Combustion in microreactors, and its subsequent conversion to useful power has generated interest due to the need for distributed energy generation and efficient transformation of chemical energy of fuels into various useful forms. A thermoelectric generator (TEG) module can be integrated with micro-combustors to convert thermal energy into electrical energy. Several challenges for such integrated micro-device include thermal management to maintain appropriate skin temperatures, using fuel-lean conditions to minimize fuel utilization and ensuring sustained combustion over a wide range of operation. However, it is difficult to sustain stable and efficient device operation in straight channel reactors coupled with TEG, especially in presence of heat sinks attached on the cold side of the TEG. Therefore, one of the objectives of this thesis is to study the combustion characteristics of stand-alone and heat recirculating geometries, and develop simulation strategy and analyze performance of integrated microreactor-TEG systems.

Towards this objective, development and validation of a simplified model to mimic the behaviour of TEG module in an integrated micro-device will be discussed in this presentation. A 1D energy conservation model is first solved analytically using aggregated properties for the entire TEG module, modelled as a solid block. The model accounts for Seebeck, Peltier and Thomson effects, as well as Joules heating, which are incorporated into the energy conservation equation to model the TEG behaviour at steady state. The properties of Seebeck coefficient, internal resistance and thermal conductance aggregated for the entire block are estimated as polynomial functions of temperature. The TEG module parameters can be estimated from the manufacturer data. The TEG model is validated with experiments in literature, with a simple heater and a water-cooled heat exchanger. The TEG model is subsequently coupled with a validated CFD model of catalytic combustion in microreactor. The combined model is able to reasonably predict the performance of a catalytic microreactor integrated with TEG module for power generation. Further, the power extracted by various load resistances from the coupled device are calculated to compare with experimental data in the literature, with no further tuning of model parameters.