Search Results (2,823)

Reducing environmental impacts and energy consumption in construction is increasingly important, prompting the use of renewable, ecological, and cost-effective materials. This research investigates an ecological building material combining clay and ground reed fibers, offering a promising alternative to conventional resources. A composite made of 50% clay and 50% ground reed was developed to study the influence of fiber size after grinding, as reed is typically used in its unprocessed form. Initial analyses included a physico-chemical characterization of both clay and reed. Thermal performance was then evaluated under steady-state and transient conditions to assess heat storage, heat transfer, and the material’s thermal inertia. The results showed a thermal conductivity of 0.38 W/m·K and an estimated 50% energy savings compared to clay alone, demonstrating the composite’s enhanced insulation capacity. Mechanical tests revealed compressive strengths of 2.48 MPa and flexural strengths of 0.79 MPa, with no significant effect from fiber size. The composite is lighter and more insulating than traditional clay blocks, indicating potential for reduced heating demand and improved indoor comfort. This study confirms the feasibility of incorporating ground reed fibers into clay-based composites to produce more sustainable building materials, supporting the transition toward energy-efficient and environmentally responsible construction practices. Full article

In the three-roll planetary rolling process, excessively high surface temperature of the rolls can easily lead to copper adhesion, deterioration of roll surface quality, shortened rolling lifespan, and severely affect the quality of copper tube products as well as production efficiency. To improve the cooling efficiency of the roll cooling system, this study developed a fluid–solid–heat coupled model and validated it experimentally to investigate the effects of nozzle diameter, spray angle, and axial position of the spray ring on the cooling performance of the roll surface. Given the low computational efficiency of finite element simulations, three machine learning models—Random Forest (RF), Gradient Boosting Decision Tree (GBDT), and Support Vector Machine (SVM)—were introduced and evaluated to identify the most suitable predictive model. Subsequently, the Particle Swarm Optimization (PSO) algorithm was employed to optimize the geometric parameters of the spray ring. The results show that the maximum deviation between the coupled model predictions and experimental data was 4.36%, meeting engineering accuracy requirements. Among the three machine learning models, the RF model demonstrated the best performance, achieving RMSE, MAE, and R² values of 1.7336, 1.3203, and 0.9082, respectively, on the test set. The combined RF-PSO optimization approach increased the heat transfer coefficient by 44.72%, providing a robust theoretical foundation for practical process parameter optimization and precision tube manufacturing. Full article

Meso-scale combustors face persistent challenges in sustaining stable combustion and efficient heat transfer due to high surface-to-volume ratios and attendant heat losses. In contrast, larger outlet diameters exhibit weaker recirculation and more diffused temperature zones, resulting in reduced combustion efficiency and thermal confinement. The behavior of non-premixed flames in meso-scale combustor has been investigated through a comprehensive numerical study, utilizing computational fluid dynamics (CFD) under stoichiometric natural gas (methane)–air conditions; three outlet configurations (6 mm, 8 mm, and 10 mm) were analysed to evaluate their impact on temperature behaviour, vortex flow, swirl intensity, and central recirculation zone (CRZ) formation. Among the tested geometries, the 6 mm outlet produced the most robust central recirculation, intensifying reactant entrainment and mixing and yielding a sharply localised high-temperature core approaching 1880 K. The study highlights the critical role of geometric parameters in governing heat release distribution, with the 6 mm configuration achieving the highest exhaust temperature (920 K) and peak wall temperature (1020 K), making it particularly suitable for thermoelectric generator (TEG) integration. These findings underscore the interplay between combustor geometry, flow dynamics, and heat transfer mechanisms in meso-scale systems, providing valuable insights for optimizing portable power generation devices. Full article

Waste heat recovery using Organic Rankine Cycle (ORC) systems shows significant potential for reducing CO₂ emissions from ships. This study designs and analyzes ORC systems for recovering multi-grade waste heat from the exhaust gas, jacket water, and scavenging air of a marine two-stroke diesel engine. A thermodynamic model is developed to investigate the effects of working fluid preheating temperature, evaporation pressure, and heat source conditions on system performance. Results show that appropriately increasing the preheating temperature of the working fluid can enhance power output. For hydrocarbons with higher critical temperatures, power output exhibits an extremum as preheating temperature increases, while for fluids with lower critical temperatures, power output increases continuously until the evaporation pressure limit is reached. Increasing evaporation pressure decreases power output but improves thermal efficiency, with a corresponding increase in heat transfer and exergy loss rates in the exhaust gas preheater. Additionally, the temperature of the heat source has an important effect on the energy and exergy balance distribution and power output of the ORC. For every 10 K rise in exhaust temperature, the bottoming cycle power output of cyclohexane increases by approximately 12.3%. This study provides theoretical support for efficient marine waste heat recovery and working fluid selection. Full article

