonstrate the feasibility of the RESS process for producing inhalable pirfenidone microparticles and provide fundamental solubility data for supercritical CO2 processing.
{"title":"Solid solubility measurement and microparticle production by supercritical process: A case study of pirfenidone","authors":"Yun Chang , Yung-Chun Yang , Chieh-Ming Hsieh , Chie-Shaan Su","doi":"10.1016/j.supflu.2026.106899","DOIUrl":"10.1016/j.supflu.2026.106899","url":null,"abstract":"<div><div>Pirfenidone is an orally active antifibrotic agent for the treatment of idiopathic pulmonary fibrosis. For designing effective pulmonary drug delivery, microparticle production with controlled particle size is crucial. To select the appropriate supercritical process to meet the goal of particle design of pirfenidone, the solubility of pirfenidone in supercritical carbon dioxide (CO<sub>2</sub>) was measured at 313 K to 333 K and 10 MPa to 22 MPa, yielding dissolved mole fractions between 3.90 × 10⁻<sup>5</sup> and 1.77 × 10⁻<sup>3</sup>. The measured solubility data were also correlated using four semi-empirical models, with the Chrastil equation providing the best fit. Due to its high solubility, the rapid expansion of supercritical solutions (RESS) was selected for microparticle generation. The effects of extraction temperature, extraction pressure, pre-expansion temperature, and spray distance were investigated. Under the appropriate screening conditions, pirfenidone microparticles with a mean size of 2.5 μm, which fall within the size range suitable for pulmonary drug delivery, were produced. In addition, solid-state characterizations, including PXRD, DSC, and FTIR, confirmed that the crystalline form, thermal behavior, and spectroscopic properties of pirfenidone remained consistent before and after RESS processing. These results demonstrate the feasibility of the RESS process for producing inhalable pirfenidone microparticles and provide fundamental solubility data for supercritical CO<sub>2</sub> processing.</div></div>","PeriodicalId":17078,"journal":{"name":"Journal of Supercritical Fluids","volume":"232 ","pages":"Article 106899"},"PeriodicalIF":4.4,"publicationDate":"2026-01-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146014442","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-01-20DOI: 10.1016/j.supflu.2026.106905
Işık Sena Akgün , Ayça Tüter Semercioğlu , Emine Yapıcı , Berat Keçeci , Derin Aktaş , Gökhan Sır , Sevil Yücel
This study investigates the volatile organic compound adsorption and thermal regeneration properties of four different silica aerogels which were synthesized via supercritical carbon dioxide drying and spray drying using methyl ethyl ketone as a model indoor air pollutant. The goal was to assess the impact of structural properties (surface area, pore size, drying technique) and magnesium doping on both initial adsorption capacity and long-term reusability over 15 adsorption/desorption cycles. The silica aerogel dried with supercritical carbon dioxide, characterized by high BET surface area (976.7 ± 0.4 m2/g) and average pore size (11.7 ± 0.1 nm), exhibited the superior initial methyl ethyl ketone adsorption capacity compared to the spray-dried aerogels and commercial activated carbon. While magnesium doping did not significantly improve the initial uptake, it was associated with a more stable desorption performance. Regeneration temperature was found to be the dominant factor for performance retention. Increasing the regeneration temperature from 55°C to 130°C significantly mitigated capacity decline by enhancing methyl ethyl ketone desorption efficiency. Kinetic analysis revealed that methyl ethyl ketone adsorption on both the silica aerogel dried with supercritical carbon dioxide and commercial activated carbon was best described by the Pseudo-Second-Order model, suggesting a primary rate-limiting step involving surface adsorption. Overall, the silica aerogel dried with supercritical carbon dioxide sample demonstrated an initial adsorption capacity approximately 1.5 times higher than commercial activated carbon, proving that supercritically dried silica aerogels are highly promising, durable, and regenerable adsorbents for effective indoor volatile organic compound removal.
