Control System Modification of a 5-kW Pellet Stove: Study and Analysis

The use of sustainable energy sources is an alternative for fossil fuels, which can represent a positive factor to alleviate many current environmental issues. In that sense, not only sustainable industrial development is important, but also sustainable practices at the local level, including households. Specifically, heating and cooking are one of the most important activities that require energy in households, where the role of biomass could be of interest, as it can provide an energy source with lower environmental impact. However, there is room for improvement in biomass stoves, whose adaptability to specific wastes, as well as their improvement in efficiency, should be accomplished. The aim of this work was to assess the improvement of combustion performance of a domestic stove by the implementation of a programmable logic converter for a better adaptation to different biomass samples (holm oak, pear tree, poplar, and sugarcane bagasse pellets). This work provides further information about the current working protocol, being an alternative for better approaches that could be implemented in future works. Thus, the working regime of the stove was controlled, especially concerning the screw conveyor (to regulate pellet feeding) and flue gas fan (to change oxygen supply). As a result, better combustion performances were obtained, with heat capacities from 5.66 to 8.67 kW for the selected samples. Also, thermal capacities of the stove (1.43, 1.60, 2.22, and 1.83 kW for holm oak, pear tree, poplar, and sugarcane bagasse, respectively) were obtained, with a better combustion performance compared to previous studies (1600 and 120 ppm peak emissions for CO and NOx, respectively, and 15% as the lowest O2 concentration). On the other hand, different improvements of the combustion stove to avoid blockages, for instance, are proposed as further steps.