Reflood Heat Transfer in SiC and Graphene Oxide Coated Tubes

Quenching experiments were conducted to investigate the effect of nanoparticle deposition on boiling heat transfer during rapid quenching in long vertical tubes. SiC and graphene oxide (GO) nanoparticles were deposited by boiling 0.01 vol% SiC/water and GO/water nanofluids in the vertical tube for 600 and 900 s to observe the repeatability of the nanoparticle deposition. Reflood tests were performed by passing water through bare tube and nanoparticle-coated tube at a constant flow rate (3 cm/s). Quenching curves (temperature vs. time) and saturated boiling curves were obtained at atmospheric pressure. We observed a more enhanced cooling performance in nanoparticle-coated tubes. The quenching time of tubes coated with SiC nanoparticles for 600 and 900 s were reduced by more than 20 and 25 s, respectively, compared to that of the bare tube. For the tubes boiled with GO nanoparticles for 600 and 900 s, the quenching times decreased by 10 and 12 s, respectively, compared to that of the bare tube. Scanning Electron Microscopy (SEM) images were acquired, and the contact angles were measured to observe the effects of surface structures and wettability on the cooling performance.