{"title":"Investigation of volatile organic compounds adsorption capacities and regeneration properties of silica aerogel particles","authors":"Işık Sena Akgün , Ayça Tüter Semercioğlu , Emine Yapıcı , Berat Keçeci , Derin Aktaş , Gökhan Sır , Sevil Yücel","doi":"10.1016/j.supflu.2026.106905","DOIUrl":"10.1016/j.supflu.2026.106905","url":null,"abstract":"<div><div>This study investigates the volatile organic compound adsorption and thermal regeneration properties of four different silica aerogels which were synthesized via supercritical carbon dioxide drying and spray drying using methyl ethyl ketone as a model indoor air pollutant. The goal was to assess the impact of structural properties (surface area, pore size, drying technique) and magnesium doping on both initial adsorption capacity and long-term reusability over 15 adsorption/desorption cycles. The silica aerogel dried with supercritical carbon dioxide, characterized by high BET surface area (976.7 ± 0.4 m<sup>2</sup>/g) and average pore size (11.7 ± 0.1 nm), exhibited the superior initial methyl ethyl ketone adsorption capacity compared to the spray-dried aerogels and commercial activated carbon. While magnesium doping did not significantly improve the initial uptake, it was associated with a more stable desorption performance. Regeneration temperature was found to be the dominant factor for performance retention. Increasing the regeneration temperature from 55°C to 130°C significantly mitigated capacity decline by enhancing methyl ethyl ketone desorption efficiency. Kinetic analysis revealed that methyl ethyl ketone adsorption on both the silica aerogel dried with supercritical carbon dioxide and commercial activated carbon was best described by the Pseudo-Second-Order model, suggesting a primary rate-limiting step involving surface adsorption. Overall, the silica aerogel dried with supercritical carbon dioxide sample demonstrated an initial adsorption capacity approximately 1.5 times higher than commercial activated carbon, proving that supercritically dried silica aerogels are highly promising, durable, and regenerable adsorbents for effective indoor volatile organic compound removal.</div></div>","PeriodicalId":17078,"journal":{"name":"Journal of Supercritical Fluids","volume":"232 ","pages":"Article 106905"},"PeriodicalIF":4.4,"publicationDate":"2026-01-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146014440","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-01-19DOI: 10.1016/j.supflu.2026.106902
Enhui Sun , Weiqi Zhang , Zhenyu Leng , Qinchai Chen , Jinliang Xu , Tai Wang , Zhiming Qin
Oxygen-enriched direct-combustion cycles hold significant potential for efficient carbon capture. However, mainstream technologies face inherent limitations regarding operating pressure and system complexity. The excessive temperature rise during working fluid compression remains a primary bottleneck in constructing these systems. Based on a thermodynamic analysis of gas compression processes, this study reveals an intrinsic correlation between compression temperature rise and the molecular degrees of freedom. Specifically, it is found that the compression temperature rise of triatomic gases (e.g., CO2) is significantly lower than that of diatomic gas mixtures (such as air). Building on this theoretical insight, the feasibility of constructing a low-pressure, subcritical CO2 direct-recuperative Brayton cycle (LPBC) is demonstrated. This approach breaks the conventional parameter selection paradigm for semi-closed Brayton cycles, greatly reducing the difficulty and complexity of system construction. To further unlock the potential of this cycle, direct-contact spray cooling is introduced to replace conventional intercooling. Numerical simulations demonstrate that this method achieves near-isothermal compression with a minimal pressure drop of only 20 Pa. Consequently, the optimized system (III-LPBC) achieves a thermal efficiency of 66.09 %, surpassing that of typical high-pressure cycles (63.43 %). This study not only provides a theoretical framework for working fluid selection based on molecular properties but also offers a novel technical pathway for constructing next-generation fossil fuel-based power generation systems that balance high efficiency, operational flexibility, and low-carbon emissions.
