Efficient heat dissipation is crucial for various industrial and technological applications, ensuring system reliability and performance. Advanced thermal management systems rely on materials with superior thermal conductivity and stability for effective heat transfer. This study investigates the thermal conductivity, viscosity, and stability of hybrid Al2O3-CuO nanoparticles dispersed in Therminol 55, a medium-temperature heat transfer fluid. The nanofluid formulations were prepared with CuO-Al2O3 mass ratios of 10:90, 20:80, and 30:70 and tested at nanoparticle concentrations ranging from 0.1 wt% to 1.0 wt%. Experimental results indicate that the hybrid nanofluids exhibit enhanced thermal conductivity, with a maximum improvement of 32.82% at 1.0 wt% concentration, compared to the base fluid. However, viscosity increases with nanoparticle loading, requiring careful optimization for practical applications. To further analyze and predict thermal conductivity, a Type-2 Fuzzy Neural Network (T2FNN) was employed, demonstrating a correlation coefficient of 96.892%, ensuring high predictive accuracy. The integration of machine learning enables efficient modeling of complex thermal behavior, reducing experimental costs and facilitating optimization. These findings provide insights into the potential application of hybrid nanofluids in solar thermal systems, heat exchangers, and industrial cooling applications.

Center of Excellence for Advanced Research in Fluid Flow Universiti Malaysia Pahang Pekan 26600 Pahang Malaysia

Centre for Advanced Mechanical and Green Technology Faculty of Engineering and Technology Multimedia University Jalan Ayer Keroh Lama Bukit Beruang Melaka 75450 Malaysia

Centre for Sustainable Materials and Surface Metamorphosis Chennai Institute of Technology Chennai India

Faculty of Computing and Information Technology Sohar University Sohar Oman

Faculty of Mechanical and Automotive Engineering Technology Universiti Malaysia Pahang Pekan 26600 Pahang Malaysia

Institute of Fluid Dynamics and Thermodynamics Faculty of Mechanical Engineering Czech Technical University Prague Technická 4 Prague 166 07 Czech Republic

School of Engineering and Technology Central Queensland University Brisbane QLD 4008 Australia

See more in PubMed

Rafiq, M., Shafique, M., Azam, A. & Ateeq, M. Transformer oil-based nanofluid: the application of nanomaterials on thermal, electrical and physicochemical properties of liquid insulation-A review. Ain Shams Eng. J.12 (1), 555–576 (2021).

Korkmaz, S. & Kariper, İ. A. Pyroelectric nanogenerators (PyNGs) in converting thermal energy into electrical energy: fundamentals and current status. Nano Energy. 84, 105888 (2021).

Anamalai, K. et al. Multi-objective optimization on the machining parameters for bio-inspired nanocoolant. J. Therm. Anal. Calorim.135, 1533–1544 (2019).

Ghelani, D. & Faisal, S. Synthesis and Characterization of Aluminium Oxide Nanoparticles (Authorea Preprints, 2022).

Ouyang, Y., Bai, L., Tian, H., Li, X. & Yuan, F. Recent progress of thermal conductive ploymer composites: Al2O3 fillers, properties and applications. Compos. Part A: Appl. Sci. Manufac.152, 106685 (2022).

Heuer, A. H., Hovis, D. B., Smialek, J. L. & Gleeson, B. Alumina scale formation: a new perspective. J. Am. Ceram. Soc.94, s146–s153 (2011).

Ahmed, F., Khanam, A., Samylingam, L., Aslfattahi, N. & Saidur, R. Assessment of thermo-hydraulic performance of MXene-based nanofluid as coolant in a dimpled channel: a numerical approach. J. Therm. Anal. Calorim.147 (22), 12669–12692 (2022).

Abyzov, A. Aluminum oxide and alumina ceramics (review). Part 1. Properties of al 2 O 3 and commercial production of dispersed al 2 O 3. Refract. Ind. Ceram. 60, 24–32 (2019).

Hisham, S. et al. Enhancing Stability and Tribological Applications using Hybrid Nanocellulose-Copper (II) Oxide (CNC-CuO) Nanolubricant: An Approach Towards Environmental Sustainability, 109506 (Tribology International, 2024).

Ramachandran, K. et al. Evaluation of specific heat capacity and density for cellulose nanocrystal-based nanofluid. J. Adv. Res. Fluid Mech. Therm. Sci.51 (2), 169–186 (2018).

