Search Results (881)

Internal wall loss in hot-fluid pipelines is difficult to monitor during operation because weak thermal perturbations are masked by global heating, axial cooling, and external heat dissipation. This study develops an external thermometry framework combining a flexible-base fiber Bragg grating (FBG) array with residual-peak morphology analysis. A closed-loop hot-water rig with five artificial wall-loss regions was tested under exposed-air and buried-soil boundaries, and a validated conjugate heat-transfer model generated 269 controlled scenarios. Experiments showed residual anomalies above measurement uncertainty, with a maximum repeatability standard deviation of approximately 0.12 °C and the clearest signals at 90–120 s after hot-water injection. Boundary conditions strongly affected observability at 115 mm and 70 °C, and the residual peak increased from about 0–1 °C in exposed air to 8–9 °C under the buried boundary. Simulations showed that defect width expanded the disturbed region from approximately 100 to 210 mm, while peak amplitude remained coupled to width and depth. Six morphology descriptors jointly estimated position, width, and depth, with mean absolute errors (MAEs) of 0.547, 1.647, and 0.245 mm, respectively. The method provides a recalibratable early-screening route for locating suspicious wall-loss regions before confirmatory inspection. Full article

The construction sector plays a significant role in global energy consumption and carbon emissions; improving the energy efficiency of existing buildings a fundamental requirement for sustainable development. Retrofitting the internal walls of buildings requires insulating materials that not only provide effective thermal performance but are also environmentally friendly, low-carbon, and compatible with circular-economy principles. In this context, recycled textile materials, especially cotton and polyester, are gaining increasing attention as sustainable insulation systems. This review article aims to critically evaluate the thermal insulation, environmental performance, and potential use of woven textile insulation structures based on recycled cotton, recycled polyester, and an equal combination of both in internal wall retrofitting. This article systematically reviews the available scientific literature and presents a conceptual framework based on multilayer woven structures. This review highlights that increasing the number of layers can play a significant role in improving thermal resistance, reducing heat transfer, and limiting internal energy loss by increasing the static air spaces between the fibers. Furthermore, the use of recycled textiles can also achieve environmental benefits such as reducing textile waste, conserving natural resources, and reducing overall carbon emissions. The research also offers a useful guiding framework for the development of sustainable building technologies based on low-carbon construction, efficient use of resources, and a circular economy. Full article

Surface recession can underestimate laser-induced damage in 2.5D C/SiC composites because thermochemical degradation extends beneath the visible pit. Infrared thermography and micro-CT data from six laser conditions (400–1600 W·cm⁻², 3–12 s), together with SEM/EDS observations, were reanalysed using a layered phase-selective model tracking C, SiC and SiO₂ evolution. For the four conditions with resolvable damage, the internal degradation front lay 0.84–1.07 mm below the recession surface. At 800 W·cm⁻², the 0.02 mm difference between the 6 and 12 s front depths was below the 25 μm voxel size and within specimen uncertainty. The calibrated model matched rear-centre peak temperatures with a mean absolute percentage error of 4.37%, although larger transient discrepancies remained. Temperatures sampled at the measured front coordinates ranged from 2890 to 3080 K. Relative to 800 W·cm⁻² for 12 s, the 1600 W·cm⁻², 6 s condition caused greater near-surface SiC consumption and solid-mass loss, while the maximum retained SiO₂ density decreased from approximately 360 to 180 kg·m⁻³. These results distinguish geometric recession from internal degradation and support experimental-front mapping and mechanistic interpretation. The mapped states are condition-specific and do not constitute an independently predicted front criterion. Full article

Low thermal conductivity of metal hydride beds significantly limits the hydrogen absorption kinetics and performance of metal hydride storage systems. This study presents a new design of a passive internal heat exchanger for a certified MNTZV-159 low-pressure hydrogen storage tank using the Triply Periodic Minimal Surface (TPMS) structures. The parametric improvement in the design of a cylindrical Diamond TPMS-based geometry was performed by applying various cell dimensions, arc counts, and wall thicknesses while maintaining the original volume of the heat exchanger. The analysed configuration was subsequently evaluated through three-dimensional numerical heat-transfer simulations conducted in ANSYS CFX. Compared with the original finned heat exchanger, the TPMS-based design reduced the average metal hydride temperature from 107.7 °C to 86.2 °C and the maximum temperature from 130.9 °C to 114.0 °C. The improved temperature uniformity enhanced the heat removal from the hydride bed and created more favourable conditions for hydrogen absorption. The results demonstrated that TPMS structures constitute a promising solution for improving passive thermal management in metal hydride hydrogen storage systems while maintaining the storage capacity of the vessel. Full article

