Predicting combustion characteristics in externally heated micro-tubes
| Autor: | Pawan Sharma, Vinicius M. Sauer, Ingmar Schoegl |
|---|---|
| Rok vydání: | 2019 |
| Předmět: |
Quenching
Materials science 010304 chemical physics General Chemical Engineering General Physics and Astronomy Energy Engineering and Power Technology 02 engineering and technology General Chemistry Activation energy Mechanics Combustion 01 natural sciences law.invention Physics::Fluid Dynamics Chemical kinetics Ignition system Temperature gradient Fuel Technology 020401 chemical engineering Extinction (optical mineralogy) law 0103 physical sciences Heat transfer Physics::Chemical Physics 0204 chemical engineering |
| Zdroj: | Combustion and Flame. 204:33-48 |
| ISSN: | 0010-2180 |
| DOI: | 10.1016/j.combustflame.2019.02.029 |
| Popis: | This study employs a simplified analytical model to obtain qualitative predictions of transitions between non-adiabatic combustion regimes found in non-catalytic tubular micro-flow reactors, i.e. normal stable flames, flames with repetitive extinction and ignition (FREI), and weak flames that are stabilized by wall heat transfer. Assuming large activation energy for single-step kinetics, a comparison of exact solutions for constant and variable wall temperature profiles reveals that while a non-zero wall temperature gradient introduces a temperature lag, it has no impact on the structure of the flame solution itself. This result is significant as it establishes a link to quenching characteristics within heated micro-tubes, and further facilitates a simplified micro-flow reactor analysis. Predictions for sweeps of wall temperatures are combined to S-curves, which allow for a combustion regime classification for a given combination of micro-flow reactor geometry and mixture properties. A variation of parameters such as tube diameter or mixture stoichiometry yields predictions of shifts in regime transitions, thus providing insights on interactions between heat transfer and first order effects of chemical kinetics. A comparison to experimental data illustrates that the theoretical framework, – within inherent limitations, – captures qualitatively correct trends that reflect experimental observations, thus providing valuable insights for micro-flow reactor design and operation. |
| Databáze: | OpenAIRE |
| Externí odkaz: |
|
Full Text from ScienceDirect