Adaptive fuzzy model identification to predict the heat transfer coefficient in pool boiling of distilled water

2009 ◽  
Vol 36 (2) ◽  
pp. 1142-1154 ◽  
Author(s):  
Mihir K. Das ◽  
Nand Kishor
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Transfer Coefficient ◽  
Pool Boiling ◽  
Model Identification ◽  
Fuzzy Model ◽  
Distilled Water ◽  
Adaptive Fuzzy ◽  
The Heat Transfer Coefficient

Efficacy of Microscopic Interconnected Channels and Surfactants on Enhancing Pool Boiling Heat Transfer

2007 ◽  
Author(s):  
Rene Reyes Mazzoco
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Transfer Coefficient ◽  
Boiling Heat Transfer ◽  
Bubble Diameter ◽  
Pool Boiling ◽  
Liquid Mixtures ◽  
Vapor Flow ◽  
Pool Boiling Heat Transfer ◽  
The Heat Transfer Coefficient

Nucleate pool boiling heat transfer increases with certain liquid mixtures and some coatings over the heater’s surface. The effects of these modifications are best measured by the relative values of the convective heat transfer coefficient that quantify the ability for transferring heat. The mechanisms that increase pool boiling heat transfer are reflected in the formation of smaller bubbles that escape away from the heater’s surface at a higher velocity, than those formed under not enhanced conditions. The bubble diameter depends on a chemical effect from the liquid composition acting at the bubble’s interface, and on the physical effect of the porous coverings to break the bubbles and to allow the resulting vapor flow. The reduction in bubble diameter in liquid mixtures comes from the action of intermolecular forces at the liquid-vapor interface similar to those associated to surfactants. Several studies have concentrated on increasing the heat transfer coefficient in pool using surfactants in concentrations close to the critical micelle concentration (cmc) of the surfactant in the liquid. The surfactants achieve the highest reduction of bubble diameter by accommodating the lowest surface of their molecules at the interface. However, the mixture of 16% ethanol in water also showed an increase in the convective heat transfer coefficient by producing the lowest size of bubbles from any other ethanol-water mixture. Surface tension and sessile drop contact angle for this mixture have a behavior similar to the cmc; therefore, the mixture effect on boiling is explained through the presence of ethanol-hydrated-states accommodated at the interface. Other liquid mixtures, containing propylene glycol, ethylene glycol, ethanol and water, with cmc behavior had been found through surface tension and sessile contact angle measurements, and showed that they increased the heat transfer coefficient. The mechanical effect that increases the heat transfer coefficient with porous coverings has been explained as the breaking of emerging bubbles at the heater’s surface and the proper handling of the resulting vapor flow away from the covering. Experiments with a mesh located at a distance half the bubble diameter, at a specific power supplied, released the bubbles from the heater before finishing its formation increasing their departure frequency. An array of layers of the same mesh produced and additional increment in the heat transfer coefficient if the array is accommodated to favor the gas flow out of the heater’s region.

scholarly journals Experimental determination of the heat transfer coefficient during evaporation and boiling of thin liquid film

2018 ◽  
Vol 194 ◽  
pp. 01022
Author(s):  
Anastasia Islamova
Keyword(s):  
Heat Transfer ◽  
Thin Films ◽  
Heat Transfer Coefficient ◽  
Transfer Coefficient ◽  
Thin Liquid Film ◽  
Distilled Water ◽  
Transfer Coefficients ◽  
Heat Transfer Coefficients ◽  
The Heat Transfer Coefficient

Thin films evaporation of distilled water, ethanol and HFE-7100 liquid was experimentally studied. The dependences of heat transfer coefficients in time were determined. It has been established that with a decrease in the layer thickness of distilled water and ethanol, the heat transfer coefficient increases. For the HFE liquid, the nature of the change is different: as the time increases, the heat transfer coefficient decreases.

Characterization and Pool Boiling Heat Transfer Studies of Nanofluids

2009 ◽  
Vol 131 (8) ◽  
Author(s):  
R. Kathiravan ◽  
Ravi Kumar ◽  
Akhilesh Gupta ◽  
Ramesh Chandra
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Transfer Coefficient ◽  
Copper Nanoparticles ◽  
Boiling Heat Transfer ◽  
Base Fluid ◽  
Pool Boiling ◽  
Outer Diameter ◽  
Distilled Water ◽  
Pool Boiling Heat Transfer