With the increase in energy density of power batteries, the risk of thermal runaway significantly increases under extreme working conditions. Therefore, this article proposes a biomimetic liquid cooling plate design based on the fractal structure of fir needle leaf veins, combined with Murray’s mass transfer law, which has significantly improved the heat dissipation performance under extreme working conditions. A multi-field coupling model of electrochemistry fluid heat transfer was established using ANSYS 2022 Fluent, and the synergistic mechanism of environmental temperature, coolant parameters, and heating power was systematically analyzed. Research has found that compared to traditional serpentine channels, leaf vein biomimetic structures can reduce the maximum temperature of batteries by 11.78 °C at a flow rate of 4 m/s and 5000 W/m³. Further analysis reveals that there is a critical flow rate threshold of 2.5 m/s for cooling efficiency (beyond which the effectiveness of temperature reduction decreases by 86%), as well as a thermal saturation temperature of 28 °C (with a sudden increase in temperature rise slope by 284%). Under low-load conditions of 2600 W/m ³, the system exhibits a thermal hysteresis plateau of 40.29 °C. To predict the battery temperature in advance and actively intervene in cooling the battery pack, based on the experimental data and thermodynamic laws of the biomimetic liquid cooling system mentioned above, this study further constructed a support vector machine (SVM) prediction model to achieve real-time and accurate prediction of the highest temperature of the battery pack (validation set average relative error 1.57%), providing new ideas for intelligent optimization of biomimetic liquid cooling systems. Full article

The vaporization of urea–water solution (AdBlue) plays a critical role in the performance of selective catalytic reduction (SCR) systems for modern diesel engines. This study presents mathematical models describing the vaporization of AdBlue droplets under ultrasonic excitation generated by a magnetostrictive effect, focusing on both film and volumetric regimes. The models rigorously incorporate heat and mass transfer equations, including acoustic cavitation effects induced by ultrasound. The influence of magnetostrictive-induced atomization and combined inductive preheating on droplet detachment and SCR catalyst efficiency was analyzed. Additionally, the impact of ultrasound frequency and amplitude on thermal vaporization efficiency and reactive mixture formation was investigated with the aim of enhancing NOx emission reduction. Model validation against literature data confirmed the practical applicability of the proposed approach, offering valuable insights for optimizing ultrasound-assisted AdBlue injection systems. Full article

In order to solve the problem of low thermal efficiency of a 130 t/h industrial circulating fluidized bed boiler, a computational particle fluid dynamic approach was used in this work to study two-phase gas–solid flow, heat transfer, and combustion. The factors influencing coal particle size distributions, air distribution strategies, and operational loads are addressed. The results showed that particle distribution exhibits “core–annulus” flow with a dense-phase bottom region and dilute-phase upper zone. A higher primary air ratio (0.8–1.5) enhances axial gas velocity and bed temperature but reduces secondary air zone (2.5–5.8 m) temperature. A higher primary air ratio also decreases outlet O₂ mole fraction and increases fly ash carbon content, with optimal thermal efficiency at a ratio of 1.0. In addition, as the coal PSD decreases and the load increases, the overall temperature of the furnace increases and the outlet O₂ mole fraction decreases. Full article

Electric vehicles (EVs) provide a feasible solution for the electrification of the transportation sector. However, the large-scale deployment of EVs over wide working conditions is limited by the temperature sensitivity of lithium-ion batteries (LIBs). Therefore, an efficient and reliable battery thermal management system (BTMS) becomes essential to achieve precise temperature control of batteries and prevent potential thermal runaway. Owing to their high heat-transfer efficiency and controllability, liquid-based cooling technologies have become a key research focus in the field of BTMS. In both design and operation, BTMSs are required to comprehensively consider thermal characteristics, energy consumption, economics, and environmental impact, which demands more scientific and rational evaluation criteria. This paper reviews the latest research progress on liquid-based cooling technologies, with a focus on indirect-contact and direct-contact cooling. In addition, existing evaluation methods are summarized. This work proposes insights for future research on liquid-cooled BTMS development in EVs. Full article

