Paper details

Title:

Influence of User Behaviour on Emissions from Firewood Stoves

Author(s):

Mack, R., Hartmann, H., Schön, C.

Document(s):

Abstract:

Firewood stoves may cause high particulate matter (PM) and gaseous emissions, and user behaviour is an important influence, although to date only rarely quantified. Therefore, a manually operated modern firewood stove (7 kW) was selected and tested on a combustion test stand in a comprehensive experimental plan where in total 5 stove ignition variants (cold starts at natural draught) and 9 stove operational variants were investigated, each in 3 replications. Ignition variants differed in the position of starter blocks igniters as well in the orientation and position of wood logs and kindling used, including the “top down” and “bottom up” ignition modes, which both were additionally tested in a setup with controlled chimney draught at -12 Pa. Operational variants comprised a refilling according to the stove user manual (a), different primary air settings (b), overload of fuel (c), different moisture contents between 7 and 30 w-% (d), too long logs (e), delayed recharging (f) a "quasi-continuous" charging of individual logs (g). The ignition from the bottom caused lower CO-, OGC, and PM-emissions compared to the ignition from the top, but highest concentrations were observed when using crumped newspaper as igniter from the bottom in an "inaccurate" fuel arrangement. In subsequent batches the firewood stove performed very well when operated according to the user manual (CO: 1,687 mg/m3; OGC: 212 mg/m3; PM: 22 mg/m3, related to 13 % O2-conc.). Highest emissions were released when the primary air flap remained open after the ignition batch (CO: 9,379 mg/m3; OGC: 1,283 mg/m3; PM: 142 mg/m3). Such maloperation would be avoided if the stove was equipped with a relatively simple automatic combustion air control. High emissions also occurred when the stove was recharged after the flames were already extinguished or when the fuel was too wet. By throttling the combustion air flow, the CO emissions were increased by the factor 1.7 compared to the proper stove operation. Similarly, an overfilling of the combustion chamber also led to increased gaseous emissions. The use of too long wood logs, too dry wood or the continuous refilling with single logs led to similar or slightly lower gaseous and particulate matter emissions compared an orderly stove operation as defined as reference case.

Keywords:

wood stoves, user impact, fuel moisture, combustion control systems

Topic:

Biomass Conversion Technologies for Heating, Cooling and Electricity

Subtopic:

Biomass and bioliquids combustion for small and medium scale applications

Event:

27th European Biomass Conference and Exhibition

Session:

2AO.2.1

Pages:

409 - 418

ISBN:

978-88-89407-19-6

Paper DOI:

10.5071/27thEUBCE2019-2AO.2.1

Price:

FREE