Air pollution levels in Ulaanbaatar, Mongolia’s capital, are among the highest in the world. Coal-burning heating stoves used in the Gers (traditional dwellings) around Ulaanbaatar are a primary contributor to this pollution. Several efforts are underway to replace traditional heating stoves with improved low-emission high-efficiency stoves. Testing protocols for these high-efficiency stoves are typically based on manufacturers’ recommended operating procedures. So, white these procedures demonstrate the stoves’ optimal performance when operated in accordance with manufactures’ instructions, they may not be representative of actual field performance and emissions. The combination of stove design, fuel characteristics, and operational factors, along with the dynamic nature of the combustion process, leads to significant levels of variability and uncertainty in quantifying emissions. Therefore, selection of these high-performance stoves must be based on extensive field observations and lab measurements. The objective of this project is to identify the key factors that influence stove performance (fuel efficiency and emissions) in the field and to quantify the impact of these factors.
A highly-instrumented stove testing facility was constructed to allow for rapid and precise adjustment of factors influencing stove performance. Tests were performed using high-efficiency stoves currently available in Ulaanbaatar. Tests included complete burn cycles where a number of factors such as startup parameters, refueling events, and fuel characteristics were varied. All tests were run with internal chimney draft and ceiling height calibrated to represent winter conditions experienced within a Ger in Ulaanbaatar. Redundant emissions measurements were collected from both diluted chimney gas and plume gas mixed with air above the chimney. Measured emissions included CO, CO2, oxygen, temperature, pressure, and fine particulate matter (PM). Nailakh coal from the Ulaanbaatar region was used for testing.
Initial results from laboratory experiments focused on the emissions impact of refueling events and coal characteristics. Both of these factors strongly influenced PM emissions and stove performance. Refueling events lead to increased PM emissions. The duration of the elevated PM emission event depended on what time during the burn cycle the refueling occurred and how much fuel was added. Finally, the moisture content and size of coal lumps added during refueling impacted the emissions profile.
This work highlights an opportunity to provide better guidance on refueling procedures and fuel handling. These behavior changes can sustain the air quality gains from deployment of high‐ performance heating stoves in the Ger districts around Ulaanbaatar. Future work to better characterize the emissions impact of refueling, air intake settings, and coal material characteristics could lead to even more detailed guidance; this guidance would maximize the sustained environmental quality gains from deployment of high-performance heating stoves in the Ger districts around Ulaanbaatar.