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Keywords = pressure ratio drop

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13 pages, 3081 KiB  
Review
Surface Air-Cooled Oil Coolers (SACOCs) in Turbofan Engines: A Comprehensive Review of Design, Performance, and Optimization
by Wiktor Hoffmann and Magda Joachimiak
Energies 2025, 18(15), 4052; https://doi.org/10.3390/en18154052 - 30 Jul 2025
Viewed by 242
Abstract
Surface Air-Cooled Oil Coolers (SACOCs) can become a critical component in managing the increasing thermal loads of modern turbofan engines. Installed within the bypass duct, SACOCs utilize high-mass flow bypass air for convective heat rejection, reducing reliance on traditional Fuel-Oil Heat Exchangers. This [...] Read more.
Surface Air-Cooled Oil Coolers (SACOCs) can become a critical component in managing the increasing thermal loads of modern turbofan engines. Installed within the bypass duct, SACOCs utilize high-mass flow bypass air for convective heat rejection, reducing reliance on traditional Fuel-Oil Heat Exchangers. This review explores SACOC design principles, integration challenges, aerodynamic impacts, and performance trade-offs. Emphasis is placed on the balance between thermal efficiency and aerodynamic penalties such as pressure drop and flow distortion. Experimental techniques, including wind tunnel testing, are discussed alongside numerical methods, and Conjugate Heat Transfer modeling. Presented studies mostly demonstrate the impact of fin geometry and placement on both heat transfer and drag. Optimization strategies and Additive Manufacturing techniques are also covered. SACOCs are positioned to play a central role in future propulsion systems, especially in ultra-high bypass ratio and hybrid-electric architectures, where traditional cooling strategies are insufficient. This review highlights current advancements, identifies limitations, and outlines research directions to enhance SACOC efficiency in aerospace applications. Full article
(This article belongs to the Special Issue Heat Transfer Analysis: Recent Challenges and Applications)
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18 pages, 3997 KiB  
Article
Simulation of Dynamic Particle Trapping and Accumulation in HGMS Based on FEM-CFD-DEM Coupling Approach
by Xiaoming Wang, Yonghui Hu, Yefei Hao, Zhengchang Shen, Guodong Liang and Ming Zhang
Processes 2025, 13(8), 2391; https://doi.org/10.3390/pr13082391 - 28 Jul 2025
Viewed by 287
Abstract
High-gradient magnetic separation (HGMS) is a conventional and effective method for processing weak magnetic materials. A multi-field dynamic coupling simulation method integrating the Finite Element Method (FEM), Computational Fluid Dynamics (CFD), and the Discrete Element Method (DEM) was employed to investigate the separation [...] Read more.
High-gradient magnetic separation (HGMS) is a conventional and effective method for processing weak magnetic materials. A multi-field dynamic coupling simulation method integrating the Finite Element Method (FEM), Computational Fluid Dynamics (CFD), and the Discrete Element Method (DEM) was employed to investigate the separation behavior in HGMS. The dynamic deposition process of magnetic particles under the interactions of magnetic fields, fluid flow fields, and particle–particle forces was simulated using a two-way fluid–solid coupling algorithm based on the FEM-CFD-DEM coupling approach. Experimental results demonstrated that the particle deposition profiles predicted by the double-wire medium model were in good agreement with the measured data. The research findings indicated that the separation process could be divided into three distinct stages—the adsorption stage, the closure stage, and the clogging stage—each characterized by unique dynamic behaviors and pressure-drop evolution patterns. Additionally, the effects of key parameters such as the feeding velocity and medium filling ratio on the separation process were analyzed, providing theoretical foundations and technical support for the optimization of HGMS processes and the enhancement of separation efficiency. Full article
(This article belongs to the Special Issue Mineral Processing Equipments and Cross-Disciplinary Approaches)
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15 pages, 1256 KiB  
Article
A New Method for Quantitative Evaluation Concentration Polarization Under Different Conditions for the Forward Osmosis Process
by Ping Xiao and Liang Liu
Membranes 2025, 15(8), 223; https://doi.org/10.3390/membranes15080223 - 25 Jul 2025
Viewed by 261
Abstract
Concentration polarization (CP) is one of the inherent problems that lowers the operating performance of forward osmosis (FO) membranes. Therefore, a quantitative evaluation of CP is vital to understand its impact on the FO process. This study systematically investigated the influences of different [...] Read more.
