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Integrated CFD–drying model for design optimisation of multi-layer rack drying systems for mackerel processing
(2026-08-01)
Nabudda, Kriengkrai
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Thasnas, Natakorn
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Poungthong, Pongthep
This study presents an integrated Computational Fluid Dynamics (CFD)–Page model framework for analysing and optimising the drying performance of a six-layer mackerel drying system. Experimental drying data were fitted using the Page model (k = 0.185, n = 1.32), achieving high predictive accuracy (RMSE = 0.018). The coupled CFD–drying model was applied to evaluate moisture removal behaviour and the effect of rack spacing on airflow distribution, temperature uniformity, and heat transfer. Results revealed distinct layer-dependent drying characteristics, with the uppermost layer exhibiting the fastest moisture removal due to greater exposure to hot, low-humidity airflow. CFD simulations for rack spacings of 8–12 mm showed that spacing significantly influences airflow penetration and thermal distribution. A mesh-independent model with 261,785 elements ensured numerical reliability. The optimal rack spacing was identified as 10 mm, providing the most uniform airflow and temperature distribution. Surrogate model optimisation further predicted an optimal spacing of 10.21 mm, improving drying uniformity, energy efficiency, and overall system performance.
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Physics-Guided CFD–ML Framework for Sustainable Classical Wire Coating with Power-Law Fluids
(2026-07-01)
Nabudda, Kriengkrai
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Poungthong, Pongthep
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Ritthong, Wirote
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Elumalai, P. V.
This study presents an integrated Computational Fluid Dynamics (CFD) and machine learning framework for analyzing and optimizing classical wire coating processes involving non-Newtonian power-law fluids. A two-dimensional axisymmetric CFD model was developed in ANSYS Fluent 2024R1 to investigate the effects of the power-law index (n = 0.3–1.0) on flow, pressure, temperature, and density fields under non-isothermal conditions. A Latin Hypercube Sampling-based Design of Experiments was coupled with surrogate modelling and Sobol sensitivity analysis to evaluate process performance and identify optimal operating conditions. The results showed that velocity distributions were highly dependent on fluid rheology, with shear-thinning fluids producing broader plug-like flow regions and more uniform velocity profiles. In contrast, pressure, temperature, and density fields exhibited limited sensitivity to variations in the power-law index. Optimization indicated that low power-law indices, moderate pressure gradients, and low-to-moderate wire speeds maximize coating thickness while minimizing material loss. Ridge Polynomial Regression achieved excellent predictive accuracy for all response variables (R<sup>2</sup> > 0.995). Sensitivity analysis revealed that the initial die gap is the dominant factor governing coating thickness, whereas material loss is influenced by combined effects of die geometry, fluid rheology, and wire speed. The proposed framework provides an efficient tool for process optimization and material conservation in industrial wire coating applications.
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Innovative educational technology for visually impaired learners using a 3D-Printed foot reflexology robot
(2026-06-01)
Nabudda, Kriengkrai
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Nabudda, Kanokpit
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Kitprathaung, Nustha
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Phumpho, Suwilai
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Poungthong, Pongthep
This study presents the design, development, and validation of a foot reflexology teaching robot that integrates multidisciplinary design, rapid prototyping, and user-centred assistive educational strategies to support tactile learning for visually impaired individuals. A digital foot model, derived from anthropometric data of an average Thai female, was refined to achieve a balance between anatomical accuracy and manufacturability. The structural design featured modular internal compartments, precision openings, and detachable covers to support maintenance without compromising anatomical realism. Fabrication using PLA-based fused deposition modelling (FDM) produced a lightweight, durable, and cost-effective prototype incorporating interactive tactile sensing and modular electrical components. A Raspberry Pi platform programmed in Python enabled audio-based instructional feedback triggered by tactile interaction, creating a multisensory educational device for experiential reflexology training. Structured evaluation sessions with 29 visually impaired learners confirmed its effectiveness in facilitating hands-on engagement, multisensory learning, and usability, with high satisfaction across safety and practicality. Overall, this work establishes a replicable framework for developing accessible and inclusive assistive educational technologies.• Integrated multidisciplinary design and user-centred development approach.• Applied rapid prototyping to translate digital anatomical models into functional physical components.• Conducted user-based evaluation to assess educational effectiveness and accessibility.
