Influence of fuel moisture, charge size, feeding rate and air ventilation conditions on the emissions of PM, OC, EC, parent PAHs, and their derivatives from residential wood combustion

Controlled combustion experiments were conducted to investigate the influence of fuel charge size, moisture, air ventilation and feeding rate on the emission factors （EFs） of carbonaceous particulate matter, parent polycyclic aromatic hydrocarbons （pPAHs） and their derivatives from residential wood combustion in a typical brick cooking stove. Measured EFs were found to be independent of fuel charge size, but increased with increasing fuel moisture. Pollution emissions from the normal burning under an adequate air supply condition were the lowest for most pollutants, while more pollutants were emitted when an oxygen deficient atmosphere was formed in the stove chamber during fast burning. The impacts of these factors on the size distribution of emitted particles was also studied. Modified combustion efficiency and the four investigated factors explained 68%, 72%, and 64% of total variations in EFs of PM, organic carbon, and oxygenated PAHs, respectively, but only 36%, 38% and 42% of the total variations in EFs of elemental carbon, pPAHs and nitro-PAHs, respectively.

Experimental study of stratified lean burn characteristics on a dual injection gasoline engine

Due to increasingly stringent fuel consumption and emission regulation,improving thermal efficiency and reducing particulate matter emissions are two main issues for next generation gasoline engine.Lean burn mode could greatly reduce pumping loss and decrease the fuel consumption of gasoline engines,although the burning rate is decreased by higher diluted intake air.In this study,dual injection stratified combustion mode is used to accelerate the burning rate of lean burn by increasing the fuel concentration near the spark plug.The effects of engine control parameters such as the excess air coefficient(Lambda),direct injection(DI)ratio,spark interval with DI,and DI timing on combustion,fuel consumption,gaseous emissions,and particulate emissions of a dual injection gasoline engine are studied.It is shown that the lean burn limit can be extended to Lambda=1.8 with a low compression ratio of 10,while the fuel consumption can be obviously improved at Lambda=1.4.There exists a spark window for dual injection stratified lean burn mode,in which the spark timing has a weak effect on combustion.With optimization of the control parameters,the brake specific fuel consumption(BSFC)decreases 9.05%more than that of original stoichiometric combustion with DI as 2 bar brake mean effective pressure(BMEP)at a 2000 r/min engine speed.The NO_(x) emissions before threeway catalyst(TWC)are 71.31%lower than that of the original engine while the particle number(PN)is 81.45%lower than the original engine.The dual injection stratified lean burn has a wide range of applications which can effectively reduce fuel consumption and particulate emissions.The BSFC reduction rate is higher than 5%and the PN reduction rate is more than 50%with the speed lower than 2400 r/min and the load lower than 5 bar.