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The recent increase in natural gas availability has made compressed natural gas (CNG) an option for fueling the transportation sector of the United States economy. In particular, CNG is advantageous in dual-fuel operation alongside ultra low sulfur diesel (ULSD) for compression ignition (CI) engines. This work investigates the usage of natural gas mixtures at varying Energy Substitution Rates (ESRs) within a high compression ratio single-cylinder CI engine, including performance and heat release modeling of dual-fuel combustion. Results demonstrate the differing behavior of utilizing CNG at various substitution rates.

Given the need of the automotive industry to improve fuel efficiency, many companies are moving towards lean burn and low temperature combustion regimes. Critical control of these methods requires an accurate Exhaust Gas Recirculation (EGR) system that can maintain its desired rate and temperature. In this area, the literature illustrates different methodologies to control and monitor this EGR system; however, it lacks a discussion of how the non-linear nature of wave dynamics and time responses of an engine must be taken into account. In order to perform research into the use of EGR for these combustion regimes, an automated, closed-loop EGR system that uses a microprocessor to compute the slope change of the EGR rate and temperature as part of its feedback algorithm was constructed for use in a teaching and research laboratory. The findings illustrate that the system works as intended by replicating known combustion trends with EGR.

The use of Compressed Natural Gas (CNG) has demonstrated the potential to decrease Particulate Matter (PM) and nitrogen oxide (NOx) emissions simultaneously when used in a dual-fuel application with diesel fuel functioning as the ignition source. However, some authors do find that NOx emissions can increase. One postulation is that the conflicting results in the literature may be due to the difference in composition of natural gas around the world. Therefore, in order to investigate if CNG composition influences combustion performance and emissions, four unique mixtures of CNG were tested (i.e., 87% to 96% methane) while minimizing the combined difference of the density, heating value, and constant pressure specific heat of each mixture. This was accomplished at moderate energy substitution ratios (up to 40%) in a single cylinder engine operating at various loads.

The growth of hydraulic fracking has resulted in a dramatic cost reduction of Compressed Natural Gas (CNG), a low carbon fuel. CNG cannot be used as singular fuel in conventional Compression Ignition (CI) engines because of its high auto-ignition characteristics. However, CNG-assisted diesel combustion represents a means to shift the energy consumption of CI engines away from liquid fossil fuels. Calculation of the rate of heat release is vital for understanding and optimizing this mode of engine operation. A previously constructed three-zone equilibrium heat release model that is calibrated to engine exhaust emission measurements was augmented in order to allow for the addition of CNG in the engine intake. The model was also adapted to permit reuse of unburned CNG gas with other exhaust species via exhaust gas recirculation. This is because experiments demonstrated a potentially significant increase in methane emissions under high CNG flowrates.

Diesel Particulate Filters (DPFs) have become a required aftertreatment device for Compression Ignition engine exhaust cleanup of Particulate Matter (PM). Moreover, with the increased prevalence of Spark Ignition Direct Injection (SIDI) systems, discussions are currently underway regarding the need of Gasoline Particulate Filters to handle the PM emanating from their combustion process. In this area, the two-channel DPF model has been widely successful in predicting the temperature, pressure drop, and species conversion in these devices. Because of the need to simulate compressible flow through the channels and a porous wall, these models have a difficult time achieving real-time predictive results suitable for an Engine Control Unit (ECU). As a result, this effort describes the creation of a lumped DPF model intended for an ECU. Model formulation was based on the standard governing equations, but simplified in order to remove as much computational overhead as possible.

In order to perform cutting-edge engine research that applies to modern Compression Ignition (CI) engines, a sophisticated test cell is needed that allows control of the engine and its auxiliary systems. The primary obstacle to the completion of such a test cell is the up-front expense. This paper covers the construction of a low cost, single-cylinder engine test cell while demonstrating the type of research that can be accomplished along the way. The components necessary for the construction, instrumentation, and operation of such a test cell, neglecting emissions analysis equipment, can be obtained for less than $150,000. The engine utilized, a naturally-aspirated single-cylinder Yanmar L100V, was purchased as an engine-generator package.