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Papers by Bryan Willson

Investigations of the fuel injection process for large bore natural gas engines are performed on ... more Investigations of the fuel injection process for large bore natural gas engines are performed on an off-engine test fixture. Two types of fuel injectors are studied, a low pressure (0.39 MPa) and a high pressure (3.5 MPa) gas injection valve. Planar laser induced fluorescence is implemented to image fuel jet concentration. The fuel jet from each injector is imaged from the start of injection though their valve-open duration. Effects of injection pressure, piston interaction, and injection event repeatability are investigated. The results are related to previous engine studies of high pressure fuel injection and Schlieren photography of in-cylinder events on a Cooper-Bessemer GMV large bore natural gas engines. The images indicate that the low pressure valve achieves more effective mixing during jet penetration. The high pressure injection event shows relatively little mixing during jet penetration. However, the high pressure jet has much more energy when it impinges on the piston. It is evident that the important time for mixing using high pressure injection occurs after piston impingement.

Acta Agronomica Hungarica, Jun 1, 2009

Nannochloropsis oculata was evaluated as a source for animal feed. Protein, carbohydrate, mineral... more Nannochloropsis oculata was evaluated as a source for animal feed. Protein, carbohydrate, mineral and amino acid analyses were performed on samples before and after lipid extraction, and compared with soybean meal and steam-flaked maize. Nannochloropsis appears to have an excellent composition for use as a supplement for poultry, cattle or swine. The algae meal contains all the essential amino acids required for animal feed. It also showed comparable amounts of nutrients before and after lipid extraction. The initial review is encouraging, suggesting subsequent animal feeding studies to document digestibility, weight gain and animal acceptance. Algae have emerged as one of the most promising sources for biodiesel production. Even though no traditional land crop presents a complete solution, microalgae promise to address numerous limiting factors of biofuels. This is increasingly important as the price of maize, soy, rice and other biofuel sources continues to increase. The growth and productivity of algae is significantly greater than that of crops like soybeans, and algae production does not compete for agricultural lands. Algae production facilities are closed and do not require soil for growth, use 99% less water than conventional agriculture, and can be located on non-agricultural land far from water (Chisti, 2007). Nannochloropsis oculata is a marine unicellular alga commonly cultivated in aquaculture industries for growing rotifers. One of the very important economic issues in algae growth and production is the ability to use algae residue after lipid extraction for animal feed. In this study the nutritional characteristics of algae before and after extraction were compared with those of steam-flaked maize and soybean meal.

American Control Conference, Jun 10, 1987

A study of the dynamics of a liquid piston engine/pump is undertaken using the bond graph modelin... more A study of the dynamics of a liquid piston engine/pump is undertaken using the bond graph modeling technique. Several of the highly transient hydraulic components used in liquid piston engines are studied with a control volume analysis and their bond graph representations are presented. These components form a set of "building blocks" which can then be joined together by "non-potential" hydraulic junctions to model complex liquid piston engine configurations. A total bond graph of a simple 2-stroke liquid piston engine is assembled using these components and results from a simulation study of the state equations derived from this bond graph are presented.

Sustainable Materials and Technologies, Apr 1, 2023

Energy and Power Engineering, 2011

Formaldehyde is an air toxic that is typically emitted from natural gas-fired internal combustion... more Formaldehyde is an air toxic that is typically emitted from natural gas-fired internal combustion engines as a product of incomplete combustion. The United States Environmental Protection Agency (EPA) regulates air toxic emissions, including formaldehyde, from stationary reciprocating internal combustion engines. National air toxic standards are required under the 1990 Clean Air Act Amendments. This work investigates the effect that hardware modifications, or retrofit technologies, have on formaldehyde emissions from a large bore natural gas engine. The test engine is a Cooper-Bessemer GMV-4TF two stroke cycle engine with a 14" (35.6 cm) bore and a 14" (35.6 cm) stroke. The impact of modifications to the fuel injection and ignition systems are investigated. Data analysis and discussion is performed with reference to possible formaldehyde formation mechanisms and in-cylinder phenomena. The results show that high pressure fuel injection (HPFI) and precombustion chamber (PCC) ignition significantly reduce formaldehyde emissions.

