Heat transfer performance of an automotive radiator with MWCNT nanofluid cooling in a high operating temperature range

• Published in: Applied thermal engineering 2022-05, Vol.207, p.118149, Article 118149
• Main Authors: Cardenas Contreras, Edwin Martin, Bandarra Filho, Enio Pedone
• Format: Article
• Language: English
• Subjects: Antifreeze solutions; Automotive parts; Automotive radiator; Binary mixtures; Bouguer law; Carbon; Coolants; Ethylene glycol; Heat transfer; Heat transfer coefficients; Inlet temperature; Mass flow rate; Multi wall carbon nanotubes; Nanofluid; Nanofluids; Nanoparticles; Nanotubes; Operating temperature; Performance enhancement; Radiators; Spectrophotometry; Stability; Stability analysis; Thermal conductivity; Thermophysical properties
• ISSN: 1359-4311; 1873-5606
• DOI: 10.1016/j.applthermaleng.2022.118149

•An update review on nanofluids in an automotive radiator is presented.•Evaluation of the nanofluid stability using the UV–vis spectrophotometric method.•Thermophysical properties of MWCNT water/EG nanofluids are experimentally investigated.•Thermal performance of MWCNT nanofluids in a temperature range of 80–105 °C.•Observed agglomeration and sedimentation after experimental test in high temperature. This study investigates the heat transfer performance of multiwalled carbon nanotube nanoparticles (MWCNT) dispersed in a binary mixture of water-EG (ethylene glycol) at a volumetric ratio of 50:50 in an automotive radiator. The nanofluids were prepared using the two-step synthesis method at volumetric ratios of 0.025%, 0.05% and 0.1%. The UV–vis spectrophotometry method was used to evaluate the colloidal stability of the samples, reporting the absorbance-concentration relationship according to the Beer-Lambert law. Thermophysical properties such as thermal conductivity and viscosity were measured experimentally and compared with correlations in the literature. The influence of nanoparticle concentration as well as the coolant inlet temperature, of up to 105 °C, on the heat transfer rate and in the overall heat transfer coefficient were evaluated experimentally. The air velocity was maintained constant at 2 m/s and the coolant mass flow rate ranged between 0.09 kg/s and 0.11 kg/s. The maximum increases for the heat transfer rate and for the overall heat transfer coefficient were 4.6% and 4.4%, respectively. The results show that the increase in the concentration of nanoparticles can improve the performance in heat transfer, although the performance decrease for high nanofluid inlet temperatures in the radiator was significant. Finally, the stability of the nanofluids was reassessed after performing tests on the radiator, demonstrating high aggregation and sedimentation of nanoparticles.