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Heat Transfer Fluids Heat Transfer Fluids

Measuring the Thermal Conductivity of Heat Transfer Fluids

Temperature management and heat transfer are essential components of industrial processes and systems. Heat transfer fluids (HTFs) are often used in cases where materials or devices need to be heated, cooled or maintained at stable operating temperatures. Such fluids serve to absorb, transports and dissipate heat in a variety of industries such as electronic transformers and polymer production.

Improving thermophysical parameters of a HTF is an important part of making an industrial process more efficient. With a wide range of available fluids specific to various applications, reliable and accurate thermal conductivity characterization is critical.

C-Therm’s Transient Hot Wire (THW) is the preferred method for testing the thermal conductivity of heat transfer fluids due to its short testing times, minimizing the effect of convection on the fluids. C-Therm’s Modified Transient Plane Source is also capable of measuring the thermal conductivity of heat transfer fluids with the MTPS Liquid and Powder Cell. This is another great option as MTPS is the easiest sensor to use with its plug-and-play design.

Trident Instrument with THW and MTPS

  • C-Therm's Trident delivers rapid, accurate thermal conductivity testing to optimize engine coolant performance and heat transfer efficiency.

    C-Therm's Trident delivers rapid, accurate thermal conductivity testing to optimize engine coolant performance and heat transfer efficiency.

  • C-Therm's Trident delivers fast, precise thermal conductivity testing to optimize e-liquid formulations and ensure consistent vaping performance.

    C-Therm's Trident delivers fast, precise thermal conductivity testing to optimize e-liquid formulations and ensure consistent vaping performance.

  • C-Therm’s Transient Hot Wire sensor delivers fast, accurate thermal conductivity measurements across liquids, solids, and pastes.

    C-Therm’s Transient Hot Wire sensor delivers fast, accurate thermal conductivity measurements across liquids, solids, and pastes.

  • C-Therm's patented MTPS offers a more robust, accurate, and user-friendly solution, especially for materials with low thermal conductivity or where ASTM compliance is required

    C-Therm's patented MTPS offers a more robust, accurate, and user-friendly solution, especially for materials with low thermal conductivity or where ASTM compliance is required

  • National Aeronautics and Space Administration (NASA)

    We purchased the C-Therm TCi Thermal Conductivity Analyzer after seeing a demonstration of how fast and easy it is to operate. The instrument provides unequivocal results and provides the flexibility to test powders and liquids. In terms of our satisfaction with the purchase, I’d give it a 10 out of 10 - extremely satisfied.”

    Dr. Enrique Jackson,
    NASA (Sector: Aerospace)

    National Aeronautics and Space Administration (NASA) More Testimonials

Case Highlights

Measuring the Thermal Conductivity of Heat Transfer Fluids via the Modified Transient Plane Source

Oil offers advantages over water-based fluids in transformers via its large temperature range and electrical insulating properties. Appropriate thermal conductivity of the transformer oil is necessary to prevent failures during instantaneous overload.

Water, ethylene glycol, and mineral oil are popular heat transfer materials in engines, nuclear systems, energy production and supply, as well as many other fields. For this reason the three heat transfer fluids used in this study include distilled water, ethylene glycol from Evans Cooling Systems and Luminol TR-1 transformer oil from Petro-Canada.

The TCi’s small volume test kit (left) was utilized to test the liquid samples. Convection effects are minimized with a required sample volume of 1.25 ml per test. Test results over a temperature range of -25°C to 100°C are displayed below. Experimental data was found to compare within 1.85% accuracy of the comparable calculated book values.

 

 

Measuring the Thermal Conductivity of e-Liquids via the Transient Hot Wire

In the design and performance of e-cigarettes (vapes), the thermal behaviour of the e-liquid plays a critical role in determining vaporization efficiency, aerosol composition, and overall user experience.

Thermal conductivity (k) is the property that quantifies how well a material conducts heat. For e-liquids, this determines how quickly and uniformly the coil’s heat distributes into the fluid. If an e-liquid cannot conduct heat away efficiently, even a modest-sized coil can develop a steep temperature gradient: extremely hot at the coil surface and much cooler just a short distance away.

Transient Hot Wire (THW) is an excellent choice due to its short test times and low power inputs, which are two factors that help mitigate the impact of convection during measurement. The following data demonstrates the use of the THW in  testing the different components of e-liquids and a commercially available e-liquid containing 70% VG and 30% PG.

The results above are the average of 5 consecutive measurements. Both PG and VG align with the expected literature values (within 3%). Comparing a 70/30 mix to a commercially available e-liquid, we observe near identical results (0.268 vs 0.263 W/mK).

Resources

Frequently Asked Questions

Measuring a fluid’s thermal conductivity helps evaluate:

  • Cooling efficiency in electronics and industrial systems
  • Heat-transfer performance under different conditions
  • Material suitability for design and production

Request a quote or call +1-877-827-7623 (toll-free) or +1 (506) 457-1515 (international) to speak with one of our experts to learn how fluid measurements can support your product development.

Common fluids include:

  • Water-based coolants and glycols
  • Thermal oils and phase-change fluids
  • Emulsions, gels, and slurries
  • Specialty nanofluids and engineered formulations

Both low- and high-viscosity fluids can be measured reliably. The Trident system can handle a wide variety of formulations, making it suitable for R&D and industrial applications. Request a demo to see your fluid types tested.

Key properties include:

  • Thermal conductivity
  • Thermal diffusivity
  • Thermal effusivity

These measurements are critical for fluid performance evaluation, system optimization, and material qualification. The Trident system can accurately measure all of these properties using advanced transient plane source (MTPS) techniques, and the heat capacity is calculated.

Yes. Temperature-controlled setups allow measurement across a wide temperature range, helping you understand how fluids behave under real operating conditions. Applications include:

  • Cooling systems and heat exchangers
  • Energy storage fluids
  • Process fluids in industrial applications

Call one of our experts at +1-877-827-7623 (toll-free) or +1 (506) 457-1515 (international) to determine the best temperature setup for your fluid testing.

It varies by method, but a minimum of 2 ml is typically required. This small volume allows rapid testing while keeping sample usage efficient.

Measurements are typically better than ±5% with high repeatability. Modern transient methods provide:

  • Stable results across low- and high-viscosity fluids
  • Low sensitivity to operator variation
  • Reliable performance for R&D and industrial quality control

Thermal conductivity measurements follow recognized standards:

  • ASTM D5930 – Transient Line Source (TLS) method
  • ASTM D7896-19 – C-Therm’s THW method
  • ASTM D7984 – C-Therm’s MTPS method

These standards ensure reliable, repeatable, and comparable results across different fluids. For details on the four different methods available on the Trident system, please see this link.

Selection depends on:

  • Fluid type and viscosity
  • Temperature range
  • Required measurement precision.

A technical specialist can recommend the optimal setup and sensor configuration to ensure accurate results. Request a consultation to select the best method for your fluids.

SIMPLIFYING THERMAL CONDUCTIVITY

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