Michael Mangus

Performance and Emissions Characteristics of Hydroprocessed Renewable Jet Fuel Blends in a Single-Cylinder Compression Ignition Engine with Electronically Controlled Fuel Injection

To offset the usage of petroleum-based jet-propellant, alternative jet fuels made from sustainable sources are being researched. Due to the Single Fuel Forward Policy, these jet propellant fuels are being used in compression ignition (CI) engines designed to burn ultra-low-sulfur-diesel (ULSD). In the current study, a single-cylinder CI engine with electronic injection timing burns ULSD, jet propellant (Jet-A), and blends of Jet-A with hydrotreated renewable aviation fuel (R-8). Results for Jet-A and R-8 indicate that injection modulation provides performance that is similar or improved compared to ULSD, particularly when considering fuel consumption. Nitrogen oxides, carbon monoxide, and hydrocarbon emissions are all lower than ULSD for both aviation fuels while yielding similar particulate matter emissions. Results show that re-calibration of engine injection timing in order to account for differing aviation fuels could prove advantageous for military logistics through improved fuel consumption.

Employing Adaptive Mesh Refinement for Simulating the Exhaust Gas Recirculation Mixing Process

One significant emissions issue of compression ignition engines that directly influences human health is the production of nitrogen oxides (NOx). Once produced, these species are difficult to convert catalytically in the exhaust and often require a complex aftertreatment system to mitigate their release into the environment. The common methodology by the internal combustion engine community to reduce the amount of NOx is to employ Exhaust Gas Recirculation (EGR) in order to dilute the intake mixture with inert species (e.g., water). This lowers the combustion temperature lessening the thermal NO production mechanism. Improper mixing of EGR with the intake (species in-homogeneity, low levels of mixing turbulence, etc.) can lead to significant cylinder-to-cylinder variation in combustion temperatures and NOx emissions, making it more difficult to achieve regulatory standards.In this effort, a three-dimensional (3-D), transient, computational fluid dynamics (CFD) analysis was performed in order to more accurately model the mixing of EGR and intake for a single-cylinder test engine. Mixing is achieved for this engine by using a small rectangular box in which clean air and engine exhaust for controlled recirculation are mixed prior to engine intake. A matrix of computational analyses at different engine loads, and simulation types (large eddy and Reynolds-averaged Navier-Stokes) at 25% EGR were performed to check computational time and agreement with experimental measurements. Moreover, this effort employs the use of adaptive mesh techniques in order to understand their usage and validate correct implementation for later endeavors including more complex geometries, such as the manifold of a multi-cylinder engine. The simulation results indicate that mass flow rate and temperature of the mixture as it leaves the mixing box agree to within 3% of experimental values. Furthermore, pressures at the air and EGR inlet boundaries showed agreement to around 1% and 12%, respectively, with the experimental measuring points indicated as the reason for the difference. In addition, species mixing of carbon monoxide was uniform to within 440 ppm. Finally, the use of the models may also account for a prior discrepancy in the output power of the single-cylinder engine test stand.Copyright

Diesel Particulate Filter Model With Detailed Permeability Analysis

Recent legislation of engine exhaust Particulate Matter (PM) emission levels cannot be met with in-cylinder PM reduction techniques, thus resulting in the need for a Diesel Particulate Filter (DPF). Modern DPFs use a honeycomb of long channels with porous walls in order to filter PM with near 100% efficiency. They must be designed to balance trapping efficiency and pressure drop, as flow restriction decreases engine efficiency. This paper describes the construction of two Matlab models in order to predict properties within the filter. Two methods for simultaneously solving the differential conservation equations along with the algebraic ideal gas law in the inlet and outlet channels have been developed. The first method solves the channel equations by transforming the differential algebraic equations (DAEs) into an ordinary differential equation (ODE) system. In addition, a second method is developed that directly solves DAE systems of index-one. In order to link the inlet and outlet channel profiles, modeling of the wall flow is necessary. Four permeability models from different disciplines are used in Darcy’s law to determine their applicability in calculating DPF wall velocity profiles. The resulting inlet, wall, and outlet parameters are compared with published results to demonstrate each model’s accuracy.Copyright

Influence of Fuel Injection System and Engine-Timing Adjustments on Regulated Emissions from Four Biodiesel Fuels

The use of biofuels for transportation has grown substantially in the past decade in response to federal mandates and increased concern about the use of petroleum fuels. As biofuels become more common, it is imperative to assess their influence on mobile source emissions of regulated and hazardous pollutants. This assessment cannot be done without first obtaining a basic understanding of how biofuels affect the relationship between fuel properties, engine design, and combustion conditions. Combustion studies were conducted on biodiesel fuels from four feedstocks (palm oil, soybean oil, canola oil, and coconut oil) with two injection systems, mechanical and electronic. For the electronic system, fuel injection timing was adjusted to compensate for physical changes caused by different fuels. The emissions of nitrogen oxides (NOx) and partial combustion products were compared across both engine injection systems. The analysis showed differences in NOx emissions based on hydrocarbon chain length and degree of fuel unsaturation, with little to no NOx increase compared with ultra-low sulfur diesel fuel for most conditions. Adjusting the fuel injection timing provided some improvement in biodiesel emissions for NOx and particulate matter, particularly at lower engine loads. The results indicated that the introduction of biodiesel and biodiesel blends could have widely dissimilar effects in different types of vehicle fleets, depending on typical engine design, age, and the feedstock used for biofuel production.