HEAT TRANSFER CHARACTERISTICS OF FOAM FLOW AT TEMPERATURE UP TO 373K OF HEATING SURFACE

An experimental study on heat transfer of water-air foam was conducted under forced convection conditions. A cylindrical heating surface whose temperature was lower than 373K, i.e., less than the boiling temperature of water, was employed. Heat transfer coefficient was obtained for various combinations of foam density, foam velocity, and temperature of the heating surface. The coefficients were found to increase with increasing the density and the velocity of the foam. Abrupt increase in the coefficient was also obtained as the temperature of the heater rises to 373K. A numerical analysis based on a lubricated plug flow model shows that one of the reason of the increase in the coefficient is latent heat transfer due to vapor diffusion in void space in the foam