Experimental Study on the CHF Enhancement of the Nanofluids containing Exfoliated Graphite Nanoplatelets(xGnP)

The enhancement of the critical heat flux (CHF) contributes to increasing the safety margin of the thermal system. Nanofluids, stably dispersed nano-sized particles in base fluids, have been drawing attention as heat transfer fluids due to the CHF enhancement. The CHF enhancement can be explained by changing the morphology of the heater surface during the pool boiling. However, there are many factors to affect the CHF of the nanofluids, including the nanomaterials, the particle concentration and size, thermophysical properties of the nanofluids (surface tension, thermal conductivity and specific heat), and dispersibility. Carbon based nanomaterials have drawn the tremendous interest from various areas due to their superior thermal and electrical properties. Among them, The exfoliated graphite nanoplatelets (xGnP) are the candidate to enhance the CHF of nanofluids due to the economical benefits compared to CNTs and grapheme. The xGnPs have layered structure with an average thickness of approximately 6-8nm. Since the manufacturing cost of xGnPs is much lower than that of CNTs and graphene, they can be the effective alternative. In this study, nanofluids containing xGnP and xGnP oxide are prepared. We carried out the pool boiling experiments using xGnP and xGnP oxide nanofluids with different concentrations to examine the CHF enhancement