Search Results (1,124)

The thermal safety and longevity of lithium-ion batteries are critically constrained by excessive temperature rise and spatial thermal non-uniformity, particularly during high-rate discharges. Most existing numerical investigations rely on simplified heat generation models that fail to capture the spatiotemporal heterogeneity of electrochemical heat sources, leading to compromised predictive accuracy. To address this deficiency, this study develops a comprehensive three-dimensional electrochemical–thermal coupled framework, integrating the Newman pseudo-two-dimensional (P2D) electrochemical model with conjugate heat transfer and laminar flow dynamics. The predictive robustness of this framework is rigorously validated against experimental data across multiple discharge rates (3 C and 5 C). The validated model is then deployed to evaluate a water-cooled microchannel cold plate designed for prismatic $\mathrm{L}\mathrm{i}\mathrm{M}{\mathrm{n}}_2{\mathrm{O}}_4$/graphite cells under a demanding 5 C discharge. A systematic parametric investigation is conducted to quantify the effects of ambient temperature (293–343 K), microchannel number (2–6), and coolant inlet velocity (0.1–0.6 m/s) on the maximum battery temperature (${\mathrm{T}}_{\mathrm{m}\mathrm{a}\mathrm{x}}$) and temperature difference ($\mathsf{\Delta }\mathrm{T}$). Results demonstrate that the proposed system exhibits exceptional environmental robustness: over a 50 K ambient temperature span, ${\mathrm{T}}_{\mathrm{m}\mathrm{a}\mathrm{x}}$ increases by merely 2.0 K, remaining safely below the 323 K industry limit. Densifying the channel count from 2 to 6 further reduces ${\mathrm{T}}_{\mathrm{m}\mathrm{a}\mathrm{x}}$ by 1.55 K and narrows $\mathsf{\Delta }\mathrm{T}$ to 4.25 K, successfully satisfying the strict 5 K temperature uniformity standard. Furthermore, the thermal benefit of elevating inlet velocity exhibits a pronounced diminishing-return trend governed by the asymptotic reduction in bulk coolant temperature rise, dictating a critical trade-off against the quadratically escalating pumping power. Ultimately, these findings provide robust theoretical guidelines for the rational design of safe and energy-efficient battery thermal management systems. Full article

Nuclear energy has emerged as a crucial technological solution for ensuring energy security and achieving carbon neutrality goals, given its ultra-high energy density and near-zero carbon emissions against the backdrop of rapid socioeconomic development, increasing energy demands, and accelerated global transition toward low-carbon energy structures. As the core component for energy conversion in nuclear reactors, fuel elements critically determine reactor efficiency and safety performance, with the fission product retention capability of silicon carbide layers in multilayer-coated fuel particles having been thoroughly validated through high-temperature gas-cooled reactor irradiation tests. The precise sphericity control of large-sized UO₂ fuel kernels represents a fundamental requirement for enhancing tristructural isotropic (TRISO) fuel particle performance and advancing Generation IV nuclear power plant development. This study presents a sphericity control strategy based on sol–gel processing that synergistically integrates physicochemical regulation of gelling media with multi-field washing flow field optimization. By implementing silicone oil-mediated interfacial tension gradient control, we effectively suppressed gel sphere destabilization while developing an innovative three-phase sequential washing technique involving kerosene washing, anhydrous ethanol interfacial transition, and ammonia solution replacement, which significantly enhanced mass transfer diffusion in stagnant liquid films and revolutionized fuel microsphere washing technology with improved efficiency and quality. Experimental results demonstrate that this integrated approach increases kernel sphericity qualification to 99.8%, reduces washing solution consumption by 79%, and achieves an average sphericity of 1.03. The research establishes a coupling mechanism between gelling media and multi-field washing processes, elucidating the synergistic effect between interfacial tension regulation and washing optimization, thereby providing both theoretical foundations and engineering application basis for the precision manufacturing of high-performance nuclear fuels. Full article

