Robinson Michael A, Olson Michael R, Liu Z Gerald, Schauer James J
a Cummins Emission Solutions, Inc. , Stoughton , WI , USA.
J Air Waste Manag Assoc. 2015 Jun;65(6):759-66. doi: 10.1080/10962247.2015.1005850.
Control of atmospheric black carbon (BC) and brown carbon (BrC) has been proposed as an important pathway to climate change mitigation, but sources of BC and BrC are still not well understood. In order to better identify the role of modern heavy-duty diesel engines on the production of BC and BrC, emissions from a heavy-duty diesel engine operating with different emission control strategies were examined using a source dilution sampling system. The effect of a diesel oxidation catalyst (DOC) and diesel particulate filter (DPF) on light-absorbing carbon (LAC) was evaluated at three steady-state engine operation modes: idle, 50% speed and load, and 100% speed and load. LAC was measured with four different engine configurations: engine out, DOC out, DPF out, and engine out with an altered combustion calibration. BC and BrC emission rates were measured with the Aethalometer (AE-31). EC and BC emission rates normalized to the mass of CO₂emitted increased with increasing engine speed and load. Emission rates normalized to brake-specific work did not exhibit similar trends with speed and load, but rather the highest emission rate was measured at idle. EC and OC emissions were reduced by 99% when the DOC and DPF architecture was applied. The application of a DPF was equally effective at removing 99% of the BC fraction of PM, proving to be an important control strategy for both LAC and PM. BC emissions were unexpectedly increased across the DOC, seemingly due to a change aerosol optical properties. Removal of exhaust gas recirculation (EGR) flow due to simulated EGR cooler failure caused a large increase in OC and BrC emission rates at idle, but had limited influence during high load operation. LAC emissions proved to be sensitive to the same control strategies effective at controlling the total mass of diesel PM.
In the context of black carbon emissions, very small emission rates of brown carbon were measured over a range of control technologies and engine operating conditions. During specific idle engine operation without EGR and adjusted fueling conditions, brown carbon can be formed in significant amounts, requiring careful management tactics. Control technologies for particulate matter are very effective for light-absorbing carbon, reducing black carbon emissions to near zero for modern engines equipped with a DPF. Efforts to control atmospheric brown carbon need to focus on other sources other than modern diesel engines, such as biomass burning.
控制大气中的黑碳（BC）和棕碳（BrC）已被提议作为缓解气候变化的重要途径，但BC和BrC的来源仍未得到很好的理解。为了更好地确定现代重型柴油发动机在BC和BrC产生中的作用，使用源稀释采样系统检查了采用不同排放控制策略运行的重型柴油发动机的排放。在三种稳态发动机运行模式下评估了柴油氧化催化剂（DOC）和柴油颗粒过滤器（DPF）对吸光碳（LAC）的影响：怠速、50%转速和负载以及100%转速和负载。使用四种不同的发动机配置测量LAC：发动机尾气排放、DOC尾气排放、DPF尾气排放以及燃烧校准改变后的发动机尾气排放。使用黑碳仪（AE - 31）测量BC和BrC排放率。归一化到所排放CO₂质量的EC和BC排放率随着发动机转速和负载的增加而增加。归一化到制动比功的排放率在转速和负载方面没有呈现类似趋势，而是在怠速时测量到最高排放率。当应用DOC和DPF架构时，EC和OC排放减少了99%。DPF的应用在去除99%的PM中的BC部分方面同样有效，证明是控制LAC和PM的重要控制策略。BC排放意外地在DOC中增加，似乎是由于气溶胶光学性质的变化。由于模拟的废气再循环（EGR）冷却器故障导致EGR流量去除，在怠速时OC和BrC排放率大幅增加，但在高负荷运行期间影响有限。事实证明，LAC排放对控制柴油PM总质量有效的相同控制策略敏感。
在黑碳排放的背景下，在一系列控制技术和发动机运行条件下测量到的棕碳排放率非常低。在特定的无EGR且调整了燃油条件的怠速发动机运行期间，可能会大量形成棕碳，这需要谨慎的管理策略。颗粒物控制技术对吸光碳非常有效，对于配备DPF的现代发动机，可将黑碳排放降低到接近零。控制大气中棕碳的努力需要关注现代柴油发动机以外的其他来源，如生物质燃烧。
