Showing papers on "Boiling published in 2018"
TL;DR: In this paper, a two-part study is focused on critical heat flux (CHF) for pool boiling from flat surfaces, and the first part will review different CHF models and associated mechanisms and parametric trends.
228 citations
TL;DR: In this paper, the authors provide a comprehensive review of published literature concerning enhancement methodologies of surfactant and polymer additives, and nanofluids for nucleate pool boiling by modifying fluid properties has drawn considerable attention in recent years.
174 citations
171 citations
TL;DR: Wang et al. as mentioned in this paper studied the pool boiling characteristics of the micro nano bi-porous copper surface with optimal cavity size and presented an efficient way to further enhance its boiling heat transfer performance by wettability modification of enlarging the particle size to lower the surface energy.
159 citations
TL;DR: Results show that boiling from a superhydrophobic surface in an initial Wenzel state, in which the surface texture is infiltrated with liquid, results in remarkably low surface superheat with nucleate boiling sustained up to a critical heat flux typical of hydrophilic wetting surfaces, and thus upends this conventional wisdom.
Abstract: A variety of industrial applications such as power generation, water distillation, and high-density cooling rely on heat transfer processes involving boiling. Enhancements to the boiling process can improve the energy efficiency and performance across multiple industries. Highly wetting textured surfaces have shown promise in boiling applications since capillary wicking increases the maximum heat flux that can be dissipated. Conversely, highly nonwetting textured (superhydrophobic) surfaces have been largely dismissed for these applications as they have been shown to promote formation of an insulating vapor film that greatly diminishes heat transfer efficiency. The current Letter shows that boiling from a superhydrophobic surface in an initial Wenzel state, in which the surface texture is infiltrated with liquid, results in remarkably low surface superheat with nucleate boiling sustained up to a critical heat flux typical of hydrophilic wetting surfaces, and thus upends this conventional wisdom. Two distinct boiling behaviors are demonstrated on both micro- and nanostructured superhydrophobic surfaces based on the initial wetting state. For an initial surface condition in which vapor occupies the interstices of the surface texture (Cassie-Baxter state), premature film boiling occurs, as has been commonly observed in the literature. However, if the surface texture is infiltrated with liquid (Wenzel state) prior to boiling, drastically improved thermal performance is observed; in this wetting state, the three-phase contact line is pinned during vapor bubble growth, which prevents the development of a vapor film over the surface and maintains efficient nucleate boiling behavior.
140 citations
TL;DR: In this paper, an experimental investigation has been carried out to investigate pool boiling heat transfer characteristics of segmented finned (SF) microchannels structured surface and compare its performance with that of uniform cross-section (UCS) structural surface and plane surface.
123 citations
TL;DR: In this paper, an anodized magnesium alloy AZ31 with and without boiling water sealing was pre-prepared, and then MgAl-layered double hydroxide (LDH) films were fabricated on it through hydrothermal chemical conversion of the preprepared anodic layer.
Abstract: In this work, anodized magnesium alloy AZ31 with and without boiling water sealing was pre-prepared, and then MgAl-layered double hydroxide (LDH) films were fabricated on it through hydrothermal chemical conversion of the pre-prepared anodic layer. The morphology, structure, and composition of the films were characterized by XRD, SEM, EDS, FT-IR, XPS and GDOES. It was found that the porosity of the films was reduced after in situ fabrication of the LDHs. The effects of boiling water sealing treatment on the anodized substrate were also discussed. Moreover, the polarization curve, EIS, and immersion tests showed that LDHs fabricated on the anodized substrate with boiling water sealing treatment exhibited a significant long period of protection for the substrate.
120 citations
TL;DR: In this article, the effect of surface roughness on the pool boiling of water on hydrophobic surfaces was investigated over the entire boiling regime, from the onset of nucleate boiling to film boiling.
120 citations
TL;DR: In this article, a data-driven approach based on deep feed-forward neural networks was proposed to predict the boiling heat transfer in a pool of pool boiling under varying input heat fluxes.
114 citations
TL;DR: In this paper, the authors present an experimental methodology that enables accurate measurement of fundamental subcooled flow boiling quantities, such as nucleation site density, bubble growth and wait time, and bubble departure diameter, up to the Critical Heat Flux (CHF) limit.
109 citations
TL;DR: In this paper, a combined CFD/visualization investigation was carried out in order to promote the understanding of geyser boiling in two-phase closed thermosyphon.
TL;DR: In this paper, the second part of a two-part study on pool boiling critical heat flux (CHF) from flat surfaces is dedicated to the assessment of both models and correlations.
TL;DR: In this paper, a novel refrigerant-based battery thermal management system for electric vehicles is proposed, modeled, simulated and analyzed with a one-dimensional electrochemical model integrated with a three dimensional heat and mass transfer model.
TL;DR: In this paper, the physical mechanisms associated with the evolution of a micro-layer beneath a bubble and the transition between contact line and micro layer regimes are investigated with fully resolved numerical simulations, in the framework of nucleate pool boiling.
TL;DR: This work provides a new nanostructuring approach to achieve ultrahigh heat flux in phase change heat transfer and will benefit both theoretical understanding and application in thermal management of high power devices of boiling heat transfer.
