Motion and swelling of single coal particles during volatile combustion in a laminar flow reactor |
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| Affiliation: | 1. Technical University of Darmstadt, Department of Mechanical Engineering, Reactive Flows and Diagnostics, Otto-Berndt-Straße 3, Darmstadt 64287, Germany;2. RWTH Aachen University, Department of Mechanical Engineering, Institute for Combustion Technology, Templergraben 64, Aachen 52056, Germany;1. State Key Laboratory of Clean Energy Utilization, Zhejiang University, Hangzhou, 310027, China;2. Department of Mechanical Engineering and Science, Kyoto University, Kyoto, Japan;3. JSPS International Research Fellow, Kyoto University, Japan;1. Simulation of Reactive Thermo-Fluid Systems, TU Darmstadt, Otto-Berndt-Straße 2, Darmstadt 64287, Germany;2. Institute of Heat and Mass Transfer, RWTH Aachen University, Augustinerbach 6, Aachen 52056, Germany;1. Technical University of Darmstadt, Department of Mechanical Engineering, Reactive Flows and Diagnostics, Otto-Berndt-Str. 3, Darmstadt 64287, Germany;2. Barlow Combustion Research, Livermore, USA;1. Technical University of Darmstadt, Department of Mechanical Engineering, Simulation of reactive Thermo-Fluid Systems, Otto-Berndt-Straße 2, 64287 Darmstadt, Germany;2. Technical University of Darmstadt, Department of Mechanical Engineering, Reactive Flows and Diagnostics, Otto-Berndt-Straße 3, 64287 Darmstadt, Germany |
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| Abstract: | Motion and swelling behavior of single bituminous coal particles during volatile combustion are investigated in a laminar flow reactor using a joint experimental and numerical approach. Three different particle samples with mean diameters of 90, 120, and 160 µm are studied in a conventional N/O atmosphere with 20 vol% O mole fraction. Diffuse backlight-illumination (DBI) measurements with high temporal (10 kHz) and spatial ( 19 lp/mm) resolutions, combined with detailed parameter evaluation methods, provide fundamental insights into interactions of particle with flow and flame. The acceleration behavior of different particles is assessed based on the response time following the viscosity drag law. Rotation speed is determined by temporally tracking the orientation angle and shown to strongly correlate with the particle size and the devolatilization process. Simultaneously measured slip velocity and particle diameter enable evaluating time-dependent particle Reynolds numbers . The swelling behavior is temporally synchronized with the devolatilization process and reveals a strong dependency on particle diameters. To better understand experimental observations, detailed simulations are first quantitatively validated against experimental ignition delay times and then applied to predict particle temperature histories. Further, the reduction of particle heating rates with increasing diameters is numerically quantified. The maximum swelling ratio decreases from 1.22 to 1.07 as the heating rate increases from approximately 3 10 to 8 10 K/s. |
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