This study presents a comparative evaluation of the thermal and economic performance of two ground source heat pump (GSHP) systems utilizing vertical U-tube and horizontal linear-type ground heat exchangers (GHEs). A high-resolution numerical model was developed to simulate system behavior under realistic operating conditions, incorporating annual hourly building load profiles, environmental fluctuations, and unsaturated soil characteristics. The lengths of both GHE configurations were determined using validated design equations and analytical methods, ensuring a technically sound and non-arbitrary comparison. Subsequently, a comprehensive techno-economic assessment framework was established, integrating initial capital, operational, and maintenance costs, along with key techno-economic indicators—levelized cost of energy (LCoE), net present value (NPV), and payback period (PP)—to rigorously evaluate economic efficiency. Sensitivity analyses were further conducted to examine the influence of input parameters on the relative performance gap between the two systems. Results demonstrate that the vertical GSHP system outperforms the horizontal counterpart in both thermal and economic terms, exhibiting smaller annual variations and higher average values in fluid outlet temperature, Tf,o, heat pump coefficient of performance, COPhp, and system COP, COPsys, as well as lower initial and operational expenditures and favorable techno-economic indicators. Transitioning from horizontal to vertical GSHP system results in reductions of 61.96%, 46.94%, and 9.46% in the fluctuation ranges of Tf,o, COPhp, and COPsys, increases of 1.48 °C, 0.26, and 0.24 in the annual average Tf,o, COPhp, and COPsys, a reduction of 769.31 Chinese Yuan reduction in initial costs, a decrease of 0.02 CNY·kWh−1 in LCoE, an increase of 4428.05 CNY in NPV, and a reduction of 0.24 year in PP. The thermal-economic advantage of the vertical system is inversely related to unit drilling cost and horizontal GHE burial depth, while positively correlated with interest rate and the unit costs of excavation and pipe. Even at a burial depth of 3.00 m, the horizontal system remains inferior to the vertical system in both thermal efficiency and economic viability.
Urban rail transit has been widely adopted to alleviate surface traffic congestion. However, subway fire safety remains a critical concern because of the confined carriage space, high occupant density, and complex ventilation conditions. Most previous studies have focused on fires located at a single or central position, whereas actual fire events may originate from various locations within a carriage. In this study, reduced-scale experiments and full-scale simulations were conducted to investigate the effects of fire-source location and heat release rate (HRR) on flame behavior and temperature distribution in subway carriages. The results demonstrate that flame inclination and plume structures are strongly governed by the fire-source location due to asymmetric air entrainment induced by side door openings and wall boundaries. Quantitatively, for end carriage scenarios (A1–A4), only 25% of fire locations (A1) exhibit a symmetric flame structure. For middle carriage scenarios (B1–B6), only 16.7% of fire locations (B5) display a symmetric flame structure. In end carriages, door-facing flames tend to deflect toward the end wall, resulting in localized heat accumulation. Fires near the end wall produce higher maximum temperatures than those near the side wall, indicating that stronger confinement enhances local heat accumulation and increases the peak ceiling temperature. As HRR increases, the temperature difference between the two regions gradually decreases. Based on the experimental and simulation results, predictive models for the maximum ceiling temperature rise were developed. Moreover, fire-source location has little effect on longitudinal temperature attenuation but significantly affects transverse and near-source vertical temperature distributions. These findings provide guidance for temperature prediction, fire detection, and fire protection design in subway carriages.
