Pub Date : 2026-06-01Epub 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":"2026-06-01","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 : 2026-06-01Epub 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":"2026-06-01","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 : 2026-06-01Epub Date: 2026-01-16DOI: 10.1016/j.supflu.2026.106895
Shang Mao , Shengli Zhang , Xuehong Wu , Yong Liu , Leigang Zhang , Cai Lv , Tao Zhou , Songzhen Tang
The utilization of supercritical CO2 (sCO2) for cooling aero-engine combustion chambers can effectively alleviate the hydrocarbon fuel slagging issue in hypersonic vehicles. Nevertheless, research on sCO2 heat transfer and performance optimization in regenerative cooling channels under high heat flux unilateral heating conditions remains limited. Influence of heat flux, mass flux, operating pressure and heating position on the flow dynamics and heat transfer was numerically investigated. Results indicated that wall temperature (Tw) peak intensified with increase of heat flux and decrease of pressure and mass flux. Heat transfer deterioration (HTD) can be alleviated by elevating inlet temperature above the pseudo-critical temperature Tin>Tpc. Furthermore, temperature non-uniformity coefficient served as an effective predictor of heat sink performance of regenerative cooling channels. A lower coefficient indicated a higher heat sink utilization rate. Analysis revealed that turbulent kinetic energy within the boundary layer was primary factor governing heat transfer performance. Friction loss dominated and acceleration loss comprised approximately 1/4 of total pressure drop. Comparative assessment demonstrated that top heating led to the highest Tw, whereas side heating induced the greatest pressure drop. Finally, sinusoidal wavy channels were proposed, with amplitude A= 0.2 mm and period p = 4 mm exhibiting optimal flow and heat transfer capabilities for various heating position.
{"title":"Performance of convective heat transfer of supercritical CO2 in unilaterally heated rectangular channel","authors":"Shang Mao , Shengli Zhang , Xuehong Wu , Yong Liu , Leigang Zhang , Cai Lv , Tao Zhou , Songzhen Tang","doi":"10.1016/j.supflu.2026.106895","DOIUrl":"10.1016/j.supflu.2026.106895","url":null,"abstract":"<div><div>The utilization of supercritical CO<sub>2</sub> (sCO<sub>2</sub>) for cooling aero-engine combustion chambers can effectively alleviate the hydrocarbon fuel slagging issue in hypersonic vehicles. Nevertheless, research on sCO<sub>2</sub> heat transfer and performance optimization in regenerative cooling channels under high heat flux unilateral heating conditions remains limited. Influence of heat flux, mass flux, operating pressure and heating position on the flow dynamics and heat transfer was numerically investigated. Results indicated that wall temperature (<em>T</em><sub>w</sub>) peak intensified with increase of heat flux and decrease of pressure and mass flux. Heat transfer deterioration (HTD) can be alleviated by elevating inlet temperature above the pseudo-critical temperature <em>T</em><sub>in</sub>><em>T</em><sub>pc</sub>. Furthermore, temperature non-uniformity coefficient served as an effective predictor of heat sink performance of regenerative cooling channels. A lower coefficient indicated a higher heat sink utilization rate. Analysis revealed that turbulent kinetic energy within the boundary layer was primary factor governing heat transfer performance. Friction loss dominated and acceleration loss comprised approximately 1/4 of total pressure drop. Comparative assessment demonstrated that top heating led to the highest <em>T</em><sub>w</sub>, whereas side heating induced the greatest pressure drop. Finally, sinusoidal wavy channels were proposed, with amplitude <em>A</em>= 0.2 mm and period <em>p</em> = 4 mm exhibiting optimal flow and heat transfer capabilities for various heating position.</div></div>","PeriodicalId":17078,"journal":{"name":"Journal of Supercritical Fluids","volume":"232 ","pages":"Article 106895"},"PeriodicalIF":4.4,"publicationDate":"2026-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145981962","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}
A laboratory-scale wall-cooled reactor for hydrogen hydrothermal combustion was scaled up by factors of 10 and 100 using four scale-up criteria: constant velocity (CV), constant residence time (CRT), constant volume to jet momentum ratio (CM), and constant volume to jet kinetic energy ratio (CK). Computational fluid dynamics (CFD) simulations were then conducted to evaluate the performance of the scaled reactors. The results show that the overall flow field is predominantly controlled by the momentum ratio of the multiple jets, rather than the nozzle’s internal flow regime, specifically the Reynolds number. Reactor scale-up weakens radial jet diffusion, slightly reducing local fuel–oxidizer mixing and suppressing the radial transport of high-temperature combustion products. The global residence time follows the order CV > CK > CM > CRT, consistent with reactor volume changes induced by scale-up. The peak temperature along the centerline exhibits a slight decrease and shifts downstream with increasing reactor size, due to reduced entrainment and weakened radial momentum exchange. Wall temperatures decrease under the CV criterion but increase under CRT, CM, and CK, reflecting the combined effects of heat transfer area per unit heat load and local fuel–oxidizer mixing intensity. Species concentrations in the reactor core remain nearly constant, with scale-up effects only marginally observed in the cooling water layer near the wall. The CV criterion is recommended for scaling up hydrothermal combustion, as it reduces peak and wall temperatures, thereby lowering material performance requirements for large-scale reactors.
