Investigation of the thermal characteristics of water-based hybrid and mono nanofluids containing cerium oxide-CuO-MWCNT nanoparticles at various temperatures and volume fraction of nanoparticles and propose a new relationship

In this study, the preparation of nanofluid (NF) is performed by the two-stage method by dispersing nanoparticles (NP) into the base fluid (BF). Hybrid nanofluids (HNFs) were prepared in the solid volume fractions (SVFs) of SVF=0.1, 0.2, 0.3, 0.4 and 0.5% and mono nanofluids (MNFs) were made in SVF=0.1 and 0.3 %. After ensuring stability, the thermal conductivity (TC) of HNFs and MNFs is measured by the hot wire method at a temperature range of T=20 to 60°C. The results indicate that the TC (For HNFs and MNFs) increases as the temperature increases. Increasing the SVF also increases TC, which is more evident in the higher SVFs. According to the obtained results, the highest increase in the TC is related to the MWCNT-CuO-cerium oxide/water HNF in SVF=0.5% and T=60°C, which is a 26.7% increase compared to BF. In SVF=0.3%, the MNFs containing MWCNTs NPs have a better performance than the HNFs. Compared to the results with the relationship of Lu-Lin, it was found that the temperature is critical in increasing the TC. There are no temperature parameters in the Lu-Lin model, therefore there is a difference between the laboratory results and the Lu-Lin model results. Finally, based on experimental data, a mathematical relationship between temperature and SVF was proposed to predict the TC for HNF water/cerium oxide-CuO-MWCNT. Comparing the experimental data to the outputs of the proposed relationship shows that this relationship is accurate.