Naz, S., Gul, A. & Zia, M. Toxicity of copper oxide nanoparticles: a review study. IET Nanobiotechnol.14 (1), 1–13 (2020). PubMed PMC

Samylingam, L. et al. Green engineering with nanofluids: elevating energy efficiency and sustainability. J. Adv. Res. Micro Nano Eng.16 (1), 19–34 (2024).

Younes, H. et al. Nanofluids: Key parameters to enhance thermal conductivity and its applications. Appl. Therm. Eng.207, 118202. (2022).

Khan, S. et al. Kinetic and thermodynamic analysis of ammonia electro-oxidation over alumina supported copper oxide (CuO/Al2O3) catalysts for direct ammonia fuel cells. Int. J. Hydrog. Energy. 52, 1206–1216 (2024).

Plant, R. D., Hodgson, G. K., Impellizzeri, S. & Saghir, M. Z. Experimental and numerical investigation of heat enhancement using a hybrid nanofluid of copper oxide/alumina nanoparticles in water. J. Therm. Anal. Calorim.141, 1951–1968 (2020).

El-Shafai, N. M. et al. Investigation of a novel (GO@ CuO. γ-Al2O3) hybrid nanocomposite for solar energy applications. J. Alloys Compd.856, 157463 (2021).

Fathy, A. & El-Kady, O. Thermal expansion and thermal conductivity characteristics of Cu–Al2O3 nanocomposites. Mater. Des.46, 355–359 (2013).

Vadivelu, M., Kumar, C. R. & Joshi, G. M. Polymer composites for thermal management: a review. Compos. Interfaces. 23 (9), 847–872 (2016).

Turco, M. et al. Cu/ZnO/Al2O3 catalysts for oxidative steam reforming of methanol: the role of Cu and the dispersing oxide matrix. Appl. Catal. B. 77 (1–2), 46–57 (2007).

KS, R. & KS, S. ZnO nanostructures modulate the thermo-physical properties of therminol 55 favorably for heat transfer applications. J. Nanopart. Res.26 (3), 1–19 (2024).

Das, L. et al. Insight into the investigation of diamond nanoparticles suspended Therminol® 55 nanofluids on concentrated photovoltaic/thermal solar collector. Nanomaterials12 (17), 2975 (2022). PubMed PMC

Ganesh Kumar, P. et al. Exploring the Thermo-physical Characteristic of Novel multi-wall Carbon Nanotube—Therminol-55-based Nanofluids for Solar-thermal Applications, 1–12 (Environmental Science and Pollution Research, 2022). PubMed

Naresh, Y., Dhivya, A., Suganthi, K. & Rajan, K. High-temperature thermo-physical properties of novel CuO-therminol® 55 nanofluids. Nanosci. Nanatechnol. Lett.4 (12), 1209–1213 (2012).

Gulzar, O., Qayoum, A. & Gupta, R. Experimental study on stability and rheological behaviour of hybrid Al2O3-TiO2 Therminol-55 nanofluids for concentrating solar collectors. Powder Technol.352, 436–444 (2019).

Gulzar, O., Qayoum, A. & Gupta, R. Photo-thermal characteristics of hybrid nanofluids based on Therminol-55 oil for concentrating solar collectors. Appl. Nanosci.9, 1133–1143 (2019).

Muraleedharan, M., Singh, H., Udayakumar, M. & Suresh, S. Modified active solar distillation system employing directly absorbing therminol 55–Al2O3 nano heat transfer fluid and Fresnel lens concentrator. Desalination457, 32–38 (2019).

Yu, W., Timofeeva, E. V., Singh, D., France, D. M. & Smith, R. K. Investigations of heat transfer of copper-in-Therminol 59 nanofluids. Int. J. Heat Mass Transf.64, 1196–1204 (2013).

Eaki, M., Kadirgama, K., Abou El Hossein, K., Samylingam, L. & Kok, C. Enhancing machining performance in stainless steel machining using MXene coolant: A detailed examination. Int. J. Automot. Mech. Eng.21 (1), 10993–11009 (2024).

Sujith, S. V., Kim, H. & Lee, J. A review on thermophysical property assessment of metal oxide-based nanofluids: industrial perspectives. Metals12 (1), 165 (2022).