This paper presents a methodology to evaluate the entire process of thermal evolution and fracture failure within stay cables subjected to sheath fires. Computer software FDS 2021 and ABAQUS 2021 are applied to build a sequentially thermos–mechanics coupled method integrating thermal, structural, and fracture dynamic analyses in stay cables under sheath fire exposure conditions. Herein, three representative fire scenarios including full-circumferential, top-side, and bottom-side ignition are reconstructed. Further, 127 individual wires, accounting for interstitial cavity radiation and contact heat transfer, are utilized to perform analysis on sectional temperature in stay cables. The results indicate that the ignition mode dictates the cross-sectional temperature gradient, with localized ignitions inducing highly asymmetric thermal fields and pronounced internal bending moments. Elevated temperatures trigger a progressive load redistribution from the degraded fire-facing wires to cooler internal layers. Ultimately, abrupt global fracture occurs when the residual ultimate load-carrying capacity intersects with the actual applied tension, resulting in a fracture morphology that closely corresponds to the spatial thermal distribution. Furthermore, the structural capacity degradation exhibits three distinct time-dependent stages: a slow degradation stage, a sharp decline stage, and a recovery stage. Among the analyzed scenarios, full-circumferential ignition induces the most drastic overall capacity reduction, while bottom-side ignition poses a markedly greater rupture risk than top-side ignition. Full article

Thermal runaway of lithium-ion batteries involves rapid heat release, gas generation, and multiphase transport, but their interaction inside a cell remains difficult to resolve. A multiscale computational fluid dynamics model was developed for a single 18650 cell by coupling microscale reaction kinetics, mesoscale interfacial heat transfer, and macroscale gas–liquid transport with a stationary porous-solid energy balance. The model describes internal temperature and the evolution of carbon dioxide, oxygen, water vapour, and hydrogen fluoride while examining the effects of porosity and the modelled dimethyl carbonate mass fraction. The medium-to-fine grid difference in carbon dioxide mass fraction was approximately 0.16%. Time steps of 0.01, 0.001, and 0.0001 s produced mass fractions of 0.0564, 0.0617, and 0.0618, respectively. Increasing the solvent mass fraction and porosity primarily shortened the induction period, while the peak temperature and terminal species levels remained similar. A quadratic response surface fitted to the simulation database was searched using grey wolf, genetic, and particle swarm methods. Grey wolf and particle swarm gave candidate times to peak temperature of about 238.8 s, whereas the genetic method gave 237.2 s, a difference of 1.6 s (0.67%). Particle swarm reached the high-response region within fewer iterations, while grey wolf maintained broader exploration. The proposed model connects reaction kinetics with macroscopic temperature and species evolution and clarifies how electrolyte composition and porous structure regulate the time scale of thermal runaway. Full article

A computational fluid dynamics and conjugate heat transfer (CFD+CHT) methodology is developed for the thermal simulation of a commercial prismatic ${\mathrm{LiFePO}}_4$ cell under charging and discharging operating conditions. The approach couples a three-dimensional representation of the battery, including a simplified description of its internal layered structure, with an electrochemical–thermal heat-generation model implemented as a temperature- and time-dependent volumetric source term. The heat source is applied within the active layers of the cell and updated during the transient simulation according to the local thermal state and to the evolution of the state of charge. The methodology is applied to 1C and 2C cycles under natural convection and forced-air cooling at free-stream velocities of $10\mathrm{m}{\mathrm{s}}^{-1}$ and $20\mathrm{m}{\mathrm{s}}^{-1}$. A dedicated wind-tunnel campaign is carried out on the same cell, instrumented with type-K thermocouples distributed over its external surfaces, to provide experimental data for model validation. The results show that the proposed framework accurately reproduces the main wall-temperature trends observed experimentally. Under natural convection, the temperature distribution remains nearly uniform, whereas forced convection produces more pronounced vertical and in-plane gradients. For the charge cycles, the comparison between CFD predictions and end-of-cycle measurements yields a mean absolute error (MAE) of ${0.66}^{\circ }\mathrm{C}$ and a root-mean-square error (RMSE) of ${0.82}^{\circ }\mathrm{C}$ over 168 measurement locations. The discharge cycles yield a comparable level of agreement (MAE ${0.65}^{\circ }\mathrm{C}$, RMSE ${0.81}^{\circ }\mathrm{C}$ over 168 probe points), confirming the predictive capability of the methodology for both operating modes. Full article