Concentration polarization (CP) is one of the inherent problems that lowers the operating performance of forward osmosis (FO) membranes. Therefore, a quantitative evaluation of CP is vital to understand its impact on the FO process. This study systematically investigated the influences of different CPs on the osmotic pressure drop across the membrane under different conditions by using the water transmission coefficient, ηWT, defined as the ratio of the measured water flux to the theoretical water flux. The results showed that ηWT decreased with an increase in the concentration gradient between the draw solution (DS) and the feed solution (FS) under different conditions. The proportions of osmotic pressure drop caused by dilutive internal concentration polarization (ICP) increased, while those caused by concentrative external concentration polarization (ECP) decreased, in different types of DSs in FO mode. Both ECP and ICP were found to be capable of reducing osmotic pressure. However, the internal CP had the dominant influence. To better understand the adverse effects of CP, using an organic FS provided greater insight than using deionized (DI) water as the FS. As the FS concentration increased, the water flux reduced, and the adverse effects of CP worsened. CaCl2 led to a greater reduction in water transfer efficiency than NaCl when used as the DS. In comparison to FO mode, pressure-retarded osmosis (PRO) mode led to greater pure water flux and flux decline. In FO mode, both the proportion of dilutive ICP and the ηWT decreased, while the proportion of concentrative ECP increased over time. However, in PRO mode, the proportions of dilutive ECP and concentrative ICP increased, and ηWT gradually decreased. Dilutive ICP had a significant negative effect on osmotic pressure in the former, while dilutive ECP was dominant in the latter. Full article
(This article belongs to the Special Issue Membrane Separation and Water Treatment: Modeling and Application)
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14 pages, 3940 KiB  
Article
DOC Study on the Effects of Catalyst Active Component Loading and Carrier Properties on the Catalytic Conversion Efficiency of Key Gaseous Pollutants
by Yantao Zou and Liguang Xiao
Sustainability 2025, 17(14), 6354; https://doi.org/10.3390/su17146354 - 11 Jul 2025
Viewed by 358
Abstract
Based on engine bench testing, this study investigated the effect of diesel oxidation catalytic converter (DOC) formulations on the gaseous emissions performance of diesel engines equipped with a DOC+ catalyzed diesel particulate filter (CDPF)+selective catalytic reduction (SCR) system after the treatment system. The [...] Read more.
Based on engine bench testing, this study investigated the effect of diesel oxidation catalytic converter (DOC) formulations on the gaseous emissions performance of diesel engines equipped with a DOC+ catalyzed diesel particulate filter (CDPF)+selective catalytic reduction (SCR) system after the treatment system. The experimental results indicate that changes in DOC formulations have no significant effect on engine fuel economy. As the precious metal loading increases and the Pt/Pd ratio decreases, the T50 for CO and HC decreases, and the low-temperature conversion rates (<300 °C) for CO and HC increase. However, as the temperature continues to rise, the beneficial effect of increased precious metal loading or Pd on CO and HC conversion rates gradually weakens. The average conversion rates in the high-temperature range (≥300 °C) show little difference. The NO conversion rate increases with increasing precious metal loading. The NO conversion rate is more sensitive to Pt content, with higher Pt content formulations promoting NO oxidation, contrary to the trends observed for CO and HC conversion rates. When the SCR inlet temperature is low, high NO2 concentrations are beneficial for improving the SCR’s NOx conversion efficiency. When the SCR inlet temperature is high, the SCR’s NOx conversion efficiency exceeds 90% with no significant differences. No significant impact of DOC formulation changes on CDPF pressure drop under external conditions was observed. Full article
(This article belongs to the Special Issue Technology Applications in Sustainable Energy and Power Engineering)
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22 pages, 7206 KiB  
Article
The Impact of Diesel Injection Strategy and In-Cylinder Temperature on the Combustion and Emissions of Ammonia/Diesel Dual-Fuel Marine Engine
by Wei Guan, Songchun Luo, Jie Wu, Hua Lou, Lei Wang, Feng Wu, Li Li, Fuchuan Huang and Haibin He
Energies 2025, 18(14), 3631; https://doi.org/10.3390/en18143631 - 9 Jul 2025
Viewed by 296
Abstract
This study investigates the impact of different combustion control strategies on marine engine combustion and emission characteristics at a high ammonia energy ratio. Compared to the strategy of maintaining a constant fuel injection duration, the strategy of keeping the fuel injection pressure constant [...] Read more.
