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Particulate Matter (PM) is one of the world’s most problematic pollutants in terms of harm to environment and human health. It has been found out that PM emission levels are very high during traffic congestion and thus, PM is considered as the primary pollutants in city areas. Many literatures suggested that PM emitted during braking sequence from both internal combustion engines and electrified vehicles are considered high and could be the major cause of this issue. Many studies regarding to PM from brake wear were done in the pin disc laboratory setup with a brake dynamometer that might not represent real-world driving scenarios. Various studies of on road non-exhaust PM measurement were mostly focused on driving cycles. Parametric studies to identifying factors that affect brake wear during real-world driving scenarios are still needed for more investigations.

The diesel dual fuel engine emits CH4 in the exhaust gas. This makes the exhaust gas more difficult to treat comparing to the exhaust gas from the conventional engine since CH4 requires high exhaust temperature to oxidize. In addition, another parameter such as exhaust flow rate, specie concentrations, especially CO, C3H8, and H2O have tremendous impact on Diesel Oxidation Catalyst performance on reducing CH4. This research is aimed to propose a kinetic model based on Langmuir Hinshelwood mechanisms that includes several terms such as CH4, C3H8, CO, O2, and H2O concentrations in order to gain a better understanding on the catalytic reaction and to provide a simulation with an accurate prediction. The model’s kinetic parameters are determined from the experiment by using synthetic gas. The composition of synthetic gas is simulated to be similar to the real exhaust gas from diesel dual fuel engines.

Towards the effort of using natural gas as an alternative fuel for a diesel engine, the concept of Diesel Dual Fuel (DDF) engine has been shown as a strong candidate. Typically, DDF's engine-out emission species such as soot and nitrogen oxides are decreased while carbon monoxide and hydrocarbons are increased. The aftertreatment system is required in order to reduce these pollutant emissions from DDF engines. Additionally, DDF engine exhaust has a wide temperature span and is rich in oxygen, which makes HC emissions, especially methane (CH₄), difficult to treat. Until now, it is widely accepted that the key parameter influencing methane oxidation in a catalytic converter is high exhaust temperature. However, a comprehensive understanding of what variables in real DDF engine exhausts most influencing a catalytic converter performance are yet to be explored.

The current study examined diesel dual fuel (DDF) operations in a four-cylinder turbocharged diesel engine under low load conditions. Experiments were performed to investigate effects of diesel injection timings and exhaust valve timing advance for DDF operations under high levels of natural gas utilization. Results showed that diesel injection timings played an important role in DDF combustion. Increasing the ratio of natural gas to total fuel resulted in greater amounts of HC and CO emissions. Advancing the exhaust valve timing increased the internal EGR, raised the in-cylinder temperature at IVC, and improved the combustion efficiency. To maximize the ratio of natural gas to total fuel, a combination of proper exhaust valve timing advance and a tuned timing of diesel injection should be employed to avoid excessive HC and CO emissions.

Diesel Dual Fuel (DDF) operation is a promising alternative engine operating mode. Previous research studies have reported a DDF engine operating under low load conditions suffers from high HC emissions, mostly Methane. The current study investigated the use of a multiple direct injection strategy for improvement of low-load DDF operation in a commonrail direct injection single-cylinder diesel engine. Natural gas was supplied at 70% of energy replacement ratio. Results indicated that depending on engine conditions, a double-pulse injection had potential for combustion control and provided an effective way to reduce NOx and methane emissions. Moreover, the double-pulse injection helped improve the combustion stability, reduce the pressure rise rate, and decrease the maximum cylinder pressure, compared to DDF operation with a single pulse injection.

The diesel/natural gas engine configuration provides a potential alternative solution for PM and NOx emissions reduction from typical diesel engine operations. However, their engine operations suffer from high NMHC/methane emissions and poor engine performance, especially at light loads. By increasing the diesel pilot quantity, the performance and reduction of NMHC/methane emissions can be improved but the emission levels are still very high. Clearly, a typical DOC is not good enough to treat NMHC/methane emissions. Methane has been known as one of most stable species that is difficult to catalytically oxidize in lean burn environment and low exhaust temperatures. An aftertreatment system exclusively designed for treating methane emissions from DDF operations is therefore necessary. The current work is aimed to establish an effective computational tool in order to study the newly proposed catalytic converter system concept on treating methane from DDF operations.

The development of the Diesel Exhaust Filtration Analysis system (DEFA), which utilizes a rectangular wafer of the same substrate material as used in a full-scale Diesel Particulate Filter (DPF), is presented in this paper. Washcoat variations of the wafer substrate (bare, washcoat, and catalyzed washcoat) were available for testing. With this setup, the complications of flow and temperature distribution that arise in the full-scale DPF can be significantly minimized while critical parameters that affect the filtration performance can be fully controlled. Cold flow experiments were performed to test the system's reliability, and determine the permeability of each wafer type. A Computational Fluid Dynamics (CFD) package was utilized to ensure the flow uniformity inside the filter holder during the cold flow test.

An experimental study was performed to investigate diesel particulate filter (DPF) performance during filtration with the use of real-time measurement equipment. Three operating conditions of a single-cylinder 2.3-liter D.I. heavy-duty diesel engine were selected to generate distinct types of diesel particulate matter (PM) in terms of chemical composition, concentration, and size distribution. Four substrates, with a range of geometric and physical parameters, were studied to observe the effect on filtration characteristics. Real-time filtration performance indicators such as pressure drop and filtration efficiency were investigated using real-time PM size distribution and a mass analyzer. Types of filtration efficiency included: mass-based, number-based, and fractional (based on particle diameter). In addition, time integrated measurements were taken with a Rupprecht & Patashnick Tapered Element Oscillating Microbalance (TEOM), Teflon and quartz filters.

Three distinct types of diesel particulate matter (PM) are generated in selected engine operating conditions of a single-cylinder heavy-duty diesel engine. The three types of PM are trapped using typical Cordierite diesel particulate filters (DPF) with different washcoat formulations and a commercial Silicon-Carbide DPF. Two systems, an external electric furnace and an in-situ burner, were used for regeneration. Furnace regeneration experiments allow the collected PM to be classified into two categories depending on oxidation mechanism: PM that is affected by the catalyst and PM that is oxidized by a purely thermal mechanism. The two PM categories prove to contribute differently to pressure drop and transient filtration efficiency during in-situ regeneration.