{"title":"Construction and optimization of a low-pressure direct-fired semi-closed CO2 cycle based on the temperature rise patterns of working fluid compression","authors":"Enhui Sun , Weiqi Zhang , Zhenyu Leng , Qinchai Chen , Jinliang Xu , Tai Wang , Zhiming Qin","doi":"10.1016/j.supflu.2026.106902","DOIUrl":"10.1016/j.supflu.2026.106902","url":null,"abstract":"<div><div>Oxygen-enriched direct-combustion cycles hold significant potential for efficient carbon capture. However, mainstream technologies face inherent limitations regarding operating pressure and system complexity. The excessive temperature rise during working fluid compression remains a primary bottleneck in constructing these systems. Based on a thermodynamic analysis of gas compression processes, this study reveals an intrinsic correlation between compression temperature rise and the molecular degrees of freedom. Specifically, it is found that the compression temperature rise of triatomic gases (e.g., CO<sub>2</sub>) is significantly lower than that of diatomic gas mixtures (such as air). Building on this theoretical insight, the feasibility of constructing a low-pressure, subcritical CO<sub>2</sub> direct-recuperative Brayton cycle (LPBC) is demonstrated. This approach breaks the conventional parameter selection paradigm for semi-closed Brayton cycles, greatly reducing the difficulty and complexity of system construction. To further unlock the potential of this cycle, direct-contact spray cooling is introduced to replace conventional intercooling. Numerical simulations demonstrate that this method achieves near-isothermal compression with a minimal pressure drop of only 20 Pa. Consequently, the optimized system (III-LPBC) achieves a thermal efficiency of 66.09 %, surpassing that of typical high-pressure cycles (63.43 %). This study not only provides a theoretical framework for working fluid selection based on molecular properties but also offers a novel technical pathway for constructing next-generation fossil fuel-based power generation systems that balance high efficiency, operational flexibility, and low-carbon emissions.</div></div>","PeriodicalId":17078,"journal":{"name":"Journal of Supercritical Fluids","volume":"232 ","pages":"Article 106902"},"PeriodicalIF":4.4,"publicationDate":"2026-01-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146000779","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-01-18DOI: 10.1016/j.supflu.2026.106900
Luis A. Roman , Gary A. Leeke
The determination of critical curves is important for the design of chemical processes. The accuracy of fast and rigorous methods for estimating the vapour-liquid critical curves of n-alkane + dimethyl carbonate, and n-alkane + chloroalkane binary systems is tested. The n-alkanes range from propane to n-decane, whereas the chloroalkanes are dichloromethane, 1,1-dichloroethane and 1,2-dichloroethane. The fast estimation methods evaluated are: the conformal solution theory (CM); the method of He et al. (2017); and the method of Tang et al. (2024). The rigorous methods studied are: the corresponding states principle (CSP) with the one-fluid van der Waals equation of state (vdW EoS); and the Heidemann-Khalil-Michelsen (HKM) method with the Peng-Robinson EoS. Despite the simplicity of the EoS, CSP provides the best correlations, resulting in overall average absolute relative errors () for temperature and pressure of and , respectively. CM is the only recommended fast method due to its scientific soundness and accuracy ( ). The methods of He and Tang exhibit parameter degeneracy, questioning their reliability. This work underscores the importance to reconsider CSP as a reliable method for estimating critical curves and presents, for the first time, the explicit equations required to apply this method using the VdW EoS.
临界曲线的确定对化工工艺设计具有重要意义。对正构烷烃+ 碳酸二甲酯和正构烷烃+ 氯烷烃二元体系汽液临界曲线的快速、严格估算方法的准确性进行了验证。正烷的范围从丙烷到正癸烷，而氯烷是二氯甲烷、1,1-二氯乙烷和1,2-二氯乙烷。评估的快速估计方法有：保角解理论（CM）；He et al. (2017)；和Tang et al.（2024）的方法。研究的严格方法是：对应状态原理（CSP）与单流体范德华斯状态方程（vdW EoS）；以及Heidemann-Khalil-Michelsen （HKM）方法与Peng-Robinson EoS。尽管EoS简单，但CSP提供了最好的相关性，导致AARETc和AAREpc的温度和压力的总体平均绝对相对误差（AARE）分别为0.36%和1.68%。CM法具有良好的科学性和准确性（AARETc=0.55%, aarepc =5.10%），是唯一推荐的快速检测方法。何和唐的方法表现出参数退化，质疑其可靠性。这项工作强调了重新考虑CSP作为估计临界曲线的可靠方法的重要性，并首次提出了使用VdW EoS应用该方法所需的显式方程。