Deep-mine residual coal often undergoes pre-oxidation, thermal disturbance, and tensile damage, altering its pore structure, oxygen transport, and oxidation reactivity. To elucidate the evolution mechanism under thermal-tensile stress coupling, pre-oxidized coking coal samples were studied using thermal analysis, pore characterization, oxygen transport simulation, FTIR, and ESR. Results show that the coupled effect reconstructs the pore-fracture network, enlarging oxygen pathways. As pore size increases from 0.5 to 5 nm, the O2 diffusion coefficient rises from 3.97 to 9.85 Å2/ps, indicating enhanced oxygen transport. The thermal-tensile coupling exerts stage-dependent regulation: the maximum endothermic temperature (TD1) is delayed by 8.97–14.91 °C, enhancing low-temperature physical endothermy; the initial exothermic temperature (TD2) drops by 2.89–9.95 °C; the ignition temperature (TD3) shifts lower; total heat release increases by 9.88–17.15%, intensifying medium-to-high temperature oxidation FTIR and ESR reveal that aliphatic side-chain cleavage, carbonyl/carboxyl formation, and free-radical accumulation promote radical-chain oxidation upon reheating. CRITIC analysis indicates that dominant risk factors shift sequentially from oxygen-containing functional group activation and initial radical generation (before TD1) to aliphatic decomposition, radical accumulation, and enhanced heat release (after TD2). This study reveals a stage-dependent transition from low-temperature inhibition to medium-/high-temperature oxidation promotion in pre-oxidized coal under thermal-tensile stress coupling, offering theoretical support for controlling thermal instability in disturbed deep-mine residual coal.
Electrothermal coatings have great application potential for building heating. However, conventional carbon-based electrothermal coatings feature inferior thermal stability and are incompatible with photovoltaic low-voltage heating systems. Herein, waterborne carbon-based electrothermal coatings matched with photovoltaic low-voltage power supply are prepared with graphene filter cake (GFC) and carbon nanotube slurry (CNS) as conductive fillers and acrylic resin (AR) as binder. The effects of component loadings on electrothermal behaviors are systematically explored. By synergistically building continuous 3D conductive networks using dual carbon fillers, efficient and stable electrothermal performance is realized under low photovoltaic voltage, overcoming slow heating and poor thermal durability of single-carbon-filled coatings. The optimal formulation contains 20 wt% graphene filter cake, 26.7 wt% carbon nanotube slurry and 21.7 wt% acrylic resin. The corresponding coating achieves a steady-state peak temperature of 68.72°C and a heating rate of 6.3°C/min (90.91% higher than the baseline), with a thermal conductivity of 0.95 W/(m·K). Under photovoltaic low-voltage operation, the coating quickly maintains the mean radiant temperature of enclosed space at 36°C, and demonstrates excellent storage stability, thermal aging resistance and adhesion.
When multiple heat sources are arranged sequentially along the airflow direction in power electronic equipment, streamwise air heating weakens the downstream heat-transfer driving force, causing outlet-side hot spots and temperature non-uniformity. Building on established variable-density concepts, this study develops a streamwise partitioned variable-density (SPVD) plate-fin heat sink for sequentially arranged heat sources. Within the same installation envelope, an inlet low-fin-density region preserves flow-through capacity, while a downstream high-fin-density region strengthens cooling near the thermal bottleneck. A three-dimensional steady-state conjugate heat-transfer model was calibrated against experimental data. The partition ratio, inlet fin number, and downstream channel densification coefficient were optimized using a geometry-feature-enhanced Kriging surrogate coupled with NSGA-II, with maximum temperature, pressure drop, and mass as objectives. The maximum inter-source temperature difference, ΔT, was retained as a uniformity metric rather than an optimization objective because a small ΔT alone does not ensure hot-spot safety. Compared with full-length uniform-fin configurations having the same total fin number, representative SPVD designs reduced maximum temperature by 8.43%–13.74%, pressure drop by 11.36%–28.61%, mass by 20.90%–24.33%, and ΔT by 66.38%–84.12%. Near-equal-mass benchmarks further showed 15.39%–17.77% lower maximum temperature and 65.65%–84.50% lower ΔT, accompanied by a 14.07%–32.83% pressure drop penalty. Off-design simulations under downstream-biased heat loads also retained the maximum-temperature advantage. Under the investigated conditions, these results show that streamwise fin-density partitioning redistributes cooling capacity, mitigates downstream thermal bottlenecks, and improves inter-source temperature uniformity without relying on additional material.
