10:20   Control of heat transfer I Artificial Neural Network-Based Design of Air Duct Outlets for Household Refrigerators Eunseop Yeom, Heewook Jung, Yongbum Cho, Hoyoon Kim Abstract: The performance of a household refrigerator is highly influenced by the internal temperature distribution and the efficiency of airflow. In particular, uniform temperature distribution within the refrigerator plays a critical role in maintaining energy efficiency and preserving food freshness, making its optimization essential to meet consumer demands. Computational Fluid Dynamics (CFD) has long been a vital tool for visualizing thermal and flow fields and optimizing refrigerator designs. Oh, M. J. conducted a three-dimensional steady-state numerical simulation to analyze the characteristics of cold airflow inside a refrigerator, accurately modeling internal flow and heat transfer involving fan and evaporator operation. (1) Similarly, Yoo, J. H. carried out a steady-state simulation aimed at improving airflow uniformity by redesigning the air duct structure. (2) In addition, Wang, L. performed CFD simulations under transient conditions to evaluate three-dimensional airflow and temperature variation inside a freezer cabinet, thereby optimizing temperature uniformity and cooling performance while analyzing internal flow patterns and thermal behavior. (3) Recently, advances in artificial neural networks have opened new opportunities for refrigerator design optimization. AI models can learn from large-scale simulation data to identify optimal design parameters that maximize temperature uniformity and cooling efficiency. This study integrates conventional CFD techniques with AI-based design optimization methods to analyze internal temperature characteristics and propose optimal design solutions for improved refrigerator performance. Thermal Nucleated Bubbles Investigation in Subcooled Novec 7100 Boiling Induced by Megasound Streaming for Electronics Cooling Applications Teerapat Thungthong, Tatsuo Sawada, Kunthakorn Khaothong, Jetsadaporn Priyadumkol, Weerachai Chaiworapuek Abstract: This study examines how megasound-induced streaming affects nucleated bubble behavior and heat transfer in the subcooled flow boiling of Novec 7100, which is crucial for advanced electronics cooling. The peak dimensionless temperature of 1.8 was found at the lowest heat flux highlights a significant enhancement in heat transfer coefficients. The mechanism is visualized using DSLR cameras and Particle Image Velocimetry (PIV) measurements. The visualize results demonstrated that megasound effectively disperses thermal bubbles, particularly at lower heat fluxes, preventing the formation of large insulating vapor blankets on the heated surface. PIV measurements quantified this effect, revealing an increment in near-wall fluid velocity due to megasound-induced acoustic streaming. This enhanced flow effectively removes heat from the surface. The combination of bubble dispersion and increased fluid velocity significantly improves heat transfer efficiency, highlighting the potential of megasound-induced streaming for next-generation, high-performance electronics cooling solutions. Investigation of Enhanced Fluid Velocity Induced by Megasonic Waves Teerapat Thungthong, Weerachai Chaiworapuek, Tatsuo Sawada Abstract: This study investigates enhanced fluid velocity induced by megasonic waves (2.4 MHz) in silicone fluid, using single and dual-ultrasound setups with varying propagation angles (0°, 30°, 40°, 50°). Particle Image velocimetry (PIV) was used to measure the flow fields in a chamber. Results show that dual-ultrasound configurations, particularly at a 30° propagation angle, significantly enhance fluid velocity compared to single-ultrasound. It is also achieved a maximum average velocity of approximately 6.75 cm/s at a specific location. This enhancement is attributed to optimized interaction between the ultrasound waves and the fluid, maximizing flow dynamics. The findings suggest that dual-ultrasound systems, offer significant potential for enhancing fluid mixing and transport in various applications. Future research will focus on further optimizing these configurations for practical use.

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