Photopyroelectric Investigation of Thermal Effusivity of Binary Liquid Mixtures by FPPE-TWRC Method

An alternative front photopyroelectric configuration (FPPE) that uses the thermal wave resonator cavity method (TWRC) is proposed for measuring the thermal effusivity of a liquid, inserted as backing in the detection cell. A theory for a 5 layers (air, sensor, coupling fluid, solid separator layer, and liquid backing) detection cell is developed. The method seems to be particularly suitable when measuring the thermal effusivity of binary liquid mixtures. If the coupling fluid is one component of the binary mixture, the technique acts a “quasi-differential” method and low concentration of the second component of the mixture can be detected. In the paper the method was applied to binary liquid mixtures of water with ethanol, ethylene glycol and DMSO.