Development of advanced energy harvesters: theoretical and experimental studies

Author: Mohammad Khorsand

Khorsand, Mohammad, 2020 Development of advanced energy harvesters: theoretical and experimental studies, Flinders University, College of Science and Engineering

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This thesis deals with advanced energy harvesting approaches including piezoelectric-based energy harvesters and triboelectric nanogenerators (TENGs). As a traditional strategy, piezoelectric materials have extensively been used in many energy harvesting systems. Since piezoelectric and pyroelectric materials respond excellently to pressure and temperature variations, pressure-based piezoelectric energy harvesters are designed in the current study. The cylindrical and spherical geometries were considered, and the patterns of field variables were graphically drawn. It was demonstrated that the harvested energy can goes up by 74% with a proper design.

Next, the study was shifted on the most modern method for powering electronics in micro/nano scales. TENGs have been proposed as an effective approach to harvest mechanical energy from various sources in the ambient environment. TENGs have a wide range of applications in sensors, biomedical, defense technology, environmental monitoring, and personal electronics. This thesis deals with in-plane sliding and contact-separation configurations to scavenge mechanical energy. A high-output and lightweight sliding-mode TENG was designed to improve the efficiency of the TENGs system. The TENGs output was numerically simulated with the help of analytical methods and optimization theories. A great match between the experiment data and simulation results was reported. The sliding-mode TENG successfully generated a peak voltage and current of 150 V and 0.9 μA respectively. The new design was found to harvest 3.65 mJ at each cycle where the weight is almost 43 g. Meanwhile, a sensitivity analysis was showed that the resistor, contact area and thickness of dielectric film are respectively the most important design parameters in the sliding-mode TENG. Because of the prevalence of rotation in the environment, the rotary TENGs were fabricated and simulated to harvest the maximum accessible energy. The device can work in fully contact mode as well as the non-contact mode. Through the rotation, measurement showed a peak of 30 V and 0.6 μA, respectively. It was demonstrated that the spacing, grating number and angular velocity can significantly affect the TENG’ performance. A general algorithm was introduced to achieve the best performance for the rotary system with appropriate values for design parameters. It was concluded that the optimized TENGs can scavenge almost 0.369 mJ at each cycle.

Keywords: Triboelectric nanogenerators, Nanoenergy, Energy harvesting, Optimization, Augmented power output

Subject: Nanotechnology thesis

Thesis type: Doctor of Philosophy
Completed: 2020
School: College of Science and Engineering
Supervisor: Youhong Tang