Copper nanoparticles with an average size of 10 nm are prepared by the sputtering method and are characterized using different techniques, viz., X-ray diffraction spectrum, atomic force microscopy, and transmission electron microscopy. The pool boiling heat transfer characteristics of 0.25%, 0.5%, and 1.0% by weight concentrations of copper nanoparticles dispersed in distilled water and in distilled water with 9.0 wt % of sodium dodecyl sulfate (SDS) are studied. Also the data for the boiling of pure distilled water and water with SDS are acquired. The above data are obtained using commercial seamless stainless steel tube heater with an outer diameter of 9.0 mm and an average surface roughness of 1.09 μm. The experimental results concluded that (i) critical heat flux (CHF) obtained in water with surfactant nanofluids gives nearly one-third of the CHF obtained by copper-water nanofluids, (ii) pool boiling heat transfer coefficient decreases with the increase in the concentration of nanoparticles in water base fluids, and (iii) heat transfer coefficient increases with the addition of 9.0% surfactant in water. Further addition of nanoparticles in this mixture reduces the heat transfer coefficient. (iv) CHF increases nearly 50% with an increase in concentration of nanoparticles in the water as base fluid and nearly 60% in the water with surfactant as base fluid.

scholarly journals Pool Boiling of Water on Surfaces with Open Microchannels

Energies ◽  
2021 ◽  
Vol 14 (11) ◽  
pp. 3062
Author(s):  
Robert Kaniowski ◽  
Robert Pastuszko
Keyword(s):  
Heat Transfer ◽  
Heat Flux ◽  
Heat Transfer Coefficient ◽  
Transfer Coefficient ◽  
Computational Models ◽  
Pool Boiling ◽  
Experimental Investigations ◽  
Maximum Heat ◽  
Area Of Interest ◽  
The Heat Transfer Coefficient

Boiling, as the most efficient type of convective heat transfer, is an area of interest in many fields of industry and science. Many works have focused on improving the heat transfer efficiency of boiling by altering the physical and chemical properties of surfaces by using different technological processes in their fabrication. This paper presents experimental investigations into pool boiling on enhanced surfaces with open microchannels. The material of the fabricated surface was copper. Parallel microchannels made by machining were about 0.2, 0.3, and 0.4 mm wide, 0.2 to 0.5 mm deep, and spaced with a pitch equal to twice the width of the microchannel. The experiments were carried out in water at atmospheric pressure. The experimental results obtained showed an increase in the heat flux and the heat transfer coefficient for surfaces with microchannels. The maximum (critical) heat flux was 2188 kW/m2, and the heat transfer coefficient was 392 kW/m2K. An improvement in the maximum heat flux of more than 245% and 2.5–4.9 times higher heat transfer coefficient was obtained for the heat flux range of 992–2188 kW/m2 compared to the smooth surface. Bubble formation and growth cycle in the microchannel were presented. Two static computational models were proposed to determine the bubble departure diameter.

scholarly journals AN EXPERIMENTAL STUDY OF THE EFFECT OF SURFACTANT AND TI02 NANOPARTICLES ADDITIVES IN R141B ON THE NUCLEATE POOL BOILING PROCESS

2017 ◽  
Vol 39 (5) ◽  
pp. 37-40
Author(s):  
O. Khliyeva ◽  
T. Gordeychuk ◽  
A. Nikulin ◽  
N. Lukianov ◽  
V. Zhelezny
Keyword(s):  
Heat Transfer ◽  
Experimental Study ◽  
Heat Flux ◽  
Heat Transfer Coefficient ◽  
Transfer Coefficient ◽  
Tio2 Nanoparticles ◽  
Pool Boiling ◽  
Nucleate Pool Boiling ◽  
Boiling Process ◽  
The Heat Transfer Coefficient

The results of experimental study of effect of TiO2 nanoparticles (0.1 % mass.) and surfactant Span80 (0.1 % mass.) additives in refrigerant R141b on the heat transfer coefficient of nucleate pool boiling process at three values of pressure 0.2, 0.3 and 0.4 MPa and range of heat flux from 5 to 70 kWm-2 are presented in paper.  

