Energy characterization of wood briquettes and possible use in automated domestic heating systems

Abstract

Lignocellulosic biomasses, in particular woody biofuels, represent a valuable resource for contributing to the energy demand of European countries, helping to increase the share of renewable energy produced. Among the biofuels used for domestic heating are wood briquettes. Although they have better quality characteristics than firewood, they are still poorly appreciated. The aim of this work was to highlight the physical-mechanical characteristics of the wood briquettes commonly found on the Italian market for domestic combustion. The possible existing relationships between the determined parameters, the effects they have during the combustion of briquettes and the possibility of use them inside automatic boilers and stoves was also discussed. Forty-three samples were analyzed in the period between 2016 and 2022. The moisture content, ash, heating value, particle density, mechanical durability and energy density were determined for all samples. Based on the results obtained, the briquettes prove to be fuels characterized by low ash content $\boldsymbol{(< 1.0\%)}$, high particle density $\boldsymbol{(> 1.0\mathrm{g}/\text{cm}^{3}})$, high mechanical durability $\boldsymbol{(>91 \%)}$ and high energy density $\boldsymbol{\left(>13\ \text{GJ} / \mathrm{m}^3\right)}$. The lower heating value is similar to that of other woody biofuels (15.6 MJ/kg and 17.4 MJ/kg), with an average moisture content of about 10.0%. Thanks to their physical, energy and geometric homogeneity characteristics these could be positive exploited inside automatic domestic stoves and boilers. The diffusion of these systems, combined with an implementation of low-cost sensors for the monitoring of the combustion process, would lead to an increase of the combustion efficiency as well as a significant reduction in polluting emissions.