EFFECTIVE THERMAL CONDUTIVITY OF LIQUID-GAS FOAMS

Abstract

Effective thermal conductivity of liquid-gas foams was studied experimentally and analytically. The transient hot-wire method was employed in the measurement of the thermal conductivity of foams. Foam liquid was the dilute aqueous solution of a surface active agent (Kao MX-968). The expansion ratio of the foams fell in the range from 14 to 67. Mean bubble diameter of the foams was about 0.8mm. The experiments were conducted at the room temperature and atmospheric pressure.
Measured thermal conductivity of foams was about four times larger than that of the dry air. This value is also in good agreement with the analytical prediction. From this result, it is concluded that latent heat transfer by the vapor diffusion plays a predominant role in the heat transfer through the liquid-gas foams.