Yasmin, H., Giwa, S. O., Noor, S. & Sharifpur, M. Thermal conductivity enhancement of metal oxide nanofluids: a critical review. Nanomaterials13 (3), 597 (2023). PubMed PMC

Ouabouch, O., Kriraa, M. & Lamsaadi, M. Stability, thermophsical properties of nanofluids, and applications in solar collectors: A review. AIMS Mater. Sci.8 (4), 659–684 (2021).

Wang, J. et al. A review on nanofluid stability: Preparation and application. Renew. Sustain. Energy Rev.188, 113854 (2023).

Li, M., Dai, L. & Hu, Y. Machine learning for Harnessing thermal energy: from materials discovery to system optimization. ACS Energy Lett.7 (10), 3204–3226 (2022). PubMed PMC

Aslfattahi, N., Samylingam, L., Abdelrazik, A., Arifutzzaman, A. & Saidur, R. MXene based new class of silicone oil nanofluids for the performance improvement of concentrated photovoltaic thermal collector. Sol. Energy Mater. Sol. Cells. 211, 110526 (2020).

Bindu, M. & Herbert, G. J. A review on application of nanomaterials in heat transfer fluid for parabolic trough concentrator. Mater. Today Proc.46, 7651–7660 (2021).

Gürbüz, E. Y., Variyenli, H. İ., Sözen, A., Khanlari, A. & Ökten, M. Experimental and numerical analysis on using CuO-Al2O3/water hybrid nanofluid in a U-type tubular heat exchanger. Int. J. Numer. Methods Heat. Fluid Flow.31 (1), 519–540 (2021).

Famakinwa, O., Koriko, O. & Adegbie, K. Effects of viscous dissipation and thermal radiation on time dependent incompressible squeezing flow of CuO – Al2O3/water hybrid nanofluid between two parallel plates with variable viscosity. J. Comput. Math. Data Sci.5, 100062 (2022).

Jcgm, J. Evaluation of measurement data—Guide to the expression of uncertainty in measurement. Int. Organ. Stand. Geneva ISBN. 50, 134 (2008).

Keabadile, O. P., Aremu, A. O., Elugoke, S. E. & Fayemi, O. E. Green and traditional synthesis of copper oxide nanoparticles—comparative study. Nanomaterials10 (12), 2502 (2020). PubMed PMC

Qamar, H., Rehman, S., Chauhan, D. K., Tiwari, A. K. & Upmanyu, V. Green synthesis, characterization and antimicrobial activity of copper oxide nanomaterial derived from Momordica charantia. Int. J. Nanomed., 2541–2553 (2020). PubMed PMC

Lin, M., Huang, Y., Ran, C., Dong, G. & Zhao, Y. Study on sintering properties of aluminum oxide nano-powder for electronics packaging. J. Phys. Conf. Ser. (2024).

Liu, S., Tian, J. & Zhang, W. Fabrication and application of nanoporous anodic aluminum oxide: A review. Nanotechnology32 (22), 222001 (2021). PubMed

Khan, S. et al. Alumina supported copper oxide nanoparticles (CuO/Al2O3) as high-performance electrocatalysts for hydrazine oxidation reaction. Chemosphere315, 137659 (2023). PubMed

Khan, S., Shah, S. S., Anjum, M. A. R., Khan, M. R. & Janjua, N. K. Electro-oxidation of ammonia over copper oxide impregnated γ-Al2O3 nanocatalysts. Coatings11 (3), 313 (2021).

Ambreen, T. & Kim, M. H. Influence of particle size on the effective thermal conductivity of nanofluids: A critical review. Appl. Energy. 264, 114684 (2020).

Zhang, Z. et al. Size-dependent phononic thermal transport in low-dimensional nanomaterials. Phys. Rep.860, 1–26 (2020).

Adun, H., Kavaz, D. & Dagbasi, M. Review of ternary hybrid nanofluid: synthesis, stability, thermophysical properties, heat transfer applications, and environmental effects. J. Clean. Prod.328, 129525 (2021).

Stoyanov, E. S., Bagryanskaya, I. Y. & Stoyanova, I. V. IR-Spectroscopic and X-ray-Structural study of Vinyl-Type carbocations in their carborane salts. ACS Omega. 7 (31), 27560–27572 (2022). PubMed PMC

Samylingam, L. et al. Thermal and energy performance improvement of hybrid PV/T system by using Olein palm oil with MXene as a new class of heat transfer fluid. Sol. Energy Mater. Sol. Cells. 218, 110754 (2020).