采用恒速度（CV）、恒停留时间（CRT）、恒体积与射流动量比（CM）和恒体积与射流动能比（CK） 4个放大标准，对实验室规模的壁冷式氢水热燃烧反应器进行了10倍和100倍的放大。然后进行了计算流体力学（CFD）模拟，以评估规模化反应器的性能。结果表明，整个流场主要由多个射流的动量比控制，而不是由喷嘴内部流型，特别是雷诺数控制。反应器放大减弱了径向射流扩散，略微降低了局部燃料-氧化剂混合，抑制了高温燃烧产物的径向输运。总体停留时间遵循CV >； CK > CM >； CRT的顺序，与放大引起的反应器体积变化一致。随着反应器尺寸的增大，由于夹带的减少和径向动量交换的减弱，沿中心线的峰值温度呈现出轻微的下降并向下游移动。CV条件下壁温降低，而CRT、CM和CK条件下壁温升高，反映了单位热负荷换热面积和局部燃料-氧化剂混合强度的综合作用。反应堆堆芯的物质浓度几乎保持不变，在靠近堆壁的冷却水层中只略微观察到放大效应。CV标准被推荐用于扩大水热燃烧，因为它降低了峰值和壁温，从而降低了大型反应器的材料性能要求。
{"title":"Numerical assessment of scale-up criteria in a wall-cooled reactor for hydrogen combustion in supercritical water","authors":"Mingjing Fan, Xiaoge Zhang, Yu Zhang, Haoze Wang, Hao Wang, Youjun Lu","doi":"10.1016/j.supflu.2026.106919","DOIUrl":"10.1016/j.supflu.2026.106919","url":null,"abstract":"<div><div>A laboratory-scale wall-cooled reactor for hydrogen hydrothermal combustion was scaled up by factors of 10 and 100 using four scale-up criteria: constant velocity (CV), constant residence time (CRT), constant volume to jet momentum ratio (CM), and constant volume to jet kinetic energy ratio (CK). Computational fluid dynamics (CFD) simulations were then conducted to evaluate the performance of the scaled reactors. The results show that the overall flow field is predominantly controlled by the momentum ratio of the multiple jets, rather than the nozzle’s internal flow regime, specifically the Reynolds number. Reactor scale-up weakens radial jet diffusion, slightly reducing local fuel–oxidizer mixing and suppressing the radial transport of high-temperature combustion products. The global residence time follows the order CV > CK > CM > CRT, consistent with reactor volume changes induced by scale-up. The peak temperature along the centerline exhibits a slight decrease and shifts downstream with increasing reactor size, due to reduced entrainment and weakened radial momentum exchange. Wall temperatures decrease under the CV criterion but increase under CRT, CM, and CK, reflecting the combined effects of heat transfer area per unit heat load and local fuel–oxidizer mixing intensity. Species concentrations in the reactor core remain nearly constant, with scale-up effects only marginally observed in the cooling water layer near the wall. The CV criterion is recommended for scaling up hydrothermal combustion, as it reduces peak and wall temperatures, thereby lowering material performance requirements for large-scale reactors.</div></div>","PeriodicalId":17078,"journal":{"name":"Journal of Supercritical Fluids","volume":"232 ","pages":"Article 106919"},"PeriodicalIF":4.4,"publicationDate":"2026-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146109703","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 : 2026-06-01Epub 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":"2026-06-01","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 : 2026-06-01Epub Date: 2026-01-16DOI: 10.1016/j.supflu.2026.106897
Ai Lin Hong , Chun Yang Chiu , Cheng Yi Kao , Chen-Yu Fang , Kiday Fiseha Gebremedhin , Shu Kai Yeh , Sen Yeu Yang , Chul B. Park
Foam injection molding (FIM) has remained largely empirical due to the opacity of molds preventing direct observation of foaming dynamics. This study establishes a visualization platform for systematic investigation of FIM processes, enabling future research across diverse polymer systems. Building upon established methodologies, this work successfully reproduces and validates previous findings while extending investigations to unexplored parameter regimes. A custom-designed mold with integrated optics and pressure sensors enabled simultaneous visual and pressure monitoring of polystyrene foaming with CO2. Systematic experiments investigated both low-pressure (LPFIM) and high-pressure (HPFIM) FIM with core-back technology, demonstrating the platform’s capability to capture fundamental process-structure relationships across different processing modes. In LPFIM, an insufficient mold venting design can affect mold filling, with better mold filling achieved at lower injection speeds (50 cm3/s) compared to higher speeds (80 cm3/s). This finding contrasts with previous studies using optimized venting systems, underscoring the crucial role of mold design in achieving LPFIM success. In HPFIM with core-back, a critical transition was observed at 0.8 mm core-back distance, triggering cell density increases from < 60 cells/cm3 to > 4500 cells/cm3. An optimal core-back velocity of 33 mm/s was identified, with higher velocities causing pressure rebound and rapid gas consumption that suppress further nucleation. These fundamental insights provide qualitative guidelines for process optimization while establishing a robust research platform for future investigations across different polymer-blowing agent systems.