This work develops a Boundary Element Method (BEM) formulation for simulating bioheat transfer in perfused biological tissues using the Atangana–Baleanu fractional derivative in the Caputo sense (ABC). The ABC operator incorporates a nonsingular Mittag–Leffler kernel to model thermal memory effects while preserving compatibility with standard boundary conditions. The formulation combines boundary discretization with cell-based domain integration to account for volumetric heat sources, and a recursive time-stepping scheme to efficiently evaluate the fractional term. The model is applied to a one-dimensional cylindrical tissue domain subjected to metabolic heating and external energy deposition. Simulations are performed for multiple fractional orders, and the results are compared with classical BEM $(a=1.0)$, Caputo-based fractional BEM, and in vitro experimental temperature data. The fractional order $a\approx 0.894$ yields the best agreement with experimental measurements, reducing the maximum temperature error to 1.2% while maintaining moderate computational cost. These results indicate that the proposed BEM–ABC framework effectively captures nonlocal and time-delayed heat conduction effects in biological tissues and provides an efficient alternative to conventional fractional models for thermal analysis in biomedical applications. Full article

Hydrate-based CO₂ sequestration is considered one of the most promising methods in the field of carbon capture, utilization, and storage. The abundant fractured environments in marine sediments provide an ideal setting for the sequestration of CO₂ hydrate. Investigating the kinetics and morphological characteristics of CO₂ hydrate formation within fractures is a critical prerequisite for achieving efficient and safe CO₂ sequestration using hydrate technology in subsea environments. Based on the aforementioned considerations, the kinetic experiments on the formation, dissociation, and reformation of CO₂ hydrates were conducted using a high-pressure visualization experimental system in this study. The kinetic behaviors and morphological characteristics of CO₂ hydrates within sandstone fractures were comprehensively investigated. Particular emphasis was placed on analyzing the effects of fracture width, type, and surface roughness on the processes of hydrate formation, dissociation, and reformation. The experimental results indicate the following: (1) At a formation pressure of 2.9 MPa, the 10 mm width fracture exhibited the shortest induction time, the longest formation duration, and the highest hydrate yield (approximately 0.52 mol) compared to the other two fracture widths. The formed CO₂ hydrates exhibited a smooth, thin-walled morphology. (2) In X-type fractures, the formation of CO₂ hydrates was characterized by concurrent induction and dissolution processes. Compared to I-type fractures, the hydrate formation process in X-type fractures exhibited shorter formation durations and generally lower hydrate yields. (3) An increase in fracture roughness enhances the number of nucleation sites for the formation of hydrates. In both fracture types (I-type and X-type), the induction time for CO₂ hydrate formation was nearly negligible. However, a significant difference in the trend of formation duration was observed under varying roughness conditions. (4) Hydrate dissociation follows a diffusion-controlled mechanism, progressing from the fracture walls towards the interior. The maximum gas production was achieved in the 10 mm-width fracture, reaching 0.24 mol, indicating optimal heat and mass transfer conditions under this configuration. (5) During the reformation process, the induction time was significantly shortened due to the “memory effect.” However, the hydrate yield after the reformation process remained consistently lower than that of the first formation, which is primarily attributed to the high solubility of CO₂ in the aqueous phase. Full article

In Directed Energy Deposition (DED), modeling the molten pool temperature field is crucial for precise temperature control, process optimization, and quality improvement. However, conventional numerical methods suffer from limitations such as high computational costs and poor transferability. This study proposes a physics-informed neural network with dynamic learning rate (DLR-PINN) model, which integrates transfer learning to enable rapid prediction of 3D temperature fields and dimensions of molten pools across process parameters. Its validity is verified by a finite element method (FEM) calibrated via single-track DED experiments. Results show that DLR-PINN exhibits superior convergence and stability compared to traditional PINN. Combined with transfer learning, training efficiency is significantly enhanced, with a single prediction taking only 10 s. Using the FEM as the benchmark, it achieves a mean absolute percentage error (MAPE) of 0.53% for temperature prediction, and MAPE of 3.69%, 2.48%, and 6.96% for molten pool dimension predictions, respectively. Sensitivity analysis of process parameters reveals that scanning speed has a significantly greater regulatory effect on molten pool characteristics than laser power. Additionally, the temperature field of the flat-top heat source is more uniform than that of the Gaussian heat source, which is more conducive to improving printing quality and efficiency. Full article

During drilling, different kick locations significantly impact the formation-wellbore temperature (FWT) profile under the co-existence of kick and leakage condition (CKL). To ensure safety and efficiency during drilling, we study the effect of different kick locations on the FWT under the CKL. In this paper, a full transient heat transfer model based on the first law of thermodynamics is established to obtain four distinct WFT profiles under CKL conditions, incorporating both convective heat transfer and variable mass flow effects. Compared with the actual temperature measurement data, the reliability of the developed model is verified. The case studies show that the annular temperature (AT) is lower under the single-point leakage (SL), continuous leakage (CL), and CKL conditions than that in the normal drilling condition. Wellhead temperature in CKL differs significantly from that in normal drilling (ND). As the kick location gets closer to the bottom hole, the AT gets higher, and the temperature difference between the formation and annular gets smaller. Compared with the wellbore temperature profile under ND, the kick location can be detected by real-time monitoring of the FWT profile under the CKL. Full article