{"title":"Estimation of critical curves by empirical and rigorous modelling methods: Case studies on n-alkane + dimethyl carbonate and n-alkane + chloroalkane","authors":"Luis A. Roman , Gary A. Leeke","doi":"10.1016/j.supflu.2026.106900","DOIUrl":"10.1016/j.supflu.2026.106900","url":null,"abstract":"<div><div>The determination of critical curves is important for the design of chemical processes. The accuracy of fast and rigorous methods for estimating the vapour-liquid critical curves of n-alkane + dimethyl carbonate, and n-alkane + chloroalkane binary systems is tested. The n-alkanes range from propane to n-decane, whereas the chloroalkanes are dichloromethane, 1,1-dichloroethane and 1,2-dichloroethane. The fast estimation methods evaluated are: the conformal solution theory (CM); the method of He et al. (2017); and the method of Tang et al. (2024). The rigorous methods studied are: the corresponding states principle (CSP) with the one-fluid van der Waals equation of state (vdW EoS); and the Heidemann-Khalil-Michelsen (HKM) method with the Peng-Robinson EoS. Despite the simplicity of the EoS, CSP provides the best correlations, resulting in overall average absolute relative errors (<span><math><mi>AARE</mi></math></span>) for temperature and pressure of <span><math><mrow><mi>AARE</mi><msup><mrow><mi>T</mi></mrow><mrow><mi>c</mi></mrow></msup><mo>=</mo><mn>0.36</mn><mo>%</mo></mrow></math></span> and <span><math><mrow><mi>AARE</mi><msup><mrow><mi>p</mi></mrow><mrow><mi>c</mi></mrow></msup><mo>=</mo><mn>1.68</mn><mo>%</mo></mrow></math></span>, respectively. CM is the only recommended fast method due to its scientific soundness and accuracy (<span><math><mrow><mi>AARE</mi><msup><mrow><mi>T</mi></mrow><mrow><mi>c</mi></mrow></msup><mo>=</mo><mn>0.55</mn><mo>%</mo></mrow></math></span> <span><math><mrow><mi>and</mi><mi>AARE</mi><msup><mrow><mi>p</mi></mrow><mrow><mi>c</mi></mrow></msup><mo>=</mo><mn>5.10</mn><mo>%</mo></mrow></math></span>). The methods of He and Tang exhibit parameter degeneracy, questioning their reliability. This work underscores the importance to reconsider CSP as a reliable method for estimating critical curves and presents, for the first time, the explicit equations required to apply this method using the VdW EoS.</div></div>","PeriodicalId":17078,"journal":{"name":"Journal of Supercritical Fluids","volume":"232 ","pages":"Article 106900"},"PeriodicalIF":4.4,"publicationDate":"2026-01-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145995408","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-01-17DOI: 10.1016/j.supflu.2026.106898
Mirjana Sulejmanović , Senka Vidović , Igor Jerković , Nataša Milić , Aleksandra Popović , Jelena Jeremić , Vanja Travičić , Stela Jokić , Krunoslav Aladić , Aleksandra Gavarić
The isolation of bioactive compounds from plants has gained significant attention due to their potential in developing novel health-promoting products. Among these, marigold (Calendula officinalis) is recognized for its antioxidant, hepatoprotective, and wound-healing properties. This study examined five marigold plant parts–petals (MP), calyxes (MC), calyxes with petals (MCP), stems (MS), and stems with calyxes and petals (MSCP)–extracted using supercritical carbon dioxide (scCO₂), an advanced technique that avoids toxic solvents and reduces extraction time compared to conventional methods. GC–MS analysis of the scCO₂ extracts revealed that sesquiterpenes were the predominant constituents, including δ-cadinene (19.13–26.96 %), γ-cadinene (9.62–12.92 %), t-muurolol (2.08–10.07 %), α-cadinol (1.42–5.81 %), and ledene (1.24–8.87 %). In addition, monoterpenes such as thymol (1.85–2.87 %), camphor (1.77–2.07 %), β-thujone (0.93–1.13 %), and carvacrol (0.58–1.25 %), as well as the alkane nonadecane (0.50–23.17 %), were also identified. The in vitro antitumor potential of MP, MC, and MS plant parts was evaluated in H4IIE hepatoma cells. Cell viability, morphological analysis, and colony formation assays demonstrated cytotoxic activity, with marigold calyxes showing the most pronounced effect. In addition, hepatoprotective properties were confirmed, further supporting the therapeutic relevance of marigold extracts. These findings suggest that sc-CO₂ extracts of marigold hold promise as potential antitumor agents. However, further preclinical and clinical studies are required to assess their safety, efficacy, and applicability in human therapy.
