UPGRADING THE HEAT TRANSFER IN THE CONCENTRIC TUBE HEAT EXCHANGERS BY USING GRAPHENE/WATER NANOFLUID

Since heat exchangers have many application areas, it is possible to come across many studies in the literature on increasing their performance. Both the design improvements required by heat transfer and the type of fluid used can be given as examples. In this study, a coaxial double-tube experimental setup was manufactured and the effect of using the prepared graphene/water nanofluid on the performance increase in cocurrent and counterflow conditions was experimentally investigated. Graphene/water nanofluid was obtained by adding 2% by mass of nanosized graphene into the base fluid (water) and 0.2% sodium dodecyl benzene sulfonate (SDBS) as a surfactant. The reason why graphene is used in the preparation of nanofluids is that, unlike other nanoparticle structures, graphene is effective in increasing the heat transfer surface due to its thin sheet form. The experiments were carried out under two conditions, namely, of using prepared graphene/water nanofluid and pure water as hot fluid. By this way, a performance evaluation on the usage of the prepared graphene/water nanofluid compared to pure water as hot fluid could be made. As a consequence of the experiments, the total heat transfer coefficient provided an average improvement of 48.8% for the parallel flow heat exchanger, while an average improvement of 9.6% was observed under the counterflow conditions.