Microwave-Assisted Superheating and-or Microwave-Specific Superboiling Nucleation-Limited Boiling of Liquids Occurs under Certain Conditions but is Mitigated by StirringReportar como inadecuado




Microwave-Assisted Superheating and-or Microwave-Specific Superboiling Nucleation-Limited Boiling of Liquids Occurs under Certain Conditions but is Mitigated by Stirring - Descarga este documento en PDF. Documentación en PDF para descargar gratis. Disponible también para leer online.

Department of Chemistry and Biochemistry, Florida State University, Tallahassee, FL 32306-4390, USA





*

Authors to whom correspondence should be addressed.



Academic Editors: Marilena Radoiu, Jean-Jacques Vanden Eynde and Annie Mayence

Abstract Temporary superheating and sustained nucleation-limited -superboiling- of unstirred liquids above the normal atmospheric boiling point have been documented during microwave heating. These phenomena are reliably observed under prescribed conditions, although the duration of superheating and magnitude of superheating and superboiling vary according to system parameters such as volume of the liquid and the size and shape of the vessel. Both phenomena are mitigated by rapid stirring with an appropriate stir bar and-or with the addition of boiling chips, which provide nucleation sites to support the phase-change from liquid to gas. With proper experimental design and especially proper stirring, the measured temperature of typical organic reaction mixtures heated at reflux will be close to the normal boiling point temperature of the solvent, whether heated using microwave radiation or conventional convective heat transfer. These observations are important to take into consideration when comparing reaction rates under conventional and microwave heating. View Full-Text

Keywords: superheating; microwave; reflux; temperature; boiling point superheating; microwave; reflux; temperature; boiling point





Autor: Anthony Ferrari, Jacob Hunt, Albert Stiegman * and Gregory B. Dudley *

Fuente: http://mdpi.com/



DESCARGAR PDF




Documentos relacionados