Phase change material thermal energy storage
phase change materials thermal energy storage

Phase change material thermal energy storage characterization with Heat Flux Sensors


This short review describes how heat flux sensing technologies can be employed to characterize phase change material thermal energy storage for a broad range of research and industrial applications.


About the phase change material thermal energy storage


phase change material

Heat flux is an important metrics for understanding and optimizing Phase Change Materials (PCMs) thermal energy storage.

PCMs are nowadays very well characterized by the Differential Scanning Calorimetry (DSC) method.

The thermal storage and release characteristics not only depend on the material’s characteristics but also on its integration and application. For an optimal integration in your application, thermal characteristics need to be determined.

How to perform phase change material thermal characterization with gSKIN® Heat Flux Sensor?


Which sensor is most suitable?


Depending on your application:
To measure the heat flux from the air into the material or vice versa, we suggest using our XO sensor. The silicon package of the sensor has the advantage of adapting the surface profile very well. Furthermore, the thermal mass of the silicon helps to reduce noise from thermal convection
To integrate the sensor into a measurement setup or a heat exchanger – depending on the available space and the required resolution, we suggest you to use the Al packaged low thermal resistance XM (4mm x 4mm), XP (10mm x 10mm) or XI (18mm x 18mm) sensors.


greenteg heat flux sensor

What kind of sensor do you require for your application?

Download our purchasing guide to find out more !


What kind of data acquisition tool do I need?

Depending on your application:

  • To measure the characteristics of the PCM vs. air (for example a wall of a building), the U-Value KIT should be best suited – It includes a small powerful data logger with low energy usage which can store more than 2 million data points. The logger can also be combined with the XM, XP and the XI sensor. See above an example of data acquired from the U-value kit attached to an insulated building wall.
  • When using heat flux sensors for application where the heat flux can be larger than 500W/m2 (in a heat exchanger), one should use any kind of data logger which is able to resolve at least 1uV.
phase change materials thermal energy storage

How do I integrate or attach the sensor?

  • For the measurements vs. air, the sensor can simply be attached to the surface with tape.
  • For the integration into a measurement setup or a heat exchanger, it is recommended to make a notch of the appropriate size into the heating/cooling plate which gets in contact with the sample. Make sure to clean the surfaces where you would like to attach the sensor with Isopropanol. Then, you can either glue the sensor into that notch by a thermal epoxy glue or mechanically sandwich it between the sample and the notch in the plate using thermal paste between the sample and the sensor and the sensor and the cooling/heating plate. Another possibility is to fix the sensor on the surface of the heater/cooler in a manner that all heat is forced through the sensor. This can be done by a thermal double side sticky tape, thermal glue or thermal paste.
  • To removing of the sensor from a surface: Work very carefully – It is advised to use Isopropanol or Acetone to weaken the thermal tape. Then you can remove the sensor with a sharp blade. Avoid applying any forces onto the cable.

Are the sensors resistant against water and chemicals?

The sensors survived the standard highly accelerated stress test (HAST) at 85% humidity and 125°C for 95h without any problems. We have been also using the sensors for several experiments in deionized water. Since the surface of the sensor consist of Aluminum and Polyimide, it might also be chemical resistant. However, we have not done any tests yet into this regards. You would need to cover the contacts and the sidewall of the sensors by a protective coating (for example epoxy glue). All usage of the sensors in environments different than air are on your own responsibility.

How are the sensors calibrated?

The sensors are calibrated in a special measurement setup using NIST traceable thermal reference materials. For further information see here.


Why choosing to perform Phase change material thermal energy storage characterization with gSKIN® Heat Flux Sensor?


Advantages of gSKIN® Heat Flux Sensor

gSKIN® Heat Flux Sensor presents many advantages for your application:

  • Miniature & compact heat flux sensor with low thermal resistance.
  • Complement your DSC with our highly sensitive sensor
  • Facilitated thermal storage characterization integration into the application setups
  • Determine the thermal conductivity of your material.


Elevated body Temperature monitoring

  • Quantify the heat flow into and from your heat exchanging system or measurement setup with small and low thermal resistance heat flux sensors.
  • Use the U-Value KIT to characterize thermal storage capabilities and release characteristics of materials and walls vs. air and other media with high thermal transfer coefficient.

More R&D Uses Cases where the gSKIN® Heat Flux Sensor is employed are available here.


Examples of PCMs applications


  • Fischer and his team at the University of Applied Science in Lucerne integrated the gSKIN®- heat flux sensor into a heat exchanger to characterize the storage capacity of ice for building applications. Read the abstract for the presentation at the IERS conference here.
  • GLASSX, a company providing highly efficient PCM based windows, used the U-Value Kit with the gSKIN®-XP sensor to validate their thermal storage model for product improvements. More information available here.


Heat flux sensor measurement

Do you want to measure heat flux in your application?

We can help you finding the custom solution to suit your application.