Precise measurement of particle concentration in dilute gas–solid two-phase flows is challenging due to low particle loading and stochastic particle motion, which lead to weak signals and detection blind zones. This study develops a swirling-flow-enhanced triboelectric nanogenerator (SF-TENG) using active flow field regulation to enhance particle–wall interactions. Through CFD optimization of guide vane geometry, the SF-TENG achieved a nearly twenty-fold increase in short-circuit current compared to non-swirling configurations. The swirling flow exhibited a particle-size-dependent enhancement mechanism. For fine particles, the improvement was mainly attributed to an increased collision ratio. For coarse particles, it resulted from enhanced charge transfer per single impact. The swirling flow continuously improved the reliability and sensitivity of detection across all particle sizes. These findings provide valuable insights for designing highly sensitive, self-powered flow meters with minimized blind zones for gas–solid monitoring. Full article

As the key technology of space exploration, space power has been a major area of international research focus. A lot of research work has been carried out around the world for the space nuclear reactor using the heat pipe, liquid metal and gas cooling methods. With the development of molten salt reactor in the Generation IV reactor system, molten salt dissolving fissile material and acting as a coolant at the same time has become a new cooling scheme, which provides new ideas for the design of space nuclear reactors. In this study, a novel reactor, the liquid-solid dual-fuel space nuclear reactor (LSSNR) was preliminarily proposed, combining the molten salt fuel and cross-shaped spiral solid fuel to achieve the design goals of 30-year lifetime and an active core weight of less than 200 kg. Monte Carlo neutron transport code OpenMC based on ENDF/B-VII.1 library was employed for neutronics design in the aspect of fuel type, cladding material, reflector material and the spectral shift absorber. Then, the thickness of the control drum absorber was optimized to meet the requirement of the sufficient shutdown margin, lower solid fuel enrichment, and 30-effective-full power-years (EFPY) operation lifetime. Finally, UC solid fuel with U-235 enrichment of 80.98 wt.% and B₄C thickness of 0.75 cm were adopted in LSSNR, and BeO was adopted as the reflector and the matrix material of the control drum. A spectral shift absorber Gd₂O₃ was used to avoid the subcritical LSSNR returning to criticality in a launch accident. The k_eff with the control drum in the innermost position is 0.954949, and the k_eff reaches 1.00592 after 30 EFPY of operation. The total mass of the active core is 158.11 kg. In addition, the thermal-hydraulic feasibility of LSSNR using cross-shaped spiral fuel was analyzed based on a 4/61 reactor core model. The structure of cross-shaped spiral fuel achieves enhanced heat transfer by generating turbulence, which leads to a uniform temperature distribution of the coolant flow field and reduces local temperature peaks. Based on the LSSNR scheme, some neutronic characteristics were analyzed. Results demonstrate that the LSSNR has strongly negative reactivity coefficients due to the thermal expansion of liquid fuel, and the fission gas-induced pressure meets safety requirements. One hundred years after the end of core life, the total radioactivity of reactor core is reduced by 99% and is 7.1305 Ci. Full article

To improve the thermal management level of power battery packs for new energy vehicles, a novel cooling plate with vein flow channels was proposed. The vein flow channel structure includes bilaterally symmetrical vein-shaped branches, a dovetail-shaped outlet branch, and a side collecting branch. This study conducted a comparative analysis on the hydrodynamic characteristics, heat transfer performance, and pumping power consumption of the novel cold plate, while investigating the influence of flow channel structure on the working fluid distribution and cooling performance of the liquid cold plate (LCP). The results indicate that the dovetail-shaped outlet branch can significantly enhance the flow distribution capacity of the tail branch channels of the LCP, the side collecting channel can improve the overall flow distribution capacity of the branch channels by reducing flow resistance, and the converging main channel can effectively compensate for the insufficient flow distribution capacity at the front part of the LCP by mitigating the uneven distribution at the tail. Additionally, the results demonstrate that the optimized design achieves a 9.5 °C (21%) reduction in the maximum temperature and a 6.3 °C (32%) reduction in the temperature difference. Full article

This study experimentally investigates the thermal performance of wraparound loop heat pipes (WLHP) using R134a as the working fluid and copper tubing with an outer diameter of 8.5 mm. A dedicated experimental apparatus was developed to evaluate thermal resistance under varying heat loads (200–500 W), inclination angles (15° and 30°), and coolant temperatures (5–15 °C) at a constant coolant flow rate of 3.2 L/min. Key performance metrics, including evaporator wall temperature and overall thermal resistance, were analyzed to identify optimal operating conditions. The results reveal that increasing the heat load significantly reduces thermal resistance, reaching a minimum of 0.056 °C/W at 500 W. An inclination angle of 30° improved heat transfer, lowering the evaporator temperature by approximately 5 °C compared to 15°. Moreover, lower coolant temperatures enhanced the temperature gradient between the evaporator and condenser, further improving heat transfer. Principal component analysis (PCA) was employed for dimensionality reduction and identification of the dominant thermal variables affecting system performance. Based on the experimental dataset, a regression model was developed to predict thermal resistance, achieving a coefficient of determination of R² = 0.96. These findings confirm the WLHP’s potential as an efficient and reliable passive thermal management system for medium- to high-power applications in tropical and industrial environments. Full article

