Jonathan Mattson

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.

Moderate Substitution of Varying Compressed Natural Gas Constituents for Assisted Diesel Combustion

ABSTRACT The recent growth of hydraulic fracking has made compressed natural gas (CNG) a viable option for fueling the United States transportation sector in a dual fuel scenario with ultra low sulfur diesel (ULSD). To clarify literature trends, this effort investigates the influence of CNG speciation (methane, ethane, propane, and isobutane) by employing energy substitution rates (ESR) of 7%, 18%, and 40% (approximately) to prevent significant changes to ignition delay. Results demonstrate that maintaining hydrocarbon (HC) constituents within typical global levels has no noticeable bearing on the findings; however, added CNG does noticeably change the peak rate of heat release. Overall, nitrogen oxides (NOx) and particulate matter emissions remained lower than ULSD values except for the highest load and ESR rate when NOx increased due to a significant growth of the premixed combustion phase. At all ESR values, methane and non-methane hydrocarbons increased subsequently leading to a decrease in combustion efficiency.

Exergy Analysis of Dual-Fuel Operation with Diesel and Moderate Amounts of Compressed Natural Gas in a Single-Cylinder Engine

ABSTRACT An energy-exergy heat release model is used with in-cylinder pressure measurements to analyze dual-fuel combustion in a high compression ratio diesel engine. Compressed natural gas (CNG) addition does not exceed 40% of total fuel energy, in order to avoid significant changes to liquid fuel injection timing needed to maintain efficient engine operation. Increasing CNG usage is observed to enhance exergetic efficiency, as premixed combustion is promoted over diffusion burn. In addition, CNG usage is associated with higher exergy retention by the exhaust gases. However, this comes with decreased combustion efficiency as CNG survives combustion and is lost to the exhaust. Overall, the analysis shows that CNG usage may result in lower absolute exergy consumption by the engine, even alongside the lost exergy from unburned fuel, as the wasted CNG is simultaneously less exergetically useful, and thermal efficiency rises due to increased premixed combustion.

Second Law Heat Release Modeling of a Compression Ignition Engine Fueled With Blends of Palm Biodiesel

Modeling of engine-out heat release is of great importance for engine combustion research. Variations in fuel properties bring about changing combustion behavior within the cylinder, which may be captured by modeling of the rate of heat release. This is particularly true for biodiesel fuels, where changes in fuel behavior are linked to viscosity, density, and energy content. Heat release may also be expanded into an analysis using the 2nd Law of Thermodynamics, which may ascertain the pathways through which availability is either captured as useful work, unused as thermal availability of the exhaust gas, or wasted as heat transfer. In specific, the 2nd Law model identifies the period of peak availability, and thus the ideal period to extract work, and is of use for power optimization.A multi-zone (fuel, burned, and unburned) diagnostic model using a 1st Law of Thermodynamics analysis is utilized as a foundation for a 2nd Law analysis, allowing for a simultaneous energy and exergy analysis of engine combustion from a captured pressure trace. The model calibrates the rate and magnitude of combustion through an Arrhenius equation in place of a traditional Wiebe function, calibrated using exhaust emission measurements.The created model is then utilized to categorize combustion of diesel and palm biodiesel fuels, as well as their blends. The 2nd Law analysis is used to highlight the effects of increasing biodiesel usage on engine efficiency, particularly with respect to fuel viscosity and combustion temperature. The 2nd Law model used is found to provide a more clear understanding of combustion than the original 1st Law model, particularly with respect to the relationships between biodiesel content, viscosity, temperature, and diffusion-dominated combustion.Copyright

Availability Analysis of Alternative Fuels for Compression Ignition Engine Combustion

Modeling of engine heat release from in-cylinder pressure is a common practice for characterizing engine combustion. Fuel property variation induces changes in engine performance, which can be categorized through heat release modeling. One under-utilized form includes an availability analysis that links changes in fuel properties to the amount of availability extracted as work or lost through inefficiencies. Here, a diagnostic heat release model is used to catalogue both the 1st and 2nd Law behavior of numerous alternative fuels. Conventional engine combustion using diesel, biodiesel, renewable jet fuel, and waste-plastic derived diesel are studied, alongside dual-fuel operation of compressed natural gas (with diesel) and synthesis gas (with biodiesel), allowing for the exploration of combustion with respect to changing fuel properties. In particular, more ideal fuel mixing is generally reflected directly in the 2nd Law efficiency. However, high viscosities largely result in a later availability addition that is not extracted as work. While this availability would be wasted at exhaust blowdown, deliberately increasing later temperatures may be useful if paired with exhaust heat recovery systems. Overall, the 2nd Law model presents these tradeoffs more clearly than a traditional 1st Law analysis; thus, its further use may be warranted in concert with advanced engine combustion modes.

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.

Fixed Bed Solid Fuel Combustor for the Purpose of Testing Solid Biomass Emissions Properties

Fossil fuels place a large strain on the environment due to the pollution produced through their extraction and usage. One method to reduce societal fossil fuel usage is through co-combustion of coal with woody biomass. However, overproduction of this biomass may lead to significant environmental deterioration. A potential sustainable substitute for the woody biomass is in the form of dried algae. Because the emission characteristics of algae combustion are unknown, a simple dry mass combustor was constructed, including necessary instrumentation, as part of an undergraduate design class with the goal of a more thorough characterization of algae’s combustion properties. The combustor is a simple and affordable design, in keeping with the classes’ principles of sustainability through a focus on energy, environment, and economy. The combustor consists of a flow controller that sends air into a metallic plenum, where modulations in flow are reduced before it is sent to a steel pipe for combustion. This paper describes the concepts involved in the design of this combustor, and preliminary assessment efforts employing the system when testing biomass pellets. Testing showed combustion efficiency greater than 98%, and the data clearly illustrates three separate phases to the reaction process, with rapid changes in emissions and temperature punctuating the ends of these phases.Copyright