This review attempts to provide a comprehensive assessment of recent methodologies, structures, and devices for pool boiling heat transfer enhancement. Several enhancement approaches relating to the underlying fluid route and the capability to eliminate incipient boiling hysteresis, augment the nucleate boiling heat transfer coefficient, and improve the critical heat flux are assessed. Hence, this study addresses the most relevant issues related to active and passive enhancement techniques and compound enhancement schemes. Passive heat transfer enhancement techniques encompass multiscale surface modification of the heating surface, such as modification with nanoparticles, tunnels, grooves, porous coatings, and enhanced nanostructured surfaces. Also, there are already studies on the employment of a wide range of passive enhancement techniques, like displaced enhancement, swirl flow aids, and bi-thermally conductive surfaces. Moreover, the combined usage of two or more enhancement techniques, commonly known as compound enhancement approaches, is also addressed in this survey. Additionally, the present work highlights the existing scarcity of sufficiently large available databases for a given enhancement methodology regarding the influencing factors derived from the implementation of innovative thermal management systems for temperature-sensitive electronic and power devices, for instance, material, morphology, relative positioning and orientation of the boiling surface, and nucleate boiling heat transfer enhancement pattern and scale. Such scarcity means the available findings are not totally accurate and suitable for the design and implementation of new thermal management systems. The analysis of more than 100 studies in this field shows that all such improvement methodologies aim to enhance the nucleate boiling heat transfer parameters of the critical heat flux and nucleate heat transfer coefficient in pool boiling scenarios. Finally, diverse challenges and prospects for further studies are also pointed out, aimed at developing important in-depth knowledge of the underlying enhancement mechanisms of such techniques.
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http://dx.doi.org/10.3390/mi15020281 | DOI Listing |
Polymers (Basel)
January 2025
Department of Physics, Washington State University, Pullman, WA 99163, USA.
This work aims to determine the mechanism of the photomechanical response of poly(Methyl methacrylate) polymer doped with the photo-isomerizable dye Disperse Red 1 using the non-isomerizable dye Disperse Orange 11 as a control to isolate photoisomerization. Samples are free-standing thin films with thickness that is small compared with the optical skin depth to assure uniform illumination and photomechanical response throughout their volume, which differentiates these studies from most others. Polarization-dependent measurements of the photomechanical stress response are used to deconvolute the contributions of angular hole burning, molecular reorientation and photothermal heating.
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January 2025
Faculty of Mechanics, University Politehnica of Timisoara, Piata Victoriei 2, 300006 Timisoara, Romania.
This study investigated silicone composites with distributed boron nitride platelets and carbon microfibers that are oriented electrically. The process involved homogenizing and dispersing nano/microparticles in the liquid polymer, aligning the particles with DC and AC electric fields, and curing the composite with IR radiation to trap particles within chains. This innovative concept utilized two fields to align particles, improving the even distribution of carbon microfibers among BN in the chains.
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January 2025
Institute of Electric Power Engineering, Czestochowa University of Technology, Armii Krajowej 17, 42-200 Czestochowa, Poland.
During the heat treatment of round steel bars, a heated charge in the form of a cylindrically formed bundle is placed in a furnace. This type of charge is a porous granular medium in which a complex heat flow occurs during heating. The following heat transfer mechanisms occur simultaneously in this medium: conduction in bars, conduction within the gas, thermal radiation between the surfaces of the bars, and contact conduction across the joints between the adjacent bars.
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January 2025
School of Mechatronics Engineering, Harbin Institute of Technology, Harbin 150001, China.
C-UHTC is an ideal aerospace material because of its exceptional properties, but its machinability is facing great challenges. Electrical discharge machining (EDM) offers a potential solution, but its removal mechanism remains unclear, lacking reliable prediction tools to guide the actual production. This paper deeply explores the EDM removal mechanism of C-ZrB-SiC through single-pulse experiments, high-speed camera observations, and thermal-fluid coupling simulations, revealing key processes like heat transfer, phase transformation, molten pool dynamics, crater formation, and reinforcing phase effects.
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January 2025
Department of Industrial Engineering, University of Salerno, 84084 Fisciano, SA, Italy.
This paper presents a comprehensive numerical investigation to simulate heat transfer and residual stress formation of Ti-6Al-4V alloy during the Laser Powder Bed Fusion process, using a finite element model (FEM). The FEM was developed with a focus on the effects of key process parameters, including laser scanning velocity, laser power, hatch space, and scanning pattern in single-layer scanning. The model was validated against experimental data, demonstrating good agreement in terms of temperature profiles and melt pool dimensions.
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