LowCostEmissionStove - Development of a novel, cost-efficient pellet and wood log stove technology with very low emissions

Biomass fired stoves are still popular. It is due to low fuel costs, the ecological aspect of a renewable energy source and the visual attraction of the flame which causes a pleasant feeling. However, the stoves are either expensive (high quality pellet stoves) or the emissions are high (log wood and cheap pellet stoves). Therefore, the main objective of the project is the development of a new certified stove technology, which has low emissions and a high efficiency at very low costs. To fulfill this goal, certain parts of the stove, e.g. the fuel feeding system and the firelighter, have to be newly developed and integrated into the overall stove technology. The development and optimization of the stove technology shall be performed by test runs with detailed emission measurements and comprehensive steady and unsteady CFD simulations in order to enable a sound scientific process analysis. Therefore, within this project, a novel detailed and flexible CFD model for stoves shall be developed that enables a coupled simulation of solid biomass fuel (pellet and wood log) and the gas phase combustion in laminar to moderately turbulent flow regimes. Three versions of the new stove concept shall be developed with 40-50 % lower costs than current state-of-the-art stoves with low emissions and high efficiencies. First a gridindependent natural draft pellet stove shall be developed, which has a very low price, an appealing flame, but with a higher operating convenience and considerably lower emissions than (grid-independent) wood log stoves. Up to now there is no certified natural draft and grid-independent pellet stove, hence the development of such a technology represents a worldwide innovation. The second version of the new concept is a pellet stove with a low electricity demand. The new pellet stove shall be considerably cheaper than currently available high quality pellet stoves. On the other hand it shall meet the currently strictest certificate for continuously operated indoor combustion devices (“Blauer Engel”) regarding emissions and efficiency (>90%). The third version is an electrically operated combined stove for pellets and wood logs. This stove combines the advantages of pellet and wood log stoves. Generally, wood log stoves have the advantages of lower investment and fuel costs and the visual attraction of the flame. However, they have considerably higher emissions and lower efficiencies in comparison to pellet stoves. In the combined stove, the pellet flame stabilizes combustion and strongly reduces emission peaks during the ignition and burnout phase of the wood logs. Hence, this stove has considerably lower emissions and higher efficiencies than modern wood log stoves. For the electrically operated versions of the stove technology an optional and novel heat storage system with convection air channels will be developed in order to achieve an improved thermal management and longer heat release of the stove.