Investigation of Thermal Accommodation Coefficients in Time-Resolved Laser-Induced Incandescence

2008 ◽  
Vol 130 (12) ◽  
Author(s):  
K. J. Daun ◽  
G. J. Smallwood ◽  
F. Liu
Keyword(s):  
Particle Size ◽  
A Priori ◽  
Accommodation Coefficient ◽  
Particle Sizing ◽  
Time Resolved ◽  
Polyatomic Gases ◽  
Thermal Accommodation ◽  
Laser Induced Incandescence ◽  
Accommodation Coefficients ◽  
Thermal Accommodation Coefficient

Accurate particle sizing through time-resolved laser-induced incandescence (TR-LII) requires knowledge of the thermal accommodation coefficient, but the underlying physics of this parameter is poorly understood. If the particle size is known a priori, however, TR-LII data can instead be used to infer the thermal accommodation coefficient. Thermal accommodation coefficients measured between soot and different monatomic and polyatomic gases show that the accommodation coefficient increases with molecular mass for monatomic gases and is lower for polyatomic gases. This latter result indicates that surface energy is accommodated preferentially into translational modes over internal modes for these gases.

scholarly journals Measurement of Thermal Accommodation Coefficients Using Laser-Induced Incandescence

2007 ◽  
Author(s):  
K. J. Daun ◽  
P. H. Mercier ◽  
G. J. Smallwood ◽  
F. Liu ◽  
Y. Le Page
Keyword(s):  
Deformation Rate ◽  
Surface Deformation ◽  
Accommodation Coefficient ◽  
Polyatomic Gases ◽  
Thermal Accommodation ◽  
Laser Induced Incandescence ◽  
Translational Mode ◽  
Accommodation Coefficients ◽  
Thermal Accommodation Coefficient ◽  
Gas Molecules

Laser-induced incandescence (LII) is used to measure the thermal accommodation coefficient between soot sampled from a well-characterized flame and various monatomic and polyatomic gases. These measurements show that the thermal accommodation coefficient between soot and monatomic gases increases with molecular mass due to the decreasing speed of incident gas molecules and corresponding decrease in surface deformation rate, and that energy is transferred preferentially from the surface to the translational mode of the polyatomic gas molecules over internal energy modes.

Thermal Accommodation Coefficients for Time-Resolved Laser-Induced Incandescence Sizing of Metal Nanoparticles in Monotomic Gases

2012 ◽  
Author(s):  
T. A. Sipkens ◽  
K. J. Daun ◽  
J. T. Titantah ◽  
M. Karttunen
Keyword(s):  
Metal Nanoparticles ◽  
Accommodation Coefficient ◽  
Time Resolved ◽  
Thermal Accommodation ◽  
Fundamental Relationship ◽  
Laser Induced Incandescence ◽  
Accommodation Coefficients ◽  
Thermal Accommodation Coefficient ◽  
Molybdenum Nanoparticles ◽  
First Time

There is recent interest in adapting time-resolved laser-induced incandescence (TiRE-LII) to measure aerosolized metal nanoparticles, which requires knowledge of the thermal accommodation coefficient between the gas and the laser-energized particle. This paper presents accommodation coefficients for various metal particles in monatomic gases derived using molecular dynamics (MD). A comparative analysis of different gas/metal systems reveals a fundamental relationship between the thermal accommodation coefficient and the potential well depth. Finally, MD derived accommodation coefficients are used, for the first time, to recover particle sizes from TiRe-LII measurements made on molybdenum nanoparticles in helium and argon atmospheres.

Thermal Accommodation Coefficients Between Nitrogen and Soot in Laser-Induced Incandescence Experiments

2008 ◽  
Author(s):  
K. J. Daun
Keyword(s):  
Md Simulation ◽  
Accommodation Coefficient ◽  
Monte Carlo Integration ◽  
Detailed Knowledge ◽  
Gas Temperature ◽  
Time Resolved ◽  
Thermal Accommodation ◽  
Laser Induced Incandescence ◽  
Accommodation Coefficients ◽  
Thermal Accommodation Coefficient

Time-resolved laser-induced incandescence demands detailed knowledge of the thermal accommodation coefficient, but to date little is understood about the gas/surface scattering physics underlying this parameter. We present a molecular dynamics (MD) simulation that models nitrogen molecules as rigid rotors and soot as crystalline graphite at 3000 K. A Monte Carlo integration over incident gas molecular speeds and surface atomic vibrational phases yields a simulated thermal accommodation coefficient that matches the experimentally-measured value. The MD simulation is then extended to assess how α changes with gas temperature, and finally to define a Cercingnani-Lampis-Lord scattering kernel.

Time Resolved Laser Induced Incandescence for Sizing Aerosolized Iron Nanoparticles

2014 ◽  
Author(s):  
T. A. Sipkens ◽  
N. R. Singh ◽  
K. J. Daun ◽  
N. Bizmark ◽  
M. Ioannidis ◽  
...  
Keyword(s):  
Iron Nanoparticles ◽  
Accommodation Coefficient ◽  
Time Resolved ◽  
Thermal Accommodation ◽  
Laser Induced Incandescence ◽  
Accommodation Coefficients ◽  
Ab Initio Potentials ◽  
Thermal Accommodation Coefficient ◽  
Carrier Gases ◽  
Pneumatic Atomizer

This paper summarizes the results of Time-Resolved Laser-Induced Incandescence (TiRe-LII) measurements of iron nanoparticles in He, Ne, Ar, N2, CO, CO2, and N2O. The iron nanoparticles are formed in solution and then aerosolized with a pneumatic atomizer using various carrier gases, so the nanoparticle size is the same for each aerosol and the TiRe-LII signal only differs due to the different thermal accommodation coefficient (TAC). Thermal accommodation coefficients for the Fe-Ar, and Fe-N2 aerosols, derived from molecular dynamics using ab initio potentials, are compared with values inferred from the TiRe-LII measurements.

