Characteristics analysis and parameter optimization of a micro-combustion based thermoelectric generator

Micro combustion based thermoelectric generator (micro-CTEG) has great potential to provide reliable electricity for portable electronic devices. Previous works on micro-CTEG has focused on the micro combustion issue, here we explore the heat transfer and thermoelectric (TE) coupling mechanism and give the guidelines for optimizing the performance of micro-CTEG. An analytical model was derived considering heat exchange inside the combustor, TE generator structure and temperature dependent material properties. Based on the optimization results, the temperature drop across the TE leg remains nearly constant for filling fraction approaching 1.0 and decreases remarkably with decreasing input fuel power for filling fraction approaching 0.1 due to the excessive gap heat loss. High filling fraction and high input fuel power is preferred to balance the power density and total efficiency. With identical thermoelectric figure of merit (ZT), increasing power factor under low filling fraction and decreasing thermal conductivity under high filling fraction are preferred respectively. The optimal load resistance factor, which represents the ratio of load resistance to internal resistance of TE generator, shows a decreasing trend with increasing temperature drop across TE leg. The optimal leg length remains nearly unchanged as thermal resistance of the heat sink is lower than 1 K/W.