Investigation and Evaluation of Pyroelectric Materials for Thermal Energy Harvesting

A simplified thermodynamics-based model on pyroelectricity is used to estimate the sample transient temperature fields, electrical outputs, and induced thermal stresses during pyroelectric energy conversion. A numerical analysis presents an optimal saturated voltage of 73.0 V for a 4.7 mu F capacitor obtained by a 0.1 mm-thick disk pyroelectric cell under an input heat flux of 10 000 W m(-2) and an applied forced convection of 50 W m(-2) K-1 at 0.06 Hz to prevent the sample from undergoing phase transition due to high temperature. Thermal stress analysis shows that the maximum strain energy density occurs near the edge of the cell, and it increases with increasing thermal convection coefficient. Moreover, it is observed that a thinner sample possesses a lower thermal capacitance and an excellent pyroelectric response. However, this may lead to a higher temperature gradient near the edge region during the cooling process at a lower frequency and put the sample at a higher risk of damage.