Lee Weinstein

Lee Weinstein
Advisor: Paul Wright
Email: lweinstein@berkeley.edu
Battery-Replacement Scale Energy Harvesting from HVAC Flows for Wireless Sensor Networks

Through sensing and control the efficiency, reliability and quality of commercial and residential HVAC systems can be improved significantly. Wireless sensor networks are an appealing option to provide sensing for these systems, due to the low power requirements of sensor nodes and the remote locations of the sensors. Sensor motes in these networks can be powered by batteries, but using energy scavenging devices offers a lower maintenance, longer-life solution. A piezoelectric bender connected to a fin can harvest a small amount of energy from the air flow through ducts, causing the bender to deflect. These deflections generate a voltage potential in the bender and can be used to trickle charge a capacitor which powers low power circuitry.
An energy harvester has been fabricated composed of a cylindrical obstacle and a fin mounted on a piezoelectric bender. Air flow past the obstacle results in vortex shedding, and these vortices excite the fin and bender into vibration. Ideal performance is observed when the shedding frequency matches the natural frequency of the fin and bender. Focus has been on performance of the harvester in flows ranging from 2-5 m/s (speeds typical of HVAC systems), and early results have shown power outputs of over 1 mW.

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