Unmanned aerial vehicles (UAVs) used in low-altitude mobility and electric aviation are increasingly required to carry higher payloads, operate for longer durations and maintain reliable performance under constrained installation conditions. In compact power cabins, batteries, controllers, power distribution units and auxiliary actuators are densely arranged, making cabin thermal management a critical design issue. In this study, a full-scale conjugate flow and heat transfer model is developed for the power cabin of a UAV and validated against thermal management experiments. The validated model is then used to examine how a conventional rectangular ram-air inlet and a proposed stepped ram-air inlet affect air capture, internal flow organization and temperature distribution. The inlet area of the rectangular configuration is first varied to establish a baseline, after which the transition arc ratio, spacing ratio and area ratio of the stepped inlet are parametrically investigated. The results show that increasing the rectangular inlet area from 0.002 to 0.008 m² increases the total captured mass flow rate from 0.258 to 1.084 kg/s, whereas the cabin average temperature decreases by 0.34 °C. By contrast, the cabin maximum temperature decreases nonlinearly, with a 27.2% reduction when the area increases from 0.004 to 0.006 m². These results indicate that air capture and the cabin average temperature alone are insufficient to evaluate cooling effectiveness in a compact multi-source cabin. For the stepped inlet, the transition arc ratio controls the turning of the incoming flow, the spacing ratio governs shielding and backflow between adjacent inlet sections, and the area ratio redistributes the dominant inlet sections. The best-performing stepped-inlet configuration among the tested cases increases the captured mass flow rate by 32.8% compared with the rectangular baseline under the same opening constraint and improves the utilization of cooling air around high heat load components. This study demonstrates that ram-air inlet design for UAV power cabins should be treated as a coupled problem of the mass flow capture, internal flow path and component-level thermal response. Full article

Mineral-scale deposition remains a persistent flow-assurance and asset-integrity constraint in oil and gas production. Calcium carbonate, calcium sulfate, barium sulfate, iron sulfide, and mixed inorganic scale deposits reduce tubing internal diameter. They also impair near-wellbore permeability, block safety-critical valves, reduce heat-transfer efficiency, and intensify under-deposit corrosion. Conventional management relies on prediction, chemical inhibition, squeeze treatments, acid dissolution, chelation, mechanical scraping, milling, jetting, and operational water management. These methods are indispensable, but each has a restricted operating envelope. Key limitations include mineral selectivity, corrosion risk, environmental discharge, intervention cost, debris generation, and poor effectiveness against chemically resistant sulfate scales, particularly BaSO₄. Ultrasound has therefore attracted interest as a non-chemical technology. Acoustic cavitation, microstreaming, pressure oscillation, mechanical vibration, and micro jetting may suppress nucleation, disturb boundary layers, weaken adhesion, and fragment brittle deposits. This review critically evaluates ultrasound-assisted scale prevention and removal, with emphasis on production tubing and oilfield relevance. Existing studies show credible mechanistic plausibility and promising laboratory performance for CaCO₃, CaSO₄/gypsum, KCl, NaCl, and membrane or heat-transfer fouling systems. It also compares performance metrics, field cases, and technology-readiness barriers. The evidence is less mature for long steel tubulars operating under high-pressure, high-temperature, multiphase production conditions. Current evidence positions ultrasound at technology-readiness level (TRL) 3–4 for CaCO₃ and CaSO₄ systems, where laboratory and bench-scale validation is established, and at TRL 2–3 for BaSO₄, where mechanistic plausibility exists but controlled experimental validation remains absent. The technology is not yet at the pilot–production transition for downhole tubing applications, but it is approaching that threshold for surface process equipment. Its most credible near-term role is as an intensifier paired with low-dose chemical inhibitors, where acoustic boundary-layer disruption can reduce the minimum inhibitory concentration threshold of inhibitors, and with mild chelating agents for early-stage BaSO₄ management, where ultrasound-enhanced mass transfer may accelerate chelant penetration into deposit microstructure. Advancing ultrasound from its current TRL toward field qualification requires targeted BaSO₄ scale validation in steel tubing systems, acoustic field mapping under HPHT multiphase conditions, mass-removal metrics, and a structured pilot programme. Full article

