A Transient Modeling of the Thermoelectric Generators for Application in Wireless Sensor Network Nodes

Abstract

This paper reports results of the transient modeling of thermoelectric cooling/heating modules as power generators with the aim to select preferable ones for use in thermal energy harvesting wireless sensor network nodes. A study is conducted using the selected commercial thermoelectric generators within the node of a compact design with aluminum PCBs. Their equivalent electro-thermal models suitable for SPICE-like simulators are presented. Model components are extracted from the geometrical, physical and thermo-electrical parameters and/or experimentally. SPICE simulation results mismatch within 7% in comparison with the experimental measurements. The presented model is used for the characterization of different thermoelectric generators within the wireless sensor network node from the aspects of harvesting efficiency, cold boot time, node dimensions and compactness, and maximum applicable temperature. The choice of the preferred generator is determined by its electrical resistance, the number of thermoelectric pairs, external area and thermoelectric legs length, depending on the primary design goal and imposed thermal operating conditions. The node can provide load power of 1.3mW and the cold boot time of 66 s for generator with 31 thermoelectric pairs at a temperature difference of 15 C with respect to the ambient, and 7.6mW of load power and the cold boot time of 40 s for generator with 71 thermoelectric pairs at a temperature difference of 25 C.