Comparison of stability and thermophysical properties of CNT–GNP hybrid nanofluids using different surface modification techniques

Abstract

This study examines how non-covalent and covalent surface modification methods affect the stability and thermo-physical characteristics of carbon nanotubes (CNTs) and graphene platelets (GNP) when distributed in solar thermal fluids. Surfactants are employed for examining non-covalent surface modification, while acid treatment is utilized for investigating covalent modification. Nanofluid samples are created with concentrations of 0.0625%, 0.125%, 0.25%, and 0.5% by weight in pure ethylene glycol (EG) and EG–water (80:20). Zeta potential analysis was utilized to study the stability of the nanofluids. The oxidized CNT–GNP nanofluids showed outstanding stability, with zeta potential values remaining almost constant for 60 d. Experiments were conducted on pure, surfactant-dispersed, and oxidized CNT–GNP nanofluids. The thermal conductivity of oxidized CNT–GNP nanofluids increased by 16% when 0.5 wt% was dispersed in the EG–water (80:20) sample. Nanofluids with CTAB and SDS showed a 14% and 13% enhancement in thermal conductivity, respectively. Formulas were created to forecast thermal conductivity and dynamic viscosity values.

Keywords:

• Solar thermic fluids
• nanofluids
• covalent functionalization
• surfactants
• thermal conductivity

REVIEWING EDITOR:

• Swadesh Kumar Singh, Gokaraju Rangaraju Institute of Engineering and Technology, INDIA

SUBJECTS:

• Heat Transfer
• Nanoscience & Nanotechnology
• Solar energy

Acknowledgments

The authors gratefully acknowledge the support received from GITAM (Deemed to be University), and Osmania University, Hyderabad for conducting the tests.

Author contributions

S. Bhanuteja: Data Collection, Experimentation, Manuscript Writing.

V. Srinivas: Conceptualization, Design, Experimentation, and Manuscript Writing.

K. Satyanarayana: Data Collection and Data Interpretation.

N. Darya Viktorovna: Methodology, Critical Feedback and Manuscript Review.

Ankita Joshi: Data Analysis and Data Visualization.

Disclosure statement

No conflicts to disclose.

Data availability statement

The data that support the findings of this study are available from the corresponding author, V. Srinivas, upon reasonable request.

Additional information

Funding

No funding received.