Comparison of heat transfer performance of water-based graphene nanoplatelet- and multi-walled carbon nanotube-nanofluids in a concentric tube heat exchanger

Carbon nanomaterials are of great interest for next generation nanofluids. nanotubes and graphene are, in particular, highly thermally conductive their use as thermal fluid is gaining momentum among the research community. This work investigates performance nanoplatelet (GnP)-nanofluid multi-walled carbon nanotube (MWCNT)-nanofluid by using a concentric pipe heat exchanger. The prepared nanofluid flowed inner hot fluid, which was opposite direction colder water flow annulus pipe. investigation conducted varying volumetric (from 1.5 to 2.5 L/min) concentration 0.01 0.35 vol%). transfer coefficient (HTC) GnP-nanofluid observed be superior that MWCNT-nanofluid. maximum increase HTC relative pure base approximately 16.8, 24.2 26.1% GnP-nanofluid; 8.8, 13.8 14.4% MWCNT-nanofluid flowing at 1.5, 2.0 L/min, respectively. positive impact on enhancement reached when an optimum both Compared ratio brought 0.15 vol% produced greater ratio, even relatively low (0.05 vol%) (1.5 rather desirable practical applications.