This study elucidates the evolution mechanisms of spontaneous combustion in deep coal bodies under thermal-fluid-solid coupling through macroscopic programmed temperature-rise experiments using a coal spontaneous combustion temperature-programmed heating system, mesoscale triaxial compression-seepage tests using a triaxial seepage test apparatus, and microscopic electron spin resonance (ESR) spectroscopy. As temperature rose from 60 °C to 210 °C, oxygen consumption and CO/CO2/C2H4 production increased continuously. Dry coal oxygen consumption first decreased, then increased with stress; 8 % moisture coal continued to rise with stress; 15 % moisture coal exhibited different response characteristics around 140 °C. Triaxial tests showed that confining pressure from 5 MPa to 15 MPa increased elastic modulus from 1980 MPa to 2493 MPa and peak strength from 32.8 MPa to 41.7 MPa; moisture from 0 % to 15 % reduced peak strength to 21.3 – 26.7 MPa. Permeability decreased sharply at 0.3 – 0.9 MPa CO2 and stabilized beyond. ESR revealed that 8 % moisture coal reached 8.23 × 1016 g−1 at 210 °C, exceeding 6.27 × 1016 g−1 in dry coal. The results confirm that deep coal spontaneous combustion arises from synergistic effects of “stress-enhanced reactions, delayed moisture release, and oxygen supply constrained by seepage,” refining the mechanism and providing new insights for prevention and control.
Clothing radiative properties—solar reflectivity (ρsr) and longwave emissivity (εlr)—fundamentally influence thermal comfort in outdoor environments during summer. This study simulated the effect of three clothing fabrics with different radiative properties, namely ordinary yellow fabric (OYF: ρsr = 0.67, εlr = 0.89), ordinary white fabric (OWF: ρsr = 0.79, εlr = 0.91), and radiative cooling fabric (RCF: ρsr = 0.98, εlr = 0.96), on summer outdoor thermal comfort across 34 major Chinese cities during August 2024 using modified calculation methods for mean radiant temperature (MRT) and physiological equivalent temperature (PET). Results demonstrated significant thermal comfort improvements with higher solar reflectivity and longwave emissivity: MRT values decreased from 49.0 °C (low reflectivity: OYF) to 42.4 °C (moderate reflectivity: OWF) and 31.4 °C (RCF: high reflectivity and emissivity), and PET improved from 35.2 °C (OYF) to 32.3 °C (OWF) and 28.9 °C (RCF). The proportion of PET values within the slightly cool to slightly warm range increased from 19.8% (OYF) to 29.1% (OWF) and 40.5% (RCF), and the combined proportion of hot and very hot conditions decreased from 56.6% to 9.6%. Correlation and regression analyses indicated that the difference between the MRT for OYF and RCF was primarily driven by global solar radiation and that for PET reflected the combined effects of solar radiation, ground surface temperature, and relative humidity. These findings provide quantitative guidance for fabric selection under diverse summer climatic conditions.
Open loop heat pipe desalination (OHLPD) can achieve a high water production rate with a small temperature difference, without consuming additional mechanical power. In this study, a steady-state model of the OLHPD system was established to investigate its water-production performance, operating modes, pressure-drop distribution, and the effects of compensation-chamber position and vapor-line geometry. The simulation results demonstrate that the system can effectively utilize low-grade waste heat at 33-37 °C (such as thermal discharge from coastal power plants, resulting in near-zero thermal energy cost) achieving a water production rate of 10-45 kg/(m2·h). The overall flow resistance is identified as the primary factor limiting system performance, with the vapor line contributing approximately 45% of the total pressure drop. Consequently, shortening the vapor line or enlarging its inner diameter can significantly enhance the water production. The driving temperature difference also exerts a marked influence: within the investigated heat-source temperature range of 33-37 °C, the water production rate increases by approximately 46% on average for each 1 °C increase in the heat-source temperature, whereas a 1 °C decrease in the heat-sink temperature yields an approximate 4% improvement. Positioning the compensation chamber above the evaporator allows gravity to assist the capillary driving force, thereby enhancing water production. In this configuration, the system operates in either a gravity-driven or a capillary-gravity co-driven regime, with the former to be avoided to prevent seawater breakthrough.
