Heat and Mass Transfer

The performance of D2 Tool Steel, Inconel 718, and Ti-6Al-4 V in Electro-Discharge Machining (EDM) has been evaluated by utilizing a Taguchi L16 orthogonal array. The significant parameters in the machining process are gap voltage (3–9 V), duty cycle (4–10

Deep metal mine working faces require timely decisions on where thermal monitoring, ventilation inspection, and cooling review should be prioritized. This study evaluates a conservative same-mine screening framework that separates direct WB-RH-v exposure assessment from engineering-boundary prioritization. The dataset comprised 288 five-minute averaged operational records nested within 12 fixed monitoring points; therefore, the effective spatial validation units were the monitoring points rather than 288 independent working-face cases. Application of the pre-specified operational warning rule identified 117 high-risk records distributed across nine monitoring points. Wet-bulb temperature, relative humidity, and measured local air velocity were used only for target construction and were excluded from model inputs. The Q-assisted logistic model achieved pooled LOMO F1 = 0.836, MCC = 0.718, AUC = 0.947, and Brier score = 0.093. Point-wise analysis detected at least one high-risk record at seven of the nine high-risk monitoring points, whereas P08 and P09 had zero point-wise recall. Detecting all nine high-risk monitoring points required lowering the threshold to 0.05, which increased false alarms to 95. Because Q was calculated from measured local velocity and cross-sectional area, it was interpreted as an auxiliary ventilation-management proxy rather than an independent predictor. The framework is suitable for increasing monitoring and ventilation-cooling review priority within comparable same-mine conditions, but not for ruling out high-risk states identified by direct monitoring.

This study focuses on the modelling of density and thermal conductivity of Mg(NO3)2–KNO3–NaNO3 ternary salt systems. The salt system was chosen as a potential candidate for thermal energy storage because of its high Cp, density and thermal conductivity. Heat and mass transfer studies when applied to practical systems require proper thermophysical property estimation of the material. This not only reduces the cost of conducting complicated experiments but also allows integration with advanced software tools to map real-time processes. Geometric modelling was used for estimating the densities, while the unit cell model was used for thermal conductivity estimations of the ternary salt system. The challenge faced in this system was the lack of experimental data for Mg(NO3)2–KNO3–NaNO3 ternary salt systems as well as pure magnesium nitrate. Using modelling techniques, the thermophysical properties of pure Mg(NO3)2 was estimated as ρ _Mg(NO3)2 =2.7061 -0.0009 *T ; 523K

Accidental cryogenic spills can impose severe thermal loading on liquefied natural gas (LNG) containment structures through rapid local cooling, restrained thermal contraction, and stress concentration near hot–cold transition regions. This study compares direct prescribed-temperature loading with a transient boiling-curve-controlled film condition for a shell-based 9

Flow boiling heat transfer in rectangular micro-channel flat tubes is substantially influenced by cross-sectional geometry, yet the independent role of aspect ratio remains insufficiently clarified. In this study, R410A flow boiling heat transfer was experimentally investigated in two horizontal micro-channel flat tubes with aspect ratios of 1.62 and 0.80. The effects of mass flux, heat flux, saturation temperature, and aspect ratio on the heat transfer coefficient (HTC) were examined over mass fluxes of 150–250 kg/m2s, heat fluxes of 10–20 kW/m2, and saturation temperatures of 5–15 °C. Increasing mass flux enhanced the HTC and delayed deterioration, whereas increasing heat flux raised the heat transfer level but promoted earlier deterioration in the high vapor quality region. The effect of saturation temperature was comparatively moderate. For the two investigated flat-tube geometries, the AR = 0.80 tube exhibited higher heat transfer coefficients than the AR = 1.62 tube under the tested operating conditions, demonstrating a measurable influence of aspect ratio within the present experimental scope. Existing correlations generally performed better in the pre-dryout region than in the dryout region. The Oh and Son correlation was retained as an empirical benchmark, whereas a preliminary dryout-informed modification based on the Kim and Mudawar framework achieved a MAPE of 5.19

This study presents a practical workflow for quantitatively evaluating the oil‑bearing potential of heterogeneous volcanic reservoirs by integrating density and neutron logging responses. Traditional petrophysical models, such as the Archie equation, often fail in volcanic formations due to complex pore structures, conductive minerals, and dual‑porosity systems. To address this, we introduce a multi‑factor empirical model that combines the density‑neutron porosity difference—a well‑established indicator of light hydrocarbons—with a Fracture‑Porosity Composite Index (FPCI). The FPCI is a composite index that integrates sonic-derived porosity with the resistivity invasion ratio and serves as an empirical proxy for matrix storage capacity and fracture connectivity. Based on core‑log‑production data from the Carboniferous C4 reservoir in Block 1 (10 wells, 263 core samples), reservoirs are classified into three types: Type 1 (best), Type 2 (intermediate), and Type 3 (poor). The classification is based on independent petrophysical parameters (core porosity, MICP data, fracture density), with production data used only for post‑classification validation. The model shows good agreement with actual production history (R = 0.73, n = 22, 95

