QUENCHING PERFORMANCE IN NANOFLUIDS AND NANOPARTICLES-DEPOSITED SURFACES

摘要

Quenching experiments were conducted to investigate the effect of SiC and Graphene Oxide (GO) nanoparticles on the heat transfer during rapid cooling in vertical tubes. Temperature histories during the quenching were measured for each test section to confirm the effects of nanoparticles-coated layer and nanofluids on the quenching performance. The quenching time was decreased for nanoparticles-coated tubes about 20-31 % compared to bare tube. Also, SiC/water and GO/water nanofluid enhanced the quenching performance. Better quenching performance was observed for GO/water nanofluid compared to GO-coated tubes, while SiC/water nanofluid showed similar quenching performance with SiC-coated tubes. And scanning electron microscope (SEM) images of inner surfaces of tubes after experiments were acquired, and the contact angles were measured to observe the effect of surface structures and wettability on the quenching performance. In case of tubes coated with GO nanoparticles for 900 s, the quenching performance was enhanced although the contact angle increased. To confirm the surface effect on the enhanced quenching performance of GO-coated tubes, the FC-72 refrigerant was used as working fluid of quenching experiment to reduce the wettability effect on the heat transfer.