Heat transfer enhancement in vehicle cabin heating system with hybrid nanofluid: An experimental and artificial intelligence approach

• Published in: Applied thermal engineering 2025-01, Vol.259, p.124892, Article 124892
• Main Author: Elibol, Emre Askin
• Format: Article
• Language: English
• Subjects: Artificial neural network; Cabin heating; Flat tube; Hybrid nanofluid; Louvered fin
• ISSN: 1359-4311
• DOI: 10.1016/j.applthermaleng.2024.124892

•An experimental study integrated with the ANN is employed for the heat exchanger.•The study examines various Al2O3-TiO2/water nanofluid concentrations.•Hybrid nanofluid usage enhances thermal performance compared to pure water.•The proposed ANN model shows proper R2 values for the forecast outputs.•The maximum enhancement in ε is at the configuration of 0.2 %, 7.65 LPM and 50 °C. In louvered fin-and-flat-tube aluminum heat exchangers, the interrupted surfaces of the louvered fin channel, through which air flows, enhance heat transfer by growing and degrading laminar boundary layers, while the large surface-to-cross-section flow area ratio of the flat tube further enhances heat transfer. Consequently, due to their relatively good heat transfer performance and compact design, louvered fin-and-flat-tube aluminum heat exchangers are often utilized for cabin heating systems. Considering previous studies involving louvered fin-and-flat-tube aluminum heat exchangers with conventional fluids and with mono-nanofluids, this is the first study employing Al2O3-TiO2/water hybrid nanofluid experimentally in this context, and utilizing a forward-looking ANN forecasting model for scenarios that cannot be experimentally conducted in such systems. Accordingly, the heat transfer enhancement in the louvered fin-and-flat-tube heat exchanger is experimentally investigated for both pure water alone and for different volume concentrations of Al2O3-TiO2/water hybrid nanofluid. Heat transfer rate, convection heat transfer coefficient, Nusselt number, effectiveness, overall heat transfer coefficient, pressure drop, and performance evaluation index were assessed for different inlet temperatures (50 °C, 60 °C, 70 °C) and volume flow rates (3.65 LPM, 5.65 LPM, 7.65 LPM) in the range 0–0.2 % volume concentration. The experimental results show that the highest heat transfer rate enhancement was 113.32 % using the hybrid nanofluid at φ = 0.2 % compared to pure water at a 50 °C inlet temperature and 7.65 LPM flow rate. It was further shown that even using only the hybrid nanofluid, the effectiveness can be increased up to 0.422 at a constant fan speed without the need to enlarge the heat exchanger size, at a flow rate of 7.65 LPM and an inlet temperature of 70 °C. It has also been found that the maximum values of the performance evaluation index calculated according to two different formulas are 2.260 and 2.049 at φ = 0.2 %. In the following part of the study, heat transfer rate, effectiv