Measurement of the thermal conductivity of fluids using laser spot lock-in thermography
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Date
2020-03-25Author
Bedoya Pérez, Adrián Felipe
Marín Moares, Ernesto
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Measurement 158 : (2020) // Article ID 107740
Abstract
In this work, we propose a new method to retrieve the thermal conductivity of fluids, kf, using laser spot
lock-in infrared thermography. The measurement cell consists in two paralepidid blocks separated by a
narrow gap of variable and known width, L. This gap can be filled with a gas or a liquid, producing a thermal
contact resistance, Rth, which quantifies the thermal barrier to heat propagation. By focusing the laser
spot close to the interface between the two solids, this thermal contact resistance can be obtained by fitting
the temperature field recorded by the infrared camera to its analytical expression. Using the wellknown
relationship Rth = L/kf, the thermal conductivity of the fluid is obtained from a simple linear relation.
Measurements performed in test samples show a good agreement between determined thermal
conductivities and literature reported values, demonstrating the validity of the method.