Optimizing thermoelectric generators based on Mg2(Si, Sn) alloys through numerical simulations

Abstract

• A Mg 2 (Si, Sn) based thermoelectric generator (TEG) system is optimized and analysed using the modeling approach. • The performance of TEG module is notably determined by the geometry of thermoelectric leg and thermal contact resistances. • An effective heat sink system is designed with optimal number of fins and fin spacing. • A conversion efficiency of 8.35% and power output of 18.90 W is produced from the optimized model. Thermoelectric generator (TEG) that works in medium and high temperature ranges has appeared as a necessity in combating with the waste heat management from various industries. Therefore, design of TEG with thermoelectric materials capable to exhibit high capacity for thermoelectric power generation is of emerging technological interest. It is known that alloys based on Mg 2 (Si, Sn) and PbTe thermoelectric materials are best suited for the intermediate temperature scale (400–900 K). For constructing a TEG, higher manganese silicides (HMS) are often used for integration with n-type Mg 2 X (Si, Ge, Sn) alloys. The thermo-mechanical property-mismatch reasons out the option for such a combination in fabrication of a sustainable thermoelectric generator. This makes one focus on evolving a generation system that comprises of both n- and p-type thermo elements prepared from suitable Mg 2 X (Si, Ge, Sn) alloys. The present research analyses the feasibility of designing a Mg 2 (Si, Sn) alloy based thermoelectric generator by modeling approach. It presents a comprehensive take on the effect of thermoelectric leg dimensions and contact resistances on the output voltage, output power and efficiency, with alteration in the operating temperature span. The COMSOL modeling results indicate that the power output reduces considerably with increment in the thermoelectric leg length, while the conversion efficiency enhances. Contrarily, augmenting the cross-sectional area of a thermoelectric leg follows an opposite trend i.e., it increases the power output and decreases the conversion efficiency. The power output and the conversion efficiency values diminish when contact resistances are considered in the modeling study. This study also incorporates an efficient heat exchanger system including contact resistances and conductive and convective heat losses for accurate estimation of power output and efficiency of the optimized TEG module.