Gunasekhar, R., Dhevi, D. M., Ponnan, S. & Prabu, A. A. Synthesis of aromatic hyperbranched polymer based on diphenolic acid and pentaerythritol: reaction kinetics using FTIR technique. ECS Trans.107 (1), 11137 (2022).

Zhou, Y., Klinger, G. E., Hegg, E. L., Saffron, C. M. & Jackson, J. E. Multiple mechanisms mapped in Aryl alkyl ether cleavage via aqueous electrocatalytic hydrogenation over skeletal nickel. J. Am. Chem. Soc.142 (8), 4037–4050 (2020). PubMed

Tan, K., Samylingam, L., Aslfattahi, N., Saidur, R. & Kadirgama, K. Optical and conductivity studies of Polyvinyl alcohol-MXene (PVA-MXene) nanocomposite thin films for electronic applications. Opt. Laser Technol.136, 106772 (2021).

Yakasai, F., Jaafar, M. Z., Bandyopadhyay, S., Agi, A. & Sidek, M. A. Application of iron oxide nanoparticles in oil recovery–A critical review of the properties, formulation, recent advances and prospects. J. Petrol. Sci. Eng.208, 109438 (2022).

Shakya, A. K. & Singh, S. Performance analysis of a developed optical sensing setup based on the Beer-Lambert law. Plasmonics19 (1), 447–455 (2024).

Li, L. et al. Study on the origin of linear deviation with the Beer-Lambert law in absorption spectroscopy by measuring sulfur dioxide. Spectrochim. Acta Part A Mol. Biomol. Spectrosc.275, 121192 (2022). PubMed

Noor, M. M., Santana-Pereira, A. L., Liles, M. R. & Davis, V. A. Dispersant effects on single-walled carbon nanotube antibacterial activity. Molecules27 (5), 1606 (2022). PubMed PMC

Sharma, S., Acharya, A. D., Thakur, Y. S. & Bisoyi, S. Optimizing BiOCl concentration for enhanced LDPE performance: investigation of structure, thermal stability, and optical characteristics. J. Mol. Struct.1294, 136382 (2023).

Mayerhöfer, T. G., Pahlow, S. & Popp, J. The Bouguer-Beer‐Lambert law: shining light on the obscure. ChemPhysChem21 (18), 2029–2046 (2020). PubMed PMC

Yasmin, H., Giwa, S. O., Noor, S. & Sharifpur, M. Experimental exploration of hybrid nanofluids as energy-efficient fluids in solar and thermal energy storage applications. Nanomaterials13 (2), 278 (2023). PubMed PMC

Razzaq, I. et al. Nanofluids for advanced applications: A comprehensive review on Preparation methods, properties, and environmental impact. ACS Omega (2025). PubMed PMC

Das, L. et al. Thermo-optical characterization of Therminol55 based MXene–Al2O3 hybridized nanofluid and new correlations for thermal properties. Nanomaterials12 (11), 1862 (2022). PubMed PMC

Kalidoss, P., Venkatachalapathy, S. & Suresh, S. Optical and thermal properties of therminol 55-TiO2 nanofluids for solar energy storage. Int. J. Photoenergy. 2020 (1), 7085497 (2020).

Rabby, M. I. I. et al. Recent progresses in tri-hybrid nanofluids: A comprehensive review on preparation, stability, thermo-hydraulic properties, and applications. J. Mol. Liq., 125257 (2024).

Tian, S., Arshad, N. I., Toghraie, D., Eftekhari, S. A. & Hekmatifar, M. Using perceptron feed-forward artificial neural network (ANN) for predicting the thermal conductivity of graphene oxide-Al2O3/water-ethylene glycol hybrid nanofluid. Case Stud. Therm. Eng.26, 101055 (2021).

Said, Z. et al. Recent advances on improved optical, thermal, and radiative characteristics of plasmonic nanofluids: academic insights and perspectives. Sol. Energy Mater. Sol. Cells. 236, 111504 (2022).

Asokan, N., Gunnasegaran, P. & Wanatasanappan, V. V. Experimental investigation on the thermal performance of compact heat exchanger and the rheological properties of low concentration mono and hybrid nanofluids containing Al2O3 and CuO nanoparticles. Therm. Sci. Eng. Progress. 20, 100727 (2020).

Rajamony, R. K. et al. Energizing the thermophysical properties of phase change material using carbon-based nano additives for sustainable thermal energy storage application in photovoltaic thermal systems. Mater. Today Sustain.25, 100658 (2024).

