Thermohydraulic performance augmentation and heat transfer enhancement of automotive radiators using nano-coolants: a critical review

Automotive radiators are essential for cooling engines and preventing overheating by using advanced coolants with superior thermophysical properties. Nanofluids, as coolants, can significantly boost the engines heat performances due to their excellent thermal properties. Hence, the objective of this study is to present an extensive literature review addressing the recent progress and future research avenues concerning the use of nanofluids as coolants in automotive radiators. This review highlights the potential of nanofluids as a viable alternative for enhancing engine performance and minimizing environmental emissions. Initially, the nanofluid mechanisms, synthesis methods, involved in heat transfer augmentation through the use nano-coolants within automotive radiators are briefly highlighted. Then, the thermohydraulic performances of nano-coolants in car radiators are comprehensively evaluated, considering factors such as nanoparticle volume fraction, type, and nanoparticle size as well as inlet temperature and nano-coolant flowrate on the heat transfer capability in automotive radiators. Lastly, challenges and future prospective with significant potential research directions have been emphasized as well. The outcomes indicated that recent studies on hybrid nanofluids, namely Al₂O₃/TiO₂, SiC/MWCNTs, and graphene/Al₂O₃/CNT for automotive radiators, reveal promising improvements (6.30–124%) in thermal performance. It also showed that increasing the concentration and flow rate of nanofluids in car radiators boosts the heat transfer coefficient and Nusselt number. Optimal performance is achieved with nanoparticle concentrations ranging from 0.05 to 2% by volume. In conclusion, the existing nano-coolants offer significant potential for enhancing the efficiency of automotive radiators; their effective implementation demands ongoing research and development efforts to address current challenges and fully exploit their advantages.