Numerical analysis of hydrogen absorption in a large-scale modular metal hydride reactor with a hybrid heat exchanger comprising an internal finned tube and an external helical coil

Optimization of thermal performance in closed-loop wickless heat pipes with helical coil evaporators by neuro-genetic approach

Electromagnetic Launcher (EML) systems are classified into two main categories based on their fundamental operating principles: rail guns and coil guns. Rail guns accelerate a conductive projectile using magnetic force by passing a high current between two parallel rails, but they suffer from wear and heat accumulation due to mechanical contact. Coil launchers use electromagnets to accelerate ferromagnetic or conductive projectiles without contact, thus minimising energy losses and wear. Rail guns are preferred in military applications requiring high velocity and kinetic energy, whereas coil guns are more prominent in controlled acceleration applications such as space launch systems and laboratory experiments. Since the velocity of the generated electromagnetic field in coil launchers has no theoretical limit, the accelerated projectile also does not have a predefined velocity limit. However, the use of randomly sized coils and an increased number of sequential coils in coil guns disrupts the linearity of the projectile velocity increase. To address this issue, this study develops a “New Helical Coil Gun”, consisting of four-stage helical coils designed to achieve linear velocity increase. First, the self-inductance coefficient of a coil was simulated based on the time-dependent variations of the current passing through it, and the inductance value that could provide a maximum instantaneous current of 25A (without direction change) under laboratory conditions was determined. Then, the design of the helical coil with a rectangular cross-section to provide this coefficient value was implemented. This design was then transferred to the ANSYS Maxwell magnetic analysis software, where an optimisation process was conducted to determine the ideal projectile size that would maximise the magnetic force exerted on a ferromagnetic projectile when a 25 A current was applied to the coil. Following this stage, a “Helical Coil Gun”, composed of four-stage helical coils, was designed and manufactured based on the determined projectile and coil dimensions. Optical sensors were placed at the initial positions of the coils to measure the projectile’s velocity. An FPGA-based project was developed for data acquisition, processing, and triggering control. This project, designed using the LabVIEW FPGA module, was carried out on the NI myRIO-1950 board containing Xilinx FPGA. After each launch, the collected data was stored on a flash drive connected to myRIO and monitored in real time via a display. What distinguishes this study from literature is its approach to determining the optimal coil geometry by correlating the current variation characteristics with the coil’s self-inductance coefficient and using Genetic Algorithm-based optimisation to identify the ideal projectile size that achieves maximum velocity under maximum force. Experiments with the developed coil gun showed that the projectile velocity change from the beginning of the first coil to the end of the fourth coil was linear.

An innovative method, termed FRAP/ABTS-SIA, was developed to simultaneously integrate the FRAP and ABTS antioxidant assays within a single sequential injection analysis (SIA) system with spectrophotometric detection. Leveraging the kinetic differences between the assays and controlling the dispersion, a compact aspiration sequence (antioxidant-FRAP-ABTS-antioxidant-water) was optimized using a central composite design, defining a flow rate of 40 μL s-1 and aspiration volumes of 43, 38, 38, 43, and 100 μL, respectively. The system incorporated a helical reaction coil positioned before the detector, allowing the antioxidant-FRAP bolus to react while the ABTS-antioxidant-water sequence was aspirated into the holding coil. This configuration enhanced the FRAP signal and enabled clear separation of both analytical responses. Compared to conventional batch protocols, this strategy reduced FRAP reagent concentrations by 70% and ABTS•+ radical concentrations by 50%. The method delivers responses within a 2 min run, achieving a throughput of ∼30 samples h-1. Linearity was confirmed for both assays over the range 10-120 μmol L-1 Trolox, with detection limits of 0.031 μmol L-1 (FRAP) and 0.0047 μmol L-1 (ABTS). Intralaboratory precision was below 2% RSD, and recoveries ranged from 97.3 to 106.2% (FRAP) and 92.8 to 105.4% (ABTS). The method was successfully applied to complex food matrices─including coffees, wines, juices, and spices─showing correlations ≥0.99 with microplate reference assays. High-throughput, reagent savings, metrological robustness, and simplified data processing position FRAP/ABTS-SIA as an efficient and reliable tool for routine antioxidant capacity evaluation in food and biomedical applications.

