Electrical and crystallographic study of an electrothermodynamic cycle for a waste heat recovery

廃熱回生のための熱電サイクルにおける電気的及び結晶学的研究

Kim, J.*; 山中 暁*; 中島 啓*; 加藤 孝典*; Kim, Y.*; 福田 竜生  ; 吉井 賢資  ; 西畑 保雄; 馬場 将亮*; 武田 雅敏*; 山田 昇*; 中山 忠親*; 田中 裕久*

Kim, J.*; Yamanaka, Satoru*; Nakajima, Akira*; Kato, Takanori*; Kim, Y.*; Fukuda, Tatsuo; Yoshii, Kenji; Nishihata, Yasuo; Baba, Masaaki*; Takeda, Masatoshi*; Yamada, Noboru*; Nakayama, Tadachika*; Tanaka, Hirohisa*

An innovative electrothermodynamic cycle (pyroelectric effect with an external electric field) was recently presented, which is based on temporal temperature variations in wasted heat from engine exhaust gas. In this paper, for further improvement, a generating mechanism of the cycle is investigated using in-operando time-resolved synchrotron X-ray diffraction with generating assessment. The polarizations of the sample are gained from both crystal/domain changes and simultaneous electrical measurements. Three types of materials are prepared: soft and hard types of lead zirconate titanate (PZT) and lead magnesium niobate-lead titanate (PMN-PT). Among them, PMN-PT has the highest generating power. When an external electric field is applied, the PMN-PT exhibits only 180 domain rotations, whereas PZTs exhibit both 90 and 180 rotations. A strong driving force for 180 rotation depresses rotations in other angles and increases polarization changes. The results show that the material development, which has only 180 switching domains, has potential for use in the establishment of a high-efficiency waste heat recovery system.