FHF05SC series heat flux sensors

FHF05SC sensors are sensors for general-purpose heat flux measurement, combined with a heater. This combination is used when the highest level of quality assurance is required and for long-term heat flux measurements. FHF05SC sensors are thin, flexible and versatile. The heat flux sensor in  FHF05SC measures heat flux through the object in which it is incorporated or on which it is mounted, in W/m². The sensor within is a thermopile. This thermopile measures the temperature difference across FHF05SC’s flexible body. A type T thermocouple is integrated as well to provide a temperature measurement. The thermopile and thermocouple 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 FHF05SC sensors is independent of their environment. Many competing sensors do not have thermal spreaders so their sensitivity cannot be relied upon; it depends on the material on which they are mounted. The passive guard area around the FHF05SC sensor reduces edge effects and is also used for mounting.

The unique feature of the FHF05SC sensors is an incorporated heater. This heater may be used for self-testing purposes. When activated, the heater does require power.

Looking only for heat flux and temperature measurement without the heater? See our FHF05 series heat flux sensors.

Unique features and benefits:

• heater for self-test
• flexible (bending radius ≥ 15 x 10⁻³ m)
• low thermal resistance
• wide temperature range 
• fast response time
• integrated type T thermocouple
• robustness, including potted connection block, may be used as strain relief
• IP protection class: IP67 (essential for outdoor application)
• integrated thermal spreaders for low thermal conductivity dependence

Using an FHF05SC sensor is easy. For heat flux measurements, it can be connected directly to commonly used data logging systems. The heat flux in W/m² is calculated by dividing the sensor output, a small voltage, by the sensitivity.

The sensitivity is provided with the sensor on its product certificate. When used under conditions that differ from the calibration reference conditions, the FHF05SC series sensitivity to heat flux may be different than stated on its certificate. See the user manual for suggested solutions.

Make sure your data acquisition accepts type T thermocouples to perform temperature measurements.

Measuring heat flux, users may wish to regularly check their sensor performance. During use, the film heater can be activated to perform a self-test.

The heat flux sensor's response during self-test verifies its performance. Implicitly also, cable connection, data acquisition, thermal connection of the sensor to its environment and data processing are tested. Heat flux sensors are often installed for long periods of time. Using self-testing, the user no longer needs to take sensors to the laboratory to verify their stable performance. The heater has a well-characterised and traceable surface area and electrical resistance.

Equipped with a potted cable connection block, that prevents moisture from entering and may also serve as strain relief, FHF05SC sensors have proven to be very robust and stable. 

Requirements for data acquisition and control:

• for heat flux: one millivolt measurement
• for heater voltage: one voltage measurement
• optional, for heater current: one current measurement or voltage measurement over a resistor
• for switching the heater current on and off: one relay with 12 VDC nominal output

Would you like to study energy transport / heat flux in detail? Hukseflux helps taking your measurement to the next level: order FHF05SC series 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. There are stickers for every sensor dimension. Optionally,  they can be ordered pre-applied. See the BLK – GLD sticker series user manual and installation video for instructions.