Thermally driven adsorption cooling systems are gaining increasing attention as a promising solution to use low-grade waste heat and reduce electricity consumption. However, their performance is strongly limited by inefficient heat and mass transfer within adsorption heat exchangers, and there is still a lack of experimentally validated models for full-scale devices. This study presents the development and full-scale experimental validation of a CFD model for a finned-tube adsorption heat exchanger dedicated to thermally driven cooling applications. A custom laboratory-scale test facility was designed and specially constructed for this purpose, replicating the operation of a real adsorption chiller while enabling direct gravimetric measurement of the total mass of vapour adsorbed by the entire exchanger. The experimentally tested reference exchanger (ADHX_2_2) featured a fin spacing of 2 mm and a fin thickness of $0.2$ mm. Systematic numerical analyses assessed the effects of fin thickness (0.2 mm to 0.4 mm), fin spacing (2 mm to 8 mm), absence of fins, and water-flow velocity (0.2–4 m s⁻¹) on heat transfer efficiency and adsorption capacity. The CFD model (ANSYS Fluent) was calibrated with experimental data and achieved a maximum result difference of 5%. Optimal performance occurred with minimal fin thickness, moderate fin spacing (6 mm to 8 mm), and flow velocity around 1.5 m s⁻¹, balancing heat transfer, sorbent mass, and pumping power. The study demonstrates that combining validated CFD modelling with targeted experiments provides a robust pathway to optimise adsorption heat exchangers and enhance the efficiency of thermally driven cooling systems. Full article

Improving the quality of welded joints, as well as the advancement of equipment and materials, inevitably requires deep theoretical knowledge of the physical phenomena occurring in the arc column and in the cathode and anode regions. Achievements in the field of controlling metal transfer at the micro- and nanoscale through the regulation of current and voltage in welding power sources have encountered the problem of the formation of cathode and anode spots, which affect the stability of welding arcs and the quality of the weld. Under short current pulses and pauses, the stability of the arc discharge depends on the ability to form a cathode spot, melt the wire metal, and transfer it through the arc column. In this article, based on the generalization of known experimental facts and studies performed using a high-speed camera, it is shown that the current-carrying channel of the electric arc has a discrete structure consisting of a multitude of thin channels through which the main discharge current flows. The cathode spot of the arc discharge represents a highly heated and brightly luminous region on the cathode surface. Electron emission sustaining the discharge and the removal of cathode material occur from this region. A new method is proposed for investigating the reverse side of the cathode spot, which makes it possible to identify a structure consisting of individual cells or fragments of the cathode spot. For the first time, anode spots recorded with a high-speed camera are presented. An analysis of the spot structure is carried out. The parameters influencing the mobility of cathode and anode spots are determined. Based on the obtained experimental facts, a hypothesis is proposed regarding the non-uniform structure of cathode and anode spots in the arc discharge. Full article

Amines are indispensable structural motifs in pharmaceuticals, agrochemicals, functional materials, and beyond, driving continuous demand for efficient synthetic methods. While established strategies like cross-coupling and reductive amination are prevalent, traditional batch processes often suffer from limitations in mixing, heat/mass transfer, safety, and scalability. Flow chemistry emerges as a powerful process intensification technology, offering enhanced transport properties, precise parameter control, and improved safety profiles, thereby presenting a highly efficient approach for amine synthesis. This review systematically summarizes representative advances in flow chemistry for amination reactions from 2015 onward. It encompasses a broad range of enabling scenarios (e.g., heterogeneous, thermally activated, and enzymatic amination, among others), analyzed through the lens of process intensification. This review also examines the development of novel continuous-flow amination processes and the study of reaction kinetics leveraging flow chemistry. By providing a consolidated reference on the field’s evolution over the past decade, this review aims to guide researchers toward developing more efficient, sustainable, and scalable flow-based amination processes. Full article

