Thermophoresis is a phenomenon which causes small particles
to be driven away from a hot surface and towards a cold one. Small particles,
such as dust, when suspended in a gas with a temperature gradient, experience a
force in the direction opposite to the temperature gradient.
The velocity acquired by the particles is called the
thermophoretic velocity and the force experienced by the suspended particles
due to the temperature gradient is known as the thermophoretic force. Themagnitudes of the thermophoretic force and velocity are proportional to thetemperature gradient, thermal conductivity of aerosol particles and the carrier
gas, thermophoretic coefficient and the heat capacity of the gas. This
phenomenon has many practical applications in removing small particles from gas
streams, in determining exhaust gas particle trajectories from combustion
devices, prevention of fouling and corrosion in heat exchangers and turbines,
semiconductor manufacture and ceramic powder production.
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