The sustainable development of the ceramics industry is severely impeded by its intensive energy consumption and the concomitant deficits in cooling and freshwater resources. To address these bottlenecks, this study proposes an integrated ejector refrigeration (ER)–humidification–dehumidification (HDH) hybrid system, harnessing ceramic waste heat as the driving energy source to improve overall energy efficiency. A thermodynamic model was developed to analyze the heat transfer characteristics of the ER-HDH system. Comprehensive investigation focuses on the influences of key operating parameters on refrigeration performance, desalination output and overall system efficiency. The results demonstrate that the proposed ER–HDH hybrid system facilitates the efficient thermodynamic cascading of waste heat from both flue gas and internal thermodynamic processes, achieving a high energy utilization factor (EUF) of 0.64 and an exergy efficiency η_Ex of 15.7%. The freshwater yield significantly outperforms that of a standalone HDH system, with the gain output ratio (GOR) more than tripling. The system performance is optimized under elevated generator and evaporator temperatures (T_g and T_e), coupled with a reduced condenser temperature T_c. Across their respective tested ranges, the EUF increases by averages of 19.1%, 45.1% and 38.9%. Furthermore, raising the feed seawater temperature T_{sw_in} significantly elevates the moist air humidity ratio, which in turn drives substantial enhancements in GOR and EUF, by over 83.2% and 58.1%, respectively. T_e and T_{sw_in} should be prioritized to enhance refrigeration and freshwater productions, respectively, while T_c serves as the key determinant for maximizing η_Ex. This study introduces an open dual-cascade ER-HDH system for mid/low-grade flue gas utilization and elucidates the distinct thermodynamic mechanisms governing subsystem interactions, and it addresses a critical knowledge gap in prevalent closed-loop solar-driven ER-HDH systems. Full article

This study numerically investigates the dielectric recovery characteristics of underwater pulsed discharge by coupling the Keller–Miksis equation with interfacial phase-change mass transfer. The model incorporates the time-varying internal pressure and temperature of the bubble, enabling accurate prediction of the second breakdown voltage during both the gradual expansion–contraction stage and the initial collapse stage. Three representative values of the phase-change mass transfer coefficient ${\mathrm{\alpha }}_{\mathrm{M}}$ are examined to quantify its influence on bubble pulsation and dielectric performance. Results indicate that ${\mathrm{\alpha }}_{\mathrm{M}}$ exerts a distinct differential effect: while the first pulsation is governed primarily by liquid inertia and remains insensitive to ${\mathrm{\alpha }}_{\mathrm{M}}$, the energy dissipation during the first collapse is critically regulated by interfacial condensation. High ${\mathrm{\alpha }}_{\mathrm{M}}$ intensifies condensation, removing vapor mass and latent heat, thereby reducing residual energy for subsequent pulsations and accelerating pulsation decay. These cumulative attenuation effects shorten the dielectric recovery time. The calculated recovery voltages show good agreement with experimental measurements, confirming the validity of the proposed model for predicting dielectric recovery in repetitive underwater pulsed discharge systems. Full article

Hydrogen storage and separation remain major technical challenges limiting the broader implementation of hydrogen-based energy systems. Metal–hydride alloys offer a promising solution because they enable reversible hydrogen storage within their crystal structure and can selectively absorb hydrogen from multicomponent gas mixtures. However, the practical application of metal–hydride systems requires storage vessels that combine sufficient mechanical strength with effective heat removal, as hydrogen absorption is accompanied by significant heat generation that can reduce the reaction rate and usable storage capacity. This study addresses hydrogen storage within the crystal structure of metal alloys and introduces the potential of metal–hydride (MH) alloys for hydrogen separation from gas mixtures. It subsequently presents the structural design and strength assessment of a low-pressure, double-walled, tubular steel MH storage vessel intended for hydrogen storage in a MnTiVFeZr-based alloy. Structural simulations were performed in ANSYS 2025 R2 Static Structural at three operating pressures: 3, 5, and 7 MPa. For all three simulated pressure conditions, the gravimetric hydrogen storage capacity of the alloy was 0.992 ± 0.016 wt.%. Following the selection of the most suitable design with an operating pressure of 3 MPa, an analytical calculation was performed to verify the results obtained from the numerical analysis. The storage vessel was subsequently manufactured and subjected to experimental strength validation using the test procedures specified in the STN EN 13322-2 standard. The design of the low-pressure tubular steel MH storage vessel also incorporates an efficient thermal management system based on a combination of active and passive cooling modules. The passive cooling module takes the form of an internal heat-transfer enhancement element, which is inserted into the primary storage vessel together with the MH alloy. The active cooling module uses a coolant flowing around the outer wall of the primary vessel. The optimal design of the aluminium passive cooling module was selected from four variants based on a steady-state temperature-field analysis conducted in ANSYS CFX. The selected module was subsequently manufactured and integrated into the proposed storage vessel. The vessel equipped with the passive cooling element was then subjected to experimental temperature measurements during hydrogen absorption by the MH alloy. The experimentally obtained data were compared with the numerical simulation results to evaluate the temperature fields within the vessel and the heat dissipation from the core of the MH storage system during hydrogen absorption. The main contribution of this work is the development of a mechanically validated and thermally managed tubular metal–hydride vessel that integrates structural design, numerical optimisation, manufacturing, and full-scale experimental testing within a single methodology. The proposed approach provides a practical basis for the further development and scaling of low-pressure metal–hydride systems for hydrogen storage, purification, and separation applications. Full article