Infrastructure development in extreme cold regions poses ongoing challenges primarily due to the high rigidity of permafrost caused by its ice content, but traditional heating methods fail and lack scalability. Here, we introduce microwave heating technology to unlock new solutions for parallel, high-intensity permafrost fracture. We innovatively designed a horn antenna array with electromagnetic shielding and a mobile transmission system, delivering up to 5 kW microwave heating power. Using COMSOL simulations, the 3×4 microwave array is determined, the matching layer function is illustrated, and the heating distance is evaluated. After 15 s of microwave heating, the temperature at a depth of 400 mm in the permafrost obviously increases. Then, these qualitative simulation results are used to guide the experimental process, such as applying a matching layer, adjusting the radiation distance, and avoiding power loss. In prototype experiments, the fracturing efficiency of permafrost increases by about 60% as water content rises from 20% to 40%, but fracturing efficiency decreases at low temperatures. With a microwave input power of 5 kW, the electric field strength reaches 104 V/m, and the volume power density reaches 107 W/m3, fulfilling the fracturing criteria in the simulation. The fracturing effect is further validated by pressure resistance and shear resistance testing on samples at 293.15 K and 313.15 K. This work undertakes numerical simulations for fracturing permafrost using high-power microwave heating, explores the electromagnetic-thermal coupling effects, and experimentally demonstrates its application in fracturing permafrost. These practical engineering results provide valuable insights for microwave heating-induced permafrost fracturing scenarios.
Natural convection-based cooling technology has attracted considerable attention as a promising approach for achieving both lightweight characteristics and efficient thermal management in electronic devices and energy systems. In this study, a novel heatsink in which the upper portions of conventional cylindrical pin fins were replaced with spring structures was proposed, and its thermal performance in naturally convective flow conditions was evaluated through numerical and experimental analyses. The wire diameter, height, and pitch of the spring were selected as design variables, and optimization was carried out employing the Response Surface Methodology (RSM) based on numerical results. The findings revealed that the spring height was the dominant parameter affecting thermal resistance. Under the optimal conditions of a diameter of 1.25 mm, height of 10 mm, and pitch of 2.2 mm, the difference between the RSM prediction and numerical result was only 0.72%, confirming the accuracy of the model. Compared with the reference heatsink composed only of cylindrical pin fins, the optimized cylindrical-spring pin fin heatsink reduced thermal resistance by 10.4% while decreasing mass by 5.7%. Flow field analysis revealed that the spring structure promoted fluid mixing and accelerated upward flow through the interaction between the internal core flow and external side flow, facilitating natural convection heat transfer enhancement. The experimental and numerical outcomes agreed with a discrepancy of less than 5.14%, while the maximum experimental uncertainty was evaluated as 5.83%. The proposed cylindrical-spring pin fin heatsink is anticipated to offer a promising design strategy for simultaneously improving cooling performance and reducing weight.
This study proposes a thermal management strategy that integrates a zero-net-mass-flux synthetic jet (SJ) into a ribbed channel to intensify heat transfer in confined spaces. A validated finite-volume method is employed to assess the SJ-induced phase-dependent modulation of the thermo-hydraulic performance at an SJ Reynolds number of 377.5. Quantitative analysis indicates that the combined effects of the SJ and rib turbulators promote flow disturbances, yielding a maximum local velocity increase of 33.3%. During the ejection phase, the inherently unsteady SJ reduces the instantaneous hydraulic loss by approximately 26.5% through momentum injection at a constant channel mass flow rate, whereas the suction phase produces a comparable increase in flow resistance. The instantaneous comprehensive performance coefficient (CPC) ranges from 0.937 to 1.071, corresponding to a maximum deterioration of 6.3% during suction and a maximum enhancement of 7.1% during ejection relative to the inactive-SJ baseline. However, the time-averaged CPC over five consecutive statistically periodic cycles is 0.996, indicating that the opposing effects of the ejection and suction phases largely compensate over complete actuation cycles. When turbulence-induced transport is incorporated into the entropy-generation analysis, thermal and viscous irreversibility become comparable in magnitude, while the cycle-averaged total entropy generation changes by only approximately 0.17% relative to the inactive-SJ case. Overall, under the investigated operating condition, SJ actuation produces pronounced phase-dependent modulation of the flow, thermo-hydraulic performance, and irreversibility, while its influence on the cycle-averaged performance remains marginal.
