Theoretical Efficiency of Pyroelectric Power Converters

Abstract

In recent years, a number of power converters utilizing the pyroelectric effect have been reported in the literature, and attempts at computing their efficiency have been made. In this paper the maximum efficiency for power converters made with nonferroelectric pyroelectrics, with ferroelectric pyroelectrics having a first-order ferroelectric-paraelectric transition, and with ferroelectric pyroelectrics having a second-order transition is computed. The last two cases have been evaluated starting from Devonshire's equations, which describe the properties of ferroelectrics better than other equations used in previous calculations of efficiency.

Next-generation electrocaloric and pyroelectric materials for solid-state electrothermal energy interconversion

“…Fatuzzo et al 18 examined various types of ferroelectric power converters and reached a conclusion similar to that of Childress, namely, that the efficiencies are low (~0.5%) and that the limiting factor is the fact that "the energy required to 7 increase the temperature of the lattice is nearly always much larger than the energy required to destroy part of the polarization." Olsen et al pointed out 12 that the type of Stirling cycle illustrated in Figure 3d requires the use of heat regeneration to minimize irreversible heat flows.…”

“…Fatuzzo et al 18 examined various types of ferroelectric power converters and reached a conclusion similar to that of Childress, namely, that the efficiencies are low (~0.5%) and that the limiting factor is the fact that "the energy required to Figure 3d requires the use of heat regeneration to minimize irreversible heat flows. This is an essential feature of all engines employing these cycles.…”

Harvesting Nanoscale Thermal Radiation Using Pyroelectric Materials

“…Unfortunately, this process is highly irreversible and theoretical analysis predicts low efficiency and small power density [19][20][21]. This intrinsic limitation can be attributed to the fact that "the energy required to increase the temperature of the lattice is nearly always much larger than the energy required to destroy part of the polarization thus releasing electric charges" [20].…”

“…More recently, Itskovsky [22] noted that the above mentioned analysis [19][20][21] assumed very small temperature amplitudes of a few mK or K. Then, the pyroelectric current i is proportional to the time rate of change of temperature dT /dt and the pyroelectric effect is linear, i.e., i = p c dT /dt, where p c is the pyroelectric coefficient. However, for energy conversion applications the amplitude of the temperature oscillation is typically large and the pyroelectric effect is nonlinear.…”

Novel Electrothermodynamic Power Generation

“…The produced loop area is considered as an energy density ( N D , the area of the D -E loop); the power density ( P D , = N D f ) is also evaluated from the area. [7][8][9][10][11][12][13][14] To the best of our knowledge, there is no application that satisfi es a true energy breakeven because of the diffi culties associated with fi nding a suitable energy source that can simultaneously give alternative heat and an electric fi eld. [7][8][9][10][11][12][13][14] In this study, a novel electrothermodynamic cycle is presented based on temporal temperature variation to obtain practical net energy from exhaust heat of automobile.…”