Numerical simulation has played a crucial role in modeling the behavior of natural gas hydrate (NGH). However, the existing numerical simulators worldwide have exhibited limitations in functionality, convergence, and computational efficiency. In this study, we present a novel numerical simulator, GPSFlow/Hydrate, for modeling the behavior of hydrate-bearing geologic systems and for addressing the limitations in the existing simulators. It is capable of simulating multiphase and multicomponent flow in hydrate-bearing subsurface reservoirs under ambient conditions. The simulator incorporates multiple mass components, various phases, as well as heat transfer, and sand is treated as an independent non-Newtonian flow and modeled as a Bingham fluid. The CH₄ or binary/ternary gas hydrate dissociation or formation, phase changes, and corresponding thermal effects are fully accounted for, as well as various hydrate formation and dissociation mechanisms, such as depressurization, thermal stimulation, and sand flow behavior. In terms of computation, the simulator utilizes a domain decomposition technology to achieve hybrid parallel computing through the use of distributed memory and shared memory. The verification of the GPSFlow/Hydrate simulator are evaluated through two 1D simulation cases, a sand flow simulation case, and five 3D gas production cases. A comparison of the 1D cases with various numerical simulators demonstrated the reliability of GPSFlow/Hydrate, while its application in modeling the sand flow further highlighted its capability to address the challenges of gas hydrate exploitation and its potential for broader practical use. Several successful 3D gas hydrate reservoir simulation cases, based on parameters from the Shenhu region of the South China Sea, revealed the correlation of initial hydrate saturation and reservoir condition with hydrate decomposition and gas production performance. Furthermore, multithread parallel computing achieved a 2–4-fold increase in efficiency over single-thread approaches, ensuring accurate solutions for complex physical processes and large-scale grids. Overall, the development of GPSFlow/Hydrate constitutes a significant scientific contribution to understanding gas hydrate formation and decomposition mechanisms, as well as to advancing multicomponent flow migration modeling and gas hydrate resource development. Full article

Polymer fouling in batch and tubular reactors creates safety hazards from heat buildup and blockages. The continuous Corning Advanced-Flow™ Reactor (AFR) offers enhanced mass and heat transfer, improving safety and efficiency. This study evaluated three reactor systems—a monolithic AFR, an AFR with an external pipe, and a conventional tubular reactor—for the mini-emulsion polymerization of styrene and subsequent styrene–acrylic acid copolymerization. The AFR operability under varying monomer concentrations was assessed and investigated, with the residence time’s effects on conversion. For styrene polymerization at 20–35 wt% monomer, the highest conversions achieved were 88.0% in the AFR, 85.8% in the tubular reactor, and 98.9% in the AFR with pipe. Uniform particles were obtained at ≤30 wt%, whereas at 35 wt%, the monolithic AFR experienced clogging and loss of particle uniformity. Similarly, in styrene–acrylic acid copolymerization (15–17.5 wt% monomer), the maximum conversions reached 80.1% in the AFR and 95.4% in the AFR with pipe, while the monolithic AFR again experienced blockage at 17.5 wt%. In conclusion, integrating an external pipe with the AFR, coupled with higher flow rates, significantly improved initiator diffusion, enhanced monomer conversion, and mitigated blockage. This approach enabled the efficient, continuous production of nanoscale, uniformly sized polystyrene and styrene–acrylic acid copolymers even at high monomer concentrations. Full article

This study reviews heat transfer fluids (HTFs) and their velocity effects on the thermal behavior of ground heat exchangers (GHEs) within geothermal heat pump (GHP) applications. It examines the classification, thermophysical properties, and operational behavior of standard working fluids, including water–glycol mixtures, as well as emerging nanofluids. Fundamental heat exchange mechanisms are discussed, with emphasis on how conductivity, viscosity, and heat capacity interact with fluid velocity to influence energy transfer performance, hydraulic resistance, and system reliability. Special attention is given to nanofluids, whose enhanced thermal behavior depends on nanoparticle type, concentration, dispersion stability, and flow conditions. The review analyzes stabilization strategies, including surfactants, functionalization, and pH control, for maintaining long-term performance. It also highlights the role of velocity optimization in balancing convective benefits with pumping energy demands, providing velocity ranges suited to different GHE configurations. Drawing from recent experimental and numerical studies, the review offers practical guidelines for integrating nanofluid formulation with engineered operating conditions to maximize energy efficiency and extend system lifespan. Full article