The miniaturization trend in electronics creates major challenges in managing heat dissipation, calling for efficient, passive and environmentally sustainable thermal management solutions. Among various heat pipes, pulsating heat pipes (PHPs) stand out due to their simple design and excellent heat transfer capabilities. The performance is highly dependent on the thermophysical properties of the selected working fluid. While synthetic surfactants had demonstrated enhanced thermal performance, eco-friendly biosurfactant remains unexplored in PHPs particularly through three-dimensional computational fluid dynamics (CFD) investigation. Therefore, the present study investigates numerical analysis of a 3D single-turn, closed-loop pulsating heat pipe (CLPHP) employing aqueous rhamnolipid solution as a modified working fluid and compared the thermal performance with DI water. A transient Volume of fluid (VOF) model integrated with phase change was implemented in ANSYS Fluent to observe the liquid-vapour oscillatory flow. Simulations were performed for 30

This study investigates coupled heat and moisture transfer in bio-based earthen materials, focusing on the interaction between temperature and hygroscopic behavior under different ambient conditions. Aligned and opposite heat and moisture flux directions are experimentally studied under controlled non-isothermal conditions to characterize moisture transfer and storage behavior. A numerical model based on the Künzel approach, coupled with the Guggenheim–Anderson–de Boer (GAB) formulation for moisture content, is developed. Model performance is assessed through comparison with experimental data using statistical indicators including root mean square error (RMS) and mean error (ME). The model shows satisfactory agreement, with RMS values ranging from 1.88

The development of biodegradable, thermally insulating, and flexible substrates is essential for advancing sustainable wearable and flexible electronic technologies while reducing reliance on non-biodegradable synthetic polymers. In this work, cassava starch/polyvinyl alcohol (PVA) composite films plasticised with glycerol are developed by solution casting and investigated for thermal diffusivity using photoacoustic spectroscopy. Glycerol content is varied from 0 wt

In this study, numerical simulations were conducted via the Fire Dynamics Simulator (FDS) to investigate the temperature response of main cables and suspenders of spatial cable suspension bridges under vehicle fire conditions. The temperature distribution on the cable surface and the changes in the maximum surface temperature were analyzed during the fire. Results above analyses, a passive fire protection method suitable for the cables was proposed through fire insulation experiments. The results indicate that compared with parallel suspension bridges, the structural characteristics of spatial cable suspension bridges lead to significant differences in temperature distribution. Under windless conditions, the passive fire protection height of cables in emergency lane fires reaches 16 m, with a maximum temperature of 739 °C. In contrast, the passive fire protection height of cables in inner lane fires reaches 20.8 m, with a maximum temperature of 324 °C. As wind speed increased, the required protection height decreased. A predictive model for the maximum surface temperature of space cable suspenders, incorporating the tilt angle of the slings, was proposed and further validated under the investigated working conditions. Finally, through fire insulation experiments, an appropriate passive fire protection material for the cables was selected, and a corresponding fire protection strategy was developed. This work provides effective guidance for the fire protection of spatial cable suspension bridges. Revealed unique flame-cable interaction mechanisms in spatial cable bridges under vehicle fires. Developed a predictive model for maximum cable temperature incorporating tilt angle and wind effects. Proposed an optimized passive fire protection scheme using high-silica aerogel composites.

This study examines the back-pressure-induced critical-to-subcritical transition of a supersonic R245fa ejector using a three-dimensional steady RANS model in Simcenter FloEFD. The geometry and operating conditions were reconstructed from Hao et al. for a generator temperature of 105 °C, an evaporator temperature of 30 °C, and condenser temperatures from 42.5 to 50.0 °C. R245fa was treated as a single-phase vapor with real-gas properties. Validation used the experimental entrainment ratio because local pressure, temperature, and mass-flow measurements were unavailable for the five cases. The model reproduced the measured transition trend with a mean absolute percentage error of 1.86

This study conducts an experimental analysis of performance enhancement techniques in a small-scale NH3-H2O diffusion absorption refrigeration system by utilizing a condensate pre-cooling heat exchanger. The study elucidates the impact of pre-cooling performance influences system thermodynamic behavior and cooling capacity under various operating situations, surpassing conventional performance assessment. The modified configuration was methodically evaluated against a baseline system under different generator heat inputs and condenser temperatures. Experimental results show that the controlled refrigerant sub-cooling can greatly enhance the refrigeration effect by raising the enthalpy differential at the expansion process. The cooling capacity was enhanced from 43 W to 55 W at a generator heat input of 100 W, which was a 28

