Towards optimization of a pyroelectric energy converter for harvesting waste heat

This paper reports numerical simulations of a prototypical pyroelectric energy converter as a novel approach for directly converting waste heat into electricity. The two-dimensional mass, momentum, and energy equations were solved to predict the local time-dependent pressure, velocity, and temperature. Then, heat input, pumping power, and electrical power generated were estimated, along with the thermodynamic energy efficiency and power density of the device. It was established that reducing the length of the device and/or the viscosity of the working fluid improved the energy efficiency and power density of the device by increasing the optimum operating frequency. Results show that a maximum efficiency of 5.2% at 0.5 Hz corresponding to 55.4% of the Carnot efficiency between 145 and 185 °C can be achieved with commercial 1.5 cst silicone oil as the working fluid and PZST as the pyroelectric material. The associated power density was found to be 38.4 W/L of material.