Study of electrocaloric effect and harvested pyroelectric energy density of ferroelectric material

Ferroelectric materials, due to their electrocaloric behaviour, are considered as a promising alternative for the vapour compression refrigeration system and the solid state heat engine which converts the heat energy into electrical energy. In the present work, a novel indirect method based on thermodynamic framework is introduced to obtain electrocaloric properties in terms of adiabatic temperature change. A constitutive model has also been developed with an idea of infinite yield surfaces, to capture the ferroelectric response over a range of cyclic electric field with different amplitudes and temperature values. The model parameters are identified based on the experimental results for PbZrxTi1-xO3 (PZT). Using these parameters, simulations are performed to compute the change in polarization with temperature at different values of applied electric field, based on the proposed theoretical approach. The polarization temperature relation thus obtained, is used to calculate adiabatic temperature change (ΔT). The same model is used to simulate pyroelectric energy harvesting cycle (Olsen cycle), to estimate the harvested energy density per cycle (N D) of PZT from waste heat source for low power systems.