Interest in hydrofluoro-olefin (HFO) fluids and their potential improvement through formulation and mixing refrigerants has increased due to the need for low-GWP refrigerants with good boiling heat transfer performance. The pool boiling characteristics of R-1234yf, R-1336mzz(E), and their binary mixtures on a smooth copper surface at saturation temperatures of 10°C, 15°C and 20°C are examined in this work. The heat flux ranges from 10 to 156 kW·m⁻2. Heat transfer coefficients, boiling curves and bubble images were produced for both pure and mixture refrigerants. R-1234yf showed better heat transfer performance than R-1336mzz(E) because of the thermophysical properties that promote active nucleate boiling and reduce the required wall superheat. Compared to pure refrigerants, mixtures of refrigerants have substantially lower heat transfer coefficients. The deterioration of heat transfer in typical mixtures was found to be related to both nonlinearly changing physical properties and the vapor–liquid phase equilibrium. Experimental results were compared with the existing correlation for both pure components and binary mixtures to validate the experiments and compare the results for 20°C. The analysis revealed that Stephan and Körner's correlation yield quite good findings and mostly used among the correlations studied but have some deviation after boiling starts After modifying the widely used Stephan and Körner's correlation to take heat flux into consideration, the present data was successfully correlated with a 15

This study presents a numerical investigation of coupled heat and mass transfer during drying in deformable packed beds subjected to humid-air and superheated-steam drying conditions. Unlike conventional rigid-bed approaches, the solved governing equations using the finite volume method under transient conditions, combines macroscopic transport equations with the evolution of bed structural properties; including porosity, particle diameter, specific surface area and bed height, which vary as a consequence of shrinkage during drying. Model validation was performed by comparing numerical predictions with independent experimental data available in the literature. The proposed model reproduces the evolution of moisture content during drying under identical operating conditions. Statistical analysis showed moderate agreement between numerical and experimental results (R² = 0.74, MAPE = 25.1

This study experimentally investigates the thermal hydraulic performance of plate-fin heat sinks (PFHSs) integrated with copper foam inserts using Al₂O₃/water nanofluid as the working fluid. The primary objective is to enhance convective heat transfer while mitigating the pressure drop penalty typically associated with fully foam-filled heat sink configurations. Experiments were conducted over a mass flow rate range of 0.12–0.18 kg/s, with nanoparticle volume fractions varying from 0 to 0.20 vol

This study presents a combined numerical and experimental investigation of hollow-shaft cooling for a 50 kW propulsion motor, in which a water jacket and a hollow shaft are integrated and three working fluids of air, automatic transmission fluid, and FC-3283 are supplied through the hollow shaft. Three-dimensional numerical simulations were performed and validated against experiments, and the maximum deviation in winding temperature was within 3

Tunnel kilns account for a major share of energy consumption in the ceramic brick industry, yet efficiency improvements have almost exclusively targeted heat recovery between the cooling and firing zones, leaving secondary air register positioning treated as a subordinate parameter within this coupling rather than as an independent lever. This study addresses that gap by investigating register position as a standalone optimization variable on a full-scale industrial tunnel kiln operating under real production conditions, rather than through simulation or controlled laboratory trials. The proposed strategy recovers part of the thermal energy otherwise evacuated through the chimney and redirects it toward the preheating zone, redistributing gas residence time and convective heat exchange without altering airflow rate, production throughput, or operating schedule. Brick mass, clay paste composition, and inlet moisture content (≈ 1

Under high-pressure conditions, the weld forming quality of Ti6Al4V (TC4) titanium alloy in laser welding with filler wire (LWF) deteriorates significantly. As ambient pressure increases from 5 kPa to 700 kPa, weld forming continuity drops by around 70

In this study, an experimental study and numerical analysis of tunable heat transfer enhancement in compact heat exchangers have been carried out by using porous inserts containing magnetic spheres and subjected to external magnetic field. The proposed configuration is based on the use of magnetically responsive spheres which are introduced into a reconfigurable porous matrix to provide adaptive control of permeability and effective thermal conductivity, rather than the use of conventional porous inserts with fixed thermal-hydraulic characteristics. The Reynolds number (Re = 300–2500), porosity (0.2–0.6) and magnetic field intensity (B = 0-0.25 T) were systematically investigated for the heat transfer and flow characteristics. A three-dimensional numerical model was developed using Darcy–Brinkman–Lorentz model and an effective conductivity model based on Maxwell–Eucken was set up and validated with experimental measurements. It was found that the use of a magnetic field had a significant effect on the thermal performance of the porous insert. The optimum operating condition yielded up to a 30

In industrial drying processes involving relative motion between the substrate and the airflow source, droplet removal from solid surfaces is a common requirement. In this study, a linear translation experimental system featuring a moving substrate and a fixed air knife was used to investigate droplet migration on polymethyl methacrylate (PMMA) and photovoltaic glass (PV) surfaces. The results demonstrated that droplets migrated toward the near-outlet region of the air knife and eventually reached an equilibrium position, where the local airflow velocity along the migration path increased from approximately 8 m/s to 23 m/s. Increasing the substrate translation velocity enhanced droplet deformation, although the contact-line responses differed markedly between the two surfaces. Droplets on the PMMA surface primarily exhibited relatively coordinated longitudinal elongation, whereas those on the PV surface underwent more pronounced streamwise stretching and lateral confinement owing to stronger contact-line pinning. A force-balance model was established by incorporating a dynamic characteristic length derived from the deformed droplet footprint to predict the critical airflow velocity at the equilibrium position. The predicted critical velocities agreed well with the experimental results, with relative deviations generally below 5