Experimental Nucleation Studies

Katto Y, Yokoya S, Teraoka K (1966) Experimental study of nucleate boihng in case of making interference-plate approach to the heating surface. In Proceedings of 3rd International Heat Transfer Conference, 1966, vol 3, pp 219-227... 

The detail experimental study of flow boiling heat transfer in two-phase heat sinks was performed by Qu and Mudawar (2003b). It was shown that the saturated flow boiling heat transfer coefficient in a micro-channel heat sink is a strong function of mass velocity and depends only weakly on the heat flux. This result, as well as the results by Lee and Lee (2001b), indicates that the dominant mechanism for water micro-channel heat sinks is forced convective boiling but not nucleate boiling. 

Hsu YY, Graham RW (1961) An analytical and experimental study of the thermal boundary layer and ebullition cycle in nucleate boiling. NASA TN D-594 Hwan YW, Kim MS (2006) The pressure drop in micro-tubes and correlation development. Int J Heat Mass Transfer 49 1804-1812... 

The basic condition for experimental study of nucleation on an identical surface requires that this surface be a single crystal face without screw dislocations (page 306). Such a surface was obtained by Budevski et at. when silver was deposited in a narrow capillary. During subsequent deposition of silver layers the screw dislocations died out so that finally a surface of required properties was obtained. 

Hsu, Y. Y., and R. W. Graham, 1961, An Analytical and Experimental Study of the Thermal Boundary Layer Ebullition Cycle in Nucleate Boiling, NASA TND-594, Lewis Res. Ctr., Cleveland, OH. (1)... 

Katto, Y., and S. Yokoya, 1966, Experimental Study of Nucleate Pool Boiling in Case of Making Interference-Plate Approach to the Heating Surface, Paper 103, Proc. 3rd Int. Heat Transfer Conf., Chicago, IL, vol. 3, p. 219. (2)... 

The nature of the nucleation site as well as the kinetics of formation and dissociation of the H-induced and stabilized platelets have yet to be experimentally studied in detail. However, their generation in float-zone (Johnson and Herring, 1988b) as well as Czochralski-grown (Fig. 8) silicon argues against the involvement of oxygen or carbon in platelet nucleation. 

It is shown that while solute concentration data can be used to estimate the kinetic growth parameters, information about the CSD is necessary to evaluate the nucleation parameters. The fraction of light obscured by an illuminated sample of crystals provides a measure of the second moment of the CSD. Numerical and experimental studies demonstrate that all of the kinetic parameters can be identified by using the obscuration measurement along with the concentration measurement. It is also shown that characterization of the crystal shape is very important when evaluating CSD information from light scattering instruments. 

Interest in the crucial processes of nucleation and the growth of solids from fluid phases has a long and multidisciplinary history [50-53]. This research topic involves chemistry, chemical physics, material science, chemical engineering and physics, and, as a consequence, both theoretical and experimental studies were carried out by specialists in these fields. Thus, the following discussion does not pretend to be an exhaustive literature coverage of what is known about nucleation and growth, but rather, through recent articles, tries to review contributions especially relevant to controlled chemical vapour deposition of nanoparticles, always from a multidisciplinary point of view. 

Singh, J. J., and A. C. Smith, Experimental studies of the ion-induced binary nucleation, J Aerosol Sci.,... 

Rabeony, H., and P. Mirabel, Experimental study of vapor nucleation on ions, J. Phys. Chem., 91, 1815-... 

Experimentally, nucleation and subsequent growth of surface relief structures have been investigated as a function of surface fields [44 16], molecular architecture [37], film thickness [39, 47, 48], and annealing conditions [37 10, 49], A more detailed summary of the experimental studies can be found in recent reviews [15, 19, 50, 51] theoretical work on this issue is summarized in [41,42],... 

Contact nucleation in industrial processes results from collisions of crystals with the impeller used for circulation of the magma or with other crystallizer internals such as baffles, pipe and crystallizer walls, and even other crystals. Careful experimental studies have shown that the number of crystals produced by collisions between crystals and these objects depends upon the collision energy, supersaturation at impact, supersaturation at which crystals mature, material of the impacting object, area and angle of impact, and system temperature. The collision energy for contact nucleation is small and does not necessarily result in the macroscopic degradation or attrition of the contacted crystal. 

The decomposition follows rapid nucleation and contracting sphere kinetics with an activation energy of 150 kJ, somewhat higher than the enthalpy of decomposition.43"45 Densities are given in Table 2.43, thermal expansion coefficient in Table 2.44, and thermodynamic data in Tables 2.45 to 2.47. From data in Table 2.47, it is apparent that MgC03 is unstable above 700 K, in agreement with quoted experimental studies. 

Fig. 4. Results from the nucleation kinetic studies on nickel ammonium sulphate. A, Homogeneous nucleation B, heterogeneous nucleation , experimental data. (Reproduced from ref. 10 by courtesy of The Royal Society of Chemistry.)...

The problem of crystal growth from supercooled liquids has been formulated in terms of a similar model based on the interfacial tension of microcrystals in the solution. A number of experimental studies which have been made have given further support to the qualitative concepts of the model. The time lag in nucleation required for the distribution of nuclei to change from the equilibrium value at saturation to the stationary concentration at supersaturation has been discussed in some detail by Kantrowitz. ... 

With the exception of Equation (10), all these pathways involve a precursor iron monosulfide phase. Direct precipitation of pyrite from solution (Equation (10)) is strongly inhibited. This is due to the difficulty of direct nucleation of pyrite, leading to very large supers aturation with respect to pyrite in experimental and natural solutions (Schoonen and Barnes, 1991a). Experimental studies have thus focused on the role of one or more iron monosulfide precursors to pyrite, which have long been recognized as intermediates in sedimentary pyrite formation (see review by Morse et al., 1987). Poorly crystalline mackinawite is the initial product of reaction of H2S with aqueous or solid... 

Experimental studies of authigenic apatite precipitation. Mechanisms and rates of authigenic apatite formation in the early diagenetic environment are difficult to resolve, because of the wide variety of biological, chemical, and physical factors that can affect its formation. Experimental studies of apatite formation under controlled conditions have provided important information for placing constraints on modes and rates of CEA authigenesis. Examples of such studies include those of Ames (1959), who documented nucleation of CEA on calcium carbonate Gulbrandsen et al. (1984), who documented rates of CEA formation in seawater Jahnke (1984), who evaluated the... 

Mukheqee, A. and Dhir, V.K. (2004) Numerical and experimental study of bubble dynamics associated with lateral merger of vapor bubbles during nucleate pool boiling. In Press, Journal of Heat Tranter. 

However some experimental studies in similar geometries show a dependence of the heat transfer coefficient on vapour quality. The Feldman (1996), Oh etal. (1998) and Kandlikar and Grande (2003) correlations illustrate a clear evolution of the heat transfer coefficient with vapour quality. These works indicate that nucleate boiling may not be the only mechanism governing boiling in minichannels and that new mechanisms may happen too. 

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