Screw compressors are critical equipment in oil and gas production and transportation, where efficiency losses caused by rotor geometry, inlet pressure pulsations, and harsh climatic conditions can accumulate into substantial annual energy penalties and reliability degradation. This study provides a quantitative assessment of these coupled effects within a unified multiphysics framework that combines time-accurate transient CFD simulations based on a fixed Cartesian immersed-boundary formulation with a climate-calibrated offline physics-based digital twin—functioning as a digital shadow with one-way data flow from archival SCADA records—a reduced-order seasonal model with no real-time updating, calibrated against a full calendar year of SCADA records and validated against a held-out cold-season dataset (October–December 2022, T_amb = −15 to +8 °C); summer-period predictions rely on calibrated extrapolation beyond the validation window—an integration not previously demonstrated for oil-flooded screw compressors. Two rotor profile configurations (Type A and Type B) were analyzed to quantify geometry-driven differences in static pressure distribution, leakage tendency, and pulsation sensitivity. Transient suction conditions were modeled using harmonic and quasi-random inlet pressure disturbances to evaluate pressure amplification, phase lag, leakage intensification, and efficiency degradation. Seasonal performance was assessed by integrating temperature-dependent gas properties, oil viscosity behavior, and external heat transfer into an annual climatic load framework. The results show that inlet oscillations are amplified inside the chambers (pressure amplification factor П_p ≈ 1.95; П_p up to 2.3 under quasi-random excitation), reducing mass flow and volumetric efficiency by 8–10% and decreasing polytropic efficiency from 0.78 to 0.69–0.71, while increasing leakage by up to 27% and raising peak contact pressures to 167–171 MPa. Seasonal variability (+30 to −30 °C) increased suction density by 38% but raised drive power by ~9% due to viscosity-driven mechanical losses, producing an energy penalty up to 10.8% and an estimated annual additional consumption of approximately 186 MWh per compressor, decomposed as: cold-season contribution ~113 MWh (±10 MWh, directly field-validated against October–December 2022 SCADA data) and summer-season contribution ~51 MWh (calibrated extrapolation; additional uncertainty unquantified and not included in the ±10 MWh bound). The full annual figure of 186 MWh should be interpreted as a model-based estimate rather than a fully validated result. These findings demonstrate that rotor design optimization and mitigation of nonstationary suction effects, coupled with climate-aware offline physics-based digital shadow operation, represent high-priority levers for improving efficiency and reducing energy penalties in field conditions; reliability implications require further validation against summer-season field measurements. Full article

To address the coupled challenge of heat-transfer enhancement and energy consumption in machine-tool temperature control plates under high-flow-rate conditions, a comprehensive performance evaluation method based on an equivalent thermal resistance network is developed. By introducing heat-transfer power, equivalent total thermal resistance, and a coefficient of performance (COP), the thermal performance and energy cost are quantitatively characterized. Building upon established thermal resistance modeling approaches, the method provides a systematic framework for performance evaluation. The effects of inlet flow rate and heat-source temperature are investigated using CFD under consistent conditions, and experimental validation is conducted. The results show that increasing the flow rate enhances heat transfer but exhibits diminishing returns, while the rapidly increasing pressure drop reduces energy efficiency. Increasing the heat-source temperature mainly improves heat-transfer power by strengthening the temperature difference, with a limited impact on thermal resistance. Good agreement among theoretical, numerical, and experimental results confirms the validity and engineering applicability of the proposed method. Full article

Technological development and thermal management are closely related, as chip-based units demand efficient cooling. Microchannel cooling is a key solution. This study, for the first time, experimentally and numerically investigates fin distributions with decreasing numbers, with/without staggered configurations, and the effect of dimples on single-phase flow in micro-pin-finned heat sinks. The database covers mass fluxes from 500 to 750 kg m⁻² s⁻¹ (in 50 increments) and four heat sinks (coded as MH-0, MH-1, MH-2, MH-3), with Reynolds numbers ranging from 234 to 327. Complementary numerical simulations were also employed to visualize flow structures and local Nusselt distributions to elucidate the experimental observations. It was concluded that low-velocity eddies occur in the dimples and between the successive pin-fins. The best thermal performance was obtained for MH-3, while the lowest pressure drop was measured for MH-1. Therefore, if heat transfer is the primary aim, MH-3 is preferred. MH-3 increases average Nusselt Number (Nu_avg) by between 11.45% and 14.38% compared to MH-0. However, the pumping power results underline the importance of MH-1. Compared to MH-0, the pumping power decreases by up to 18.4% for MH-1, 16.6% for MH-2, and 13.8% for MH-3. Full article

