High accuracy photopyroelectric calorimetry. Application to liquid mixtures and composites

摘要

A photopyroelectric (PPE) calorimetric method, based on the sample's thickness scan of the signal amplitude and phase, is proposed in order to obtain accurate values of thermal parameters of liquid samples. The accuracy of the method (about 1% for the determination of thermal diffusivity and 3% for thermal effusivity) makes it suitable for studies of processes associated with small changes in the values of thermal parameters. In order to prove the versatility of the technique, room temperature values of the thermal parameters of some vegetable oils were measured, molecular associations in water-ethylene glycol mixtures and a sedimentation process in a SiO2 colloidal solution were detected. Due to its qualities (high accuracy, low time consuming, small quantity of sample required) the method is recommended as an alternative for thermal properties investigations of nanofluids.