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What is a
Heat Flux Sensor?

Table of Contents


So what is a heat flux sensor?

What is a Heat Flux Sensor?

Heat flux sensors, also known as heat flow sensors, are devices used to measure the flow of heat through a material or across a surface. These sensors can be used to measure the heat transfer between two surfaces or within a single material.

Heat flux sensors operate by measuring the temperature difference between two points and the heat flow rate through a known cross-sectional area, allowing the user to calculate the heat flux, or the rate at which heat is transferred per unit of area, in W/m² for example.

What Are Heat Flux Sensors Used For?

Heat flux sensors are commonly used in a variety of applications, including building energy management, HVAC systems, aerospace, explosive research, and industrial processes. They can help to optimize energy efficiency and improve safety by monitoring temperature and heat transfer in various environments and systems.

Heat flux falls into three categories: radiative heat flux, conductive heat flux, and convective heat flux. There are heat flux sensors which are designed to measure one or a combination of all three heat flux components. To learn more about heat flux, read our article What is Heat Flux?

What Types of Heat Flux Sensors Are There?

Heat flux sensors come in various types and designs, each with its own unique features and capabilities. Some of the most common types of heat flux sensors include resistance temperature detectors (RTDs), thermocouples, and thermopiles.


  • Resistance Temperature Detectors (RTDs) are heat flux sensors that use the change in resistance of a material with temperature to measure heat flux. RTDs are highly accurate and have a wide temperature range, making them ideal for use in high-temperature applications such as solar thermal power plants.


  • Thermocouples are heat flux sensors that use the difference in voltage between two dissimilar metals to measure heat flux. They are easy to use and are commonly used in building insulation, as well as in solar thermal power plants.


  • Thermopiles are heat flux sensors that consist of multiple thermocouples connected in series. They are commonly used in solar radiometers and pyranometers, which are instruments used to measure the amount of solar radiation received by a surface.

What Does a Heat Flux Sensor Measure?

A heat flux sensor measures the flow of heat through a material or across a surface. Specifically, it measures the heat flux, or the rate at which heat is transferred per unit of area (W/m^2).

The FHF (Full Heat Flux) range of a heat flux sensor refers to the maximum heat flux that the sensor is capable of measuring. It is typically expressed in units of watts per square meter (W/m^2).

The FHF range of a heat flux sensor is determined by its design and construction, and can vary depending on the specific type of sensor. For example, some heat flux sensors may have a FHF range of 0 to 1000 W/m^2, while others may have a range of 0 to 2000 W/m^2 or more.

It is important to select a heat flux sensor with a FHF range that is appropriate for the specific application in which it will be used. If the heat flux in the application exceeds the FHF range of the sensor, it may not be able to accurately measure the heat flux.


A well-designed heat flux sensors is highly accurate, linear in response, stable, and suitable for a wide range of temperature environments, from cryogenic to extreme heat exposure environments. Heat flux sensor are also relatively easy to install and maintain, making them a popular choice for many industries.

Overall, heat flux sensors are an important tool for measuring and managing heat transfer in various applications. They provide valuable data on temperature and heat flow, which can be used to improve energy efficiency, safety, and overall performance.