TITLE:
Piezoelectric Power Harvesting Process via Phase Changes of Low-Boiling-Point Medium Together with Water for Recovering Low-Temperature Heats
AUTHORS:
Seiichi Deguchi, Akinori Miyajima, Hajime Arimura, Haruna Banno, Noriyuki Kobayashi, Norifumi Isu, Kentaro Takagi, Tsuyoshi Inoue, Takashi Nozoe, Seigo Saito, Takahiko Sano
KEYWORDS:
Piezoelectric Power Generation, Low-Temperature Heat Recovery, Biphasic Medium, Phase Change, Multiphase Flow, Power Harvesting
JOURNAL NAME:
Journal of Power and Energy Engineering,
Vol.6 No.11,
November
27,
2018
ABSTRACT: Low-temperature thermal energy conversions down to exergy zero to electric power must contribute energy sustainability. That is to say, reinforcements of power harvesting technologies from extremely low temperatures less than 373 K might be at least one of minimum roles for the current generations. Then, piezoelectric power harvesting process for recovering low-temperature heats was invented by using a unique biphasic operating medium of an underlying water-insoluble/low-boiling-point medium (i.e. NOVEC manufactured by 3M Japan Ltd.) in small quantity and upper-layered water in large quantity. The higher piezoelectric power harvesting densities were naturally revealed with an increase in heating temperatures. Excessive cooling of the operating medium deteriorated the power harvesting efficiency. The denser operating medium was surpassingly helpful to the higher piezoelectric power harvesting density. Concretely, only about 5% density increase of main operating medium (i.e. water with dissolving alum at 0.10 mol/dm3) came to the champion piezoelectric power harvesting density of 92.6 pW/dm2 in this study, which was about 1.4 times compared to that with the original biphasic medium of pure water together with a small quantity of NOVEC.