This study investigates the impact of different combustion control strategies on marine engine combustion and emission characteristics at a high ammonia energy ratio. Compared to the strategy of maintaining a constant fuel injection duration, the strategy of keeping the fuel injection pressure constant allows the kinetic energy of diesel to remain at a higher level. This results in an increase in combustion efficiency and indicated the thermal efficiency of the engine, while also reducing CO2 and soot emissions. However, when the ammonia energy ratio increases to more than 50%, the indicated thermal efficiency starts to decrease along with the increase in the emissions of N2O and unburned ammonia. To address these issues, one of the potential means is to improve the in-cylinder combustion environment by increasing the in-cylinder gas temperature. This can enhance combustion efficiency and ultimately optimize the performance and emission characteristics of dual-fuel engines, which results in an increase in the combustion efficiency to 98% and indicated thermal efficiency to 54.47% at a relatively high ammonia energy ratio of 60%. Emission results indicate that N2O emissions decrease from 1099 ppm to 25 ppm, while unburned ammonia emissions drop from 16016 ppm to 100 ppm. Eventually, the greenhouse gas emissions were reduced by about 85.3% in comparison with the baseline case. Full article
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27 pages, 5055 KiB  
Article
Physical–Mathematical Modeling and Simulations for a Feasible Oscillating Water Column Plant
by Fabio Caldarola, Manuela Carini, Alessandro Costarella, Gioia De Raffele and Mario Maiolo
Mathematics 2025, 13(14), 2219; https://doi.org/10.3390/math13142219 - 8 Jul 2025
Viewed by 298
Abstract
The focus of this paper is placed on Oscillating Water Column (OWC) systems. The primary aim is to analyze, through both mathematical modeling and numerical simulations, a single module (chamber) of an OWC plant which, in addition to energy production, offers the dual [...] Read more.
The focus of this paper is placed on Oscillating Water Column (OWC) systems. The primary aim is to analyze, through both mathematical modeling and numerical simulations, a single module (chamber) of an OWC plant which, in addition to energy production, offers the dual advantage of large-scale integration into port infrastructures or coastal defense structures such as breakwaters, etc. The core challenge lies in optimizing the geometry of the OWC chamber and its associated ducts. A trapezoidal cross-section is adopted, with various front wall inclinations ranging from 90° to 45°. This geometric parameter significantly affects both the internal compression ratio and the hydrodynamic behavior of incoming and outgoing waves. Certain inclinations revealed increased turbulence and notable interference with waves reflected from the chamber bottom which determined an unexpected drop in efficiency. The optimal performance occurred at an inclination of approximately 55°, yielding an efficiency of around 12.8%, because it represents the most advantageous and balanced compromise between counter-trend phenomena. A detailed analysis is carried out on several key parameters for the different configurations (e.g., internal and external wave elevations, crest phase shifts, pressures, hydraulic loads, efficiency, etc.) to reach the most in-depth analysis possible of the complex phenomena that come into play. Lastly, the study also discusses the additional structural and functional benefits of inclined walls over traditional parallelepiped-shaped chambers, both from a structural and construction point of view, and for the possible use for coastal defense. Full article
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20 pages, 3503 KiB  
Article
Finite Element Analysis Framework for Structural Safety Evaluation of Type IV Hydrogen Storage Vessel
by Gunwoo Kim, Hyewon Kim, Hanmin Park, Kyuhwan Park, Sujin Yoon, Hansu Lee, Seokjin Lee, Jonglyul Kim, Gyehyoung Yoo, Younggil Youn and Hansang Kim
Hydrogen 2025, 6(3), 44; https://doi.org/10.3390/hydrogen6030044 - 2 Jul 2025
Viewed by 301
Abstract
Type IV composite overwrapped pressure vessels (COPVs) store hydrogen at pressures up to 70 MPa and must meet stringent safety standards through physical testing. However, full-scale burst, plug torque, axial compression, impact, and drop tests are time-consuming and costly. This study proposes a [...] Read more.
