A5085244059- Heat Transfer and Boiling Studies
- Fluid Dynamics and Heat Transfer
- Fluid Dynamics and Thin Films
- Heat Transfer and Optimization
- Fluid Dynamics and Mixing
- Heat Transfer Mechanisms
- Spacecraft and Cryogenic Technologies
- Surface Modification and Superhydrophobicity
- nanoparticles nucleation surface interactions
- Electrohydrodynamics and Fluid Dynamics
- Recycling and Waste Management Techniques
- Membrane Separation Technologies
- Nuclear physics research studies
- Calibration and Measurement Techniques
- Adhesion, Friction, and Surface Interactions
- Crystallization and Solubility Studies
- Calcium Carbonate Crystallization and Inhibition
- Electrodeposition and Electroless Coatings
- Soil, Finite Element Methods
- Nuclear Engineering Thermal-Hydraulics
- Membrane-based Ion Separation Techniques
- Advanced Power Generation Technologies
- Corrosion Behavior and Inhibition
- Metallurgy and Material Science
- Phase Change Materials Research
University of Ljubljana
2015-2024
Functionalized interfaces enhancing phase-change processes have immense applicability in thermal management. Here, a methodology for fabrication of surfaces enabling extreme boiling heat transfer performance is demonstrated, combining direct nanosecond laser texturing and chemical vapor deposition hydrophobic fluorinated silane. Multiple strategies are explored on aluminum with subsequent nanoscale hydrophobization. Both superhydrophilic superhydrophobic laser-engineered microcavities...
This study investigates the effect of experimental setup design factors on pool boiling CHF, compares spatial temperature gradient calculation methods and analyzes uncertainty heat flux surface superheat. Reported CHF values smooth copper surfaces, measured for saturated water at atmospheric pressure flat horizontal samples, are highly scattered, which cannot be explained solely by measurement or randomness process. data 54 experiments from 47 publications is analyzed using regression...
In this study, the optimal surface pattern of low and high wettability regions for enhanced boiling heat transfer is investigated using aluminum superbiphilic surfaces. Samples are fabricated by combining chemical vapor deposition a fluorinated silane to turn them superhydrophobic nanosecond laser texturing render selected areas superhydrophilic. Triangular lattice circular spots utilized with spot diameters between 0.25 mm 1.0 pitch values 0.5–2.5 mm. Pool performance surfaces evaluated...
This publication lays the foundation for description of Multiscale Boiling Experiment, which was conducted within two measurement campaigns on International Space Station between 2019 and 2021. The experiment addresses fundamental questions about two-phase heat transfer during boiling processes. For this purpose, single or few subsequential bubbles are selectively ignited a heated substrate using short laser pulse. A detailed investigation phenomena is possible, as process temporally slowed...
Growing world population and increasing density are leading to waste production with biological amounting several billion tonnes annually. Together the need for renewable energy sources, waste-to-biogas conversion as a prime example of waste-to-energy technology represents facile way solving two problems simultaneously. This review aims address recent progress in field technology, which is lately facing intensive research development, present current status this treatment method both...
Abstract The rapid advancement of engineering systems has spurred the search for innovative thermal management solutions. Boiling, as a phase‐change heat transfer method, shown promise in dissipation, but non‐functionalized surfaces struggle with increasing cooling demands. To improve dissipation efficiency across different loads, functionalized tailored wettability have been proposed. Separately, superhydrophilic and superhydrophobic each offer benefits drawbacks boiling applications...
Long-term boiling stability marks an important and often overlooked characteristic when engineering advanced interfaces for efficient phase-change heat removal. This study presents long-term pool on functionalized smooth laser-textured copper in de-ionized water aqueous solution of calcium sulphate. Each surface was exposed to nucleate several hundred hours wettability, morphology chemistry were evaluated prior after each test. In addition, consecutive curves recorded all samples. Our...
Nucleate boiling enables effective cooling and heat transfer at low temperature differences between a heated surface the surrounding fluid. It is utilized in many applications, ranging from large power plants to small microelectronics. To enhance process by minimization of increase maximum attainable flux, several approaches for modifications were recently developed. However, each them has least one important drawback, including challenging expensive production, mechanical and/or thermal...