{"title":"High-pressure extraction of marigold (Calendula officinalis); Evaluation of chemical composition, pharmacological and antitumor potential","authors":"Mirjana Sulejmanović , Senka Vidović , Igor Jerković , Nataša Milić , Aleksandra Popović , Jelena Jeremić , Vanja Travičić , Stela Jokić , Krunoslav Aladić , Aleksandra Gavarić","doi":"10.1016/j.supflu.2026.106898","DOIUrl":"10.1016/j.supflu.2026.106898","url":null,"abstract":"<div><div>The isolation of bioactive compounds from plants has gained significant attention due to their potential in developing novel health-promoting products. Among these, marigold (<em>Calendula officinalis</em>) is recognized for its antioxidant, hepatoprotective, and wound-healing properties. This study examined five marigold plant parts–petals (MP), calyxes (MC), calyxes with petals (MCP), stems (MS), and stems with calyxes and petals (MSCP)–extracted using supercritical carbon dioxide (scCO₂), an advanced technique that avoids toxic solvents and reduces extraction time compared to conventional methods. GC–MS analysis of the scCO₂ extracts revealed that sesquiterpenes were the predominant constituents, including δ-cadinene (19.13–26.96 %), γ-cadinene (9.62–12.92 %), t-muurolol (2.08–10.07 %), α-cadinol (1.42–5.81 %), and ledene (1.24–8.87 %). In addition, monoterpenes such as thymol (1.85–2.87 %), camphor (1.77–2.07 %), β-thujone (0.93–1.13 %), and carvacrol (0.58–1.25 %), as well as the alkane nonadecane (0.50–23.17 %), were also identified. The in vitro antitumor potential of MP, MC, and MS plant parts was evaluated in H4IIE hepatoma cells. Cell viability, morphological analysis, and colony formation assays demonstrated cytotoxic activity, with marigold calyxes showing the most pronounced effect. In addition, hepatoprotective properties were confirmed, further supporting the therapeutic relevance of marigold extracts. These findings suggest that sc-CO₂ extracts of marigold hold promise as potential antitumor agents. However, further preclinical and clinical studies are required to assess their safety, efficacy, and applicability in human therapy.</div></div>","PeriodicalId":17078,"journal":{"name":"Journal of Supercritical Fluids","volume":"232 ","pages":"Article 106898"},"PeriodicalIF":4.4,"publicationDate":"2026-01-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145995409","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-01-17DOI: 10.1016/j.supflu.2026.106901
Shaoming Ding , Yanhui Li , Wang Zhu , Limei Xing , Qibo Wang , Zhouyang Bai , Pengfei Gao , Fengxiao Hou
This study examines the corrosion behavior of Inconel 600 and Inconel 625 alloys in supercritical water environments containing phosphates, with a focus on the temperature-dependent effects of phosphate in both dissolved and molten states. At 400 °C, dissolved phosphate acts as a passivating agent, forming protective metal phosphate films that reduce corrosion. At 600 °C, the low solubility of phosphate causes it to precipitate into a molten state. This significantly accelerates corrosion by dissolving the protective oxide film and enhancing ion diffusion, increasing the film thickness from 0.16 μm to 0.675 μm. The higher Cr content in Inconel 625 resulted in an 65.9 % reduction in oxide thickness relative to Inconel 600, indicating enhanced oxidation resistance. The core theoretical innovation of this study lies in identifying the dual role of phosphate in alloy corrosion: acting as a passivating agent at lower temperatures and as a corrosion accelerator at higher temperatures. This study further clarifies the competitive relationship between phosphate and oxygen, the mechanism by which molten salts accelerate corrosion, and the synergistic molten corrosion effect of Na⁺. The findings provide valuable insights into corrosion protection strategies for supercritical water oxidation systems, contributing to the optimization of material design in extreme environments.
{"title":"Phosphate-induced corrosion of nickel alloys in supercritical water: Mechanistic insights into passivation and accelerated corrosion at elevated temperatures","authors":"Shaoming Ding , Yanhui Li , Wang Zhu , Limei Xing , Qibo Wang , Zhouyang Bai , Pengfei Gao , Fengxiao Hou","doi":"10.1016/j.supflu.2026.106901","DOIUrl":"10.1016/j.supflu.2026.106901","url":null,"abstract":"<div><div>This study examines the corrosion behavior of Inconel 600 and Inconel 625 alloys in supercritical water environments containing phosphates, with a focus on the temperature-dependent effects of phosphate in both dissolved and molten states. At 400 °C, dissolved phosphate acts as a passivating agent, forming protective metal phosphate films that reduce corrosion. At 600 °C, the low solubility of phosphate causes it to precipitate into a molten state. This significantly accelerates corrosion by dissolving the protective oxide film and enhancing ion diffusion, increasing the film thickness from 0.16 μm to 0.675 μm. The higher Cr content in Inconel 625 resulted in an 65.9 % reduction in oxide thickness relative to Inconel 600, indicating enhanced oxidation resistance. The core theoretical innovation of this study lies in identifying the dual role of phosphate in alloy corrosion: acting as a passivating agent at lower temperatures and as a corrosion accelerator at higher temperatures. This study further clarifies the competitive relationship between phosphate and oxygen, the mechanism by which molten salts accelerate corrosion, and the synergistic molten corrosion effect of Na⁺. The findings provide valuable insights into corrosion protection strategies for supercritical water oxidation systems, contributing to the optimization of material design in extreme environments.