Type IV composite overwrapped pressure vessels (COPVs) store hydrogen at pressures up to 70 MPa and must meet stringent safety standards through physical testing. However, full-scale burst, plug torque, axial compression, impact, and drop tests are time-consuming and costly. This study proposes a unified finite element analysis (FEA) workflow that replicates these mandatory tests and predicts failure behavior without physical prototypes. Axisymmetric and three-dimensional solid models with reduced-integration elements were constructed for the polyamide liner, aluminum boss, and carbon/epoxy composite. Burst simulations showed that increasing the hoop-to-axial stiffness ratio shifts peak stress to the cylindrical region, promoting a longitudinal rupture—considered structurally safer. Plug torque and axial load simulations revealed critical stresses at the boss–composite interface, which can be reduced through neck boss shaping and layup optimization. A localized impact with a 25 mm sphere generated significantly higher stress than a larger 180 mm impactor under equal energy. Drop tests confirmed that 45° oblique drops cause the most severe dome stresses due to thin walls and the lack of hoop support. The proposed workflow enables early-stage structural validation, supports cost-effective design optimization, and accelerates the development of safe hydrogen storage systems for automotive and aerospace applications. Full article
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22 pages, 9463 KiB  
Article
Numerical Investigation of Spontaneous Ignition During Pressurized Hydrogen Release: Effects of Burst Disk Shape and Opening Characteristics
by Wanbing Lin, Zhenhua Wang, Guanghu Wang, Juncheng Jiang, Jingnan Wu, Lei Ni, Ru Zhou, Mingguang Zhang and Liang Ma
Fire 2025, 8(7), 246; https://doi.org/10.3390/fire8070246 - 26 Jun 2025
Viewed by 376
Abstract
Pressure relief devices are critical for the safe release of pressurized hydrogen. To address the risk of spontaneous ignition during a high-pressure release, three-dimensional (3D) numerical simulations are systematically conducted to investigate the effects of burst conditions on spontaneous ignition behavior. Eight simulation [...] Read more.
Pressure relief devices are critical for the safe release of pressurized hydrogen. To address the risk of spontaneous ignition during a high-pressure release, three-dimensional (3D) numerical simulations are systematically conducted to investigate the effects of burst conditions on spontaneous ignition behavior. Eight simulation cases are considered, involving two opening processes (instantaneous and 10-step-like), three burst disk shapes (flat, conventional domed, and reverse domed), and five opening ratios (1, 0.8, 0.6, 0.4, and 0.2). The 10-step-like opening enhances jet turbulence and promotes flame merging between the boundary layer and jet front, intensifying combustion. Domed structures cause a high-velocity region behind the leading shock wave, altering jet front evolution. Compared with reverse-domed disks, flat and conventional domed disks generate stronger vortices and a larger shock-heated area, resulting in more severe combustion and elevated fire risk. As the opening ratio decreases, both shock wave strength and propagation velocity drop significantly, and spontaneous ignition does not occur. The opening ratio has minimal influence on the distance traveled by shock-induced heating. These findings offer meaningful guidance for the design and manufacture of pressure relief devices for the safe emergency release of hydrogen. Full article
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21 pages, 2043 KiB  
Review
A Review on the Impact of Fallback Factor on Intermittent Gas and Gas-Assisted Plunger Lifts
by Erasmus Mensah and Smith Leggett
Geosciences 2025, 15(7), 237; https://doi.org/10.3390/geosciences15070237 - 20 Jun 2025
Viewed by 263
Abstract
In intermittent gas lift (IGL), not all the liquid initially in the tubing is usually produced at the surface in one cycle. This is due to a concept known as fallback, which occurs when some amount of the initial liquid column drops back [...] Read more.
