Statistical thermodynamics of aerosols and the gas–solid Joule–Thomson effect

Due to the adsorption of a gas by a solid, it is expected that an aerosol created by dispersing a fine powder in a gas would have unique thermodynamic properties not found in pure or mixed gases. The virial equation of state associated with an aerosol dusty gas is obtained from statistical thermodynamic considerations. In the theoretical model presented here, the aerosol is considered to be a two component fluid made up of solid particles and gas molecules. The aerosol virial equation of state is used to derive an expression for the Joule–Thomson effect associated with a gas–solid dispersion. The magnitude of the gas–solid Joule–Thomson effect is expressed in terms of gas and gas–solid virial coefficients. Previous adsorption data for an argon–porous carbon system is used to obtain gas–solid virial coefficients and to predict the magnitude of the gas–solid Joule–Thomson effect. A significant enhancement of the Joule–Thomson effect is predicted for gas–solid systems which display a strong interaction. For example, at a temperature of 300 K an argon–Saran 746 porous carbon aerosol system at a concentration of (0.4 g of powder/ℓ of gas) is predicted to have a gas–solid Joule–Thomson coefficient of 3.6 K/atm which is ten times greater than the effect for pure argon.