Experimental investigation on the effect of additives on different orientations of Al6061 cylindrical sample during immersion quenching

Augmentation of the quenching heat transfer at higher temperature regimes is an issue of greater importance in nuclear reactors, avionics, material science, electronic cooling, and solar thermal power plants. The occurrence of film boiling and dependency of bubble behavior on cooling surface orientation are the pressing problems associated with the two-phase cooling process. The present work aims to enhance the cooling efficiency by averting the film boiling and surface orientation effect. In this work, we performed the quenching of Al6061 in de-ionised (DI) water with various additives like tri-sodium phosphate (TSP), Na 2 SO 4, MgSO 4, and surfactants like dodecyltrimethylammonium bromide (DTAB) at vertical and horizontal orientations under standard atmospheric conditions. The influence of added additives on overall cooling performance, film boiling time, vapor layer behavior, and bubble dynamics was investigated via cooling curves and visualization techniques. At higher temperature regimes aside from surfactant, other added salt additives exhibited enhanced cooling performance than pure DI-water for all the considered orientations. Among the considered salts, TSP almost nullified the effect of surface orientation and showed an appreciable reduction in cooling time by up to 27.2% compared to de-ionized water. Visualization studies revealed that micro explosion of vapor bubbles and the absence of bubble coalescence are the significant physical mechanisms governing the enhancement in cooling performance.