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Multi-Regime GRU-Scheduled PID Control for Greenhouse VPD Regulation with Real-Time PLC Deployment
(2026-01-01)
Wanna, Natthanan
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Nabudda, Kriengkrai
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Sitthaphanit, Suphasit
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Thasnas, Natakorn
Vapor pressure deficit is a physiologically meaningful climate variable governing plant transpiration and water transport in greenhouse cultivation. However, accurate regulation in evaporative-cooled greenhouses is challenging due to nonlinear temperature-humidity coupling, time-varying dynamics, and rapidly changing solar disturbances. Conventional fixed-gain proportional-integral-derivative controllers, tuned for a single operating condition, often exhibit performance degradation under regime transitions. This study proposes a multi-regime admissible-region-constrained gain-scheduled control framework in which a gated recurrent unit network serves as a supervisory scheduler to generate smooth, near-optimal controller gains for real-time vapor pressure deficit regulation. Control-oriented first-order-plus-dead-time models are identified under representative operating regimes, and an interval-bounded plant ensemble is constructed to capture dynamic variability. Regime-wise optimal gains are obtained offline using hybrid evolutionary optimization and used as supervisory training labels. To support safe deployment, all scheduled gains are constrained within a pre-validated admissible stability region, such that each deployed gain configuration remains inside an offline-validated frozen-time stabilizing set. The controller is implemented on an industrial programmable logic controller and experimentally validated in a full-scale evaporative greenhouse under real environmental disturbances. Comparative multi-day experiments demonstrate improved tracking accuracy, reduced overshoot, smoother actuator behavior, and enhanced disturbance attenuation relative to fixed-gain strategies, while maintaining deterministic real-time execution. The results establish an industrially deployable learning-based gain-scheduling framework for practical greenhouse climate control.
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Optimization of Degradable Polylactic Acid-Based Coating Materials for Sustainable Wire Manufacturing Injection Process Using Computational Fluid Dynamics Analysis
(2025-06-01)
Nabudda, Kriengkrai
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Promjariyakoon, Rattanaporn
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Kitprathaung, Nustha
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Ritthong, Wirote
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Intasonti, Sontinan
This study investigates the impact of injection angle on polylactic acid (PLA) wire coating performance, focusing on flow dynamics, heat transfer, mass density, and pressure distribution. Three angles: 30°, 45°, and 60° were assessed for their effects on coating characteristics. At 30°, the flow is smooth with minimal turbulence, ensuring consistent deposition. The 60° angle increases velocity and material penetration but risks turbulence and uneven coating. The 45° angle optimally balances material mixing and flow stability. In terms of heat transfer, the 30° angle concentrates heat near the injection point, creating a steep thermal gradient, while the 60° angle disperses heat more broadly but with lower intensity. The 45° angle ensures uniform heat distribution, improving energy efficiency. Regarding mass density, the 30° angle favours localized deposition, ideal for concentrated applications, while the 60° angle promotes broader distribution with reduced concentration. The 45° angle optimises density uniformity and maintains structural integrity. Pressure distribution follows similar trends, with 30° and 60° angles causing uneven deposition, whereas the 45° angle ensures balanced pressure distribution. In conclusion, the 45° angle offers superior performance across all parameters, providing an optimal balance of efficiency, uniformity, and structural integrity, thus enhancing PLA wire coating quality for sustainable engineering applications.
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Optimal Design of Cooling Rooms for Mackerel Using Computational Fluid Dynamics
(2025-06-01)
Nabudda, Kriengkrai
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Suntivarakorn, Ratchaphon
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Artnaseaw, Apichart
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Ritthong, Wirote
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Poungthong, Pongthep
This study utilises computational fluid dynamics (CFD) simulations to investigate airflow and temperature distributions in cold storage environments equipped with various fan and duct configurations. It assesses the effectiveness of single and dual evaporator fans (mounted at both front and rear) and front-and rear-positioned air ducts in enhancing air circulation and thermal uniformity. Results indicate that single rear-mounted fans promote localised airflow but lead to thermal stratification and stagnant zones, while front-mounted fans struggle to circulate air effectively towards the rear. Rear-positioned ducts improve air distribution but require further optimisation to address residual stratification. Dual rear-mounted evaporator fans deliver the most consistent cooling, minimising temperature variation and reducing compressor load, thus improving energy efficiency. Although dual front-mounted fans enhance circulation, they still exhibit thermal inconsistencies. The study also underscores the importance of measuring fan outlet velocity to ensure stable environmental conditions. Overall, the findings emphasise the necessity of optimised airflow strategies, appropriate fan placement, and ongoing system monitoring to achieve uniform cooling and preserve the quality of temperature-sensitive products in cold storage applications.

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