Heat transfer performance and fouling analysis of clove-treated graphene nanoplatelet nanofluid in a double-pipe heat exchanger

Abstract Nanofluids have found widespread application across various systems to enhance heat transfer, albeit with the simultaneous occurrence of fouling on heat exchange surfaces. In examining the impact of particulate fouling from nanoparticles on the heat transfer behavior of heat exchangers, this study conducted an experimental exploration utilizing green functionalized clove-treated graphene nanoplatelets (CGNP) nanofluid within a double-pipe heat exchanger (DPHE). Previous studies on nanofluids as heat transfer fluid have largely ignored the impact of particulate fouling on heat transfer performance over time. Various concentrations (0.025, 0.075, and 0.1 mass%) and flow rates (8 and 12 L min −1 ) were systematically examined over an extended operational time, with distilled water (DW) employed as a reference liquid for comparison. The experimental data were compared with simulation results at five different flow rates. The findings reveal that DW exhibited the highest overall heat transfer coefficient (OHTC) among all tested fluids with an OHTC of approximately 1660 W m 2 K −1 . Conversely, deposition occurred in the CGNP nanofluid at all concentrations over an extended operational period. Specifically, the 0.025 mass% concentration demonstrated the lowest fouling resistance in the developing stage. The fouling resistance reached constant for all the tested concentrations with estimated values of 0.15–0.16 m 2 K kW −1 . Furthermore, a flow rate of 12 L min −1 was shown to reduce the fouling resistance by 50% when decreasing the flow rate to 8 L min −1 . Overall, applying CGNP nanofluid in the DPHE over a prolonged testing duration was deemed ineffective. Exploring optimized techniques to mitigate the deposition of CGNP particles on the heat exchange pipe surfaces is necessary.