In intermittent gas lift (IGL), not all the liquid initially in the tubing is usually produced at the surface in one cycle. This is due to a concept known as fallback, which occurs when some amount of the initial liquid column drops back to join the next slug. We conducted a review of earlier works on IGL and the behavior of the fallback factor. The dependence on the fallback factor on the operational conditions such as slug velocity, valve opening pressure, valve closing pressure, casing–tubing pressure ratio, diameter of tubing, and amount of gas injected during IGL are discussed in this paper. The effect on the shape and stability of the nose of the Taylor bubble on the lifting efficiency of the bubble is also explained. In trying to reduce the fallback factor per cycle, there have been recommendations to combine gas lift with plunger lift. We also present the results of this combination and the effects on the fallback factor in gas-assisted plunger lift (GAPL). More light is shed on the behavior of the velocity of the liquid slug and how it affects the fallback factor during IGL. The behavior of the fallback factor with an increase or decrease in plunger velocity during GAPL is also presented in this paper. This review is categorized into experimental and numerical studies on fallback factor to evaluate their impact on production efficiency in IGL and GAPL. Additionally, different formulas for fallback proposed by different literature are compiled. Full article
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15 pages, 3154 KiB  
Article
Multi-Physics Coupling of Rectangular Channels with Different Aspect Ratios in Solid Oxide Electrolysis Cells
by Jie Yao, Carsten Korte, Zhengyang Qian, Ming Chen and Jiangshui Luo
Materials 2025, 18(12), 2827; https://doi.org/10.3390/ma18122827 - 16 Jun 2025
Viewed by 293
Abstract
To explore the impact of the aspect ratio of the channels in the flow fields of solid oxide electrolysis cells on the performance of the cell, we developed three-dimensional models for cells with varying aspect ratios. Our findings revealed that channels with low [...] Read more.
To explore the impact of the aspect ratio of the channels in the flow fields of solid oxide electrolysis cells on the performance of the cell, we developed three-dimensional models for cells with varying aspect ratios. Our findings revealed that channels with low and high aspect ratios exhibit higher maximum pressure drops, whereas those with medium aspect ratios have the lowest pressure drops. Additionally, the mole fraction of the hydrogen decreases as the channel’s aspect ratio increases. We also computed the polarization curves for SOEC operating under three distinct aspect ratio channels. Our results suggest that structures with low aspect ratios exhibit the poorest electrochemical performance, suitable only for brief operations at low current densities; medium aspect ratio structures exhibit a balanced performance, making them suitable for various operating conditions; and high aspect ratio structures are best suited for operations at high current densities. This study on selecting different aspect ratios aids in determining the optimal channel parameters for different operating conditions, ultimately enhancing the performance of solid oxide electrolysis cells. Full article
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14 pages, 1115 KiB  
Article
Development of an Innovative and Sustainable Technological Process for Biogas Purification Through the Reuse of Autoclaved Aerated Concrete Waste
by Eric Dumont, Noé Kautzmann and Annabelle Couvert
Processes 2025, 13(6), 1767; https://doi.org/10.3390/pr13061767 - 3 Jun 2025
Viewed by 502
Abstract
This study demonstrated the effectiveness of using autoclaved aerated concrete AAC waste as a low-cost filtering material for removing hydrogen sulfide (H2S) from gas streams. A long-term experiment (89 days) was conducted in a packed bed reactor to purify synthetic biogas [...] Read more.
This study demonstrated the effectiveness of using autoclaved aerated concrete AAC waste as a low-cost filtering material for removing hydrogen sulfide (H2S) from gas streams. A long-term experiment (89 days) was conducted in a packed bed reactor to purify synthetic biogas composed of N2, CO2, H2S, and O2. Optimal H2S removal efficiencies, reaching up to 100%, were achieved under highly acidic conditions (pH ≈ 1–3) and low oxygen concentrations (<1%). In the presence of oxygen, calcium oxides in the AAC waste react with H2S to form gypsum (CaSO4 2H2O). The simultaneous removal of both oxygen and H2S by AAC waste, following an approximate 2:1 molar ratio, may be particularly beneficial for biogas streams containing unwanted traces of oxygen. The transformation and lifespan of AAC waste were monitored through sulfur accumulation in the material and pressure drop measurements, which indicated structural changes in the AAC waste. At the end of its lifespan, the AAC waste exhibited an H2S removal capacity of 185 gH2S kgAAC−1. This innovative and sustainable process not only provides a cost-effective and environmentally sound solution for the simultaneous removal of H2S and O2 from biogas, but also promotes waste valorization and aligns with circular economy principles. Full article
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19 pages, 9538 KiB  
Article
Research on the Impact Resistance of Sandwich-Structured Battery Pack Protective Plates
by Jun Zhou, Changjie Luo, Ruilin Shen, Fengqiang Zhang, Wenze Yu, Mingming Zhang and Weiliang Liao
Processes 2025, 13(6), 1639; https://doi.org/10.3390/pr13061639 - 23 May 2025
Viewed by 573
Abstract
With the continuous development of the new energy vehicle industry, in order to further improve the safety and range of electric vehicles, vehicle lightweighting has been a key focus of major car companies. However, research on lightweighting and the impact protection effect of [...] Read more.
