Heat flow meter

A heat flux sensor is a thermopile sensor, consisting of thermocouple junctions arranged uniformly across the sensor surface. Each individual junction generates an electrical voltage, proportional to the difference in temperature across the hot and cold junctions of the thermocouple. For accurate measurements of heat flux, one flux sensor with three surface thermocouples is integrated into the surface of each testing plate of the HFM. This intimate contact reduces the level of calibration required, resulting in improved test results.

Thermoelectric Peltier elements are used to heat and cool the HFM testing plates. A thermoelectric element is a solid-state active heat pump which transfers heat from one side of the device to the other, with consumption of electrical energy, depending on the direction of the current. This flexibility allows the user to easily change heating, and cooling direction, to best match their testing application, at a temperature resolution of <0.01°C (0.018°F). Each plate contains multiple high power thermoelectric modules, matched with a surface thermocouple, and smart temperature control to optimize the speed, and accuracy of the plate temperatures.

Accurate sample thickness is optimal for determining thermal resistance of a material with the measurement of thermal conductivity. The HFM-100 system features the advantage of either an automatic determination of sample thickness, for rigid materials, or a user defined sample thickness, for compressible materials. Sample thickness is measured using digital optical encoder technology. Four encoders are positioned at each corner of the top sample plate. Multi-position encoder placement ensures the most accurate (< 0.05 mm / 0.0019 in) measurement of sample thickness, and in the end, thermal resistance for materials being measured.

The HFM-100 offers users two versatile and convenient methods of operation—run your measurements independently using the integrated front control panel, or by using the feature packed Windows based HFM-100 software included with each system. The simple to use software offers additional features over the front panel operation, including unlimited steps of temperature automation when testing, and additional functions like saving, exporting, and printing measurement results. With front panel control, users can automate up to five steps of temperature when making measurements, or unlimited steps with the HFM software. HFM results are conveniently available in both SI, and Imperial Units of measure.

For rigid materials, plates automatically clamp together for optimum contact between sample and heat flux sensors. For compressible materials, the desired height of the sample may be entered manually and the plate will automatically stop at the entered sample height.

Every HFM-100 system comes complete with one Standard Reference Material (SRM) from the National Institute of Standards and Technology (NIST). SRM 1450e- Fibrous Glass-Board is certified for thermal conductivity from 6.85 to 66.85 ̊C (44.33 to 152.33 ̊F), and is available in a thickness of 25 mm (1 in). Additionally available is SRM 1453 – Expanded Polystyrene Board is certified for thermal conductivity from 7.85 to 39.85 ̊C (46.13 to 103.73 ̊F), and is available in a thickness of 12.5 mm (0.5 in). In addition to NIST Standard Reference Materials, Thermal Transfer Standards (TS) can be developed by Thermtest, for specialized testing applications.