Environmental Science & Technology, Sep 24, 2010

Biofuels derived from microalgae have the potential to replace petroleum fuel and first-generatio... more Biofuels derived from microalgae have the potential to replace petroleum fuel and first-generation biofuel, but the efficacy with which sustainability goals can be achieved is dependent on the lifecycle impacts of the microalgae-to-biofuel process. This study proposes a detailed, industrial-scale engineering model for the species Nannochloropsis using a photobioreactor architecture. This process level model is integrated with a lifecycle energy and greenhouse gas emission analysis compatible with the methods and boundaries of the Argonne National Laboratory GREET model, thereby ensuring comparability to preexisting fuel-cycle assessments. Results are used to evaluate the net energy ratio (NER) and net greenhouse gas emissions (GHGs) of microalgae biodiesel in comparison to petroleum diesel and soybean-based biodiesel with a boundary equivalent to "well-to-pump". The resulting NER of the microalgae biodiesel process is 0.93 MJ of energy consumed per MJ of energy produced. In terms of net GHGs, microalgaebased biofuels avoids 75 g of CO 2-equivalent emissions per MJ of energy produced. The scalability of the consumables and products of the proposed microalgae-to-biofuels processes are assessed in the context of 150 billion liters (40 billion gallons) of annual production.

<jats:title>Abstract</jats:title> <jats:p>The topic of this paper is the analyt... more <jats:title>Abstract</jats:title> <jats:p>The topic of this paper is the analytical and computational modeling of the gas injection process in a large bore natural gas fueled engine. At high injection pressures, the overall gas injection and mixing process includes compressible flow features such as rarefaction waves and shock formation. The injection geometries examined in the paper include both a two dimensional slot and an axisymmetric nozzle. The computations examine the effect of the injection pressure/back pressure ratio, with ratios ranging from 3 to 80. The computational modeling was validated by comparison with results obtained from a 2D analytical method of characteristics solution. The validation process evaluated factors such as pressure and Mach number profiles, jet boundary shape and shock location.</jats:p>

IOP conference series, Feb 1, 2009

Traditionally, thermodynamics and heat transfer have been taught at the undergraduate level as se... more Traditionally, thermodynamics and heat transfer have been taught at the undergraduate level as separate disciplines, and results in one area have usually not penetrated into the other area. The internal combustion engine is a complex engineering system with rich thermal science applications, both in thermodynamics and in heat transfer. We have developed web-based software applications written in Java which apply the disciplines of thermodynamics and heat transfer to internal combustion engines. The materials are being used in a introductory sophomore thermal science course which integrates thermodynamics and heat transfer, a junior level heat transfer course, and a senior level internal combustion engines elective class.

SAE Technical Paper Series, Sep 27, 2004

Small displacement carbureted, crankcase-scavenged, two-stroke engines are commonly used for tran... more Small displacement carbureted, crankcase-scavenged, two-stroke engines are commonly used for transportation needs in developing countries (Iyer 2000). The high emissions characteristic of this engine design creates localized acute air pollution problems and contributes significantly to global air pollution (Gorham 2002). A compression pressurized direct fuel injection system (CPDI) has been proposed as a lower cost alternative to the common air blast direct injection system (ABDI). This paper describes the application of the CPDI system as a retrofit to a two-stroke engine typical of those used in "tricycle" transports in the Philippines. Power production, emissions, and fuel consumption for the original carbureted engine, the ABDI system and the CPDI system are also compared. The DI systems show a significant reduction in both hydrocarbons (88% reduction for the ABDI system and 86% reduction for the CPDI system) and carbon monoxide (49% for the air blast system, 83% for the compression pressurized system), and similar power compared to the carbureted engine.