As zero-energy building policies expand, reliable evaluation of high-performance envelopes has become increasingly important. In highly insulated buildings, reduced heat loss through planar walls increases the relative contribution of thermal bridges, highlighting the need for reliable evaluation of linear thermal transmittance (Ψ). Conventional steady-state methods, however, cannot represent time-varying environmental conditions and construction-related variations in actual buildings. This study presents a simulation-based preliminary assessment of post-processing procedures for future in-situ thermal-bridge evaluation. Transient heat-transfer simulations were conducted for an external wall–internal wall T-shaped junction and an adjacent reference wall under field-relevant meteorological boundary conditions. The simulated heat-flow responses were used to evaluate stable measurement window (SMW) filtering and two Variable U-value approaches: Case I replaces the fixed clear-wall U-value with the time-varying U-value of the reference wall, whereas Case II further normalizes the junction heat flow by the ratio of the average to the instantaneous reference-wall U-value. SMW filtering reduced the reproducibility error of the Baseline method from 129.16% to 41.14%, and Cases I and II further reduced it to 29.91% and 10.67%. Case II showed the lowest temporal variability and closest agreement with the steady-state benchmark (relative bias +0.75%, MAPE 3.82%), remaining robust under altered insulation performance and thermal inertia.
Low-temperature fast charging of lithium-ion batteries (LIBs) is limited by the coupled evolution of internal heat generation, temperature recovery, electrochemical polarization, and lithium-plating risk. To address this issue, this paper proposes a thermally regulated fast-charging strategy based on an electrochemical-thermal coupled (ETC) model and a lithium-plating suppression criterion. In the ETC model, the heat generated by polarization, ohmic resistance, and reversible entropy effects is calculated from the electrochemical processes and coupled with a three-dimensional thermal model to describe the transient thermal response. Based on the anode-potential criterion, temperature- and state of charge (SOC)-dependent safe current boundaries are established for bidirectional pulse heating and multi-stage constant-current (MSCC) charging. A cyclic heating-charging strategy is then developed to improve low-temperature current acceptance while maintaining electrochemical safety. The effects of switching temperature and the number of heating stages on charging time, energy consumption, temperature evolution, and maximum achievable SOC are systematically investigated. Furthermore, a hybrid particle swarm optimization-genetic algorithm (PSO-GA) is employed to optimize the switching thresholds. The optimized single-stage heating strategy increases the battery SOC from 10 % to 96.5 % within 42.78 min with an energy consumption of 15.57 Wh, while the optimized two-stage heating strategy reaches 95.2 % SOC within 51.59 min with an energy consumption of 15.28 Wh. These results provide a thermally guided pathway for safe and efficient low-temperature fast charging of LIBs.
This study analyzed the thermo−structural response of reinforced concrete beams exposed to multi−vehicle fires in underground parking lots and proposed a regression−based model for predicting the time−deflection response from fire temperature histories. The heat release rate model and ceiling time−temperature model for multi−vehicle fires developed in a previous study were used as input thermal loads for structural analysis. Ceiling temperature histories for 96 fire scenarios, generated by combining the peak heat release rate of a single−vehicle fire, time to reach the maximum heat release rate, duration of the fully developed stage, and fire spread time, were applied to coupled temperature−displacement finite element analyses of an RC beam. The analysis results showed that, as the single−vehicle peak heat release rate increased, both the ceiling peak temperature and midspan deflection increased. In contrast, as the fire spread time increased, the peak temperature decreased, whereas the high−temperature duration and the area under the time−temperature curve increased. Accordingly, the deflection of the reinforced concrete beam could not be explained solely by either the peak temperature or the cumulative thermal exposure; rather, it was governed by the combined effects of both factors. Based on these results, a maximum deflection prediction equation was proposed by introducing a fire amplification factor into the ambient−temperature immediate deflection, and a model was developed to estimate the deflections at key characteristic time points using deflection ratios relative to the maximum deflection. The proposed maximum deflection model showed a coefficient of variation of 0.109 compared with the finite element analysis results, and the predicted characteristic deflection points also exhibited trends similar to those of the numerical results. Therefore, the proposed model can be used to provide a simplified estimate of the fire-induced deflection of RC beams under multi−vehicle fire conditions in underground parking lots and to assess structural fire risk at the preliminary stage of performance−based fire safety design.