{"title":"Critical process thresholds in foam injection molding revealed by real-time visualization","authors":"Ai Lin Hong , Chun Yang Chiu , Cheng Yi Kao , Chen-Yu Fang , Kiday Fiseha Gebremedhin , Shu Kai Yeh , Sen Yeu Yang , Chul B. Park","doi":"10.1016/j.supflu.2026.106897","DOIUrl":"10.1016/j.supflu.2026.106897","url":null,"abstract":"<div><div>Foam injection molding (FIM) has remained largely empirical due to the opacity of molds preventing direct observation of foaming dynamics. This study establishes a visualization platform for systematic investigation of FIM processes, enabling future research across diverse polymer systems. Building upon established methodologies, this work successfully reproduces and validates previous findings while extending investigations to unexplored parameter regimes. A custom-designed mold with integrated optics and pressure sensors enabled simultaneous visual and pressure monitoring of polystyrene foaming with CO<sub>2</sub>. Systematic experiments investigated both low-pressure (LPFIM) and high-pressure (HPFIM) FIM with core-back technology, demonstrating the platform’s capability to capture fundamental process-structure relationships across different processing modes. In LPFIM, an insufficient mold venting design can affect mold filling, with better mold filling achieved at lower injection speeds (50 cm<sup>3</sup>/s) compared to higher speeds (80 cm<sup>3</sup>/s). This finding contrasts with previous studies using optimized venting systems, underscoring the crucial role of mold design in achieving LPFIM success. In HPFIM with core-back, a critical transition was observed at 0.8 mm core-back distance, triggering cell density increases from < 60 cells/cm<sup>3</sup> to > 4500 cells/cm<sup>3</sup>. An optimal core-back velocity of 33 mm/s was identified, with higher velocities causing pressure rebound and rapid gas consumption that suppress further nucleation. These fundamental insights provide qualitative guidelines for process optimization while establishing a robust research platform for future investigations across different polymer-blowing agent systems.</div></div>","PeriodicalId":17078,"journal":{"name":"Journal of Supercritical Fluids","volume":"232 ","pages":"Article 106897"},"PeriodicalIF":4.4,"publicationDate":"2026-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145995411","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 : 2026-06-01Epub Date: 2026-02-03DOI: 10.1016/j.supflu.2026.106920
Yumi Okita, Yoshito Oshima, Makoto Akizuki
Subcritical and supercritical water have attracted attention as tunable reaction media for organic reactions because their properties can be adjusted by controlling temperature and pressure. It is expected that the appropriate solvent properties will be used for each step of a multi-step reaction process by changing only the temperature and pressure. In this study, α-pinene was converted to p-cymene using a two-stage flow reactor where subcritical and supercritical water were used as solvents. The synthesis involved acid-catalyzed isomerization and oxidative dehydrogenation. For determining appropriate reaction conditions for acid-catalyzed isomerization with WOX/TiO2 as a solid catalyst (first stage) and oxidative dehydrogenation (second stage), the temperature, pressure, initial concentration of oxidant (second stage), and starting compound (second stage) for each stage were investigated. The results confirm that the maximum yield of p-cymene exceeded 0.4 when the first stage temperature was set to 250 °C or 300 °C; the second stage temperature was set to 400 °C, and the pressure for both stages was set to 30 MPa. This yield value was approximately twice as large compared to the yield values of p-cymene synthesized in a single-stage flow reactor in supercritical water at 400 °C and 30 MPa. The first stage involved ion-mediated reactions, while the second stage involved radical-mediated reactions. Since the reactivity of these reactions differs between subcritical and supercritical water, and the reactivity can be adjusted by pressure, combining subcritical and supercritical conditions in two-stage reactors increased the target product yield.