</div></div>","PeriodicalId":17078,"journal":{"name":"Journal of Supercritical Fluids","volume":"232 ","pages":"Article 106901"},"PeriodicalIF":4.4,"publicationDate":"2026-01-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145995407","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-01-16DOI: 10.1016/j.supflu.2026.106896
Tariq Alsawy , Ramy H. Mohammed , Osama Mesalhy , Mohamed Abdelkareem
There is a growing interest in the supercritical CO2 Brayton cycle (SCO2BC) as a high-efficiency power generation technology across various energy sectors, including renewable energy. SCO2BC dynamic modelling is key to grasp its performance, especially under off-design conditions such as fluctuating operating load. Numerous studies that compare the steady-state behavior of different SCO2BC layouts are present. However, existing literature lacks in-depth analyses of transient responses of different SCO2BC layouts with accuracy-improved turbomachinery performance-map. This research fills this gap by comparing four layouts: recuperated (RCU), recompression (RCOMP), reheat (RHT), intercool (INC), through dynamic simulations with accuracy-improved turbomachinery models. The transient responses of the key SCO2BC cycle performance parameters are deeply investigated, offering novel insights into their transient behavior. An additional novelty of this work is the usage of corrected turbomachinery performance maps with improved prediction accuracy for the dynamic comparison. The study reveals that mass flow rate and compressor inlet conditions are most affected by a cooling water temperature disturbance (ColdT), while turbine inlet state is more sensitive to a heater temperature change (HotT). For all the studied layouts, net power responses are primarily driven by mass flow rate and turbine inlet temperature (TIT) for ColdT and HotT disturbances, respectively. Layout configurations (number and arrangement of turbomachines) influence transient response sensitivity. RCU and RHT layouts exhibit larger net power fluctuations for ColdT, while RCU and INC layouts show larger responses for HotT. The RCOMP is generally the most stable layout, while RHT and INC demonstrate conditional stability depending on the disturbance.
{"title":"Dynamic performance comparison of supercritical CO₂ Brayton cycle layouts using an enhanced dynamic model","authors":"Tariq Alsawy , Ramy H. Mohammed , Osama Mesalhy , Mohamed Abdelkareem","doi":"10.1016/j.supflu.2026.106896","DOIUrl":"10.1016/j.supflu.2026.106896","url":null,"abstract":"<div><div>There is a growing interest in the supercritical CO<sub>2</sub> Brayton cycle (SCO<sub>2</sub>BC) as a high-efficiency power generation technology across various energy sectors, including renewable energy. SCO<sub>2</sub>BC dynamic modelling is key to grasp its performance, especially under off-design conditions such as fluctuating operating load. Numerous studies that compare the steady-state behavior of different SCO<sub>2</sub>BC layouts are present. However, existing literature lacks in-depth analyses of transient responses of different SCO<sub>2</sub>BC layouts with accuracy-improved turbomachinery performance-map. This research fills this gap by comparing four layouts: recuperated (RCU), recompression (RCOMP), reheat (RHT), intercool (INC), through dynamic simulations with accuracy-improved turbomachinery models. The transient responses of the key SCO<sub>2</sub>BC cycle performance parameters are deeply investigated, offering novel insights into their transient behavior. An additional novelty of this work is the usage of corrected turbomachinery performance maps with improved prediction accuracy for the dynamic comparison. The study reveals that mass flow rate and compressor inlet conditions are most affected by a cooling water temperature disturbance (ColdT), while turbine inlet state is more sensitive to a heater temperature change (HotT). For all the studied layouts, net power responses are primarily driven by mass flow rate and turbine inlet temperature (TIT) for ColdT and HotT disturbances, respectively. Layout configurations (number and arrangement of turbomachines) influence transient response sensitivity. RCU and RHT layouts exhibit larger net power fluctuations for ColdT, while RCU and INC layouts show larger responses for HotT. The RCOMP is generally the most stable layout, while RHT and INC demonstrate conditional stability depending on the disturbance.</div></div>","PeriodicalId":17078,"journal":{"name":"Journal of Supercritical Fluids","volume":"232 ","pages":"Article 106896"},"PeriodicalIF":4.4,"publicationDate":"2026-01-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145995410","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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