Coil Flow Research Articles

Evaluation of coiling endovascular technique on treatment of middle cerebral artery cerebral aneurysms in different blood hematocrits: A numerical study

Intracranial aneurysms are localized dilatations of the cerebral arteries that carry a risk of rupture and subsequent subarachnoid hemorrhage, a life-threatening condition. Middle cerebral artery (MCA) aneurysms are a common type of intracranial aneurysm, and endovascular treatment using coils or flow diverters is a common intervention approach. Understanding the hemodynamics, or blood flow patterns, within MCA aneurysms and how they are affected by endovascular treatment is crucial for improving patient outcomes. This numerical study investigates the hemodynamics of blood flow within MCA aneurysms before and after endovascular treatment. Patient-specific geometric models of MCA aneurysms were reconstructed from medical imaging data. Simulations using computational fluid dynamics were conducted to examine flow characteristics, wall shear stress, and additional hemodynamic factors within the aneurysms. The study assessed and contrasted the impact of coil embolization and flow diverter placement on the hemodynamics inside the aneurysms. The findings offer a deeper understanding of the intricate flow dynamics within MCA aneurysms and illustrate the ways in which endovascular treatments can modify these dynamics.

Performance evaluation and field synergy analysis of PEMFC with novel snake coil flow field

In the development process of proton exchange membrane fuel cells (PEMFC), the design of the flow field structure plays an important role in improving its mass transfer and performance. In this survey, a novel serpentine channel flow field (SCFF) construction is initially proposed, a 3D multiphase mathematical model is developed, and the accuracy of the mathematical model is confirmed by means of experimental data. Secondly, based on the fluid simulation software, the performance difference between SCFF with different numbers of turns and conventional flow fields (single serpentine and parallel flow fields) in terms of electrochemical reaction and reactant transportation is comparatively analyzed. Finally, the effect on PEMFC performance of the mass transport capability with the novel flow field is evaluated by the theory of mass-transfer loss rate and field synergy. The studies indicate that as the number of turns grows, the output performance of the proposed flow field progressively enhances. The net power density of the flow channel structure with five turns (SC-5) is increased by 35.3% compared with that of the flow channel structure with two turns (SC-2), and the SC-5 flow field also has higher output performance compared with the two conventional flow fields, with an increase of 7.2% and 27.9% in net power, respectively. Meanwhile, the synergistic efficacy between velocity vector field and concentration field is gradually enhanced with the increase in the number of turns, and the results show that SC-5 has the most optimal mass-transfer capability.

Optimisation of Additively Manufactured Coiled Flow Inverters for Continuous Viral Inactivation Processes

This article reports the development and utilisation of an adaptive design workflow methodology for use as a platform technology for the printing, testing, and optimisation of biopharmaceutical processing reactors. This design strategy was developed by application to the complex structure of the coiled flow inverter (CFI). In this way, the many possible physical parameters of the reactor were optimised, via a combination of experimental results, computational fluid dynamics and machine learning approaches, to find the CFI setups that provide the optimal flow properties for a particular application.Additively manufactured reactors are seeing increasing interest in the field of biopharmaceutical production. This is because the desired output volumes are typically small and there is an increasing move towards adopting continuous production, to replace traditional batch production. This approach allows for the tailoring of reactors for a specific reaction, i.e. attempting to maximise the desired aspects of the reaction through refinement of the physical parameters of the reactor, so creating a large possible parameter space to explore.Consequently, the holistic optimisation of CFI reactors and 3D printing is established as providing better plug flow mixing relative to traditional tube coiled reactors. In addition, a trained metamodel in combination with multilayer equations is demonstrated to predict reactor performance quickly and accurately.

Ethanol Production Using Zymomonas mobilis and In Situ Extraction in a Capillary Microreactor

The bacterium Zymomonas mobilis is investigated as a model organism for the cultivation and separation of ethanol as a product by in situ extraction in continuous flow microreactors. The considered microreactor is the Coiled Flow Inverter (CFI), which consists of a capillary coiled onto a support structure. Like other microreactors, the CFI benefits from a high surface-to-volume ratio, which enhances mass and heat transfer. Compared to many other microreactors, the CFI offers the advantage of operating without internal structures, which are often used to ensure good mixing. The simplicity of the design makes the CFI particularly suitable for biochemical applications as cells do not get stuck or damaged by internal structures. Despite this simplicity, good mixing is achieved through flow vortices caused by Taylor and Dean vortices. The reaction system consists of two phases, in which the aqueous phase carries the bacterium and an oleyl alcohol phase is used to extract the ethanol produced. Key parameters for evaluation are bacteria growth and the amount of ethanol produced by the microorganism. The results show the suitability of the CFI for microbial production of valuable compounds. A maximum ethanol concentration of 1.26 g L−1 was achieved for the experiment in the CFI. Overall, the cultivation in the CFI led to faster growth of Z. mobilis, resulting in 25% higher ethanol production than in conducted batch experiments.