The transient variation of fuel injection rate is a critical factor affecting mixture formation and combustion phase as well as the energy supply rate in direct-injection engines. Despite its great importance, transient injection rates of hydrogen direct-injection injectors have rarely been characterized previously under various injector operating conditions considering injector dynamics. The current study measures and analyzes the transient injection rates of a pintle-type hydrogen injector under various injection and ambient pressures in choked flow conditions and examines the predictability of transient injection rates based on the compressible flow theory of converging-diverging nozzles and pintle dynamics. The transient injection rate profile is obtained by measuring the jet force at the nozzle exit and calibrating it to the time-averaged mass flow rate data. An increase in injection pressure caused a steeper rising slope of injection rate and a longer total injection duration with a linear increase in quasi-steady injection rate. As the ambient pressure increased, the rising slope of the injection rate and the total injection duration decreased, while the quasi-steady injection rate remained nearly the same. These transient and quasi-steady injection rate characteristics were able to be predicted based on the mass flow rate equation of converging-diverging nozzles in choked flow conditions and the transient pintle stroke as the input parameter.
Thermal management of CubeSats is challenging because of their compact size, high-density electronics housed, and constrained heat rejection capability in space environment. This study investigates the thermal performance of a modular porous gallium-CNT nanoparticle-enhanced phase change material (NePCM) heat sink for CubeSat thermal management using a coupled numerical model. The heat sink effectively buffers abrupt transient heat loads by storing excess thermal energy as gallium latent heat and maintaining most of the system close to the gallium phase-change temperature. Increasing CNT loading enhances the effective thermal conductivity and thermal diffusivity, thereby accelerating heat transfer and gallium melting, but simultaneously reduces the available gallium mass and latent heat storage capacity. Multi-cycle simulations demonstrate that incomplete gallium solidification between successive high-load operations leads to progressive loss of thermal buffering capacity and eventual overheating, whereas sufficient low-load recovery cycles restore the latent heat storage capacity. Overall, the porous gallium-CNT NePCM heat sink shows strong potential for passive CubeSat thermal management, provided that CNT loading, gallium inventory, porosity, heat-flux distribution, and operational sequence are considered together.
The spiral case and its surrounding concrete (SCSC) are critical structural components and primary load-bearing elements for hydropower generation, necessitating stringent safety and reliability measures. The SCSC is a mass concrete structure, with temperature control typically achieved through water pipe cooling during construction period. This study employs grey relation analysis (GRA) to investigate the effects of ambient temperature, pouring temperature, cooling temperature, and cooling water pipe layout on the poured SCSC. The study demonstrates that using concrete with a low initial temperature, appropriate cooling water, and a specified cooling duration during construction period effectively mitigates the temperature rise caused by hydration heat, regulates the temperature gradient, and improves the temperature-control performance of the concrete during construction. Furthermore, the correlation degrees obtained through grey correlation analysis are used as weight coefficients in the objective function. The established objective function is solved using optimization algorithms, thereby transforming the cooling parameter inversion problem into a mathematical optimization problem. This approach enables the inverse determination of various cooling system parameters and facilitates intelligent cooling system design. This study addresses the problem of water pipe cooling in mass concrete from both qualitative and quantitative perspectives. The findings provide theoretical guidance and technical references for the cooling design and safety evaluation of concrete structures surrounding the spiral case.
