WP5: Energy Harvesting Device Development, Dr. Bishakh Bhattacharya

Aims and Objectives
This work-package aims to develop easily deployable, light-weight, versatile energy harvesting system in modular form for extracting energy from vortex induced vibration generated by the river flow.

A multi-modal energy harvesting device “Power Pro” (Figures a and b) which is close in concept to the above model was developed and patented by the PI [1]. The output was aimed at charging low power electronic devices like mobile phones.

Figure 1: Power-pro an In-house Developed Energy Harvesting System by the PI

The “Power Pro”, a portable charger device, is in fact a combination of three energy harvesting systems (Figure b). It has a small mini-turbine to harness wind energy, a solar panel and an embedded piezoelectric disc to harness energy from vibration. A detailed diagram of the power pro showing all the components is provided in Figure b.

Figure 2: An expanded view of Power-pro System showing all the subcomponents

The New Concept

In this project, the mechanical energy converted by the transducers to electrical energy will be based on vibration caused by flowing water. The transducers would be encapsulated in an arrangement that is referred as vibration energy harvesting device (VEHD) and the electrical energy tapping and modulating circuit would finally direct the energy to charge a battery. Figure c illustrates the basic concept:

Figure 3: A Block Diagram Representation of VEHD based System

The VEHD should be designed in such a way that the flow induced vibrations are tuned for the transducers towards their resonating frequency so that the voltage yield is maximized . An array of transducers are embedded over the flexible beams which are designed to show sensitivity towards vortex induced vibration. This requires a careful selection of the bluff body at the tip of the flexible beams. From a series of experiments carried out at the Smart Materials, Structures and Systems laboratory at lIT Kanpur, it was observed that a properly curved bluff  body to obstruct the fluid flow can generate ample vibration to the host structure which in tum can be converted to electrical energy by the transducers. Figure d explains the same principle.Among various shapes of the end-mass (working as a bluff-body), the results were found to be better for a specific rectangular shaped obstruction. It has been able to drive the piezoelectric crystal towards its resonating frequency (30-35 Hz) where the output voltage is maximum. 

Figure 4: A Bluff Body Energy Harvesting Mechanism

Deliverables:

The deliverable in this work-package will be an array of VEHD devices which can be used for both the stationary platform as well the mobile robots.

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