Session: 12-10-01: Heat Transfer in Natural and Build Environments

Paper Number: 193018

Exergy Performance of FND Enhanced Mineral Oil in a Shell and Tube Heat Exchanger 

Conventional mineral oils remain the dominant working fluids in industrial thermal management systems because of their chemical stability, dielectric strength, and compatibility with existing equipment. Despite these advantages, their inherently low thermal conductivity constrains heat transfer performance and limits the efficiency of cooling processes in applications such as transformers, power electronics, and compact heat exchangers. Recent research has explored the use of functionalized nanodiamond (fND) particles as performance‑enhancing additives due to their exceptionally high intrinsic thermal conductivity, chemical inertness, and ability to disperse stably in hydrocarbon-based oils. While prior studies have demonstrated measurable improvements in heat transfer coefficients and thermal transport properties, most evaluations rely exclusively on First Law metrics that quantify energy transfer without accounting for thermodynamic irreversibilities. Such metrics overlook the role of entropy generation and exergy destruction, which ultimately govern the true thermodynamic efficiency of thermal systems.

This study presents a comprehensive Second Law numerical analysis of CT206 mineral oil enhanced with fND nanoparticles flowing through a shell‑and‑tube heat exchanger. A three‑dimensional computational fluid dynamics model is developed in ANSYS Fluent to resolve the coupled momentum, energy, and entropy generation fields. Temperature‑dependent thermophysical properties are incorporated for nanoparticle volume fractions of 0.5%, 1.0%, 1.5%, and 2.0%, and viscous heating effects are included to capture the full thermodynamic behavior of the nanofluid under realistic operating conditions. Custom field functions are implemented to compute local volumetric entropy generation and to decompose total irreversibility into contributions from thermal gradients and viscous dissipation. Model predictions are validated against available experimental steady‑state data for both base oil and nanofluid cases.

Results show that the addition of fND nanoparticles systematically reduces exergy destruction across the heat exchanger by enhancing thermal conductivity and reducing the temperature gradients required to achieve a given heat duty. Among the concentrations studied, the 2.0% fND nanofluid exhibits the greatest reduction in entropy generation while maintaining acceptable viscosity levels. Spatial maps of entropy generation identify regions of dominant thermodynamic losses, providing insight into how nanoparticle-enhanced fluids redistribute irreversibility within the exchanger geometry. The findings demonstrate that Second Law analysis offers a more complete assessment of nanofluid performance than conventional heat transfer metrics alone. The proposed CFD‑exergy framework highlights the potential of fND‑enhanced mineral oils to improve thermodynamic efficiency in advanced thermal management systems and offers a pathway for optimizing nanofluid formulations for industrial heat exchanger applications. The proposed CFD‑exergy framework highlights the potential of fND‑enhanced mineral oils to improve thermodynamic efficiency in advanced thermal management systems and offers a pathway for optimizing nanofluid formulations for industrial heat exchanger applications.

Presenting Author: Md. Abdul Goni Raju Tennessee Tech University

Presenting Author Biography: Abdul is a PhD student at TTU.

Authors:

Md. Abdul Goni Raju Tennessee Tech University
Nikita Tungar Stantec
Rajendra Tadakhe Tennessee Tech University
Ethan Languri Tennessee Tech University
Jim Davidson International FemtoScience
Lu Liu University of Tennessee Space Institute