Shahid Chamran University of AhvazJournal of Applied and Computational Mechanics2383-45368320220701A New Modified Hamilton-Crosser and Nan Models for Thermal Conductivity of Different Lengths Carbon Nanotubes Water-based Nanofluids8318371553510.22055/jacm.2020.32882.2095ENMansoorFarbodPhysic Department, Faculty of Science, Shahid Chamran University of Ahvaz, Ahvaz, I.R. Iran0000-0002-9774-705XAmenehAhangarpourPhysic Department, Faculty of Science, Shahid Chamran University of Ahvaz, Ahvaz, I.R. Iran0000-0001-8239-7440Journal Article20200308In order to investigate the shape effect of nanoadditives on thermal conductivity of nanofluids, different length carbon nanotubes (CNTs) are made and using a two-step method, different nanofluids are prepared. The CNTs are cut into different lengths by functionalization at different refluxing times of 1, 2 and 4 hours. To probe the effect of aspect ratio of CNTs on the obtained experimental data, modified Hamilton-Crosser and Nan models are developed. It is found that the original Hamilton-Crosser and Nan models could not predict the experimental thermal conductivities. By replacing <em>n</em> = 6 + <em>xL</em>/<em>D</em> instead of the shape factor of n=6 in the Hamilton- Crosser, where <em>L</em> and <em>D</em> were length and diameter of CNTs and also by replacing φ (<em>xL</em>/<em>D</em>) instead of φ (volume fraction) in the Nan model, the prediction of modified equations show very good accordance with the experimental data which means the shape of nanoadditives has high impact on nanofluids’ properties.https://jacm.scu.ac.ir/article_15535_3daa87dc03c8c5d816f45aa5795499a5.pdf