Carbon nanotubes flowing through thermal oil.

Flow Like Water: How Nanofluids Could Revolutionize Cooling Tech

Soraya Malik in Tech & Innovation August 2025 • 4 min read.

"Unlocking the potential of MWCNT-thermal oil nanofluids for advanced heat transfer – a simple guide for everyone."

Nanofluids are generating buzz because of their potential to transform many different applications. While they're already used in areas like drug delivery and electronics, the energy sector is particularly interested in their ability to improve heat transfer. However, one major hurdle is managing the increase in viscosity (thickness) that comes with these fluids. This is a big deal because it impacts how effectively they can be used in cooling systems.

The behavior of nanofluids is as important as their thermal properties when it comes to real-world use. Think about it: the amount of power needed to pump these fluids through cooling systems and heat exchangers depends directly on how they flow [4,5]. So, understanding and tweaking their rheological (flow) properties is essential.

Carbon nanotubes are increasingly viewed as an important material in various applications. Adding carbon nanotubes to oil can significantly improve its thermal conductivity, as noted by Choi et al. [6]. Still, there hasn't been much research into how different types of oil-based nanofluids behave. To really use carbon nanotubes in industrial settings, we need a complete understanding of their rheological properties when mixed with oil [7]. It's worth remembering that nanoparticles act differently depending on the type of oil, which is influenced by how well the mixture is stabilized and the oil's viscosity index.

The Secret Sauce: Mechanical Stabilization

Carbon nanotubes flowing through thermal oil.

Keeping nanofluids stable has always been a challenge [8]. Traditionally, researchers have used chemical methods to help nanomaterials disperse evenly in base fluids. This often involves adding surfactants or modifying the nanoparticles. However, these chemical stabilization techniques aren't ideal for many applications. Adding carboxylic acids to the nanoparticle surface, for example, can increase the acidity of the nanofluid [9].

There are numerous models that attempt to predict how viscous nanofluids will be, but many fall short. Bashirnezhad et al. [10] highlighted that factors like agglomeration, sonication time, and the type of base fluid must be considered to create accurate models. Baratpour et al. [11] found that increasing the concentration of single-wall carbon nanotubes (SWCNT) in ethylene glycol also increased viscosity. More data is needed about CNT-oil-based nanofluids.

Here's what this research study focused on:

Investigating the rheological behavior of carbon nanotubes in a paraffinic thermal oil.
Achieving stability through mechanical mixing alone.
Avoiding the use of stabilizers or surfactants.
Analyzing how the nanofluids behave under different conditions.

The goal was to understand how carbon nanotubes behave in paraffinic thermal oil without adding any stabilizers or surfactants. By using only mechanical mixing, the researchers aimed to create stable nanofluids and study their rheological behavior under various conditions.

The Future is Fluid

This research paves the way for using carbon nanotubes in thermal oil for advanced cooling systems. By understanding the rheological behavior of these nanofluids, we can better select the right concentrations for heat transfer applications. The insights from this study could lead to more efficient and sustainable cooling technologies.

About this Article -

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This article is based on research published under:

DOI-LINK: 10.1016/j.icheatmasstransfer.2017.07.015, Alternate LINK

Title: Rheological Behavior Of Mechanically Stabilized And Surfactant-Free Mwcnt-Thermal Oil-Based Nanofluids

Subject: Condensed Matter Physics

Journal: International Communications in Heat and Mass Transfer

Publisher: Elsevier BV

Authors: Suhaib Umer Ilyas, Rajashekhar Pendyala, Marneni Narahari

Published: 2017-10-01

Everything You Need To Know

Why is managing viscosity so important when using nanofluids for cooling?

Nanofluids have the potential to improve heat transfer, which is crucial in various applications, particularly in the energy sector. However, a major challenge is the increase in viscosity (thickness) of these fluids, impacting their effectiveness in cooling systems. Understanding and controlling the rheological properties of nanofluids is essential for optimizing their use in real-world applications like cooling systems and heat exchangers.

What is mechanical stabilization in the context of nanofluids, and why is it significant?

Mechanical stabilization involves using mechanical mixing alone to keep the nanomaterials dispersed evenly in base fluids, without adding stabilizers or surfactants. This approach avoids the downsides of chemical methods, such as increased acidity from adding carboxylic acids to the nanoparticle surface. The study aimed to understand how carbon nanotubes behave in paraffinic thermal oil using only mechanical mixing to create stable nanofluids and study their rheological behavior under various conditions.

How do carbon nanotubes enhance thermal conductivity in oil, and what knowledge gaps exist?

Carbon nanotubes are increasingly important in various applications, and adding them to oil can significantly improve its thermal conductivity. However, there hasn't been enough research into how different types of oil-based nanofluids behave. A complete understanding of their rheological properties when mixed with oil is necessary for using carbon nanotubes effectively in industrial settings. The type of oil, how well the mixture is stabilized, and the oil's viscosity index influence how nanoparticles act.

What factors influence the viscosity of nanofluids, and why is accurate modeling challenging?

Factors like agglomeration, sonication time, and the type of base fluid must be considered to create accurate models that predict the viscosity of nanofluids. Bashirnezhad et al. [10] highlighted the importance of these factors. Baratpour et al. [11] found that increasing the concentration of single-wall carbon nanotubes (SWCNT) in ethylene glycol also increased viscosity. More data is needed about CNT-oil-based nanofluids to improve the accuracy of these models.

What was the primary objective of the research on carbon nanotubes in thermal oil?

The study focused on investigating the rheological behavior of carbon nanotubes in a paraffinic thermal oil, achieving stability through mechanical mixing alone, and avoiding the use of stabilizers or surfactants. By understanding the rheological behavior of these nanofluids, we can better select the right concentrations for heat transfer applications. The insights from this study could lead to more efficient and sustainable cooling technologies.