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| Titel: |
General Requirements and Recommendations for Vapor Nucleation Rate Experiments |
| Auteur: |
Anisimov, M. P. Hopke, P. K. Berezina, A. S. |
| Verschenen in: |
Aerosol science and technology |
| Paginering: | Jaargang 37 (2003) nr. 2 pagina's 183-186 |
| Jaar: |
2003-02 |
| Inhoud: |
Agreement between experimentally measured vapor nucleation rates and current theoretical predictions exists for only a limited number of systems. These inconsistencies can result from differences in measurement methods and assumptions used to interpret the experimental results. Usually the causes of these disagreements are unclear. The current state of the art is such that experimental results using different methods can lead to very different interpretations of the same phenomenon. In this note, well-defined standard systems are suggested as a means to verify experimental system performance. The combination n-pentanol-helium is suggested as a standard reference system. Using this system, measurements produced by multiple research groups have been compiled, and from these experimental results, a nucleation rate equation was developed that can serve as a standard basis for method comparison. This equation provides a scale to relate nucleation rates over a range of nucleation temperatures and is a useful basis of comparison even if the proposed equation is not fully accurate. It is further suggested that the nucleation rate measurements be performed using small steps in nucleation temperature of around 2° or less to identify the features in the system such as phase changes in the critical embryos. In this note, a method that uses monotonicity and continuity conditions for the nucleation rate surface to detect such singularities is outlined. These monotonicity and continuity criteria can be formulated as a dimensionless quantity. The semiempirical construction of nucleation rate surfaces can indicate conditions where multiple nucleation rate surfaces may be detected. Experimental systems that include size distribution measurements have the potential to discern particles produced through multiple nucleation channels such that nucleation rates can be measured for each channel. Detection of nucleation rate surface singularities is important because these singularities indicate the existence of two-channel nucleation where one-channel nucleation theory cannot be applied. |
| Uitgever: |
Taylor & Francis |
| Bronbestand: |
Elektronische Wetenschappelijke Tijdschriften |
Details van artikel 6 van 8 gevonden artikelen
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