Marc E. Baumgardner

The Effects of Air Flow Rates, Secondary Air Inlet Geometry, Fuel Type, and Operating Mode on the Performance of Gasifier Cookstoves

Development of biomass cookstoves that reduce emissions of CO and PM2.5 by more than 50% and 95%, respectively, compared to a three-stone fire has been promoted as part of efforts to reduce exposure to household air pollution (HAP) among people that cook with solid fuels. Gasifier cookstoves have attracted interest because some have been shown to emit less CO and PM2.5 than other designs. A laboratory test bed and new test procedure were used to investigate the influence of air flow rates, stove geometry, fuel type, and operating mode on gasifier cookstove performance. Power output, CO emissions, PM2.5 emissions, fuel consumption rates, producer gas composition, and fuel bed temperatures were measured. The test bed emitted <41 mg·MJd–1 PM2.5 and <8 g·MJd–1 CO when operating normally with certain prepared fuels, but order of magnitude increases in emission factors were observed for other fuels and during refueling. Changes in operating mode and fuel type also affected the composition of the producer gas entering the secondary combustion zone. Overall, the results suggest that the effects of fuel type and operator behavior on emissions need to be considered, in addition to cookstove design, as part of efforts to reduce exposure to HAP.

Laser Ignition of Methane-Air Mixtures: An Investigation of the Lean Limit and Minimum Ignition Energy

This study examines the laser ignition of methane-air mixtures in a Rapid Compression Machine (RCM). The lean limit and the Minimum Ignition Energy (MIE) were investigated in the engine-like conditions provided by the RCM.

Laser Ignition of Methane-Air Mixtures with a Rapid Compression Machine

We present here a study of laser ignition in a rapid compression machine (RCM). Laser induced ignition of natural gas-air mixtures at various test conditions was investigated. An Nd:YAG laser (1064 nm, 12 ns pulse duration) was employed as the laser source. Methaneair mixtures ranging from stoichiometric conditions to equivalence ratio of 0.4 were ignited using the laser as part of a lean limit study where the fuel-energy was kept constant for all cases. A study of minimum laser spark energy (MSE) and minimum ignition energy (MIE) was also conducted. We show that both MSE and MIE exhibit a stochastic behavior and, as a consequence, results can only be interpreted statistically. For our conditions, we found MSE at 90 % probability of MSE90=2.3 mJ. The MIE study was conducted at an equivalence ratio of φ=0.4 yielding an MIE (90% probability) of MIE90=7.2 mJ.