Size Distribution of Active and Potential Nucleation Sites in Pool Boiling

2002 ◽  
Author(s):  
Andrea Luke ◽  
Elisabeth Danger ◽  
Dieter Gorenflo
Keyword(s):  
Size Distribution ◽  
Pool Boiling ◽  
Nucleation Sites

A micromechanistic model of microstructure development during the combustion synthesis process

1995 ◽  
Vol 10 (4) ◽  
pp. 962-980 ◽  
Author(s):  
Yangsheng Zhang ◽  
Gregory C. Stangle
Keyword(s):  
Grain Size ◽  
Size Distribution ◽  
Combustion Synthesis ◽  
Growth Parameters ◽  
Experimental Studies ◽  
Nucleation And Growth ◽  
Synthesis Process ◽  
Product Phase ◽  
Nucleation Sites ◽  
Rate Of Increase

The influence of the key nucleation and grain growth parameters on (i) the evolution of the microstructure of the product phase (on a microscopic level) and (ii) the combustion synthesis process (on a macroscopic level) were investigated for the combustion synthesis process in the Nb-C system. This work is an integral part of the continuing effort1–3 to develop a more complete theoretical model for combustion synthesis processes in general. In particular, the nucleation and growth of the NbC(s) product phase from the supersaturated liquid Nb/C mixture that appears briefly during the combustion synthesis process was treated in a greater detail by using a decidedly more sophisticated treatment of the nucleation and growth process (as developed in the field of rapid solidification and welding). It was shown that the microstructure of the NbC(s) product phase, including the evolution of the grain size and the size distribution, and the development of the grain's morphology, as well as the combustion wave velocity, are significantly influenced by the total number density of the nucleation sites, nmax, that are present in the system. The grain size distribution was shown to possess a monosize distribution, since during the combustion synthesis process the rate of increase of the degree of local undercooling was very high so that the nucleation process took place (locally) during a very brief period of time. This work provides a sound basis for developing a better control of the microstructure, and for a better understanding and interpretation of the results of related experimental studies.

scholarly journals Effect of Uniformly and Nonuniformly Coated Al2O3 Nanoparticles over Glass Tube Heater on Pool Boiling

2016 ◽  
Vol 2016 ◽  
pp. 1-6 ◽  
Author(s):  
Nitin Doifode ◽  
Sameer Gajghate ◽  
Abdul Najim ◽  
Anil Acharya ◽  
Ashok Pise
Keyword(s):  
Heat Transfer ◽  
Boiling Heat Transfer ◽  
High Speed ◽  
Pool Boiling ◽  
Glass Tube ◽  
Al2o3 Nanoparticles ◽  
High Speed Camera ◽  
Coated Nanoparticles ◽  
Nucleation Sites ◽  
Coated Surface

Effect of uniformly and nonuniformly coated Al2O3 nanoparticles over plain glass tube heater on pool boiling heat transfer was studied experimentally. A borosilicate glass tube coated with Al2O3 nanoparticle was used as test heater. The boiling behaviour was studied by using high speed camera. Result obtained for pool boiling shows enhancement in heat transfer for nanoparticle coated surface heater and compared with plain glass tube heater. Also heat transfer coefficient for nonuniformly coated nanoparticles was studied and compared with uniformly coated and plain glass tube. Coating effect of nanoparticles over glass tube increases its surface roughness and thereby creates more nucleation sites.

Sub-Atmospheric Pressure Pool Boiling of Water on a Screen Laminate-Enhanced, Wavy-Fin Array

2010 ◽  
Author(s):  
P. J. Laca ◽  
R. A. Wirtz
Keyword(s):  
Atmospheric Pressure ◽  
Pool Boiling ◽  
Bubble Nucleation ◽  
High Density ◽  
Wire Mesh ◽  
Effective Surface ◽  
Nucleation Sites ◽  
Semi Empirical ◽  
Very High ◽  
Reduced Pressures

Saturated pool boiling on vertically oriented, copper, wavy-fin surfaces in water at reduced pressures is investigated. A lamination of fine-filament, wire mesh is an effective surface enhancement for boiling since the surface can be configured to provide a very high density of potential bubble nucleation sites. Two surfaces are considered: a 0.75mm thick 4-layer laminate with approximately 4000 pores per cm2 and a 0.42mm thick 8-layer laminate with approximately 26,000 pores per cm2. The results show that the 8-layer laminate outperforms the 4-layer laminate. At reduced pressures a reduction in performance is seen for both surfaces. A semi-empirical boiling model is developed. The model predicts the boiling performance of our data within an error of 30%. The model shows that shorter fins improve boiling performance.

