Modeling and simulation of a thermoelectric Energy Harvesting System for control design purposes

This contribution presents a simulation model of an Energy Harvesting System (EHS) based on Thermoelectric Generators (TEGs) using waste heat from the exhaust pipe of an oil-fired heating system. The overall system is modeled and simulated in the component-oriented environment Modelica^®/Dymola^®. The model is used to analyze and verify different control concepts to maximize the power output of the EHS. The TEGs used are devices consisting of thermoelectric material that exploit a temperature difference to generate electrical energy due to the Seebeck Effect. By means of TEGs, the overall energy efficiency of combustion processes can be improved by converting a portion of the remaining waste heat into electric power. For this purpose, TEG pairs (pTEGs) are installed on the exhaust pipe alongside the exhaust gas stream. However, with the exhaust gas losing heat in downstream direction, the final pTEG may lower the overall EHS performance due to their electrical resistance. With the help of the presented simulation model, it is possible to remove detrimental pTEGs from the EHS. This removal may happen either statically, i.e. in the design phase, or dynamically, i.e. by finding the ideal instant of time to disconnect and to revive them during operation.