High heat flux mapping using infrared images processed by inverse methods: An application to solar concentrating systems

• Solar concentrating systems can achieve heat flux higher than 1000 kW/m2.
• The determination of the incident heat flux at the focal spot is challenging.
• A new approach using inverse methods is proposed.
• This method only requires a common steel plate and an IR camera.
• It was successfully applied to an image furnace with an heat flux overpassing 1350 kW/m2.

With the spreading of solar concentrating devices and artificial suns, it has become critical to characterize the incident heat flux at the focal spot of such devices. In this paper a new method that allows the determination of incident heat flux at the focal spot concentrating devices has been developed. This approach is based on an inexpensive experimental device and basic inverse methods which are used to compute a map of the incident heat flux. The experimental setup is made of a common steel screen and an IR camera. Starting at ambient temperature, the screen is exposed to the incident heat flux. The evolution of the screen temperature field over time is recorded using the IR camera. The inverse model then uses temperature data to compute a map of the incident heat flux. Results at moderate heat flux were validated by comparison with Gardon radiometer readings: the agreement between the two methods is very good. This method yields a high resolution map without the need of an external scaling factor which is mandatory in the method using a CCD camera.