Experiment of Enhanced Pool Boiling Heat Transfer on Coupling Effects of Nano-Structure and Synergistic Micro-Channel

2019 ◽  
Author(s):  
Linsong Gao ◽  
Jizu Lv ◽  
Minli Bai ◽  
Chengzhi Hu ◽  
Liqun Du ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Boiling Heat Transfer ◽  
Capillary Flow ◽  
Pool Boiling ◽  
Micro Channel ◽  
Nano Structure ◽  
Pool Boiling Heat Transfer ◽  
Wall Superheat ◽  
Nucleation Sites ◽  
The Heat Transfer Coefficient

Abstract The manipulation of micro- or nano-structure is a promising method to improve pool boiling heat transfer performance. However, most studies just focus on the micro- or nano-structure without considering the combination micro- and nano-structure. In this paper, we fabricated synergistic microchannel, nano-structure, and micro-nano structure surface on the nickel by different technologies. Pool boiling of DI water under saturated condition was experimentally investigated. Result shows at the wall superheat of 18 K, the heat transfer coefficient of micro-nano structure, nano-structure and synergistic micro-channel surface are 16400, 13050, and 13400 W/m2 K higher 89%, 50%, and 54% than that of smooth surface, respectively. The improved heat transfer is attributed to active nucleation sites and capillary flow.

ROLE OF EASY-TO-ACTIVATE NUCLEATION SITES IN POOL BOILING

2018 ◽  
Author(s):  
Yi Liu ◽  
Ming-Chang Lu ◽  
Dongyan Xu
Keyword(s):  
Pool Boiling ◽  
Nucleation Sites

Design of Cassie-wetting nucleation sites in pool boiling

2019 ◽  
Vol 132 ◽  
pp. 25-33 ◽  
Author(s):  
Yi Liu ◽  
Jiaqi Tang ◽  
Linxuan Li ◽  
Yi Nok Shek ◽  
Dongyan Xu
Keyword(s):  
Pool Boiling ◽  
Nucleation Sites

scholarly journals Quantification of the Dislocation Density, Size, and Volume Fraction of Precipitates in Deep Cryogenically Treated Martensitic Steels

Metals ◽  
2020 ◽  
Vol 10 (11) ◽  
pp. 1561
Author(s):  
Ajesh Antony ◽  
Natalya M. Schmerl ◽  
Anna Sokolova ◽  
Reza Mahjoub ◽  
Daniel Fabijanic ◽  
...  
Keyword(s):  
Dislocation Density ◽  
Size Distribution ◽  
Volume Fraction ◽  
Cryogenic Treatment ◽  
Atom Probe ◽  
Magnetic Scattering ◽  
Martensitic Steels ◽  
Deep Cryogenic Treatment ◽  
Nucleation Sites ◽  
Aisi D2

Two groups of martensitic alloys were examined for changes induced by deep cryogenic treatment (DCT). The first group was a range of binary and ternary compositions with 0.6 wt % carbon, and the second group was a commercial AISI D2 tool steel. X-ray diffraction showed that DCT made two changes to the microstructure: retained austenite was transformed to martensite, and the dislocation density of the martensite was increased. This increase in dislocation density was consistent for all alloys, including those that did not undergo phase transformation during DCT. It is suggested that the increase in dislocation density may be caused by local differences in thermal expansion within the heterogeneous martensitic structure. Then, samples were tempered, and the cementite size distribution was examined using small angle neutron scattering (SANS) and atom probe tomography. First principles calculations confirmed that all magnetic scattering originated in cementite and not carbon clusters. Quantitative SANS analysis showed a measurable change in cementite size distribution for all alloys as a result of prior DCT. It is proposed that the increase in dislocation density that results from DCT modifies the cementite precipitation through enhanced diffusion rates and increased cementite nucleation sites.

Remediation of Historic Buildings and Patrimony by Bacterially Induced Mineralization

2010 ◽  
Vol 133-134 ◽  
pp. 1253-1258 ◽  
Author(s):  
Pei Hao Li ◽  
Wen Jun Qu
Keyword(s):  
Pore Size Distribution ◽  
Pore Size ◽  
Size Distribution ◽  
Historic Buildings ◽  
X Ray Diffraction ◽  
Bond Behavior ◽  
Mineral Crystal ◽  
Nucleation Sites ◽  
The Matrix ◽  
Calcium Source

Laboratory experiments were conducted to protect and consolidate historic architectural heritages by bacterially induced carbonate mineralization on the surface of samples of marble and concrete. Some properties of samples and mineral, such as the composition and growth of the mineral deposited on samples, porosity or pore size distribution of samples, the efficiency of protection, the bond behavior between the deposited mineral and substratum, were analyzed by X-ray diffraction, scanning electron microscopy, mercury intrusion porosimetry and ultrasonic test. The results show that the phases of mineral crystal are calcite and vaterite, and the calcium source has an effect on the phase of calcium carbonate mineralization and precipitation. Bacteria act as nucleation sites in the course of precipitation of the mineral crystallization, and the crystal is deposited uniformly on the surface and subsurface of the matrix. The precipitation has no significant effect on the pore size distribution of the matrix, but results in a decrease of porosity, and mineral crystals are strongly attached to the substratum. Bacterial mineralization for remediation of historic buildings can be an ecological and novel alternative to traditional techniques.

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