Enhanced Nucleate Pool Boiling From Microstructured Surfaces Fabricated by Selective Laser Melting

2016 ◽  
Author(s):  
Jin Yao Ho ◽  
Kin Keong Wong ◽  
Kai Choong Leong ◽  
Chun Yang
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Transfer Coefficient ◽  
Boiling Heat Transfer ◽  
Pool Boiling ◽  
Heat Fluxes ◽  
Microstructured Surfaces ◽  
Plain Surface ◽  
Micro Cavity ◽  
The Heat Transfer Coefficient

Selective laser melting (SLM) is a promising manufacturing method which enables the production of complex structured components from base metal powders. With the development of SLM, the possibility of fabricating functional heat transfer devices such as heat pipes and heat sinks using this technique has also gained significant interest in the recent years. In this paper, the possibilities of producing microstructured surfaces using SLM to promote nucleate pool boiling heat transfer were explored. The SLM facility (SLM 250 HL by SLM Solutions GmbH) at the Future of Manufacturing Laboratory 1 of Singapore Centre for 3D Printing (SC3DP) in Nanyang Technological University (NTU), Singapore was employed for the fabrication of the surfaces. The machine is comprised of a Gaussian distributed Yb:YAG laser with maximum power of 400 W and laser beam spot size of 80 μm which melts and fuses the AlSi10Mg base powder of distribution size 20 μm to 63 μm layer-by-layer to develop three-dimensional structures. In total, four 1 cm × 1 cm microstructured surfaces were produced; namely micro-cavity surface, micro-fin surface, micro-sized rectangular channel (MRC) surface and micro-sized square channel (MSC) surface. Saturated pool boiling experiments were conducted on these surfaces in a water-cooled thermosyphon with FC-72 as the coolant fluid under atmospheric condition. In comparison with a plain surface, the MRC and MSC surfaces exhibited marginal improvements in the average heat transfer coefficient whilst more significant enhancements of up to 51.2% were demonstrated with the micro-cavity and micro-fin surfaces. At low heat fluxes (< 7 W/cm2), minimal differences in heat transfer performances between the microstructured surfaces and plain surface were observed. For increased heat fluxes, incremental enhancements in the heat transfer coefficients were observed for the micro-cavity and micro-fin surfaces as compared to the plain surface. The highest enhancement in the heat transfer coefficient over the plain surface was determined to be 63.5% for the micro-fin surface at the heat flux of 17.9 W/cm2 and it was also observed that the heat transfer coefficient of micro-fin surface is consistently higher that of other microstructured surfaces for the range of heat fluxes tested. In addition, higher critical heat fluxes were also achieved with all microstructured surfaces as compared to the plain surface with the highest CHF of 46.2 W/cm2 for the micro-fin and MRC surface. Visual observations suggest that the enhancement in heat transfer from the microstructured surfaces is likely to be due to the increased bubble nucleation sites created from the extended surfaces and the artificial cavities. In summary, these results indicate the promising use of SLM to produce surface features that will enhance pool boiling heat transfer.

Evolution of Heat Transfer in Pool Boiling in Contaminated Water

2020 ◽  
Author(s):  
Jacob Graham ◽  
Angelo Hawa ◽  
Patricia Weisensee
Keyword(s):  
Heat Transfer ◽  
Heat Flux ◽  
Heat Transfer Coefficient ◽  
Transfer Coefficient ◽  
Boiling Heat Transfer ◽  
Calcium Sulfate ◽  
Pool Boiling ◽  
Surface Orientation ◽  
Aluminum Surface ◽  
The Heat Transfer Coefficient

Abstract Boiling heat transfer serves as an efficient mechanism to dissipate large amounts of thermal energy due to the latent heat of phase change. In academic studies, typically ultra-pure deionized (DI) water is used to avoid contamination. However, in industrial and commercial settings, the working fluid might be contaminated with sediments, dust, salts, or organic matter. Long-term boiling processes in non-DI water cause substantial build-up of a stable layer of deposit that dramatically reduces the heat transfer coefficient. Therefore, heating applications in a contaminated medium demand strategies to prevent such fouling. Here, we studied the use of lubricant infused surfaces (LIS) and their ability to possibly minimize the deposition of calcium sulfate. Aluminum samples were infused with Krytox 102 oil and the heat transfer coefficient was investigated at a vertical and horizontal surface orientation. Fouling effects were introduced by pool boiling for 7.5 hours in a 6.97 mM calcium sulfate solution at constant heat flux. Heat flux curves for both plain aluminum and LIS were calibrated before contamination. Initially, the LIS was unable to support a nucleate phase and transitioned directly from liquid convection to film boiling heat transfer. Upon partial degradation of the lubricant layer during long-run experiments, nucleate boiling ensued. Over 7.5 hours, the heat transfer coefficient of each sample (Al and LIS) degraded between 5.4% and 7.9% with no significant correlation with either lubricant treatment or surface orientation. Post boiling profilometry was conducted on each sample to characterize the thickness and distribution of the calcium sulfate layer. In these experiments, the plain aluminum surface outperformed the LIS at both orientations in minimizing calcium layer thickness. The LIS oriented vertically outperformed the LIS oriented horizontally.

