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Open access Jul 2026

Computational Fluid Dynamics-Based Characterization of Heat Transfer and Airflow in an Indirect Solar Fish Dryer Under Tropical Conditions

Indirect solar drying is a widely adopted fish preservation technique in tropical regions, valued for its low energy requirement and capacity to enhance product quality. However, non-uniform airflow and temperature distribution within drying chambers remain persistent design challenges that compromise drying efficiency and product consistency. This study investigated the airflow characteristics and convective heat transfer performance of an indirect solar fish dryer through computational fluid dynamics (CFD) simulation and experimental validation. A three-dimensional CFD model was developed to simulate temperature distribution and airflow patterns under forced convection, with an inlet air velocity of 1.2 m·s⁻¹ and an inlet air temperature of 60 °C. Experimental air temperatures were recorded inside the drying chamber during actual drying operations and compared with simulated values using linear regression and root-mean-square error (RMSE). The regression analysis yielded a strong linear relationship between simulated and experimental temperatures (R² = 0.9413), with an RMSE of 3.41 °C, indicating reasonable agreement in absolute temperature prediction. These results confirm that the CFD model accurately represents the thermal behavior and convective heat transfer characteristics of the dryer. The validated CFD framework provides a reliable, cost-effective tool for evaluating and optimizing the design and operational performance of indirect solar fish dryers under tropical conditions, thereby reducing reliance on iterative physical prototyping.

Yvonne Elizalde, Jonathan Perez, Freddie Simeon Jr. et al. · 0 citations
Aug 2026

Physics-informed modeling and optimization of heat and mass transfer in porous mineral raw materials during energy-efficient industrial drying

Industrial drying of porous mineral raw materials is one of the energy-intensive stages of mineral processing, especially when the material contains bound moisture, fine particles, and heterogeneous pore structures. Inefficient drying regimes may lead to excessive energy consumption, nonuniform temperature distribution, incomplete moisture removal, thermal degradation of material properties, and reduced technological performance in subsequent processing operations. This study proposes a physics-informed modeling approach to describe and optimize coupled heat and mass transfer processes in porous mineral raw materials during industrial drying. The proposed framework combines heat conduction, convective heat exchange, moisture diffusion, evaporation-driven mass transfer, and boundary-condition constraints within a unified model structure. The model represents temperature and moisture fields as time-dependent variables and incorporates conservation laws to improve the reliability of drying-process predictions. Special attention is given to the interactions among thermal gradients, internal moisture migration, surface evaporation, and drying-air parameters. The methodological approach includes formulating governing equations, specifying initial and boundary conditions, constructing a physics informed residual function, and interpreting drying efficiency indicators. The proposed model can be used to estimate temperature-moisture dynamics, identify zones of delayed moisture removal, and support the selection of energy-efficient drying regimes. The study contributes to the development of digital and physics-based decision-support tools for mineral processing systems by linking industrial drying technology with heat and mass transfer modeling.

Makhsuma Ismoilova, Zuhra Namozova, Kamola Gadoymurodova et al. · 0 citations
Open access Aug 2026

Experimental Investigation and CFD Modeling of Heat and Mass Transfer During Drying of Alfalfa Leaf Fraction in a Rotary Drum Dryer

The convective drying of agricultural materials is an energy-intensive process, and optimizing dryer design is critical for improving efficiency and product quality. This study presents a comprehensive heat and mass transfer model for the convective drying of alfalfa leaves in a rotary drum dryer. Freshly harvested leaves with an initial moisture content of approximately 70% (w.b.) were used as the test material. The proposed system features a simplified drum design aimed at enhancing process efficiency while reducing equipment complexity. The primary objective was to reduce the moisture content of alfalfa leaves to below 50% to ensure their quality during subsequent storage and transportation. To determine the optimal operating conditions, the kinematics of leaf motion inside the rotating drum and the associated heat and mass transfer phenomena were investigated through analytical modeling, numerical simulation, and experimental studies on a laboratory-scale physical model. An analytical model was developed to establish relationships between transverse kinematic characteristics (detachment condition, Froude number, drum inclination angle), average longitudinal velocity, and residence time. Numerical simulations based on the Navier–Stokes equations (continuity, momentum, and energy) provided detailed moisture content distributions within individual leaves under varying airflow orientations and drying durations. The novelty of this work lies in the integrated determination of optimized operating parameters through combined analytical, numerical, and experimental approaches. A regression model relating final moisture content to key process variables (air velocity, temperature of 60 °C, drum rotation frequency and mass of loaded material) was developed from experimental data, yielding practical recommendations for the design and operation of rotary drum dryers for alfalfa and similar agricultural materials.

