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IC Engines. AERL. Thermodynamics. Combustion. Advanced Engine Research Laboratory Dr. Timothy Jacobs.

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IC Engines

AERL

Thermodynamics

Combustion

  • Advanced Engine Research Laboratory

  • Dr. Timothy Jacobs

The Advanced Engine Research Laboratory is a research education program housed at Texas A&M University with the long-range purpose of advancing energy conversion for internal combustion engines. This purpose is met through fundamental experimental and theoretical investigations of:  in-cylinder combustion processes, the coupling to advanced concepts, the use of alternative fuels, and the integration of exhaust after treatment systems.

Aftertreatment

Advanced Combustion

Alternative Fuels

Conventional Combustion

For several reasons, including a lean (oxygen rich) exhaust and low exhaust temperatures, diesel engines are difficult to outfit with after treatment systems (also known as catalytic converters). As a result, current configurations consist of integrating several devices that eliminate specific species from the exhaust. For example, a lean NOx trap (LNT) removes NO2 from the exhaust. Similarly, a diesel oxidation catalyst (DOC) removes carbon monoxide (CO) and hydrocarbons (HC) from the exhaust.

The development of such devices, along with novel modes of combustion such as diesel PCI, are making it possible to effectively and efficiently eliminate harmful emissions from exhaust systems. Integrating new after treatment systems, including their orientation in the exhaust system (see figure below), with novel modes of combustion is a young and burgeoning field.

Novel approaches to advanced low temperature combustion are enabling engines to simultaneously reduce the in-cylinder formation of soot and nitric oxide (NO) while increasing efficiency. Soot is the precursor to particulate matter (PM), which is the black smoke often seen from older diesel engines.

PM is a solid air-borne pollutant and NO is a reactant in ground-level ozone formation. Both contribute to poor air quality and SMOG.

Two examples of these novel approaches are Natural Gas Homogenous Charge Compression Ignition (HCCI) combustion and Diesel Premixed Compression Ignition (PCI) combustion. The figure below illustrates the benefits of diesel PCI. A greater than 90% reduction in NO (EI-NOx) and a greater than 70% reduction in PM (EI-PM) are realized when the engine operates in a PCI mode (Lean PCI and Rich PCI) relative to a conventional mode (Lean Conv).

Diesel engines are over 100 years old, yet research into their in-cylinder fundamental mechanisms fervently persists.

In particular, an area of constant evaluation is the so-called “Soot-NOx” tradeoff (see figure below). Any attempt to decrease nitric oxides (NOx), such as an increase in exhaust gas recirculation (EGR), traditionally results in an increase in particulate matter (PM).

Novel modes of combustion, such as diesel PCI, make it possible to eliminate the soot-NOx tradeoff. However, there are several operating points where diesel PCI is impractical (i.e., full engine power). Thus, continued research in minimizing the soot-NOx tradeoff is necessary to continue the advancement of efficient power-producing technologies.

  • Alternative fuels, such as biodiesel, hold great promise for augmenting our energy resources in the transportation sector.

  • Biodiesel exhibits significantly different combustion than petroleum-based diesel fuel because of differences in certain fuel characteristics. These characteristics influence NO and PM emissions, engine performance, engine efficiency, and engine durability. The figure below identifies how certain emissions could change as the concentration of biodiesel in the fuel increases.

  • Such characteristics partially include:

    • Bulk-modulus, or compressibility, of the fuel. A different bulk modulus results in different injection timings of the fuel, leading to different fractions of premixed and diffusion combustion.

    • Oxygen content in the fuel. The higher oxygen content in biodiesel reduces in-cylinder soot formation, which decreases radiation heat transfer. The decreased radiation heat transfer results in higher combustion temperatures, which can lead to higher NO formation.

Diesel PCI Engine

C

T

DOC

LNT

Jacobs, 2007

Acceptably Low CO and HC

?% CO

?% HC

~5% CO

~0.8% HC

EPA, 2002

Jacobs, 2007

Research in the AERL develops and furthers the understanding of novel approaches to low temperature combustion modes.

Research in the AERL investigates the effects of alternative fuel characteristics on combustion, with particular emphasis on NO formation.

Research in the AERL evaluates the effectiveness and best placement of various diesel after treatment devices with diesel PCI engines

Research in the AERL furthers the understanding of in-cylinder soot and NO formation mechanisms so as to minimize them.

Facilities

People

Sponsors and Partners

  • John Deere 4.5 L Power Tech Plus diesel engine

  • 110 kW DC dynamometer

  • Fully instrumented with temperature, pressure, flow rates, gaseous exhaust emissions and smoke concentration.

  • Advanced engine technology including

    • Electronic high pressure common rail fuel system

    • Variable geometry turbocharger

    • Exhaust gas recirculation

  • Graduate Students

    • Jason Esquivel

    • Sushil Oak

    • Rahul Pillai

    • Sidharth Sambashivan

    • Brandon Tompkins

  • Undergraduate Students

    • Jesse Younger

  • Faculty Advisor

    • Dr. Timothy Jacobs

  • Biological and Agricultural Engineering Department

  • Department of Mechanical Engineering

  • Dwight Look College of Engineering

  • Dr. Jerald Caton

  • General Motors R&D and Planning

  • Houston Advanced Research Center

  • John Deere Company

  • Qatar National Research Foundation

  • Texas A&M University

  • Texas Transportation Institute

  • Texas Engineering Experiment Station


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