Pool Boiling Performance of Notched Tubes in Lithium Bromide Solution

2015 ◽  
Vol 23 (02) ◽  
pp. 1550013 ◽  
Author(s):  
Yong-Sub Sim ◽  
Nae-Hyun Kim
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Transfer Coefficient ◽  
Boiling Heat Transfer ◽  
Pool Boiling ◽  
Saturation Pressure ◽  
Lithium Bromide ◽  
Smooth Tube ◽  
Floral Tube ◽  
The Heat Transfer Coefficient

In the present study, pool boiling heat transfer coefficients in Lithium Bromide ( LiBr ) solution were obtained for smooth, floral, notched fin and notched floral tubes. Test range covered saturation pressure from 7.38 to 101.3 kPa, LiBr concentration from 0% to 50%. Floral tube yielded the highest heat transfer coefficient, and smooth tube yielded the lowest heat transfer coefficient. Effect of notching on heat transfer coefficient was dependent on tube shape. When applied to the smooth tube (notched fin tube), notching increased the heat transfer coefficient. When applied to the floral tube (notched floral tube), on the other hand, notching decreased the heat transfer coefficient. The reason has been attributed to the balance of advantage of added nucleation sites and disadvantage of added flow resistance. Boiling heat transfer correlations were developed which are applicable for saturation pressure from 7.38 to 101.3 kPa and LiBr concentration from 0% to 50%.

Effects of Surface Roughness on the Pool Boiling of Water

2007 ◽  
Author(s):  
Benjamin J. Jones ◽  
Suresh V. Garimella
Keyword(s):  
Heat Transfer ◽  
Surface Roughness ◽  
Heat Transfer Coefficient ◽  
Transfer Coefficient ◽  
Electrical Discharge Machining ◽  
Pool Boiling ◽  
Saturation Temperature ◽  
Polished Surface ◽  
Aluminum Surfaces ◽  
The Heat Transfer Coefficient

The effect of surface roughness on the pool boiling of water is studied. Five aluminum surfaces of varying roughness were prepared: one polished (0.062 μm RMS) and four roughened by electrical discharge machining (EDM) with surface roughness of 1.37, 2.81, 7.37, and 12.53 μm RMS. All experiments were performed in water at atmospheric pressure and saturation temperature. The roughest EDM surface showed up to a 100% improvement in the heat transfer coefficient compared to the polished surface. The other EDM surfaces (1.37, 2.81, and 7.37 μm) showed up to a 60% enhancement in the heat transfer coefficient compared to the polished surface. Constants are proposed for prediction of pool boiling in water from the polished and rough aluminum surfaces studied using the Rohsenow pool boiling correlation.

At Nucleate Boiling Heat Transfer Zeotropic Mixtures A Horizontal Tubes

2016 ◽  
Vol 11 (3) ◽  
pp. 46-52
Author(s):  
Nadezhda Mezentseva ◽  
Ivan Mezentsev ◽  
Valentin Mukhin
Keyword(s):  
Heat Transfer ◽  
Experimental Data ◽  
Heat Transfer Coefficient ◽  
Transfer Coefficient ◽  
Diffusion Processes ◽  
Pool Boiling ◽  
Nucleate Boiling ◽  
Horizontal Tubes ◽  
Nucleate Boiling Heat Transfer ◽  
The Heat Transfer Coefficient

Despite numerous empirical relationships, currently there is no sufficiently reliable and physically reasonable methodology for calculating the heat transfer coefficient at boiling the zeotropic binary blends. The main reason is the complexity of the boiling process mechanism. Zeotropic blends have the non-isothermal phase transition or the temperature glide. To perform the analysis, the results of experimental work on boiling the zeotropic blends inside the horizontal smooth tubes were processed. The studies were carried out with the horizontal smooth steel and copper tubes; the mass velocities were varied within 50–583 kg/m2 s; the specific heat flux was varied from 1 to 45 kW/m2 . The experimental data, corresponding to the region of nucleate boiling, were compared with the calculated dependencies. The dependences corresponding to pool boiling were also analyzed. It was proposed to determine the heat transfer coefficient by Gogonin’s dependence (2006); this coincides well with the experimental data. This dependence takes into account the effect of wall thermal properties and its roughness on heat transfer. Moreover, it was found out that, in contrast to pool boiling, for the forced vapor-liquid flow in pipes at nucleate boiling, the diffusion processes are not important.

Sign in / Sign up

Export Citation Format

Share Document