Two-stage aerosol formation in low-temperature combustion

Low-temperature combustion is a promising strategy for reducing pollutant formation in internal engines. However, there lack of understanding how the chemistry governing differences ignition between low-temperature and conventional affects emission rates physicochemical properties particulate matter (aerosols). Here, we conducted experiments an atmospheric-pressure reactor controlled at constant equivalence ratio (ϕ = 2.3) O2/N2 0.06, temperatures varied 250 °C 1035 °C. We used two fuels: toluene, which has high sooting propensity, n-heptane, comparatively lower propensity but exhibits two-stage that not present toluene combustion. performed real-time measurements aerosol size distributions, volatility, light-absorption properties. also offline molecular-size characterization. Aerosols emitted from both fuels were comprised light-absorbing organics are categorized as brown carbon. At highest temperature (1035 °C), emissions factor 20 larger than n-heptane. The had more abundance large species, less volatile, For fuels, factors exhibited steep drop with decreasing temperatures. was resurgence peak 290 n-heptane observed toluene. This consistent chemical kinetics simulations show prominent behavior