Abstract Over the last decade, there has been significant interest in renewable energy resources, with solar energy emerging as one of the most promising options. Among various technologies, the parabolic trough solar reflector with innovative receivers plays a crucial role in efficient solar power harvesting. This experimental study focuses on a stationary parabolic trough with a 2.8 m2 aperture area, integrated with a manually operated dual-axis sun-tracking system. The primary objective was to evaluate and enhance the system's thermal performance over three representative days in February, under both sunny and cloudy conditions. To optimize optical performance while minimizing design and fabrication costs, the prototype incorporated mirror strips, which also helped reduce lift and drag forces caused by high air pressure around the trough. A three-day experiment was conducted to assess the system's performance, and the results demonstrated that the water's highest recorded temperature was 84.2 °C, while the regenerative air attained 75.1 °C using a novel helical-coiled receiver design. With a maximum receiver thermal efficiency of 85.4% and an overall system efficiency of 55.4%, the design exhibits considerable promise for integrated air and water heating applications in residential and industrial contexts.

Performance Evaluation of a Microencapsulated PCM-Integrated Helical Coil Heat Exchanger Operated with SiC Nanofluid

Abstract The heat transfer properties of Helical Coil Heat Exchangers and Double Pipe Heat Exchangers are compared in this study utilizing both water and nanofluids. A three-dimensional numerical simulation assessed the heat transfer performance of both designs under equivalent heat transfer areas and fluid flow circumstances. The present study employed CFD to compare helical-coil and double-pipe heat exchangers under conditions of area-normalized, equal-Reynolds-number, and counter-current flow. The two types of exchangers are tested under the same boundary conditions in an industrially relevant hot-side temperature range. In the present study it may be observed that, the differences in performances caused by geometry while maintaining the total heat-transfer area (0.77 m²) and flow parameters the same. The incorporation of 1% Al₂O₃ nanofluid in the tube side significantly enhanced heat transmission rates. The results demonstrate that the helical coil configuration exhibited a significantly enhanced overall heat transfer coefficient, improving by as much as 60% relative to the double pipe configuration. The tube side is compatible with or without 1 vol% Al₂O₃–H₂O nanofluid. The study emphasizes the influence of differing operating temperatures and fluid velocities, with Helical Coil Heat Exchanger consistently surpassing Double Pipe Heat Exchangers under all evaluated situations. In comparison the overall heat-transfer coefficient (U) has been found to be higher up to 60 % for helical-coil heat exchanger than that of the double-pipe heat exchanger. The improved heat transmission in Helical Coil Heat Exchanger is due to its coiled design, which facilitates secondary flow and turbulence and hence optimizes thermal efficiency. As a result, the results show that Helical Coil Heat Exchanger using nanofluids works well for tasks that need better heat transfer efficiency, offering many advantages over standard double pipe arrangements.

Effect of Lead Body and Helix Design Variables on Implantation Success, Insertion Depth, and Muscle Torque in Left Bundle Branch Area: Insights from An Ex-Vivo Porcine Model.

Abstract Understanding and modelling heat transfer coefficient is essential for optimizing the performance of High-Temperature Superconducting (HTS) devices. The heat transfer coefficient exhibits highly non-linear behaviour with respect to temperature and is typically inferred from the properties of the cooling fluid. However, when the device is fully immersed in a liquid, the coefficient can deviate significantly from conventional estimations, especially if the operating conditions do not involve an extremely rapid temperature increase. This study presents a practical method for estimating the heat transfer coefficient of HTS coils immersed in liquid nitrogen, based on an experimental investigation of a prototype superconducting coil where precise temperature measurements are not guaranteed. By analysing transient temperature evolution and material properties, the coefficient is determined and validated through the comparison of measured and simulated device voltage and current. The proposed approach only relies on experimental voltage and current measurements, combined with known temperature-dependent material properties, to infer a global heat transfer coefficient. The methodology is tested on helical HTS coils under transient light over-current conditions and assumes an homogenised temperature rise along the winding. The estimated coefficient may lead to curves that slightly deviate from classical models while preserving their overall trend and physical significance. The proposed experimentally-based approach is conceived as a relatively straightforward and experimentally robust alternative to the computational burden of FEM simulations requiring reliable parameters, while overcoming the need for direct temperature measurements, within the limits of compact windings immersed in liquid nitrogen and subjected to mild transient conditions leading to distributed quench phenomena.

Heat transfer performance analysis of a helical coil tube with supercritical CO2 as a working fluid

The objective of this study is to conduct a comparative analysis of helical coil suspension springs made from chrome vanadium and hard-drawn carbon steel. The analysis includes both empirical and static strength evaluations using finite element analysis (FEA) to identify the optimal material for minimising the stress and deflection. The suspension model is created in Pro-E and structural analysis is performed using ANSYS. The physical properties of the two materials are compared through empirical analysis. The results of this comparative study help determine the most suitable material for suspension springs, ensuring improved performance and longevity.

