A novel electro-thermodynamic cycle with a higher waste heat recovery efficiency than the conventional Olsen cycle was introduced by Kim et al. in 2015. Thus, in the present study, the importance of the temperature factors was investigated, revealing the sensitivity and effectiveness of the Kim cycle on the fluctuating properties of the applied heat source over the Olsen cycle. Power generation tests at different frequencies and temperature ranges were performed using nontoxic lead-free Ba(Zr0.1Ti0.9)O3 pyroelectric ceramics. As the frequency increased, the original isodisplacement process of the Kim cycle successfully improved the pyroelectricity and increased the internal electric field of the sample, thereby enhancing the energy density of the recovery process. This phenomenon compensated for the energy density loss from the poor heat conduction, which was the factor that saturated the power density when measured with the Olsen cycle. Therefore, the Kim cycle was more effective than the Olsen cycle when considering the fluctuating frequency factor. In addition, adjusting the temperature range factor induced a power density enhancement owing to the internal electric field increase mechanism. The power generation ability of the Kim cycle was significantly improved compared to that of the Olsen cycle. This research study revealed the sensitivity and effectiveness of the Kim cycle for recovering waste heat from a high-fluctuating rate source. Thus, the new Kim cycle has the potential to be investigated for its energy conversion ability in the next decade.

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Nanogenerator energy harvesting technologies that transform thermal energies into electricity may help address the growing need for green power. Therefore, this research aims to increase power generation by combining waste heat with pyroelectric nanogenerators as a sustainable energy source. Under optimal conditions, an external multi-pulse electric field can be utilized to generate power using thermoelectric cycle power generation. The greatest power may be gathered by applying various pulses of the external electric field at temperature changes on the surface of the pyroelectric materials. To generate pyroelectric power, a C9 BZT sample was used, and the lowest temperature difference for accomplishing this was 20 °C, with all measurements made on a sample with a lower limit of 120 °C. The maximum generation density was 0.104 mJ/cm2°CkV for a pulse width of 10 ms and 20 pulses of a low voltage (250 V/mm) input electric field. A multi-pulse electric field with low input voltage increases the power generation performance ratio (η) with the pulse count. At the largest number of pulses, the greatest η value for 250 V/mm was 7.834. Finally, it was determined that the developed pyroelectric power generation system may be more effective if a low-voltage, multi-pulse electric field is used.

The energy‐harvesting ability of the lead‐free ferroelectric Ba(Zr,Ti)O3 was investigated and greatly enhanced using the Kim novel electrothermodynamic cycle for low‐temperature application. Ba(Zr,Ti)O3 was synthesized with a Zr:Ti ratio of 10:90 (BZT10) by hot‐press sintering, which exhibited a mix relaxor‐ferroelectric behavior. For power generation using the Kim cycle with low and high temperatures of TL = 25°C, TH = 120°C, the most optimized temperature pattern occurred for a heating time of 12.5 s and a cooling time of 22.5 s. Under these conditions, the electric field increased during the novel isodisplacement process, and the displacement variation in the isoelectric step reached the highest value and maximized the BZT10 cycle loop area. Applying these conditions while lowering TL to 20°C, an energy density ND = 504 mJ/cm3 was achieved. This value is the highest obtained energy density in a practical test for lead‐free ferroelectric bulk material in the BaTiO3 family.

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