The experimental analyse of grooved surface and magnetic field effects on γ-Fe2O3/water nanofluid pool boiling

Pool boiling has many applications in industrial processes. Use of nanoparticle, heater surface expansion and magnetic field applying are important and effective elements on boiling heat transfer. In this article, pool boiling of dionized water and γ-Fe2O3/water magnetic nanofluid have been analyzed on smooth and copper grooved surface at one atmosphere pressure in the presence and absence of magnetic field, experimentally. For comfirmation of results accuracy, the test of dionized water was done in three different days that had good agreement with reference relations. Nanofluid has been built in one stage and has high stability. The result showed that the boiling heat transfer coefficient of dionized water has increased in circular and rectangular grooved surfaces and has decreased in triangular grooved suface toward the smooth surface. The boiling heat transfer coefficient of nanofluid has increased 24% in circular grooved surface and has decreased 8% and 37% in rectangular and triangular grooved sufaces, respectively, toward the smooth surface. The corners existence and wettability reduction in vertical wall of rectangular and triangular grooves and the bubbles slipping cause thermal resistanse increasing toward circle groove. Two flat constant magnets have been used in two sides of boiling reservoir for magnetic field creation. By applying magnetic field with negative gradient, the boiling heat transfer cofficient of nanofluid has enhanced in circular and rectangular grooved surfaces and has reduced in triangular grooved surface. The upward magnetic force causes the formed bubbles diameter decreasing, but groove type is effective on result, too.