Time-resolved particulate emissions monitoring of cookstove biomass combustion using a tapered element oscillating microbalance

摘要

In this work, a Tapered Element Oscillating Microbalance (TEOM) system is successfully applied to time-resolved cookstove emissions monitoring of particulate matter less than 2.5 μm in diameter (PM_(2.5)). The TEOM system is compared to a standard gravimetric filter method, and is found to require calibration for cookstove applications, as the TEOM system consistently over reports PM measurements. Several changes to the TEOM system were deemed necessary, including the addition of an external dilution system and changes to internal controls. Six modifications were made to the TEOM system and sampling train operating conditions to ascertain the cause of the discrepancy. A correction factor is calculated and applied to the TEOM system output, which brings it into agreement with the gravimetric filter method. We also show the advantages of a time-resolved gravimetric system such as the TEOM, such as the ability to correlate operator actions or operating conditions with transient high PM events. The PM produced during the refueling of a standard rocket elbow cookstove is found to be roughly 37% of the total PM produced. We also investigate the PM produced during the lighting phase, which is often a significant amount due to additional combustible materials to aid lighting. This phase is especially significant in next generation stoves that under normal operating conditions produce much less PM than current baseline cookstoves - we find that the lighting phase contributes 25% of the total PM produced. We also stress the need for TEOM system calibration, as the original design use (long-term air monitoring) is inherently different than real-time cookstove emissions analysis.