This section provides an overview for heat flux sensors as well as their applications and principles. Also, please take a look at the list of 9 heat flux sensor manufacturers and their company rankings.
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Heat flux sensors, as the name implies, are sensors used to detect the amount of heat.
Let us explain heat quantity. Heat is the transfer of thermal energy from a high-temperature area to a low-temperature area. The amount of heat transferred is the heat flow. By measuring the heat flow, the amount of heat transferred can be determined and subsequent temperature changes can be estimated.
Heat flux sensors convert the amount of heat that passes through the sensor into an electrical signal, which can then be measured.
Heat flux sensors are flexible, can be attached to curved surfaces, and are waterproof.
Heat flux sensors have traditionally been used to evaluate and inspect the thermal insulation performance of housing equipment.
In recent years, applications outside of housing equipment have been increasing due to the miniaturization and flexibility of sensors. A typical example is the installation of heat flux sensors inside electronic components to measure the amount of heat generated by the electronic components. The results are then used to study heat dissipation measures.
Applications in automobiles also include an evaluation of heat loss in the engine compartment, seat heaters in the cabin, and air conditioners.
The principle of a heat flux sensor is to use a material with known thermal conductivity as a sensor and output an electrical signal due to heat flux by measuring the temperature of the front and back surfaces of the sensor. This is done using Fourier's law (which states that the amount of heat flowing per unit cross-sectional area and per unit time is proportional to the temperature gradient) and the Seebeck effect (that when a temperature difference is applied to both ends of a substance, a voltage is generated between the two ends).
The structure is sensitive because the detection is made by connecting thermocouples in series to plastic or ceramics with known thermal conductivity.
Current sensors use P-type and N-type semiconductors to reduce the size of the sensor. Since different semiconductors are used, the Seebeck effect generates a voltage, which can be measured to detect the amount of heat.
Attaching a heat flux sensor to a measured object causes errors due to contact thermal resistance. For this reason, sensors that are very thin and have low resistance have been developed in recent years.
Heat flux sensors must be selected to suit the installation location.
When using heat flux sensors, it is important to check the upper and lower limits of the usable temperature and use them under conditions within their specifications. Use under out-of-range temperature conditions can cause problems such as peeling of the adhesive surface.
Heat flux sensors are attached to the object to be measured either by embedding them in the installation surface or by attaching them to the installation surface. Adhesives or silicon grease with high thermal conductivity are used for attaching, and should be selected appropriately, depending on whether the installation is for a long or short period. When fixing, it is necessary to prevent air and foreign matter from entering the mounting surface. Before installing the Heat flux sensor, the direction of the heat flux and the polarity of the heat flux meter output should be checked by applying a temperature difference to the heat flux meter.
The heat flux is measured by converting the temperature difference that occurs between the front and back sides of the sensor as the heat flux passes through the heat flux sensor into an electromotive voltage. The heat flux is calculated from the following equation:
Q = E/k
Q: Heat flux (W/m²), E: Output voltage (mV), k: Sensitivity constant (mV/(W/m²))
As an example of the use of heat flux sensors, information on a technique for measuring the heat flux into and out of a material undergoing a phase change is reported.
In this measurement technique, the object to be measured is enclosed in a bag-shaped heat flux sensor, and the amount of heat flow in and out of the object can be measured. In addition, a system has been developed to measure the amount of heat inflow by placing a cooling agent in this bag-shaped heat flux sensor and display on an external terminal the amount of cooling capacity remaining and the remaining time for which the cooling effect will last.
According to this measurement technology, heat passes through the heat flux sensor and flows into the object, such as the refrigerant, so that the amount of heat inflow can be directly measured by measuring the output of the heat flux sensor. The system is also expected to contribute to improved convenience by making it possible to predict the melting of refrigerants used for low-temperature logistics, ice pillows, cooling of hot work clothes, etc., in advance and to acquire heat inflow histories, enabling replacement of refrigerants before they lose their refrigerant capacity.
*Including some distributors, etc.
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Wattco was founded in 1972 and is headquartered in Lachine, Quebec. Wattco is a manufacturer of electric heating products for use in many utilities including oil and gas, renewable energy, HVAC systems, as well as others. Wattco products include immersion, circulation, inline, flanged, screw plug, pipe, over the side, industrial bore, tubular, finned tubular, strip, finned strip, cartridge, band, silicone rubber, open coil element, duct, finned tubular duct heaters, infrared radiant heaters, as well as other combinations of heaters and control panels.
MOD-TRONIC Instruments Limited was established in 1972 in Brampton, Ontario, Canada. MTis a distributor of industrial sensors, transducers, heaters, controls, and instrumentation, primarily made in the USA as well as Japan, Switzerland, and Germany. MT’s customers are primarily in the aerospace, building automation, manufacturing, medical, military, oil and gas, and water treatment industries but also serves individuals. MT offers an above industry standard 5-year warranty and technical support on every product sold.
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