Development of a new micro CHP pellet stove technology

Abstract BIOS and RIKA developed within the ERA-NET-project “Small-scale BM based CHP” a new micro CHP technology based on a wood pellet stove (thermal capacity 10.5 kW) with a thermoelectric generator (TEG), that enables the operation of the stove without electric grid connection. Thereby, the wear- and maintenance-free and also noiseless TEG system is cooled by a water circuit which makes it possible to supply an additional room with heat. To achieve a self-sustaining operation of the pellet stove a TEG with an electric power of up to 50 W was installed into the casing of the pellet stove and the electricity consumption has been reduced significantly by an optimization of the control system and the selection of appropriate low voltage components. Based on transient system calculations and CFD simulations as well as test runs with two testing plants the system has been optimized. To demonstrate the practical suitability of the new technology in real life, 8 h load cycle tests were carried out. At these tests overall efficiencies up to 92.6% were achieved and in addition to the coverage of the own electricity consumption of the stove, 50 W h surplus electricity were produced which can be used to charge mobile phones or other small consumers.