Numerical Investigation of Water/Al2O3 Nanofluid Dryout Phenomenon in a Vertical Channel

Critical heat flux (CHF) has been recognized as the upper limit for the safe operation of many cooling systems which may lead to the occurrence of dryout causing a large temperature gradient in the heated wall. One way to increase the amount of the CHF is to put in nanoparticles such as Al2O3 to the base fluid. The current research investigates the nanoparticles effect on dryout phenomenon using computational fluid dynamics. Boiling phenomena are simulated using the mechanistic model organized in Rensselaer Polytechnic Institute (RPI) which is extended to analyze the CHF by partitioning wall heat flux to liquid and vapor phases. It was shown that the addition of Al2O3 nanoparticles, postpones the wall temperature jump and the liquid temperature and the vapor volume fraction increase regularly in spite of the wall temperature jump. In another effort in this study, it was shown that the dryout phenomenon can be delayed by increasing the nanoparticles concentration, and in certain concentration of nanoparticles (5 percent), dry out would not take place. It can be concluded from obtained results that the addition of Al2O3 nanoparticles, delays the CHF phenomenon and therefore the safety margins of the operation would be enhanced.