With the continuous development of the new energy vehicle industry, in order to further improve the safety and range of electric vehicles, vehicle lightweighting has been a key focus of major car companies. However, research on lightweighting and the impact protection effect of battery pack protective plates is lacking. The bottom protective plate of the battery pack in this study has a sandwich-type multi-layer structure, which is mainly composed of upper and lower glass-fiber-reinforced resin protective layers, steel plate impact resistant layers, and honeycomb buffer layers. In order to study the relationship between the impact damage response and material characteristics of the multi-material battery pack protective plate, a matrix experimental design was adopted in this study to obtain the energy absorption ratio of different material properties when the protective plate is subjected to impact damage. This work innovatively used a low-cost equivalent model method. During the drop hammer impact test, a 6061-T6 aluminum plate in direct contact with the lower part of the bottom guard plate test piece was used to simulate the deformation of the water-cooled plate in practical applications. High-strength aluminum honeycomb was arranged below the aluminum plate to simulate the deformation of the battery cell. This method provides a scientific quantitative standard for evaluating the impact resistance performance of the protective plate. The most preferred specimen in this work had a surface depression deformation of only 8.44 mm after being subjected to a 400 J high-energy impact, while the simulated water-cooled plate had a depression deformation of 4.07 mm. Among them, the high-strength steel plate played the main role in absorbing energy during the impact process, absorbing energy. It can account for about 34.3%, providing reference for further characterizing the impact resistance performance of the protective plate under different working conditions. At the same time, an equivalence analysis of the damage mode between the quasi-static indentation test and the dynamic drop hammer impact test was also conducted. Under the same conditions, the protective effect of the protective plate on impact damage was better than that of static pressure marks. From the perspective of energy absorption, the ratio coefficient of the two was about 1.2~1.3. Full article
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20 pages, 8468 KiB  
Article
Numerical Investigation of Fuel Cooling in Sudden Expansion Structures of Scramjet Engines
by Qingjun Wang, Minglei Hu, Zongjie Quan and Yu Chen
Aerospace 2025, 12(6), 456; https://doi.org/10.3390/aerospace12060456 - 22 May 2025
Viewed by 361
Abstract
Local overheating in cavities seriously threatens the safe operation of scramjet engines. To investigate the formation mechanism and control methods of local overheating, this paper conducts numerical simulations on the cooling process of cavity sudden expansion (S-E) structures. A three-dimensional numerical model coupled [...] Read more.
Local overheating in cavities seriously threatens the safe operation of scramjet engines. To investigate the formation mechanism and control methods of local overheating, this paper conducts numerical simulations on the cooling process of cavity sudden expansion (S-E) structures. A three-dimensional numerical model coupled with pyrolysis reactions is established and validated through experiments. The effects of thermal pyrolysis reactions and cooling channel parameters on flow distribution are analyzed, and comparative studies with different channel parameters are performed. The results show that S-E structures are prone to uneven fuel flow distribution, leading to local over-temperature phenomena, and thermal pyrolysis reactions will aggravate this phenomenon to a certain extent. Increasing the aspect ratio of the channel can enhance the pressure drop at the inlet of the S-E structure and improve the uniformity of flow distribution. When the aspect ratio increases from one to eight, the mass flow distribution deviation ϕm decreases from 0.954 to 0.181. More uniform flow distribution under a larger aspect ratio avoids local over-temperature in the S-E structure, and reduces the coking risk caused by local excessive pyrolysis. This work reveals the fundamental characteristics of cooling heat transfer in the S-E structure of Scramjet engines and can provide recommendations for the design of cooling channels. Full article
(This article belongs to the Section Aeronautics)
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34 pages, 22149 KiB  
Article
Heat Transfer Intensification in a Heat Exchanger Tube with Continuous V-Rib Twisted Tapes Installed
by Yuexiang Du, Khwanchit Wongcharee, Varesa Chuwattanakul, Paisarn Naphon, Naoki Maruyama, Masafumi Hirota and Smith Eiamsa-ard
Appl. Sci. 2025, 15(10), 5612; https://doi.org/10.3390/app15105612 - 17 May 2025
Viewed by 457
Abstract
This article reports the effect of twisted tapes with continuous V-ribs on the thermal performance index characteristics of a heat exchanger tube. Numerical and experimental studies were conducted to investigate the influence of V-rib attack angles (β = 15°, 30°, and 45°) [...] Read more.
