Removing the Battery Recharge/Replacement Burden of Internet-of-Things Wireless Sensor Nodes Using Thermoelectric Energy Harvesting
- Publication Type:
- Thesis
- Issue Date:
- 2024
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The release of fermentation carbon dioxide (CO2) was investigated in this research thesis, with regards to its effects on raising CO2 levels inside an Australian brewery. Using 3 wireless Internet-of-Things (IoT) sensor nodes, it was determined that, at times, the CO2 levels inside the brewery far exceeded safe limits, indicated by the maximum CO2 level recorded being in excess of 18,000 ppm. The identification of differences in measured CO2 at different times and locations throughout the brewery also revealed that a single hard-wired CO2 sensor, which is typically used as the detection standard in breweries, may be inadequate to support indoor air quality monitoring. This strengthened the need to have a network of wireless IoT CO2 sensor modes inside breweries. One identified constraint was the short battery life of current Wi-Fi IoT sensor nodes. In order to increase this battery life, LoRa was analysed alongside Wi-Fi by developing three wireless IoT sensor nodes that measured the CO2 concentration. The LoRa sensor node achieved a battery runtime that was more than 17 times greater than the Wi-Fi sensor node, equivalent to a decreased power consumption of over 94%. This significant decrease in power consumption in conjunction with no decrease in signal range and penetrability was a significant step towards creating a feasible network of wireless CO2 sensor nodes, however the battery life was still a burden, therefore further improvements were required. A thermoelectric generator (TEG) system was then developed to recover brewery waste heat from the hot pipe outlet of two steam boilers within an Australian brewery, converting it into electricity to recharge the battery of a CO2 sensor node. The TEG was successful at removing the battery recharge/replacement burden of the developed sensor node, evidenced by its ability to keep the battery charged with no input from any user/source over the (32 days) test period, while the sensor node was active and monitoring CO2 levels. The TEG was capable of producing a maximum and average power output of approximately 2.5 W and 1.02 W (period of 10 hours) respectively, while generating an average of approximately 7.29 Wh of useable energy daily, allowing for the estimate that it can support a network of LoRa IoT sensor nodes, thus creating a wireless IoT sensor network that can uniformly monitor CO2 throughout the brewery supporting a safer working environment.
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