Theoretical investigation on polar dielectric with large electrocaloric effect as cooling devices

摘要

Polar dielectric based cooling devices are modeled as a system with two degrees of freedom and represented by either an entropy-temperature or electric displacement-electric field plane. A typical thermodynamic energy cyclic path is proposed for polar dielectric as cooling devices to experience. With the influence of temperature taken into consideration, the free energy of a thermal electrical coupling system of polar dielectrics is formulated, and the variation of temperature and entropy, the absorption of heat, and the work under different electric fields are calculated for BaTiO_3, PbCZr_xTi_(1-x)O_3, P(VDF-T_rFE), and water. And the simulation results obtained agree well with the recently published experimental data [B. Neese, et al, Science 321, 821 (2008)]. It is, therefore, suggested that the high polar liquid dielectrics may possess a large electrocaloric effect.