Synthesis, characterization, stability and thermal conductivity of multi-walled carbon nanotubes (MWCNTs) and eco-friendly jatropha seed oil based nanofluid: An experimental investigation and modeling approach Wajid Ur Rehman a , Zulkifli Merican Aljunid Merican a, ⁎, Aamir Hussian Bhat b , Beh Guan Hoe a , Aliyu Adebayo Sulaimon c , Omid Akbarzadeh d , Muhammad Saad Khan e , Ahmad Mukhtar e , Sidra Saqib f , Ayesha Hameed g , Nurhayati Mellon e , Hafeez Ullah e , Sami Ullah h , Mohammed Ali Assiri h a Fundamental & Applied Sciences Department, Universiti Teknologi PETRONAS, 32610 Bandar Seri Iskandar, Perak, Malaysia b Department of Applied Sciences, Higher College of Technology, P.O. Box 74, Al-Khuwair-133, Muscat, Oman c Petroleum Engineering Department, Universiti Teknologi PETRONAS, 32610 Bandar Seri Iskandar, Perak, Malaysia d Nanotechnology & Catalysis Research Centre, University of Malaya, Kuala Lumpur 50603, Malaysia e Chemical Engineering Department, Universiti Teknologi PETRONAS, 32610 Bandar Seri Iskandar, Perak, Malaysia f Department of Chemical Engineering, COMSATS University Islamabad, Lahore, Campus, Defense Road, Punjab 54000, Pakistan g School of Chemical and Materials Engineering, National University of Science and Technology, Islamabad, Pakistan h Department of Chemistry, College of Science, King Khalid University, Abha 61413, Saudi Arabia abstract article info Article history: Received 10 May 2019 Received in revised form 13 July 2019 Accepted 7 August 2019 Available online 08 August 2019 Despite the remarkable nanofluids potential in energy storage applications, the long-term dispersion stability of the nanoparticles in a base fluid along with improved thermal conductivity is a significant challenge towards their commercialization. Therefore, a novel surfactant MWCNTs and eco-friendly Jatropha seed oil based nanofluid are synthesized via one-step synthesis method and subjected to characterization via visual analysis, FTIR, Zeta potential, pore size distribution, thermogravimetric analysis (TGA), and UV analysis to investigate MWCNTs dispersion stability along with thermal conductivity measurement. The results showed the excellent MWCNTs dispersion stability in Jatropha seed oil and thermal conductivity improvement from 2.29% to 6.76% over the temperature within the range of 25–65 °C and nanoparticle weight fraction in the range of 0.2–0.8 wt %. Furthermore, two new correlations are proposed based on multiple non-linear regression analysis and dimen- sionless group analysis in the replacement of classical models which are failed to accurate prediction of thermal conductivity. The developed models showed remarkable thermal conductivity prediction accuracy with the value of R 2 N 0.991. © 2019 Elsevier B.V. All rights reserved. Keywords: MWCNTs Jatropha seed oil Nanofluid Thermal conductivity Correlation Stability Dimensionless groups analysis 1. Introduction Environmentally friendly and highly efficient thermal systems are accounted for as one of the most critical requirements of the process in- dustries. By considering the remarkable part of the energy and environ- mental pollution, the intensification of heat transfer to minimize fuel consumption and air pollution are significant importance [1–3]. Many industrial applications including automobile radiators [4], microchannels solar thermal devices [5], microchannel heat sink cooling [6,7], coolant in annular heat exchangers [8], working fluid in plate heat exchanger [9], boiling fluid in concentric annuli [10], coolant in high flux heater [11], cooling of central processing units of electronic devices [12], refrigeration and direct solar collectors [13], energy, chem- ical engineering, manufacturing, aerospace, construction, automobile, transportation, environment, biomedicine, information, microelectron- ics, and nuclear power plants utilized heat exchanger to for heat transfer between two or more fluids [14,15]. These advancements develop deep attention to develop a micro scale-based device for fluid flow, with exceptional specific surface area, efficient ratio of a specific surface to volume in comparison with the traditional fluid flow-based devices for efficient heat transfer [15]. In the current era, extensive experimental investigations have been car- ried out on the utilization of various methods for heat transfer intensifi- cation and flow assurance in the heat transfer devices. In this regard: the most significant mode of the heat transfer, i.e., convection mode, has Journal of Molecular Liquids 293 (2019) 111534 ⁎ Corresponding author. E-mail address: zulkifli.aljunid@utp.edu.my (Z.M.A. Merican). https://doi.org/10.1016/j.molliq.2019.111534 0167-7322/© 2019 Elsevier B.V. All rights reserved. Contents lists available at ScienceDirect Journal of Molecular Liquids journal homepage: www.elsevier.com/locate/molliq