Heat flux measurement fundamentals and applications

Hukx is the global market leader in heat flux measurement. This white paper briefly explains the fundamentals of measuring with heat flux sensors. It also offers general directions what to watch out for and some, perhaps surprising, applications of heat flux sensors. More information? Please contact Hukx.

Heat flux sensors measure energy flux onto or through a surface in [W/m²]. The heat may be transported by conduction, radiation, or convection. All heat transfer is driven by temperature differences, flowing from a hot source to a cold sink. Convective and conductive heat flux is measured by letting this heat flow through the sensor. Radiative flux is measured using heat flux sensors with black absorbers; the absorber converts radiative to conductive energy. Hukx started designing heat flux sensors in 1993.

Heat flux sensors manufactured by Hukx are optimized for the demands of different applications. The most important variables are:

• rated temperature range
• rated heat flux range/with or without cooling
• sensitivity
• response time
• chemical resistance, safety requirements
• size, shape, flexibility and spectral properties

Hukx heat flux sensors typically employ thermopiles. Thermopiles generate a signal, as a result of the temperature difference between the hot and cold side of the thermopile. The signal is proportional to the heat flux. Thermopiles are passive sensors; they do not require power. The output is usually a small millivolt signal.