Elucidating flow-directed 98% CO2 absorption using millimeter-sized coiled flow inverters: Nanocellulose-aided sustainable scope

The Sustainable Development Goals (SDGs) adopted by the United Nations drive the global efforts to discover a sustainable carbon capture method for the reduction of anthropogenic CO2 emissions. Concentrated alkanolamine solutions are being used as CO2 capture mediums for batch processes amid several disadvantages, such as energy intensiveness and poor efficiency. In this work, millimeter-sized coiled flow inverters (CFI) have been explored as a point-source CO2 capture tool for highly efficient, continuous operations. Solvent and CO2 gas flow rates are found to dictate the slug flow regime and, more specfically, slug lengths. High interfacial area and residence time remain the driving factors for enhanced CO2 capture using CFI. About 98% CO2 absorption efficiency has been achieved for 3% aqueous diethanolamine solution in CFI . The efficacy of nanocellulose, a sustainable nanomaterial has been unearthed for CO2 capture at low flow rate.

Continuous Isothermal Antisolvent Crystallization of Pyrazinamide in a Coiled Flow Inverter Device

Continuous Isothermal Antisolvent Crystallization of Pyrazinamide in a Coiled Flow Inverter Device

Contralateral approach to giant ruptured and unruptured ophthalmic artery aneurysms: patient series.

Giant ophthalmic artery (OphA) aneurysms remain surgically challenging despite the progress in endovascular treatments. This study describes the contralateral interoptic corridor in select patients based on imaging criteria suitable for clipping. The aim of this study was to show that despite the growing use of novel endovascular techniques, such as coil embolization and flow diversion, for the treatment of OphA aneurysms, microsurgical clipping may still be preferred for giant ones under certain conditions. The authors retrospectively reviewed the records of the microsurgical treatment of unruptured and ruptured giant OphA aneurysms at the University Hospital Center "Mother Teresa," Tirana, from 2007 to 2016. Four patients were selected for microsurgery and the contralateral approach using ophthalmic evaluations and coronal imaging on computed tomography, magnetic resonance imaging, and digital subtraction angiography that demonstrated aneurysms with a small neck and an orientation between 11 and 13 on the coronal clock face. A prefixed chiasm was a contraindication to this approach. Giant OphA aneurysms can be safely clipped through a contralateral interoptic corridor without creating new visual deficits or a residual aneurysm. https://thejns.org/doi/10.3171/CASE2473.

Endothelial Progenitor Cells: A Review of Molecular Mechanisms in the Pathogenesis and Endovascular Treatment of Intracranial Aneurysms.

This comprehensive review explores the multifaceted role of endothelial progenitor cells (EPCs) in vascular diseases, focusing on their involvement in the pathogenesis and their contributions to enhancing the efficacy of endovascular treatments for intracranial aneurysms (IAs). Initially discovered as CD34+ bone marrow-derived cells implicated in angiogenesis, EPCs have been linked to vascular repair, vasculogenesis, and angiogenic microenvironments. The origin and differentiation of EPCs have been subject to debate, challenging the conventional notion of bone marrow origin. Quantification methods, including CD34+ , CD133+ , and various assays, reveal the influence of factors, like age, gender, and comorbidities on EPC levels. Cellular mechanisms highlight the interplay between bone marrow and angiogenic microenvironments, involving growth factors, matrix metalloproteinases, and signaling pathways, such as phosphatidylinositol-3-kinase (PI3K) and mitogen-activated protein kinase (MAPK). In the context of the pathogenesis of IAs, EPCs play a role in maintaining vascular integrity by replacing injured and dysfunctional endothelial cells. Recent research has also suggested the therapeutic potential of EPCs after coil embolization and flow diversion, and this has led the development of device surface modifications aimed to enhance endothelialization. The comprehensive insights underscore the importance of further research on EPCs as both therapeutic targets and biomarkers in IAs.

