Experimental investigation of heat transfer performance of novel bio-extract doped mono and hybrid nanofluids in a radiator

The paper investigates the heat transfer performance of distilled water (DW) and ethylene glycol-DW mixture (EG-DW) based aluminum and magnesium sulfate nanofluids and their hybrid nanofluids in a radiator. Mono and hybrid nanofluids at 0.05% and 1% volume fractions with Malay Apple (Syzygium Malaccense) extract were formulated and run in the experimental set up at 0.4 kg/s. The heat transfer performances of DW, EG-DW, mono, and hybrid nanofluids were determined using Nusselt number ( Nu ), heat transfer rate ( Q ˙ ) and coefficient (h), effectiveness (ε), heat transfer (Q), Prandtl number (Pr). An increment in the volume fraction was found to enhance Q ˙ , h, Nu , Q, Pr, and ε. The maximum heat transfer performance was obtained using mono (Mg/DW (Q = 2.26 kW and Nu = 175), Al/EG-DW (Q = 6.57 kW and Nu = 462)) and hybrid (Mg–Al/DW (Q = 10.06 kW and Nu = 348)) nanofluids. In comparison with the corresponding base fluid, maximum heat transfer enhancements of 13.9%, 306.7%, and 493.9% were obtained for Mg/DW, Mg–Al/DW, and Al/EG-DW nanofluids, respectively. This remarkable heat transfer enhancement obtained can be related to the presence of the Malay Apple (Syzygium Malaccense) extract. These novel nanofluids appeared to be suitable candidates for radiator cooling.