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The Freezing of Highly Sub-cooled H2O/D2O Droplets

by Xiao, Ruiyang

Abstract (Summary)
The condensation of H2O and D2O in a supersonic Laval nozzle was investigated at different stagnation condition by using Pressure Trace Measurements (PTM) and Fourier Transformation Infrared (FTIR) spectroscopy. PTM determined several key properties highly related to nucleation such as the temperature and pressure corresponding to the onset of condensation, Ton, pon as well as the temperature and pressure corresponding to the maximum nucleation rate TJmax and Jmax. Moreover, the results from PTM provide important information for the FTIR study. The FTIR spectra of D2O and H2O nanodroplets in N2 carrier gas were measured in our nozzle. The observed spectra of D2O droplets had some clear peaks, and the shapes of the spectra changed as a function of flow rates and position in the nozzle. The broad peak of D2O between 2400 cm-1 and 2600 cm-1 was due to ?1, ?3, and overtone of ?2 in the liquid phase, and its peak area was correlated to the product of the weight fraction of condensate (g) and the density of the flowing mixture (?), values derived from PTM. There is good correlation between the peak area and g*? (p<0.001). From our FTIR H2O nanodroplets study, the same trends regarding spectral changes and flow rate were observed. Moreover, the first observation of cubic ice in our supersonic nozzle was made by FTIR spectroscopy at a location x =6 cm from the throat. The peak in the spectra was located at a frequency of 3250 cm-1. This result is consistent with previous FTIR and electron diffraction scattering studies of H2O nanodroplets done by Buch (Buch V., Bauerecker S., Devlin J. P., Buck U., and Kazimirski J. K. 2004. Int. Rev. Phys. Chem. 23. 375-433) and Huang (Huang J. F. and Bartell L. S. 1995, J. Phys. Chem. 99. 3924-3931), respectively. To determine the freezing rate from liquid phase to cubic ice, however, requires further optimization of the experimental setup and more quantitative study
Bibliographical Information:

Advisor:

School:The Ohio State University

School Location:USA - Ohio

Source Type:Master's Thesis

Keywords:sub cooled droplets ftir supersonic nozzle

ISBN:

Date of Publication:01/01/2008

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