{"title":"Two-stage flow reactions of α-pinene to p-cymene by combining subcritical and supercritical water","authors":"Yumi Okita, Yoshito Oshima, Makoto Akizuki","doi":"10.1016/j.supflu.2026.106920","DOIUrl":"10.1016/j.supflu.2026.106920","url":null,"abstract":"<div><div>Subcritical and supercritical water have attracted attention as tunable reaction media for organic reactions because their properties can be adjusted by controlling temperature and pressure. It is expected that the appropriate solvent properties will be used for each step of a multi-step reaction process by changing only the temperature and pressure. In this study, <em>α</em>-pinene was converted to <em>p</em>-cymene using a two-stage flow reactor where subcritical and supercritical water were used as solvents. The synthesis involved acid-catalyzed isomerization and oxidative dehydrogenation. For determining appropriate reaction conditions for acid-catalyzed isomerization with WO<sub>X</sub>/TiO<sub>2</sub> as a solid catalyst (first stage) and oxidative dehydrogenation (second stage), the temperature, pressure, initial concentration of oxidant (second stage), and starting compound (second stage) for each stage were investigated. The results confirm that the maximum yield of <em>p</em>-cymene exceeded 0.4 when the first stage temperature was set to 250 °C or 300 °C; the second stage temperature was set to 400 °C, and the pressure for both stages was set to 30 MPa. This yield value was approximately twice as large compared to the yield values of <em>p</em>-cymene synthesized in a single-stage flow reactor in supercritical water at 400 °C and 30 MPa. The first stage involved ion-mediated reactions, while the second stage involved radical-mediated reactions. Since the reactivity of these reactions differs between subcritical and supercritical water, and the reactivity can be adjusted by pressure, combining subcritical and supercritical conditions in two-stage reactors increased the target product yield.</div></div>","PeriodicalId":17078,"journal":{"name":"Journal of Supercritical Fluids","volume":"232 ","pages":"Article 106920"},"PeriodicalIF":4.4,"publicationDate":"2026-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146109699","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 : 2026-06-01Epub 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":"2026-06-01","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 : 2026-06-01Epub 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":"2026-06-01","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 : 2026-06-01Epub Date: 2026-01-10DOI: 10.1016/j.supflu.2026.106890
Guang Yan, Du Wang, Mujie Xue, Jian Lu, Rongyao Jia
To enhance the peak load regulation capacity of thermal power units and improve the flexibility of power systems, this paper investigates the integration of a compressed carbon dioxide energy storage system with a 1000 MW double reheat thermal power unit. A thermodynamic model is developed for the power plant as well as for supercritical, transcritical, and liquid compressed carbon dioxide energy storage systems, and the effects of various coupling methods on the plant's performance are analyzed. Three types of compressed carbon dioxide energy storage systems and a double reheat thermal power plant coupling system are selected with the aim of minimizing heat consumption. The paper thoroughly examines the influence of key parameters on the thermal efficiency of the system and employs genetic algorithms for optimization. The results indicate that liquid compressed carbon dioxide energy storage is more suitable for coupling with double reheat thermal power units compared to supercritical or transcritical carbon dioxideenergy storage systems. The coupling process is as follows: during the energy storage phase, steam from the medium-pressure cylinder’s final stage is extracted to drive a small steam turbine for compression work, with the generated heat being