Experimental Studies of Heterogeneous Nucleation in the Turbulent Mixing Condensation Nuclei Counter

Abstract

A method for varying the supersaturation in a turbulent mixing CNC has been used to examine heterogeneous nucleation of different compounds (working fluid) on various nuclei's compositions. Supersaturation was controlled by changing the vapor pressure of working fluid in nozzle flow, which was accomplished by saturating only a predetermined fraction of the flow while the keeping the total flow and temperature constant. This approach allows the partial pressure of the working fluid to be varied while maintaining a constant flow structure and temperature field. Experimental results characterizing the initial stages of heterogeneous nucleation are presented for NaCl, KCl, AgCl, and Ag particles. Heterogeneous nucleation was examined at various pressures of dibutylphthalate, octadecane, octadecanol, and octadecanoic acid. For octadecanoic acid as the working fluid, the size distribution of the grown particles is unimodal with the size increasing with increasing pressure of the working fluid. For the other working fluids, the initial size distribution splits into a bimodal distribution with one mode approximately the same as the initial distribution and a larger sized mode that grows with increasing pressure of the condensing vapor. For NaCl and octadecane and octadecanol, the initial unimodal size distribution splits into a trimodal size distribution.

Direct observation of metal nanoparticles as heterogeneous nuclei for the condensation of supersaturated organic vapors: Nucleation of size-selected aluminum nanoparticles in acetonitrile and n-hexane vapors

“…These results are in excellent agreement with our previous work on the condensation of supersaturated trifluoroethanol vapor on Mg nanoparticles. 12 They are also consistent with the results of Mavliev et al, 27 Chen et al, 28 and Rosenorn et al, 29 where the supersaturations required for activating the nucleating particles were found to decrease with increasing the particles' diameters. Similarly, the work of Seto et al 30 on the condensation of dibutyl phthalate vapor induced by seed ions generated by electrospray ionization, showed a significant reduction in supersaturation with increasing the size of the seed ions.…”

Solvothermal in situ synthesis of Fe3O4-multi-walled carbon nanotubes with enhanced heterogeneous Fenton-like activity

“…The average crystal size of the Fe 3 O 4 calculated based on XRD pattern slightly increased with the increase of the volume ratio water/ethylene glycol from 3:10 to 6:10 (Table 1). This may be attributed to the increase of the autogeneous pressure while water content increases, while high pressure system plays part in forming larger size formation [45]. Small nanoparticles are of important for future applications for their size-dependent properties.…”

Vapor phase nucleation on neutral and charged nanoparticles: Condensation of supersaturated trifluoroethanol on Mg nanoparticles

“…Although the importance of these parameters has been well-recognized, quantitative information on the heterogeneous nucleation of supersaturated vapors on charged nanoparticles under well defined supersaturation and temperatures are rarely available. [14][15][16][17][18] Most of the recent studies have focused on the application of the condensation nuclei counter ͑CNC͒ and the flow cloud chamber ͑FCC͒ to investigate the condensation of supersaturated vapors on neutral and charged particles. [15][16][17][18] Despite the practical advantages of the CNC and FCC devices, accurate determination of the degree of the vapor supersaturation at well-defined temperatures is not possible.…”

“…[14][15][16][17][18] Most of the recent studies have focused on the application of the condensation nuclei counter ͑CNC͒ and the flow cloud chamber ͑FCC͒ to investigate the condensation of supersaturated vapors on neutral and charged particles. [15][16][17][18] Despite the practical advantages of the CNC and FCC devices, accurate determination of the degree of the vapor supersaturation at well-defined temperatures is not possible. On the other hand, the thermal diffusion cloud chamber ͑DCC͒ allows accurate measurements of both temperature and supersaturation over a wide range of carrier gas pressures.…”