EGR 2

Overview of Emission Control in Diesel Engines

  • Discussion on emission changes between different model years of diesel engines.

Chapter 29: Emission Control Systems

  • Overview of the chapter and its content, revealing a total of 14 slides.

  • Key focus on the evolution of emissions packages over the years.

Significant Changes in Emission Standards

  • Important legislative dates significantly impacting manufacturers and their emission control systems:

    • 2004-2006: Introduction of EGR (Exhaust Gas Recirculation) systems.

    • 2007: Introduction of DPF (Diesel Particulate Filter).

    • 2010: Implementation of urea (diesel exhaust fluid) injection into exhaust streams.

Purpose of EGR and After Treatment

  • The function of these systems is the reduction of oxides of nitrogen (NOx) and particulate matter.

  • After-treatment devices are defined as any system that operates downstream of the turbocharger.

Historical Context

  • Late 1980s: No emission provisions were in place, leading to high particulate matter emissions.

    • Recognition of the EPA's involvement in regulating particulate matter levels and reducing greenhouse gases.

Defining Particulate Matter

  • Definition: Particulate matter (PM) refers to tiny particles (parts per million) emitted from vehicles.

  • Substances included:

    • Unburned hydrocarbons (UHC) resulting from improper combustion due to poor air-fuel mixture.

    • NOx, which are harmful gases generated from high combustion temperatures.

Key Emission Reduction Techniques

  • NOx Emission: High temperatures and pressures in the combustion chamber are the main causes of NOx emissions.

  • EGR systems work to lower combustion temperatures, reducing NOx production by reintroducing exhaust gases into the intake air mixture.

  • Challenges with EGR systems:

    • Carbon buildup in engines due to particulate matter in the exhaust.

    • Systems like the Dodge Cummins demonstrate common issues related to carbon build-up in the intake systems.

Consequences of Emission Control Strategies

  • Risks: Excessive carbon build-up can lead to engine power losses and restricted airflow.

  • Emission controls must adapt throughout a vehicle’s lifecycle to comply with regulations that evolve over time.

Regulatory Environment and Compliance

  • In the U.S., vigorous emissions regulations exist, leading to stringent compliance requirements for vehicle emissions testing.

  • Vehicles manufactured after certain years must have emissions packages inline with those years' standards.

Engine Design and Emission Treatment

  • An overview of specific components relevant to EGR systems and their functioning in engines:

    • Variable Geometry Turbo: Adapts to optimize air pressure and assist combustion efficiency.

    • EGR Cooler: Cools exhaust gases before reintroduction into the combustion chamber to mitigate excessive temperatures.

  • Importance of proper functioning of sensors (delta P sensors) to measure exhaust gas pressure differences and regulate EGR flow efficiently.

Impact of EGR System Failure

  • Consequences of EGR cooler failure:

    • Increased combustion temperatures.

    • Potential for white smoke emissions due to coolant entering the combustion engine, which does not ignite in proper combustion processes.