Relationship Between the Material Properties and Pyroelectric‐Generating Performance of PZTs

Abstract

according to a given temperature variation during generating cycle:It was indicated that the D F could be effective as a FOM for the pyroelectric generating performance and the dielectric loss (tanδ) significantly affected the generating performance in addition to p under hightemperature and electric-field conditions. Furthermore, of the PZTs tested, the C-91 sample (see further), which showed the highest generating performance, resulted in a generated energy of 1.3 mW cm −3 in the engine dynamometer assessment. This is 13 times greater than the generated energy reported in a previous study of C-6 (0.1 mW cm −3 ). [1] How much wasted heat exists, and how can we utilize it as renewable energy? These questions have been explored in automotive applications. Recently, there has been increasing interest in thermoelectric generation as an energy-regeneration technology because of the increasing concerns about environmental pollution and commitments to a low-carbon society.Therefore, to improve the fuel efficiency (energy saving) of automobiles, in this study, we focus on exhaust losses (exhaust gas), which account for approximately 30% of the gasoline energy, which is equal to the driving energy, [2] and developed an exhaust energy-regeneration technology based on thermoelectric generation.In pyroelectric applications, the general figures of merit (FOMs) have been applied and reported near room temperature. We derived the modified FOMs in considering our electro-thermodynamic cycle for the usage environment of automotive applications. The relationship between the material properties and generating performance of PZTs was investigated at various temperatures. The F D was suggested from F D , a FOM for a pyroelectric sensor, based on the modified pyroelectric coefficient (p); p . p was calculated by the change of the spontaneous polarization (P S ) according to a given temperature variation during one cycle; ΔP S /ΔT (T max −T min ). It was indicated that the F F D D could be effective as a FOM for the pyroelectric generating performance and the dielectric loss (tanδ ) significantly affected the generating performance in addition to p p under high-temperature and electric field conditions. Furthermore, of the PZTs tested, C-91 sample which showed the highest generating performance resulted in a generating energy of 1.3 mW cm -3 in the engine dynamometer assessment. This is 13 times greater than the generating energy reported in a previous study of C-6 (0.1 mW cm -3 ).In pyroelectric applications, general figures of merit (FOMs) have been applied and reported at near room temperature. We derived modified FOMs for the usage environment of automotive applications by considering an electro-thermodynamic cycle. The relationship between the material properties and the generating performance of lead zirconate titanates (PZTs) was investigated at various temperatures. A general FOM F D for a pyroelectric sensor, quantifying the electrical noise caused by thermal energy (Johnson noise) was modified and suggested as D

Electrical and Crystallographic Study of an Electrothermodynamic Cycle for a Waste Heat Recovery

“…[26] Many attempts have been made to utilize PE based on the Olsen cycle in terms of theoretical investigations, materials, and systems. [41] They considered FOMs with temperature changes in the high-temperature regime, and the modified FOMs corresponded well with the experimental results. [36] This cycle consisted of four steps with temperature changes and electric field changes, which were not isothermal and isoelectric.…”

“…[45,46] The result of the assessments with PMN-PT is displayed with the previous results of PZT (A) [36] and soft PZT (B) [41] in Figure 8. [45,46] The result of the assessments with PMN-PT is displayed with the previous results of PZT (A) [36] and soft PZT (B) [41] in Figure 8.…”

“…The difference in the steps is that this cycle moves from point B to C 1 , not to C. When the PE is charged by an external E at point A, the E PE is increased to the value of point B, then the external E is removing and the E PE is differing from the external E on the point B to D due to the temperature variation. All results are expected to be higher than those for PZT (A), as the materials are selected by referring to a modified FOMs suggested by Yamanaka et al [41] The highest generating performance is obtained with PMN-PT, i.e., 3.18 mW cm −3 with the cycle frequency of 0.05 Hz at a T H of 170 °C and an external E of 8 kV cm −1 . It leads to additional increase of the E PE as large as the value of point C 1 by P S changes based on the electrothermodynamic equation: [24,36] dD dt −1 = ε dE PE dt −1 + p dT dt −1 , where ε, t, and p are dielectric permittivity, time, and pyroelectric coefficient, respectively.…”

“…Results of generating assessments with the real engine dynamometer (Daihatsu, home-made) during the JC-08 mode. green dotted line), and soft PZT (B) (Ref [41],. The integral power of PMN-PT (this study, red line) is presented with the previous results; PZT (A) (Ref [36],.…”

Pyroelectric power generation from the waste heat of automotive exhaust gas

“…6(d) presents the results of the assessments over the total drive cycle with PNZST samples compared to previous results. 1,9 The net mean power was 40.8 mW cm À3 (accumulated generating energy of 49 117.4 J L À1 ), which is the highest value produced by any material in our energy harvesting system to date 1,[9][10][11][12] and is 314 times greater than what we presented in our rst report. 1 The comparisons of the current maximum power and energy density for pyroelectric energy harvesting studies for various materials are shown in Table 2, together with the respective operating conditions.…”