Gani Zhumatay, O. Zhortuylov, K.A. Moshanov et al. · 0 citations
Jul 2026

Multiphysics Numerical Simulation of Supercritical CO 2 Processing in Chitosan Aerogel Beads: Coupled Heat and Mass Transfer With Porosity and Shrinkage Evolution

This study presents a transient multiphysics numerical model for analyzing supercritical CO 2 (scCO 2 ) drying of single chitosan alcogel beads, focusing on coupled heat transfer, solvent diffusion, porosity evolution, and shrinkage deformation. The model integrates Darcy‐based flow behavior, Fickian solvent diffusion, and energy conservation equations to resolve interactions between temperature, pressure, and solvent concentration fields under fixed operating conditions. A finite‐element framework was implemented and validated against experimental solvent removal data reported in the literature at 40°C and 15 MPa, showing strong agreement with drying kinetics trends. Results indicate that the temperature inside the bead remains nearly uniform throughout the process, reflecting low Biot number conditions where internal heat transfer resistance is negligible. Solvent removal follows two characteristic stages: an initial constant‐rate period dominated by external CO 2 solvent mass transfer, followed by a falling‐rate regime controlled by internal diffusion resistance. Parametric analysis demonstrates that increasing operating pressure enhances CO 2 density and solvent solubility, accelerating drying and reducing total process time by approximately 28%, while inducing moderate pore compression. The model predicts porosity reduction from 0.85 to approximately 0.68 and volumetric shrinkage of about 25%, consistent with reported experimental observations. Additional simulations show that both effective solvent diffusivity and initial porosity strongly influence drying kinetics. A qualitative comparison with conventional drying techniques confirms that scCO 2 drying provides an optimal balance between structural preservation and processing time. The developed model offers a robust predictive tool for optimizing aerogel drying processes.

N. Benmakhlouf, S. Azzouz, Salwa Fezai · 0 citations
Aug 2026

Numerical Study on Melting Dynamics and Heat Transfer Enhancement of Micro‐Encapsulated Phase Change Material–Water Slurry in Natural Convection Enclosure Using Eulerian–Eulerian Model

The two‐phase Eulerian–Eulerian solver is developed to analyze natural convection within a differentially heated square enclosure with water‐based micro‐encapsulated phase change material (MEPCM) slurry. The model solves the conservation equations for the liquid and MEPCM phases separately, with coupling between them is done through interfacial momentum and energy exchanges. Finite difference techniques, along with sixth‐order accuracy compact schemes for the nonlinear terms, are employed to discretise the equations. The MEPCM particles are considered in such a way that they melt close to the hot wall and solidify adjacent to the cold wall to make use of the latent heat benefits. After validating the solver with numerical and experimental data, the study analyses the transient evolution of the melting front, offering insights into phase transition behavior and underlying heat transfer mechanisms. This study also examines the effects of MEPCM volume fraction, hot wall temperature, and different phase change materials (n‐Octadecane and n‐Eicosane) on melting dynamics, flow fields and heat transfer. The MEPCM particles suspended in water enhance heat transfer by increasing the effective heat capacity through latent heat. At a temperature difference of ΔT=6$$ \Delta T=6 $$ K ( Gr=9.9×105$$ Gr=9.9\times {10}^5 $$ ) and volume fraction, ϕs$$ {\phi}_s $$ = 15% the heat transfer improves by 54.55% compared to water. However, at a higher temperature difference of ΔT=12$$ \Delta T=12 $$ K ( Gr=1.98×106$$ Gr=1.98\times {10}^6 $$ ), the enhancement drops to approximately 35.08%, indicating that at larger temperature differences, the stronger buoyancy forces dominate, increasing heat transfer, limiting the impact of MEPCM particles. Notably, heat transfer enhancement occurs only if the MEPCM particles undergo phase change within the cavity. If the hot wall temperature is too low to cause MEPCM melting, the lack of phase change reduces the slurry's overall thermal conductivity, thereby decreasing heat transfer.

Leelasagar Koneti, K. Venkatasubbaiah · 0 citations
Open access Jul 2026

Experimental investigation of convective drying behavior of in-shell hazelnuts: moisture diffusivity, transport phenomena, and pressure drop

This study investigates the convective hot-air drying behavior of in-shell hazelnuts under controlled operating conditions, with emphasis on drying kinetics, thin-layer modelling, heat and mass transfer characteristics, and pressure drop behavior within the hazelnut bed. The experiment was performed in a laboratory dryer set to 50–60 °C and 1.5–2.1 m s⁻¹ airflow. The temporal evolution of moisture content, drying rate, and moisture ratio was experimentally determined, and the effective moisture diffusivity was evaluated using Fick’s second law of diffusion. The results showed that internal moisture diffusion governed the drying process. Higher drying air temperature and air velocity reduced the drying time and enhanced the drying rate. Effective moisture diffusivity increased with temperature. The two-term model provided the best agreement with the experimental data, efficient R² values between 0.9770 and 0.9953, RMSE values between 0.0178 and 0.0384, and X² values between 5.26 × 10− 4 and 2.90 × 10− 3. The coefficient of heat transfer was between 131 and 180 W m⁻² K⁻¹, governed by air velocity rather than temperature. The pressure drop values predicted by the Ergun equation showed good agreement with the experimental measurements, with deviations generally remaining below approximately 8% under the investigated airflow conditions.

Emel Çelik, N. Parlak, Z. Meral et al. · 0 citations