Nanoparticle emissions and volatility of particles emitted by modern diesel and CNG transit buses

Two compressed natural gas (CNG) and two diesel transit buses were tested on road to measure the particulateemissions and gas phase emissions under real world driving conditions. Both CNG buses as well as one diesel buswere tested in Calgary, Canada while the second diesel bus was tested in Dehradun, India. For the evaluatedbuses in Canada, the particle number concentration was measured using a condensation particle counter alongwith a dilution system in order to simulate the real world conditions. A thermodenuder was also employed tocondition the sample to determine the non‐volatile particles. The particle size distribution and total numberconcentration were measured using a differential mobility spectrometer (DMS50) for the diesel bus evaluated inIndia. The results show that 72% and 7% of the particles from the diesel bus with the DPF are volatile particlesin transient and steady state operating conditions, respectively. The CNG bus produces more volatile particles,and 84% of the particles were volatile in transient tests and 95% were volatile particles in the steady state tests.On average the CNG buses produce about 200 times less particles than the diesel bus without a DPF while theyproduce 35 times more particles than the diesel bus with a DPF.

کلیدواژه ها:

Nanoparticles ، CNG bus ، diesel bus ، volatile material ، particulate emissions