Quantifying the Thermal Accommodation Coefficient for Iron Surfaces Using Molecular Dynamics Simulations

2015 ◽  
Author(s):  
T. A. Sipkens ◽  
K. J. Daun ◽  
J. T. Titantah ◽  
M. Karttunen
Keyword(s):  
Molecular Dynamics ◽  
Accommodation Coefficient ◽  
Time Resolved ◽  
Thermal Accommodation ◽  
Contemporary Science ◽  
Depth Analysis ◽  
Laser Induced Incandescence ◽  
Important Field ◽  
Thermal Accommodation Coefficient ◽  
Dynamics Simulations

With nanotechnology becoming an increasingly important field in contemporary science, there is a growing demand for a better understanding of energy exchange on the nanoscale. Techniques, such as time-resolved laser-induced incandescence, for example, require accurate models of gas-surface interaction to correctly predict nanoparticle characteristics. The present work uses molecular dynamics to define the thermal accommodation coefficient of various gases on iron surfaces. A more in depth analysis examines the scattering distributions from the surfaces and examines how well existing scattering kernels and classical theories can represent these distributions. The molecular dynamics-derived values are also compared to recent experimental time-resolved laser-induced incandescence studies aimed at evaluating the thermal accommodation coefficient across a range of surface-gas combinations.

In Situ Particle Size Measurements of Gas-Borne Silicon Nanoparticles by Time-Resolved Laser-Induced Incandescence

2013 ◽  
Author(s):  
T. A. Sipkens ◽  
N. Petermann ◽  
K. J. Daun ◽  
J. Titantah ◽  
M. Karttunen ◽  
...  
Keyword(s):  
Silicon Nanoparticles ◽  
Laser Diagnostics ◽  
Plasma Reactor ◽  
Accommodation Coefficient ◽  
Time Resolved ◽  
Thermal Accommodation ◽  
Transmission Electron ◽  
Bet Analysis ◽  
Laser Induced Incandescence ◽  
Accommodation Coefficients

The functionality of silicon nanoparticles is strongly size-dependent, so there is a pressing need for laser diagnostics that can characterize aerosolized silicon nanoparticles. The present work is the first attempt to extend time-resolved laser-induced incandescence (TiRe-LII), a combustion diagnostic used for sizing soot, to size silicon nanoparticles. TiRe-LII measurements are made on silicon nanoparticles synthesized in a low-pressure plasma reactor containing argon. Molecular dynamics (MD) is used to predict the accommodation coefficient between silicon nanoparticles and argon and helium, which is needed to interpret the TiRe-LII data. The MD-derived thermal accommodation coefficients will be validated by comparing them to experimentally-derived values found using transmission electron microscopy (TEM) and Brunauer-Emmett-Teller (BET) analysis.

Sizing of Molybdenum Nanoparticles Using Time-Resolved Laser-Induced Incandescence

2013 ◽  
Vol 135 (5) ◽  
Author(s):  
T. Sipkens ◽  
G. Joshi ◽  
K. J. Daun ◽  
Y. Murakami
Keyword(s):  
Metal Nanoparticles ◽  
Materials Science ◽  
Accommodation Coefficient ◽  
Time Resolved ◽  
Distribution Width ◽  
Size Dependent ◽  
Thermal Accommodation ◽  
Laser Induced Incandescence ◽  
Thermal Accommodation Coefficient ◽  
Molybdenum Nanoparticles

Aerosolized metal nanoparticles have numerous existing and emerging applications in materials science, but their functionality in these roles is strongly size-dependent. Very recently, time-resolved laser-induced incandescence (TiRe-LII) has been investigated as a candidate for sizing aerosolized metal nanoparticles, which requires an accurate model of the heat transfer through which the laser-energized particles re-equilibrate with the bath gas. This paper presents such a model for molybdenum nanoparticles, which is then used to analyze experimental TiRe-LII data made on aerosols of molybdenum nanoparticles in helium, argon, nitrogen, and carbon dioxide. While it is possible to estimate the particle size distribution width, recovering particles sizes requires independent knowledge of the thermal accommodation coefficient, which is presently unknown.

Molecular Dynamics Simulations of Translational Thermal Accommodation Coefficients for Time-Resolved LII

2008 ◽  
Author(s):  
K. J. Daun ◽  
F. Liu ◽  
G. J. Smallwood
Keyword(s):  
Molecular Dynamics ◽  
Accommodation Coefficient ◽  
Dynamics Simulation ◽  
Gas Temperature ◽  
Time Resolved ◽  
Thermal Accommodation ◽  
Precise Knowledge ◽  
Accommodation Coefficients ◽  
Thermal Accommodation Coefficient ◽  
Dynamics Simulations

Time-resolved laser-induced incandescence demands precise knowledge of the thermal accommodation coefficient, but little is known about the gas-surface scattering physics underlying this parameter. This paper presents a molecular dynamics simulation that shows how the thermal accommodation coefficient is influenced by gas molecular mass and the gas temperature. The MD results also define scattering kernels that form boundary conditions in DSMC simulations of heat and momentum transfer between soot aggregates and surrounding gas molecules.

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