EXPERIMENT OF CHF ENHANCEMENT BY MAGNETITE NANOPARTICLE DEPOSITION IN THE SUBCOOLED FLOW BOILING REGION

摘要

CHF experiments were conducted in subcooled flow boiling region at atmospheric pressure. Magnetite nanoparticles were deposited sufficiently on the test sections in same deposition process. Then, working fluid was changed to DI water. After the nanoparticle deposition process, the surface became very hydrophilic even after CHF experiment using DI water. The wettable surfaces were observed using static contact angle and SEM image. CHF results of bare stainless surface and nanoparticle-deposited surface were obtained in the subcooled boiling region. Experiments were conducted over a mass flux range from 1,000 kg/m2s to 5,000 kg/m2s and with inlet temperatures of 40, 60, and 80 °C. The CHF enhancement was from 0% to 40 % by the nanoparticle deposition, which is related wettability enhancement. The CHF enhancement increased as the mass flux increased, which lead to exit quality decrement.