Measurement of High-temperature Thermophysical Properties of Bulk and Coatings Using Modulated Photothermal Radiometry

In-situ thermal transport measurement of flowing fluid using modulated photothermal radiometry

“…Figure 1a displays the schematic of the MPR system integrated with a flowing liquid loop. The MPR system is the same as what was reported in our previous study [25] except that the test section is replaced with a circular tube connected to the fluid loop. A waveform-generator drove a continuous wave (CW) diode laser with its intensity modulated as sinusoidal function at the angular frequency of 𝜔.…”

“…θs was measured based on the thermal emission from the surface collected by a HgCdTe (MCT) detector after proper calibration using a pyrometer. More details of the MPR system can be found in our previous work [25].…”

“…The thermal emission from the tube surface is collected by an IR detector to measure the 𝜃 𝑠 after calibration with a pyrometer as described in detail in our earlier work [25]. Figure 2b shows the schematics of the momentum boundary layer Δ, thermal boundary layer 𝛿 and the thermal penetration depth 𝐿 𝑝 during the MPR measurement.…”

“…Photothermal radiometry (PTR) using either modulated (continuous wave) or pulsed laser is a wellknown non-contact thermal characterization tool for bulk and coating materials [23][24][25]. In the modulated photothermal radiometry (MPR), a sample is heated by an intensity-modulated laser to probe into different depths of the sample and its surface temperature response is measured with an infrared (IR) detector [24,26].…”

“…In the modulated photothermal radiometry (MPR), a sample is heated by an intensity-modulated laser to probe into different depths of the sample and its surface temperature response is measured with an infrared (IR) detector [24,26]. We have previously established the MPR technique for high-temperature measurements of bulk and thin coating samples, by using a refractory black coating for laser absorption and IR surface thermometry [25]. In this work, we applied the MPR technique for in-situ thermal conductivity measurement of flowing fluids within a pipe.…”