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Experimental estimate of energy accommodation coefficient at high temperatures
1National CRI Center for Nano Particle Control, Institute of Advanced Machinery and Design, School of Mechanical and Aerospace Engineering, Seoul National University, Seoul 151-742, Korea.
Physical Review. E, Statistical, Nonlinear, and Soft Matter Physics
|December 12, 2001
Summary
The energy accommodation coefficient (EAC) was experimentally measured at high temperatures using laser-heated nanoparticles. Results show a low EAC of 0.005, indicating inefficient heat transfer in gas-particle systems at high Knudsen numbers.
Area of Science:
- Thermodynamics
- Nanotechnology
- Physical Chemistry
Background:
- Gas-surface interactions are crucial in various high-temperature systems.
- The energy accommodation coefficient (EAC) quantifies heat transfer efficiency between gases and surfaces.
- Experimental data for EAC at high temperatures and large Knudsen numbers are scarce.
Purpose of the Study:
- To experimentally determine the energy accommodation coefficient (EAC) at high temperatures.
- To validate theoretical predictions of EAC in specific conditions.
- To investigate heat transfer dynamics in nanoparticle-flame environments.
Main Methods:
- Development of a novel method using laser irradiation to heat nanoparticles generated in a flame.
- Measurement of nanoparticle temperature as a function of laser power.
- Derivation of EAC from the temperature-power relationship.
Main Results:
- The energy accommodation coefficient (EAC) was experimentally estimated to be approximately 0.005.
- The experimental value aligns well with recent theoretical calculations.
- The results suggest a low efficiency of heat transfer between gas and nanoparticles.
Conclusions:
- The study provides the first experimental EAC measurement at high temperatures using laser-heated nanoparticles.
- The findings confirm the theoretical prediction of a small EAC under these conditions.
- This implies limited heat transfer efficiency in high-temperature systems with large Knudsen numbers.