absorbed by the power unit’s condensation water and returned to the low-pressure inlet of No.7. During the energy release phase, steam from the low-pressure cylinder’s first stage is extracted to heat the CO₂ entering the turbine, which is then returned to the low-pressure heater drain outlet of No.7. Among the key parameters, the inlet temperature of the second-stage compressor, the system expansion ratio, and the inlet temperatures of the first- and second-stage turbines have the greatest impact on system performance. Under the design conditions, the energy storage efficiency of the liquid carbon dioxide system is 56.97 %, the overall system efficiency is 46.27 %, the levelized cost of electricity is 0.118528 $/kWh, the energy storage density reaches 14.343 kWh/m³ , and the coal consumption rate is 256.61 g/kWh. After optimization, the coupled system efficiency can be improved by 1.23 %, and the LCOE can be reduced by 7.64 %. The coupling of liquid carbon dioxide energy storage with double reheat thermal power units can significantly enhance system flexibility and peak load regulation capabilities. This study offers valuable insights for engineering applications.
{"title":"Performance evaluation and optimization of a coupled system integrating compressed carbon dioxide energy storage with double reheat thermal power unit","authors":"Guang Yan, Du Wang, Mujie Xue, Jian Lu, Rongyao Jia","doi":"10.1016/j.supflu.2026.106890","DOIUrl":"10.1016/j.supflu.2026.106890","url":null,"abstract":"<div><div>To enhance the peak load regulation capacity of thermal power units and improve the flexibility of power systems, this paper investigates the integration of a compressed carbon dioxide energy storage system with a 1000 MW double reheat thermal power unit. A thermodynamic model is developed for the power plant as well as for supercritical, transcritical, and liquid compressed carbon dioxide energy storage systems, and the effects of various coupling methods on the plant's performance are analyzed. Three types of compressed carbon dioxide energy storage systems and a double reheat thermal power plant coupling system are selected with the aim of minimizing heat consumption. The paper thoroughly examines the influence of key parameters on the thermal efficiency of the system and employs genetic algorithms for optimization. The results indicate that liquid compressed carbon dioxide energy storage is more suitable for coupling with double reheat thermal power units compared to supercritical or transcritical carbon dioxideenergy storage systems. The coupling process is as follows: during the energy storage phase, steam from the medium-pressure cylinder’s final stage is extracted to drive a small steam turbine for compression work, with the generated heat being absorbed by the power unit’s condensation water and returned to the low-pressure inlet of No.7. During the energy release phase, steam from the low-pressure cylinder’s first stage is extracted to heat the CO₂ entering the turbine, which is then returned to the low-pressure heater drain outlet of No.7. Among the key parameters, the inlet temperature of the second-stage compressor, the system expansion ratio, and the inlet temperatures of the first- and second-stage turbines have the greatest impact on system performance. Under the design conditions, the energy storage efficiency of the liquid carbon dioxide system is 56.97 %, the overall system efficiency is 46.27 %, the levelized cost of electricity is 0.118528 $/kWh, the energy storage density reaches 14.343 kWh/m³ , and the coal consumption rate is 256.61 g/kWh. After optimization, the coupled system efficiency can be improved by 1.23 %, and the LCOE can be reduced by 7.64 %. The coupling of liquid carbon dioxide energy storage with double reheat thermal power units can significantly enhance system flexibility and peak load regulation capabilities. This study offers valuable insights for engineering applications.</div></div>","PeriodicalId":17078,"journal":{"name":"Journal of Supercritical Fluids","volume":"232 ","pages":"Article 106890"},"PeriodicalIF":4.4,"publicationDate":"2026-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145956802","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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