DETERMINATION OF THE BOILING ENHANCEMENT MECHANISM CAUSED BY SURFACTANT ADDITION TO WATER

In the present investigation, boiling heat transfer coefficients are m easured for art electrically heated 390-mu m-dia, platinum wire immers ed in saturated water, and in water mixed with three different concent rations of sodium dodecyl sulfate (an anionic surfactant). The additio n of a surfactant to water is known to enhance boiling heat transfer. A recently developed photographic/laser-Doppler anemometry measurement technique is used to quantify the vapor volumetric flow rate departin g from the wire during the boiling process. The volumetric flow rate d ata are used to calculate the latent heat and, indirectly, the convect ion heat transfer mechanisms that constitute the nucleate boiling heat flux Comparisons are made to determine how the heat transfer mechanis ms are affected by the surfactant addition, and thus, which mechanism promotes boiling enhancement. The present data are also compared with similar data taken for a 75-mu m-dia wire immersed in saturated FC-72 (a highly wetting liquid) to provide increased insight into the nature of the boiling heat transfer mechanisms.