Kong, M. & Lee, S. Performance evaluation of Al2O3 nanofluid as an enhanced heat transfer fluid. Adv. Mech. Eng.12 (8), 1687814020952277 (2020).

Agarwal, R., Verma, K., Agrawal, N. K., Duchaniya, R. K. & Singh, R. Synthesis, characterization, thermal conductivity and sensitivity of CuO nanofluids. Appl. Therm. Eng.102, 1024–1036 (2016).

Toghraie, D., Chaharsoghi, V. A. & Afrand, M. Measurement of thermal conductivity of ZnO–TiO 2/EG hybrid nanofluid: effects of temperature and nanoparticles concentration. J. Therm. Anal. Calorim.125, 527–535 (2016).

Neogy, R. K. Heat Transport and Related Thermal Properties in Nanofluids and Nanostructured Materials. PhD thesis (SN Bose National Centre for Basic Sciences, 2012).

Ding, Y., Alias, H., Wen, D. & Williams, R. A. Heat transfer of aqueous suspensions of carbon nanotubes (CNT nanofluids). Int. J. Heat Mass Transf.49 (1–2), 240–250 (2006).

Bacha, H. B., Ullah, N., Hamid, A. & Shah, N. A. A comprehensive review on nanofluids: synthesis, cutting-edge applications, and future prospects. Int. J. Thermofluids, 100595 (2024).

Mahian, O. et al. Recent advances in using nanofluids in renewable energy systems and the environmental implications of their uptake. Nano Energy. 86, 106069 (2021).

Banisharif, A., Estellé, P., Rashidi, A., Van Vaerenbergh, S. & Aghajani, M. Heat transfer properties of metal, metal oxides, and carbon water-based nanofluids in the ethanol condensation process. Colloids Surf., A. 622, 126720 (2021).

Urmi, W. T., Rahman, M. M., Kadirgama, K., Abd Malek, Z. A. & Safiei, W. A comprehensive review on thermal conductivity and viscosity of nanofluids. J. Adv. Res. Fluid Mech. Therm. Sci.91 (2), 15–40 (2022).

Kadirgama, K. et al. Experimental investigation on the optical and stability of aqueous ethylene glycol/mxene as a promising nanofluid for solar energy harvesting. In IOP Conference Series: Materials Science and Engineering (IOP Publishing, 2021).

Basu, A., Saha, A., Banerjee, S., Roy, P. C. & Kundu, B. A review of artificial intelligence methods in predicting thermophysical properties of nanofluids for heat transfer applications. Energies17 (6), 1351 (2024).

Yadav, N., Yadav, R. R. & Dey, K. K. Microwave assisted formation of trimetallic AuPtCu nanoparticles from bimetallic nano-islands: why it is a superior new age biocidal agent compared to monometallic & bimetallic nanoparticles. J. Alloys Compd.896, 163073 (2022).

Singh, B. & Sood, S. Hybrid nanofluids preparation, thermo-physical properties, and applications: A review. Hybrid Adv. 100192. (2024).

Barthwal, M., Dhar, A. & Powar, S. Effect of nanomaterial inclusion in phase change materials for improving the thermal performance of heat storage: A review. ACS Appl. Energy Mater.4 (8), 7462–7480 (2021).

Hussein, A., Lingenthiran, K., Kadirgamma, M., Noor & Aik, L. Palm oil based nanofluids for enhancing heat transfer and rheological properties. Heat Mass Transf.54, 3163–3169 (2018).

Munyalo, J. M. & Zhang, X. Particle size effect on thermophysical properties of nanofluid and nanofluid based phase change materials: A review. J. Mol. Liq.265, 77–87 (2018).

Babar, H., Sajid, M. U. & Ali, H. M. Viscosity of hybrid nanofluids: a critical review. Therm. Sci.23(3 Part B), 1713–1754 (2019).

Awais, M. et al. Synthesis, heat transport mechanisms and thermophysical properties of nanofluids: A critical overview. Int. J. Thermofluids. 10, 100086 (2021).

Murshed, S., Leong, K. & Yang, C. Investigations of thermal conductivity and viscosity of nanofluids. Int. J. Therm. Sci.47 (5), 560–568 (2008).

Mohammed, H., Bhaskaran, G., Shuaib, N. & Saidur, R. Heat transfer and fluid flow characteristics in microchannels heat exchanger using nanofluids: a review. Renew. Sustain. Energy Rev.15 (3), 1502–1512 (2011).