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Water nucleation: A comparison between some phenomenological theories and experiment
Thomas P Bennett1, Jonathan C Barrett
1Nuclear Department, Defence Academy, HMS Sultan, Military Road, Gosport PO12 3BY, United Kingdom.
The Journal of Chemical Physics
|October 2, 2012
Summary
Comparing homogeneous nucleation theories with water droplet experiments reveals discrepancies. Mean-field kinetic nucleation theory (MKNT) best matches experimental temperature dependence, while Gibbs p-form aligns with supersaturation trends.
Area of Science:
- Physical Chemistry
- Thermodynamics
- Materials Science
Background:
- Homogeneous nucleation is a fundamental process in phase transitions.
- Accurate theoretical models are crucial for understanding nucleation phenomena.
- Experimental validation of nucleation theories is essential for scientific progress.
Purpose of the Study:
- To compare predictions from various homogeneous nucleation theories with experimental data for water.
- To identify which theoretical models best represent experimental observations across different temperatures and supersaturations.
- To analyze the residual dependence of nucleation rates on temperature and supersaturation.
Main Methods:
- Comparison of experimental nucleation rate data for water with predictions from classical theory, Gibbs p-form, mean-field kinetic nucleation theory (MKNT), extended modified liquid drop model-dynamical nucleation theory, and two density functional theories.
- Analysis of theoretical expressions for nucleation rate, including series expansions in powers of the logarithm of supersaturation (S).
- Evaluation of the temperature and supersaturation dependence of experimental results against theoretical predictions.
Main Results:
- Experimental results show a stronger decrease in nucleation rate with increasing temperature than most theories, except MKNT.
- Experimental residual dependence on supersaturation decreases with increasing S, contrary to most theories which predict an increase.
- Experimental data suggest a zero or positive Tolman length, while most theories predict a negative Tolman length.
Conclusions:
- MKNT provides the best fit for temperature dependence, while the Gibbs p-form aligns better with supersaturation dependence.
- Discrepancies highlight the need for refined nucleation theories, particularly regarding the Tolman length and curvature corrections.
- Further investigation into the role of association and higher-order corrections in nucleation theories is warranted.
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