The use of pellets in residential boilers allows the increase of the share of renewable sources in heat production with an added advantage that this type of fuel is seldom produced through the exploitation of local resources. Thanks to the high quality of the fuel, pellet boilers have quite high efficiencies compared to other solid biomass combustion technologies.This criticality rises the need of solutions that have high conversion efficiencies in order to achieve optimal fuel use and consistent savings of primary energy.
Operational analysis in a residential building
The operation analyses in real buildings are a key factor for the improvement of innovative solutions, as the units need to face a range of operating conditions that are seldom tested in laboratory analyses. Moreover, preliminary data on system reliability, together with trial-and-error phases, are necessary in the development process of the product. The operational analysis of a pellet condensing boiler coupled to a Stirling engine in commercial operation in a residential building was conducted by researchers from Italian ENEA and the Politecnico di Torino. The unit is in operation since the heating season 2013-2014, and operation data are available with a very thick time step, resulting in a large dataset with a consistent variability of environmental conditions. The monitoring system provided by the manufacturer stores a number of data, including heat production, combustion temperature, supply and return temperature, electricity production, voltage, current, etc. A detailed analysis of the unit performance has been undertaken by analyzing the heat produced for space heating and tap water, focusing in particular on the electricity generated by the Stirling engine over the year.
A system with good reliability
The preliminary results of this analysis show the possibility of integrating innovative solutions in residential buildings, at a scale with few alternatives for CHP generation. The system has a good reliability, and the Stirling engine operation is mainly dependent on the heat requested to the boiler and on the supply and return temperatures of the water. The results have been compared with other available technologies for energy production from solid biomass or fossil fuels in residential applications.
This post is based on the abstract “Performance analysis of an innovative pellet-fired stirling engine in commercial operation” by Roberta Roberto, ENEA Research Centre, that will be presented at the European Biomass Conference and Exhibition 2016. With 72 sessions, 270 oral presentations and 750 posters, the EUBCE 2016 will cover the entire scope of innovations in biomass technologies and applications, systems and processes, markets and policies.
Thumbnail image source: Stirling DK