Thermodynamic cycle optimization for pyroelectric energy conversion in the thin film regime

Abstract

Pyroelectric energy conversion is both simulated and realized on thin film lead zirconate titanate capacitors. The thermodynamics of the energy conversion cycle were explored, and the performance of the Brayton cycle was compared with the conventional Ericsson pyroelectric cycle. Cycle performance was examined using coefficients extracted from measured isothermal polarization hysteresis loops. It was found that the Brayton cycle is slightly more efficient than the Ericsson cycle over the range of temperatures tested and has significant efficiency improvements with increasing pyroelectric coefficients. The results from actual energy conversion cycles differed slightly from simulated performance, confirming the known challenges with synchronizing pyroelectric cycles with realistic thermal excitation. Finally, a one-dimensional thermal transient model is used to explore the power conversion potential of thin film pyroelectrics. It is shown that the Brayton cycle has a significant performance advantage over the Ericsson cycle at higher operating frequencies. A power density of 8 mW/cm3 was obtained using the Brayton cycle for a thin film system at about 60 °C with an applied field of 5 V and stimulation frequency of 0.2 Hz. Copyright © 2017 John Wiley & Sons, Ltd.