Effect of coil diameter on water disinfection efficiency in a helical photoreactor using ultraviolet-C light emitting diodes

ABSTRACT This study investigated the disinfection efficiency of a photoreactor equipped with a helical water flow channel and ultraviolet-C (UV-C) light emitting diodes (LEDs). Theoretical simulations and biodosimetry tests were conducted to investigate the effects of coil diameter and flow rate on the reactor’s performance in inactivating Escherichia coli. The interplay between hydrodynamics and UV radiation was analyzed to determine the UV fluence absorbed by the microbes. The simulations revealed that, primarily due to the specific radiation pattern of the UV LEDs, the coil diameter strongly influenced the distribution of irradiance in the water and the UV fluence received by microbes. The experimental results indicated that the photoreactor achieved the highest inactivation value of 2.8 log when the coil diameter was 48 mm for a flow rate of 40 mL/min; this log value was superior to those for coil diameters of 16, 32, 64, and 80 mm by approximately 1.9, 0.4, 0.5, and 0.7 log units, respectively. This optimal coil diameter leading to the maximal UV irradiance and the highest degree of irradiance uniformity along the flow channel. This study offers design guidelines for constructing a high-efficiency water disinfection reactor with a helical flow channel configuration.

Optimized coil and current flow designs for wireless charging containers with improved even magnetic flux density distribution

AbstractThis paper introduces three different shapes of wireless charging containers (i.e. quadrangular prism, octagonal prism, and hexagonal prism) and presents optimal current flow designs for the coils to enhance the uniformity of magnetic flux distribution inside the containers. Additionally, the concept of folded coil design is introduced to further improve the even distribution of magnetic flux density within the containers. The performance of these designs is evaluated through simulations and practical experiments.

Millistructured Coiled Flow Inverter for Biphasic Continuous Flow 5‐Chloromethylfurfural Synthesis

AbstractSyntheses of alternative platform chemicals, such as 5‐chloromethylfurfural (CMF), from bio‐based starting materials are often associated with complicated kinetic schemes and mass transfer processes. Millistructured flow reactor concepts can help to elucidate kinetic schemes and determine rate constants which are of crucial importance for the design of respective technical processes. For the first time, the influence of proton concentration on the rate constants involved in the biphasic synthesis of CMF is systematically investigated. Results are discussed in terms of green chemistry metrics.

Direct V3 Vertebral Artery Access for Embolization of Partially Thrombosed Fusiform Basilar Trunk Aneurysm: Technical Case Instruction.

Fusiform vertebrobasilar aneurysms carry significant morbidity. Endovascular strategies are preferred; however, unsafe or unfeasible access can call for innovative strategies. An octogenarian patient with an enlarging fusiform proximal basilar artery aneurysm causing a sixth nerve palsy was found to have multiple anatomic features that precluded a transradial or transfemoral endovascular approach. She was thus treated with direct microsurgical access of the V3 segment of the vertebral artery for subsequent coil embolization and flow diversion. This case introduces a novel combined microsurgical and endovascular strategy for treating a complex partially thrombosed fusiform basilar artery aneurysm. This approach should be reserved only for patients where conventional endovascular access is dangerous or unfeasible.

Built-In Coil Current Sensing for 7-Tesla 1H/23Na and 1H/31P Magnetic Resonance Imaging

This article introduces two designs for dual-tuned built-in radio-frequency coil current sensing in 7-Tesla magnetic resonance imaging based on the current forcing property of the quarter-wave transmission line. The first design offers dual-tuned built-in coil current sensing at <sup>1</sup>H/<sup>23</sup>Na resonant frequencies to probe the coil current consecutively at 298 MHz and 78.8 MHz, without the need for any integrated sensor on the coil. The second design enables dual-tuned built-in coil current sensing at <sup>1</sup>H/<sup>31</sup>P resonant frequencies to probe the coil current at 298 MHz and 120 MHz consecutively. The first design achieved good matching (<-40 dB) and low insertion loss (<0.5 dB) for <sup>1</sup>H and <sup>23</sup>Na magnetic resonance signals. The <sup>1</sup>H/<sup>31</sup>P design also exhibited good matching (<-30 dB) and low insertion loss (<0.67 dB). Therefore, both designs show promising potential for monitoring current flows in dual-tuned coils at the Larmor frequencies of different atomic nuclei.

