On the Effects of Turbocharger on Particle Number and Size Distribution in a Heavy - Duty Diesel Engine

Abstract

<div class="section abstract"><div class="htmlview paragraph">Particles emitted from internal combustion engines have adverse health effects and the severity varies based on the particle size. A diesel particulate filter (DPF) in the after-treatment systems is employed to control the particle emissions from combustion engines. The design of a DPF depends on the nature of particle size distribution at the upstream and is important to evaluate. In heavy-duty diesel engines, the turbocharger turbine is an important component affecting the flow and particles. The turbine wheel and housing influence particle number and size. This could potentially be used to reduce particle number or change the distribution to become more favourable for filtration. This work evaluates the effect of a heavy-duty diesel engine’s turbine on particle number and size distribution. The particle number (PN) emissions is measured with regard to varying turbine inlet conditions namely: turbine inlet temperature, exhaust mass flow rate and particle concentration at the turbine inlet (by varying fuel injection pressures). It was found that at turbine inlet temperatures of 200°C, PN remains almost constant as the particles were assumed to be held together by the volatile material. However, at 300°C there was an increase in PN across the turbine, and the increase was higher at higher mass flow rates across the turbine. Furthermore, lower injection pressures exhibited a higher rise in PN across the turbine. Interestingly, at 400°C, a reduction in PN across the turbine was observed due to oxidation. This reduction in PN was lesser while there was an increase in mass flow rate. Additionally, with higher injection pressures, a higher reduction in PN was noticed. This result is promising as catalyst coated turbine wheels could potentially enhance the effect thereby reducing PN before the after-treatment system.</div></div>