This study presents a comparative analysis of the energy and thermal behavior of a Peltier module operating in hot environments (28 °C to 40 °C) using Python and MATLAB/Simulink. A theoretical block model was developed to define governing equations, while an empirical Python-based framework was implemented to capture real-world non-linearities. Results demonstrate that heat absorption is fundamentally dependent on efficient heat dissipation; a maximum coefficient of performance (COP) of 3.1 was achieved at 1 A. However, operation in hot environments necessitates increased current to maintain low absorption temperatures, leading to a critical “thermal runaway” threshold beyond 5 A where internal Joule heating (scaling quadratically) outweighs the Peltier cooling effect (scaling linearly). While both platforms effectively evaluate heat transfer, the Python-based empirical model provided a more realistic description of cold-side absorption with prediction errors as low as 0.14%. These findings offer a robust pathway for optimizing Peltier cooling with potential industrial applications. Full article

Kelp is a high-moisture, flexible, sheet-like marine biomass whose drying behavior is strongly affected by the coupled effects of radiative heating, convective vapor removal, internal moisture migration, tissue shrinkage, curling, and material overlap. Traditional sun drying and hot-air drying remain widely used but are limited by long processing cycles, environmental dependence, high energy consumption, and inconsistent product quality. With the development of infrared heating, heat-pump dehumidification, Internet of Things (IoT)-enabled sensing, fifth-generation (5G) mobile communication, multiphysics simulation, and digital control, kelp drying is progressively shifting toward monitored, model-assisted, and intelligent processing. This review critically summarizes recent advances in kelp and related seaweed drying, with particular emphasis on infrared-assisted heat and mass transfer, drying kinetics, coupled computational fluid dynamics–finite element method (CFD–FEM) simulation, quality evaluation, and intelligent control. Representative published studies demonstrate the engineering potential of these approaches. In a suspended infrared-array kelp drying system, an infrared power density of 1.2 kW m−2 combined with an air velocity of 3 m s−1 maintained the drying temperature at approximately 55–62 °C, while relative humidity decreased from about 80% to 20–30%. Under these conditions, the Page model achieved R² = 0.987 and RMSE = 0.019, the rehydration ratio exceeded 94%, and the total color difference remained below ΔE = 6.5. A recent CFD–FEM–MATLAB workflow further reported a composite operating-condition index of J = 0.4535, with mapped mean and maximum kelp surface temperatures of 62.23 and 63.57 °C, respectively. These quantitative results indicate that the key challenge in infrared kelp drying is not simply to increase heat input, but to coordinate radiation distribution, airflow organization, internal moisture transport, structural response, and quality preservation. Future research should therefore focus on experimentally validated heat–mass-transfer models, adaptive sensing and control, multi-objective optimization, and pilot-scale verification under realistic production conditions. Full article

The present work introduces a fully resolved three-dimensional thermal Lattice Boltzmann framework developed to investigate the impact of freely moving, finite-size spherical particles on natural convection within a cubic enclosure. The fluid-phase momentum and energy fields are resolved using coupled double-distribution function kinetic approach, while the solid phase is governed by explicitly coupled linear, angular, and thermal conservation equations. To accurately map the moving spherical surfaces onto the Eulerian lattice grid, a second-order linear interpolated bounce-back scheme is implemented. The conjugate heat transfer between the phases is simplified via a lumped capacitance model, assuming negligible internal thermal resistance within the solid spheres. Short-range particle–particle and particle–wall interactions are handled using Glowinski’s repulsive force model. The spatial accuracy of the framework is validated using a circular Taylor–Couette flow benchmark—demonstrating second-order spatial convergence and a differentially heated natural convection in a cubic cavity benchmark, yielding bulk Nusselt numbers within $1\%$ of established literature data. This validated tool is subsequently used to analyze the complex interplay between particulate motion and bulk thermal transport efficiency. Analysis of the temperature fields reveals that the overall thermal structure is governed primarily by the Rayleigh number, while the low particle concentration produces only minor modifications to the convective heat transfer. In contrast, the particle distribution exhibits a strong dependence on the flow intensity. Full article