This article reports the effect of twisted tapes with continuous V-ribs on the thermal performance index characteristics of a heat exchanger tube. Numerical and experimental studies were conducted to investigate the influence of V-rib attack angles (β = 15°, 30°, and 45°) in forward and backward arrangements. This investigation employed 0.9 mm thick, continuous V-rib twisted tapes (CVRTs) made from aluminum sheets formed with a twist ratio of y/w = 4.0. The experimental results indicated that a continuous V-rib twisted tape (CVRT) was more effective in heat transfer improvement than a typical twisted tape (TT). This was due to swirl and longitudinal vortex flows that helped increase flow mixing and reduce boundary layer thickness. Decreased V-rib attack angles (β) led to greater heat transfer enhancement, pressure drop, and thermal performance index values due to the greater turbulent mixing of fluid. The numerical result revealed that a continuous V-rib twisted tape created strong longitudinal vortex flow, especially with higher attack angles. The Turbulent Kinetic Energy (TKE) and core fluid temperature increased with the insertion of CVRTs. Local Nusselt numbers also remained relatively high for heat exchanger tubes with CVRTs. The experimental study illustrated that a tube with a CVRT installed augmented heat transfer. In the experimentally studied cases, a backward arrangement had more heat transfer, a greater friction factor, and a better thermal performance index. Compared to a plain tube, a tube with CVRT installed, having β = 15°, 30°, and 45°, showed 76.8, 71.6, and 66.2% improved heat transfer, respectively. CVRTs with these three β-values, respectively, exhibited higher thermal performance than a TT. Among the investigated CVRTs, the backward-arranged tape with β = 15° offered the maximum thermal performance index, 1.13 at Re = 6000. The results are congruent with the simulation outcomes, hence supporting the CFD analysis. Full article
(This article belongs to the Section Energy Science and Technology)
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21 pages, 8111 KiB  
Article
Intensification of Multiphase Reactions in Petroleum Processing: A Simulation Study of SK Static Mixer Using NaClO for H2S Removal
by Mengmeng Gao, Jiacheng Liu, Ying Chen, Zibin Huang, Hongfu Wang, Peiqing Yuan, Xinru Xu and Jingyi Yang
Processes 2025, 13(5), 1515; https://doi.org/10.3390/pr13051515 - 15 May 2025
Viewed by 418
Abstract
During crude oil exploration and extraction, the presence of H2S not only poses a threat to operational safety but also accelerates equipment corrosion, highlighting the urgent need for efficient and cost-effective processing solutions. This study employs a coupled numerical simulation approach [...] Read more.
During crude oil exploration and extraction, the presence of H2S not only poses a threat to operational safety but also accelerates equipment corrosion, highlighting the urgent need for efficient and cost-effective processing solutions. This study employs a coupled numerical simulation approach that integrates computational fluid dynamics (CFD) and population balance models (PBM) to systematically investigate the multiphase flow characteristics within SK static mixers. By embedding mass transfer rates and reaction kinetics equations for hydrogen sulfide and sodium hypochlorite into the Euler-Euler multiphase flow model using user-defined functions (UDFs), the effects of equipment structure on the efficiency of the crude oil desulfurization process are examined. The results indicate that the optimized SK static mixer (with 15 elements, an aspect ratio of 1, and a twist angle of 90°) achieves an H2S removal efficiency of 72.02%, which is 18.84 times greater than that of conventional empty tube reactors. Additionally, the micro-mixing time is reduced to 0.001 s, and the coefficient of variation (CoV) decreases to 0.21, while maintaining acceptable pressure drop levels. Using the CFD-PBM model, the dispersion behavior of droplets within the static mixer is investigated. The results show that the diameter of the inlet pipe significantly affects droplet dispersion; smaller diameters (0.1 and 1 mm) enhance droplet breakup through increased shear force and turbulence effects. The findings of this study provide theoretical support for optimizing crude oil desulfurization processes and are of significant importance for enhancing the economic efficiency and safety of crude oil extraction operations. Full article
(This article belongs to the Section Chemical Processes and Systems)
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