Performance evaluation of a parabolic trough collector with a uniform helical wire coil flow insert

Solar energy is an extremely useful and dependable renewable energy source for meeting our society's diverse energy demands. Solar concentrator-based energy systems are currently the most efficient methods of using solar energy. Among these technologies, the parabolic trough collector is a mature and effective concentrating solar power technology with a wide range of real-world applications using solar alone or in combination with other energy sources. Flow insert is a potential approach for improving parabolic trough solar collector performance through enhanced heat transfer and heat absorption. The purpose of this study is to determine the feasibility of using a uniform helical wire coil flow insert in the LS-2 parabolic trough solar collector module. A computational fluid dynamic model developed in Ansys 18.1 is used in the current investigation. A uniform helical wire coil flow insert is modeled and compared with the plain tube without any insert inside it. Flow analysis, overall efficiency, exergy efficiency, and thermal efficiency are compared in the evaluation process. The overall efficiency and exergy efficiency of the parabolic trough collector are the most critical criteria in determining its performance. The parabolic trough collector is examined using a range of inlet fluid temperatures ranging from 303 K to 603 K and a volumetric flow rate of 50 L per minute to 250 L per minute. The pumping work is found to be the lowest, indicating that the increase in pressure drop has a negligible effect on the overall system performance. For the flow rate of 50 L per minute and inlet heat transfer fluid temperature of 303 K, the overall, exergy and thermal efficiency using a uniform helical wire coil flow insert are found to be 2.07 %, 2.1 %, and 2.2 %, respectively.

Continuous synthesis of boron-doped carbon nitride supported silver nanoparticles in an ultrasound-assisted coiled flow inverter microreactor

Continuous synthesis of boron-doped carbon nitride supported silver nanoparticles in an ultrasound-assisted coiled flow inverter microreactor

A comparative study of polymer viscosity modifiers: Flow field challenges & alternative trends

In recent years, substantial advancements have been achieved in augmenting the energy efficiency of hydraulic fluids through the integration of polymers. This study employs a multiscale approach, encompassing an analysis of polymer coil size evolution and flow field characteristics, with the aim of investigating the behavior of both dipole and non-dipole polymers within the host solvent. The ultimate goal is to establish a comprehensive understanding of the correlation between atomic properties of additives and the macroscopic properties of the polymer solution.To achieve this, the study employs an atomistic-continuum hybrid model that combines Brownian Dynamics and Lattice Boltzmann techniques within the bead-spring concept framework. Four chains, each comprising 64 particles, are subjected to varying shear rates. The primary focus centers on the examination of alterations in the radius of gyration and the velocity field within the polymer solution. Notably, the inclusion of dipole-dipole interactions exerts a profound influence on the configuration of the polymers. The results illuminate that non-dipole polymers display a more pronounced coupling with bulk flow hydrodynamics, leading to the confinement of particle motion in directions perpendicular to the primary stream. In contrast, dipole polymers experience a slower increase in coil size when compared to their non-dipole counterparts. These findings furnish valuable insights for the enhancement of energy-efficient hydraulic fluids and contribute to a fundamental comprehension of polymer behavior in lubricants, charting the course for the development of advanced hydraulic fluids in the future.

Numerical and experimental investigation of laminar and turbulent convective heat transfer in a coiled flow reverser with twisted tape insert

This paper presents a comprehensive investigation of heat transfer enhancement and pressure drop in a Coiled Flow Reverser (CFR) with a twisted tape insert. Both laminar (10 < Re < 2000) and turbulent (12,000 < Re < 18,000) regimes have been studied using both experimental and numerical methods. The effects of twist ratio of twisted tape, inlet Reynolds number, and perforating the twisted tapes have been investigated. The study found that the best performance in the laminar regime is achieved with a twisted tape with a twist ratio of 15.73 and no holes on it at a Reynolds number of 2000. In the turbulent regime, the same twisted tape performs the best at a Reynolds number of 17,000. The highest Thermal Performance Ratio (TPR) in laminar regime is 1.55 and in turbulent regime is 0.99. In comparison to the straight pipe, all types of CFRs show better performance in heat transfer enhancement. Also, as the Reynolds number increases, the friction coefficient decreases in all configurations. The study reveals that the twisted tape insert enhances heat transfer performance while increasing pressure drop. This study provides valuable insights into the design and optimization of heat exchangers with CFR. The findings can be used to improve the efficiency and performance of various industrial processes, such as refrigeration systems, air conditioning, and power plants.