Enhanced thermohydraulic performance in helical coil heat exchangers using synthesized Cu-doped TiO2 nanofluids: An experimental approach

Experimental study on boiling heat transfer characteristics in helical coils with large coiled diameters

Latent heat thermal energy storage (LHTES) systems are essential for efficient thermal energy storage. However, these devices are often constrained by long charging and short discharging periods. This study presents a novel triplex‐tube LHTES design incorporating a copper helical coil positioned between two concentric stainless‐steel shells. Stearic acid was used as the phase change material and water as the HTF, with two separate flow paths provided for charging and discharging. During charging, HTF is circulated through the outer shell at a higher mass flow rate to increase energy input and accelerate the charging process. During discharging, HTF flows through the inner helical copper coil at a reduced mass flow rate, increasing its residence time by 97.54%. This enhances the uniformity index and extends the discharge duration by 26.8% compared to a conventional concentric triplex‐tube design. Additionally, the discharge efficiency increases to 87.5% due to a 31.4% rise in heat‐transfer area and higher thermal conductivity of copper compared to stainless steel.

CFD Simulation and Thermal Performance Optimization of a Helical Coil Heat Exchanger in a Heating Furnace

Simulation of flow field characteristics around longitudinally staggered variable-curvature helical coil bundles

This paper investigates the impact of self-consistency in modeling the laser-driven post-acceleration of proton beams using a helical coil target (HC). We adapt and apply the 1D Hamiltonian multi-particle traveling-wave tube model, DIMOHA, to simulate the HC post-acceleration. While DIMOHA does not incorporate the effects of the radial component of the coil and space charge fields, it effectively captures the axial interaction between accelerated protons and the coil's electric field. A key advantage of DIMOHA is that it is a self-consistent code significantly faster than traditional Particle-In-Cell codes, offering an efficient balance between computational time and modeling accuracy. Using DIMOHA, we present a method to assess the significance of self-consistent effects in the post-acceleration process. Through extensive simulations, we explore various beam densities and RF pulse amplitudes to identify the conditions under which self-consistency becomes critical. Our findings show that in setups with high beam densities, self-induced fields modify proton bunch energies within the range of shot-to-shot experimental fluctuations. Furthermore, under typical TNSA conditions, where the bunch energy remains significantly below the cutoff energy, these effects appear negligible for the high-energy population. Thus, simplified models with precomputed fields can be reliably used to satisfactorily evaluate proton spectra.

A novel integrated approach to heat transfer enhancement using baffles and inner fins in helical coil heat exchangers

Wheelbarrows are essential multipurpose and dual-function materials handling equipment for many industries and homes. They find exclusive use in the movement of finished goods and raw materials where no other form of transportation works. However, the traditional wheelbarrows require enormous human effort to accomplish the task of conveying a reasonable amount of load from one place to another. During the process, shock loads from road irregularities are transmitted directly to the Barrow pusher. Therefore, this study investigated a retrofitted helical coil, compression spring, wheelbarrow design for effective load transportation. A wheelbarrow with a trapezoidal bucket capacity of 50 l was fabricated and mounted on a hollow pipe galvanized steel chassis frame. The bucket was supported on the front end of the frame using two helical coil compression springs to cushion the shock loads transmitted to the Barrow pusher. For a 150-kg payload, three standard bags of cement equivalent, and a deadweight of 22kg, the spring retrofit design wheelbarrow effectively reduces the galloping shocks through bumps and other path surface irregularities better than conventional non-spring wheelbarrows. The new design can therefore provide succor to the regular wheelbarrow pushers who tend to develop unintended health issues, such as muscular build-up and cramps, as they use a wheelbarrow to move materials over a distance.

Abstract The transportation and storage of hydrogen, particularly in automotive applications, remain significant challenges to its widespread utilization. Among the various methods explored, metal hydride (MH)-based storage of hydrogen is gaining momentum due to its unique characteristics, making it well-suited for stationary and automotive applications. An efficient MH storage system requires an effective heat exchange mechanism, as the ab/desorption kinetics involve exothermic and endothermic reactions. This study developed a comprehensive mathematical model to capture the kinetics, mass transfer, and heat transfer processes in an MH system. The validated model was subsequently employed to examine how adding fins to the surface of a helical coil heat exchanger influences hydrogen storage capacity and heat transfer efficiency. The findings reveal that adding fins to the helical coil significantly enhances heat transfer and absorption rates. Notably, the duration needed to reach 90% saturation of the MH bed's maximum storage capacity is reduced by 11.11%. A comprehensive study was conducted to investigate the influence of fin dimensions on the performance of MH bed. The rate of achieving 90% hydrogen storage improves by 17.64% when the fin width increases from 3 mm to 6 mm. Similarly, it improves by 16.6% when the thickness of the fin increases from 0.5 mm to 2 mm. However, further increases in the fin dimensions do not yield significant improvements, attributing to the inherently poor heat conduction capability of the metal powder.