Abstract: Phase change heat transfer is fundamentally important for thermal energy conversion and management, such as in electronics with power density over 1 kW/cm2. The critical heat flux (CHF) of phase change heat transfer, either evaporation or boiling, is limited by vapor flux from the liquid–vapor interface, known as the upper limit of heat flux. This limit could in theory be greater than 1 kW/cm2 on a planar surface, but its experimental realization has remained elusive. Here, we utilized nanoporous membranes to realize a new “thin film boiling” regime that resulted in an unprecedentedly high CHF of over 1.2 kW/cm2 on a planar surface, which is within a factor of 4 of the theoretical limit, and can be increased to a higher value if mechanical strength of the membranes can be improved (demonstrated with 1.85 kW/cm2 CHF in this work). The liquid supply is achieved through a simple nanoporous membrane that supports the liquid film where its thickness automatically decreases as heat flux increases. The thin film...
TL;DR: In this paper, a comprehensive computational fluid dynamics (CFD) modeling was built to reproduce the pool boiling in the evaporator section and the liquid film condensation in a closed thermosyphon.
TL;DR: An extensive investigation of the heat ingress magnitude, internal flow dynamics, and convective heat transfer gives useful insights on the boiling phenomena and a reliable quantification of the BOG.
TL;DR: In this paper, the fluid flow and heat transfer features associated with slug flow boiling in a square microchannel were investigated using finite-volume solver OpenFOAM 2.3.1 and the built-in VOF method is adopted to capture the interface dynamics, while phase change has been introduced through external subroutines.
TL;DR: In this article, the effect of channel shape and geometrical parameter on the boiling heat transfer was studied and a semi-analytical model was developed to estimate the bubble departure diameter of the microchannel with mean absolute error of 5.58%.
TL;DR: In this paper, a review analyzes the present status of nano-modification for enhancing the pool boiling and critically compares the experimental results with the theoretical predictions, and better correlation between the modified surface properties to the heat flux is inevitable for further improvement.
Abstract: In order to meet the future energy demands many interesting techniques have been reported in literature for improving boiling heat transfer using nanoparticles and nano-structured surfaces. The mode of heat transfer and efficiency of water cooled reactors, direct steam generators can be substantially modified by this new technology. Boiling heat transfer is an area of increasing interest in many engineered heat transfer and cooling applications. Nucleate boiling is the efficient heat transfer region in pool boiling. The critical heat flux changes boiling mechanism from efficient mode to inefficient mode by forming a vapor film over the heater surface that leads to boiling crisis. The actual mechanism that creates this boiling crisis still remains a grey area. The CHF parameter cannot be avoided in boiling heat transfer applications; instead it can be postponed by adopting fluid and surface modification techniques. This review analyzes the present status of nano-modification for enhancing the pool boiling and critically compares the experimental results with the theoretical predictions. The existing theoretical models are not satisfactorily explaining the experimental investigations. New investigation techniques and better correlation between the modified surface properties to the heat flux is inevitable for further improvement.
TL;DR: In this paper, the phase change behaviors of nano-liquid argon films on solid surfaces display distinct features from macro-scale pool boiling, and the onset temperature for explosive boiling significantly reduces with the increase of the film thickness.
TL;DR: A comprehensive overview of CHF enhancement experiments, focusing on four broad categories of approaches, provides optimal design options for heat-transfer systems and reviews the effect of various modified channel structures on the boiling process.
TL;DR: In this article, a series of pool boiling simulations has been performed using an interface tracking method in the framework of Computational Fluid Dynamics (CFD), and the boiling regime simulated in this work covers from the nucleate boiling to the film boiling through Critical Heat Flux (CHF).
TL;DR: In this paper, the micro-pin-finned area and the smooth area are fractally distributed on the heating surface by micromaching (dry etching) method, and the results indicate that the bistructured surfaces can efficiently enhance the heat transfer performance in the nucleate boiling region and the critical heat flux (CHF) is also significantly improved.
TL;DR: In this paper, in-situ visualization experiments of interfacial polymerization (IP) were performed using a microfluidic platform, under several representative conditions, and the temperature at the interface was monitored and illustrated a two-stage time-evolution, increasing rapidly at early times and then tapering.
TL;DR: In this article, the authors have shown that the use of capillary-porous coatings leads to significant enhancement of heat transfer up to 4 times at boiling of liquid nitrogen and up to 3.5 times in the region of low heat fluxes.
TL;DR: In this article, the hydrodynamic formation of a microlayer at the base of a vapor bubble growing on a heated wall was experimentally and theoretically studied using integrated laser interferometry, infrared thermometry and shadowgraph techniques.
TL;DR: In this article, the effects of alternating current on the heat transfer characteristics of various boiling regimes, including the onset of nucleate boiling (ONB), fully developed nucleate boil, and film boiling at critical heat flux (CHF) conditions, are investigated.
TL;DR: Two types of classifiers are shown to be able to classify pool boiling frames with over 93% accuracy sufficiently fast, possibly enabling real-time execution and classification, even during indirect visualization and, hence, providing a non-intrusive and low-cost pool boiling regime identification.