To address the power supply bottleneck of unmanned polar observation equipment, this study proposes and validates, for the first time, an Arctic Ocean Thermal Energy Conversion (OTEC) system using n-dodecane as the working medium. Distinct from conventional phase change materials (PCMs), n-dodecane demonstrates high compatibility with extreme polar cross-medium temperature gradients. A 3D transient phase-change heat transfer model was established and rigorously benchmarked against experimentally-grounded reference data. Results indicate that a 60 mm baseline tube diameter effectively balances energy storage potential and thermal lag. The optimized longitudinal fin configuration (LF-8) restructures the internal heat transport topology, substantially reducing solidification time by 87 min and boosting the normalized thermal discharging power to 187.5%. Compared to the 3–7 h required by conventional OTEC devices, the proposed LF-8 system demonstrates a significantly accelerated heat transfer rate. A comprehensive bivariate sensitivity analysis reveals that even under the absolute worst-case polar meteorological combination (−17 °C ambient temperature coupled with a sluggish 6 m/s wind), a complete thermodynamic reset is achieved in a maximum of 124.5 min. This safely preserves a substantial margin against the restricted 180-min surface-dwelling window. This research fills a critical gap in OTEC exploitation under polar conditions, providing a robust power solution for long-endurance Arctic profiling floats.
High-power lithium-ion batteries operating at high charge/discharge rates face severe thermal challenges, including insufficient cooling capacity, poor temperature uniformity, and degraded thermal safety, which directly restrict the performance, cycle life, and operational reliability of the batteries. To address these critical problems in existing thermal management systems, this study introduces a novel regenerative direct cooling system with an L-shaped vapor chamber and a U-shaped flow channel. Performance evaluation via a 3D thermal resistance network model demonstrates strong thermal-management performance of the system under extreme conditions. Under a high charge or discharge rate (corresponding to a heat generation rate of 40 W/cell), the average temperature of all cells stabilizes within 24–25 °C, with a maximum inter-cell temperature difference not exceeding 1.7 °C. The highest temperature within any single cell does not exceed 27 °C, and the internal temperature difference within battery cells is controlled within 9.8 °C. The system achieves a coefficient of performance (COP) of up to 5.9. Even under an extreme heat generation rate of 60 W/cell, key indicators such as the maximum pack temperature and intra-cell temperature differences are effectively maintained within a safe and reasonable range. The L-shaped vapor chamber significantly enhances temperature uniformity and improves the system COP, while the incorporation of a recuperator and U-shaped flow channel, although slightly reducing the COP, contributes to consistent temperature distribution across the battery pack. This system provides an effective solution and research foundation for the efficient thermal management design of high-power batteries.
Translucent membrane-enclosed industrial buildings provide an effective solution for controlling fugitive dust emissions from open-air stockpiles. However, under the combined effects of solar radiation, long-wave radiation, and convective heat transfer, the indoor thermal environment of such enclosed translucent membrane structures deteriorates significantly. In this study, an indoor ventilation airflow model was established and validated using experimental data. The indoor thermal environment of industrial membrane buildings under different ventilation conditions was investigated, by considering the coupled effects of solar radiation and heat radiation from internal heat sources. The influence of key ventilation parameters-including air inlet and outlet layout, dimensionless equivalent opening area (A/H2), and inlet height-on the internal velocity and temperature fields has been characterized. It has been shown that under a two-inlet and two-outlet configuration, the average temperature in the working zone has been measured to be 31.6 °C, the ventilation rate has reached 56.22 kg/s, and the airflow velocity above the material surface ranged from 0.4 to 0.6 m/s, indicating a limited risk of significant airflow-induced dust re-entrainment under the simulated conditions. When the dimensionless equivalent opening area (A/H2) of the inlets and outlets was varied, adjusting the dimensionless(A/H2)of the inlets has been found to be more effective in reducing the working zone temperature, with an optimal range of 0.34 to 0.45. The lower edge of the air inlet should not exceed 0.75 m, under which condition fresh air has been demonstrated to adequately flow through the working area, resulting in improved ventilation performance.