Adsorptive desulfurization of thiophene using Cu-CNF slurry in a coiled flow inverter with recycling

This study presents an alternative to adsorptive desulphurization (ADS) process in packed beds by making use of enhanced radial mixing prevalent in coiled flow inverter (CFI). We describe the synthesis of Cu-tartrate as the precursor for Cu-carbon nanofiber (Cu-CNF) and the application thereof in ADS of liquid fuels in a CFI. Thiophene was removed from n-hexane using a slurry of Cu-CNF in the liquid. The data show the sulfur (S) - loading of 103 mg/g in Cu-CNF at 2000 ppmw-S concentration of thiophene in the liquid at 120 cc/min flowrate using five CFI units connected in series. Recycling was introduced for the first time in CFI, and three CFI units connected in series with the recycle ratio of 2 were sufficient to achieve the same removal efficiency as with five CFI without recycling. The results indicate that CFI is an efficient technology and has potential to replace packed bed adsorbers.

Enhancing Power Transmission Stability of AUV’s Wireless Power Transfer System with Compact Planar Magnetic Coupler

In this paper, a wireless power transfer (WPT) system with a compact planar magnetic coupler for an autonomous underwater vehicle (AUV) is proposed. A passive induction (PI) coil is integrated into the circular transmitter (Tx) coil to build a uniform magnetic field (UMF), which can guarantee the stable output of the WPT system under uncertain radial and axial misalignments for AUV. Based on normalized magnetic induction intensity distribution analysis, a UMF constructing method with a PI coil is given, aiming to eliminate the fluctuation of magnetic field intensity, and the PI coil design principles and flow chart are obtained. The theoretical analysis shows the proposed integrated coil can effectively enhance the radial misalignment tolerance compared with a conventional circular spiral coil. The zero-phase angle (ZPA) input condition can be achieved by adjusting the series capacitor connected with the Tx coil in S-S compensation topology. Experimental results show that the proposed magnetic coupler containing an integrated coil significantly improves the stability of output power and power transfer efficiency within the possible radial and axial misalignments compared with a conventional coupler. It was demonstrated that the output power changes less than 5.5% and the power transfer efficiency maintains at approximately 84.5% in arbitrary radial positions within the possible working region with an axial transfer distance of 50 mm in saltwater.

Thermal stratification characteristics during simultaneous charging and discharging for different storage tank geometries with immersed discharging coil

The geometrical shapes of the thermal energy storage and the configurations of immersed discharging coils dictate the efficacy of low-to-medium temperature hot water applications. This study uses a three-dimensional numerical model to investigate the thermal characteristics of three storage configurations for simultaneous charging and discharging. The same tank volume and height, as well as the same coil tube dimensions, are considered for three different configurations - cylindrical tank with a helical discharging coil, as well as circular truncated cone-shaped and paraboloidal tanks with conical discharging coils. The discharging flow rate is varied for a deeper understanding of the realistic interplay between energy demand and supply. Results obtained for the cylindrical tank are found to have good agreement with the observations from the in-house experiments. The energy stored, discharging coil outlet temperature, and the extent of thermal stratification decrease with increasing coil flow rate, whilst discharging efficiency and primary thermocline thickness increase. The paraboloidal tank equipped with a conical discharging coil exhibited the highest cumulative energy stored (8821 kJ) just before the commencement of dynamic dual operation, owing to the minimal thermal losses attributable to the lowest surface-area-to-volume ratio. Thermocline thickness is found to expand with time for all the cases, and the highest thermocline thickness expansion rate of 0.208 mm/s is found for the cylindrical tank indicating a higher degree of energy degradation. The peak values for the cumulative energy discharged (9788 kJ), and average discharging efficiency (0.36) occurred for the paraboloidal tank with the conical discharging coil configuration. Based on the detailed analyses, the paraboloidal storage tank configuration is found to exhibit better system reliability and energy management, leading to more efficient heat dispatch controllability due to the enhanced energy harnessing features.