High accuracy photopyroelectric investigation of dynamic thermal parameters of Fe3O4 and CoFe2O4 magnetic nanofluids

摘要

The suitability of the photopyroelectric (PPE) calorimetry in measuring the thermal parameters of nanofluids was demonstrated. The main advantages of the method (concerning nanofluids) as compared to classical calorimetric techniques are: high sensitivity and small amount of sample required. The thermal diffusivity and effusivity of some nanofluids based on Fe3O4 and CoFe2O4 type of nanoparticles (mean diameter 6.5 nm) were investigated by using two PPE detection configurations (back and front). In both cases, the information is contained in the phase of the PPE signal. Due to the high accuracy of the results (within ±0.5%) thermal diffusivity was found to be particularly sensitive to changes in relevant parameters of the nanofluid as carrier liquid, type and concentration of nanoparticles.