Thermal Energy Harvesting in Wireless Temperature Sensor Nodes for Condition Monitoring

Monitoring the temperature is an effective mean to collect useful information about the healthy conditions of machines such as a gearbox. This paper presents a novel wireless temperature sensor node powered by a thermal harvester for monitoring the healthy status of gearboxes. A thermoelectric generator module (TEG) is optimised to harvest sufficient electrical power from the heat source of the gearbox undergoing such monitoring. The power generation from this novel method is obtained based on temperature gradients emanated by sandwiching the TEG between the two aluminium plates. One plate is exposed to the heat source and has the role of a heat collector, whereas the other plate, mounted with a low profile heat-sink, acts as a heat spreader. The harvested power is then used to drive a wireless temperature node for condition monitoring. This combination allows a true powerless and wireless system to be realised. To evaluate the system, an industrial gearbox is monitored by the designed temperature node. The node is fabricated using a TEG module; an LTC3108 DC-DC converter for boosting the voltage, a super-capacitor for energy storage and a CC2650 sensor tag for measuring the temperature of the gearbox. The temperature data which is transferred via a Bluetooth low energy module and then monitored using portable monitoring devices, such as a mobile phones. The results obtained show the system can provide a continuous monitoring of the gear temperature and give an online indication of gearbox conditions