In this work, we studied the wall heat flux partitioning during pool boiling of water on thin metallic surfaces. We conducted experiments surfaces where engineered nucleation sites by nanosecond-fiber-laser texturing. These form triangular lattice patterns with different pitches. measured time-dependent temperature and distributions surface using an infrared camera. developed post-processing algorithms to measure, based these distributions, all fundamental parameters used in models (e.g.,...
Heat exchanger performance is significantly reduced in the presence of impurities one or both fluid streams, frequently by deposits inversely soluble salts. Accordingly, immense efforts were and still are spent to combat, predict, investigate such fouling problems mitigate reduction heat transfer performance. In this study, calcium carbonate crystallization a corrugated plate was investigated. Fouling monitored using temperature flow measurements, and, for first time, coupled with infrared...
This study explores the nuanced interplay between surface wettability and morphology in nucleate boiling heat transfer. Surfaces with identical microstructures but varying are created on copper substrates using laser texturing a hydrophobic agent. The spacing laser-etched microchannels is adjusted to achieve different contact angles percentages of laser-textured areas. Boiling performance assessed variations channel coverage, revealing significant differences hydrophilic surfaces. critical...
Nucleate pool boiling experiments were performed on plain and five laser-textured stainless-steel foils using saturated pure water, 100% ethanol, 0.4% 4.2% mole fraction ethanol – water mixtures. All samples contained untreated, smooth 0.5 mm wide regions intermediate textured surfaces, that differ in the width of laser patterned (from to 2.5 mm). For we measured significant decreases average heat transfer coefficients (HTC) increases bubble activation temperatures comparison with surfaces...
Increasing heat dissipation requirements of small and miniature devices demands advanced cooling methods, such as application immersion via boiling transfer. In this study, functionalized copper surfaces for enhanced transfer are developed evaluated. Samples using a chemical oxidation treatment with subsequent hydrophobization selected fluorinated silane. Pool tests water, water/1-butanol mixture self-rewetting properties novel dielectric fluid low GWP (Novec™ 649) conducted to evaluate the...
The enhancement of boiling heat transfer has been extensively shown to be achievable through surface texturing or fluid property modification, yet few studies have investigated the possibility coupling both approaches. present work focuses on exploring concomitant pool by using TiO2-water nanofluid in combination with laser-textured copper surfaces. Two mass concentrations 0.001 wt.% and 0.1 are used, along two nanoparticle sizes 4–8 nm 490 nm. Nanofluids prepared sonification degassed...
The low boiling temperature of dielectric fluids makes them suitable for satisfying the cooling requirements advanced high-energy-density devices commonly found in microelectronics. However, high wettability/wickability such coolants significantly affects dynamics, opening new research questions on crucial role played by micro- and nanostructures surface. While different studies point out importance microscale grooves, pillars cavities to promote nucleation enhance heat transfer coefficient...
Green hydrogen, produced via electrolysis using renewable energy, is a zero-emission fuel essential for the global transition to sustainable energy systems. Optimizing hydrogen production requires detailed understanding of bubble dynamics at cathode, which involves three key stages: nucleation, growth, and detachment. In this study, growth was investigated in custom-built cell with microelectrodes, combining high-speed imaging electrochemical measurements potentiostat. The results reveal...
Surface engineering aimed at tuning the wettability and morphology of boiling surface is a facile approach to moderate enhance nucleate process. Key issues include control over active nucleation site density, bubble departure frequency liquid replenishment sites while simultaneously reducing temperature. In this study, we fabricated spear-type (ST) cavity-type (CT) TiO2 nanostructures on 25 μm titanium foils via hydrothermal etching in an alkaline solution. High-speed IR video cameras were...
We present the results of a study aimed at investigating effects electric fields on quasi-static bubble departure dynamics during pool boiling perfluorohexane (FC-72) in microgravity conditions. Analysis was performed through an alternative formulation momentum balance which contribution non-uniform stress distributions interface can be quantified high-speed video measurements without having to numerically solve laws electrostatics. Data used this were obtained scope Multiscale Boiling...
Bubble removal from a solid surface is of significant importance to many technical processes and applications. In addition the conventional buoyancy-aided bubble removal, there also passive strategy remove bubbles via coalescence. However, likewise several processes, coalescence-induced masked by dominant buoyancy, hence, difficult observe in terrestrial conditions. Microgravity condition offers unique opportunity investigate such phenomenon great detail that can significantly improve our...