FHF04SC is a sensor for general-purpose heat flux measurement, combined with a heater. It is used when the highest level of quality assurance is required and for long-term heat flux measurement. It is thin, flexible and versatile. FHF04SC measures heat flux through the object in which it is incorporated or on which it is mounted, in W/m2. The sensor in FHF04SC is a thermopile. This thermopile measures the temperature difference across FHF04SC’s flexible body. A type T thermocouple is integrated as well. The thermopile and thermocouple are passive sensors; they do not require power.

Multiple small thermal spreaders, which form a conductive layer covering the sensor, help reduce the thermal conductivity dependence of the measurement. With its incorporated spreaders, the sensitivity of FHF04SC is independent of its environment. Many competing sensors do not have thermal spreaders. The passive guard area around the sensor reduces edge effects and is also used for mounting.

Using FHF04SC is easy. It can be connected directly to commonly used data logging systems. The heat flux in W/m2 is calculated by dividing the FHF04SC output, a small voltage, by the sensitivity. The sensitivity is provided with FHF04SC on its product certificate. When used under conditions that differ from the calibration reference conditions, the FHF04SC sensitivity to heat flux may be different than stated on its certificate. See the user manual for suggested solutions.

Measuring heat flux, users may wish to regularly check their sensor performance. During use, the film heater is activated to perform a self-test. The heat flux sensor response to the self-test results in a verification of sensor performance. Implicitly also cable connection, data acquisition, thermal connection of sensor to its environment and data processing are tested. Heat flux sensors are often kept installed for as long as possible. Using self-testing, the user no longer needs to take sensors to the laboratory to verify their stable performance. In a laboratory environment, using a metal heat sink, you may even perform a formal calibration. The heater has a well characterised and traceable surface area and electrical resistance.

Would you like to to study energy transport / heat flux in detail? Hukseflux helps taking your measurement to the next level: order FHF04 with radiation-absorbing black and radiation-reflecting gold stickers. You can then measure convective + radiative flux with one, and convective flux only with the other. Subtract the 2 measurements and you have radiative flux. BLK – GLD stickers can be applied by the user to the sensor. Optionally, they can be ordered pre-applied. See the BLK – GLD sticker series user manual and installation video for instructions.