Performance Investigation of the Automotive Radiator Using Functionalized Graphene Quantum Dots-Based Nanosuspension

This study investigates the performance enhancement of an automotive radiator using functionalized graphene quantum dots (FGQD)-based nanosuspensions. The primary objective is to evaluate the thermal conductivity, viscosity and heat transfer performance of FGQD-water nanosuspensions at varying concentrations (0.5wt.%, 1.0wt.% and 1.5wt.%). The research is carried out in two phases. In the first phase, the synthesis of graphene quantum dots (GQD), its dispersion in water, and the subsequent characterization of thermal properties are precisely detailed. Thermophysical properties of these nanosuspensions including thermal conductivity, viscosity and density across varying flow rates and temperatures are assessed. The thermal conductivity was measured experimentally and validated using the Hamilton model, while viscosity was assessed using the Brinkman model. In the second phase of the experimentation, experimental evaluations were conducted on a HELLA 376757051 radiator, analyzing the impact of FGQD concentration on heat transfer coefficient, pressure drop and performance index at different coolant flow rates. Nanosuspensions are experimentally examined at various coolant flow rates. The research shows a significant enhancement in heat transfer coefficients when GQD are added at concentrations of 0.50wt.%, 1.00wt.% and 1.5wt.% in comparison to the regular conventional water-based coolant. The results highlighted that increased levels of GQD led to a substantial improvement in heat transfer efficiency. It is observed that the 1.5wt.% FGQD-water nanosuspension achieves a 107% increase in heat transfer coefficient. On the other hand, 0.5wt.% offers an optimal balance between heat transfer enhancement and minimal pressure drop, making it more suitable for high-flow applications. The performance index analysis confirms that FGQD-water nanosuspensions significantly improve radiator efficiency. The findings highlight the potential of FGQD as an advanced nanofluid for automotive cooling applications, offering superior thermal performance as compared to conventional coolants.