Transient heat production and release profiles for wood stoves

Abstract

Combustion of wood logs in wood stoves and fireplaces occurs through a so-called batch combustion process, i.e. it is a highly transient process where most parameters change during the combustion cycle. This results in periods with poor combustion conditions giving high emissions of unburnt compounds and a highly varying produced power throughout the combustion cycle. The power that is actually transferred to a room/building is also highly varying and depends additionally on both the heat storage capacity of the stove materials and their conductivity. Finally, the heat will be transferred to a room via radiation and convection from the outer stove surfaces, and a smaller part will be transferred through the stove window directly to the room. The primary goal would be to achieve a more stable heat release to the room/building, which can be done by improving either or both the combustion process and the heat storage and -transfer. By applying different materials, material configurations and designs it will be possible to flatten out the heat release profile to a room. In this work different cases are analysed with regards to their influence on the heat release profile to a room. The results show the influence of improved combustion process control and using different materials including their configurations and give recommendations for material choices and localisations in wood stoves and fireplaces.