The present study examines the regulatory effects of laser heating parameters (power, position, and spot radius) on hydrothermal wave instability, heat and mass transfer, and interfacial deformation in bilayer thermocapillary systems under normal gravity. It provides theoretical support for the efficient utilization of energy and the optimization of industrial thermal systems, meeting the demands of sustainable development. The results show that increasing laser power induces asymmetric flow bifurcation nears the laser heating point, enhancing hydrothermal waves in the left region while suppressing them in the right region, with oscillation periods decreasing monotonically and amplitudes showing non-monotonic variation. Laser heating position alters convection intensity distribution, in which the convection in the hot zone is weakened as the laser point nears the cold end, while the convection in the cold zone is strengthened as the laser point nears the hot end. Reducing spot radius significantly decreases temperature gradients near the interfacial heat source, while attenuating horizontal velocity amplitude and increasing oscillation period, effectively suppressing oscillatory thermocapillary convection. This study demonstrates that precise control of laser heating parameters can effectively suppress thermocapillary instability and optimize heat transfer without introducing additional mechanical disturbances. It provides a theoretical basis for efficient, low-energy, non-contact thermal flow control technologies. Full article

Effective thermal management is critical for high-power lithium-ion batteries to mitigate excessive heat generation and ensure operational reliability. Failure to maintain a uniform temperature distribution can lead to accelerated capacity fading and severe safety risks, such as thermal runaway. In this study, a ferrofluid-based magnetohydrodynamic (MHD) microchannel cooling system was numerically investigated to elucidate the influence of magnetic intensity, magnet geometry, and electrical boundary conditions on flow behavior and heat transfer performance for battery cooling applications. A fully coupled multiphysics model incorporating electromagnetic, fluid flow, and heat transfer phenomena was developed and validated against experimental and numerical data from the literature. The results show that increasing the applied voltage enhances current density and Lorentz force almost linearly, leading to significant flow acceleration and improved convective heat transfer. Electrical insulation effectively suppresses current leakage into the channel walls, increasing the average current density by up to 222% and the Lorentz force by more than 300%. Compared with a cylindrical magnet, a rectangular magnet provides a more uniform magnetic field distribution and stronger near-wall Lorentz forcing, resulting in superior cooling performance. Under a 4C discharge condition, the insulated rectangular magnet reduces the maximum battery temperature by approximately 30% and increases the average Nusselt number by up to 103% relative to the non-insulated case. The findings reveal the critical roles of magnetic-field-controlled flow symmetry and near-wall forcing in MHD-driven microchannels, and provide practical design guidelines for battery cooling systems with no moving mechanical parts and active electromagnetic flow control. Full article

The present study deals with the problem of irregular temperature distribution, simultaneous under-firing and over-firing, and their resultant efficiency and quality problems in a mechanical lime vertical kiln powered by domestic waste flue gas. The numerical simulation and structure optimization were carried out based on a 150 kg/h pilot-scale kiln. This combined model was built on the ANSYS Fluent 2022 R1 platform with UDF and UDS, incorporating limestone decomposition kinetics to enable the solution of gas and solid energy equations separately, and simulation of complex transfer and reaction processes. To correct the separation of flows at one inlet, a symmetric four-direction (00, 900, 1800, 2700) air intake plan was suggested. The findings show that this design essentially transforms the internal flow field into uniform and symmetrical temperature and concentration distributions. The calcination region contained both gas and solid temperatures in the optimum range to produce active lime. Specifically, the optimized kiln achieved a temperature range of 1190–1450 K in the calcination zone, a decomposition rate of approximately 82.7% (compared to 5.3% in the original model), and an increase in effective CaO content from 81.7% to 87.7%, with validation errors below 15%. It was demonstrated that the model is reliable, since the outlet simulated values correlated well with the measured ones. The preheating, calcining, and cooling zones’ heights of the optimized kiln adhered to the design requirements. This research is innovative in its application of a multi-physics coupling model with a varying heat source in a kiln and, in turn, identifies the synergism improvement process in the flow, temperature, concentration, and reaction fields. Full article