Design and optimization of low-temperature gradient thermoelectric harvester for wireless sensor network node on water pipelines

Low-temperature gradients between massive solids and ambient air are ubiquitous due to a diurnal temperature cycle. The use of these gradients as a source of renewable energy to power the low power-consuming nodes of a wireless sensor network instead of batteries can solve the problem of periodic replacement of batteries with their subsequent recycling. This study successively presents the stages of modeling, development, optimization, assembling, and experimental validation of a thermoelectric harvester for replacement of a 20 Ah battery for a wireless water quality sensor located on a water pipe. The experiments confirmed that the thermoelectric harvester produces more than 0.5–2 mW at a temperature difference of about 1–2 K between the pipe surface and the surrounding air at the calm wind speed of about 1 m/s. The original dimensionless model of thermoelectric harvester is presented herein. The key role of convective heat transfer in the harvesting process is demonstrated.