SAE Technical Paper Series, Aug 1, 1995

Journal of engineering for gas turbines and power, Apr 29, 2008

The use of laser ignition for advanced gas engines may provide benefits including extension of th... more The use of laser ignition for advanced gas engines may provide benefits including extension of the lean limit and higher efficiency operation at elevated pressures. This contribution provides a short review of efforts to develop a practical laser ignition system for advanced multicylinder gas engines. The approach is to use a single laser source with fiber optic cables delivering the high power pulses from the source to the engine cylinders. The optical requirements for the fiber delivery lead us to use coated hollow core optical fibers. Characterizations and results of spark delivery tests for the fibers are presented. Single-cylinder engine test results using fiber delivered laser ignition are summarized. For multicylinder operation, a multiplexer based on a moving mirror is used to route the laser output pulses to different fiber channels (cylinders). Benchtop testing and initial engine testing of the multiplexed system are presented.

International Journal of Engine Research, Feb 1, 2004

The ability of three-way catalysts (TWCs) to effectively remove CO and NOx from the exhaust is di... more The ability of three-way catalysts (TWCs) to effectively remove CO and NOx from the exhaust is directly controlled by the air-fuel ratio at which the accompanying engine is operated. In a stoichiometric engine, small variations in the air-fuel ratio have large effects on the catalyst performance. These effects include wide variations in removal efficiencies and catalytic production of ammonia. The effect of the air-fuel ratio on catalysts has been well studied on automotive engines; these studies show the importance of maintaining an air-fuel ratio close to stoichiometric conditions. In automotive systems a ‘dithering’ technique is used in which the air-fuel ratio is modulated to widen the window of control. The effect of dithering on industrial engines has not been studied. A research programme was conducted to evaluate the effects of the air-fuel ratio on the performance of three-way catalysts operating on natural gas-fuelled industrial engines, the test programme aims at optimizing the engine based on the performance of the catalyst. This project has shown that dithering is an effective technique for enhancing the performance of TWCs on industrial engines. These results show that the allowable air-fuel ratio deviations are much larger with dithering and that the production of ammonia is significantly reduced.

Energy for Sustainable Development, Dec 1, 2014

This work examines whether a chimney has influence over the combustion characteristics of biomass... more This work examines whether a chimney has influence over the combustion characteristics of biomass within a stove. Experimental work as well as a simplified chemical kinetic model suggests that a chimney plays an active role in the performance of a stove by influencing the overall air-to-fuel ratio and subsequently the production of carbon monoxide. Two different stoves, operated at multiple wood consumption rates, were shown to run with steady state excess air of 300 % − 1250 %. The wood consumption rate was found to be independent of the chimney draft for both stoves. Increasing draft was shown to increase excess air. Draft served to cool combustion gases through dilution with makeup air. Increasing excess air decreased modified combustion efficiency in experiments and kinetic modeling. Increasing the frictional loss coefficient of a chimney by decreasing the diameter was shown to reduce CO production through a reduction of excess air.

International Journal of Global Energy Issues, Aug 4, 2014

Increasing demand for mobility, expansion of the economy, and the realisation of new goals for de... more Increasing demand for mobility, expansion of the economy, and the realisation of new goals for development have caused tremendous growth in the transport sector of Pakistan. Consequently, transport's share of commercial energy consumption has been increasing and the transport sector has emerged as Pakistan's single largest consumer of petroleum products. Road transport's growth has been more swift and significant than other modes of transport. Opportunities exist to reduce the transport energy demand by switching to energy efficient modes of transport and by employing better management practices. This paper reviews the evolution of transport, patterns of energy demand and supply, and suggests measures to reduce the transport energy demand in Pakistan.

About Solix Biofuels • Solix is the leading developer of production systems for algae-based biofu... more About Solix Biofuels • Solix is the leading developer of production systems for algae-based biofuels-with a background in fuels and a focus on low-cost, high productivity production technology • Solix's cost trajectory shows that fuel production from algae can be costcompetitive with petroleum-but requires full value extraction from the production coproducts • Solix will soon demonstrate the world's largest closed photobioreactor for biofuel production.

Formaldehyde is a hazardous air pollutant (HAP) that is typically emitted from natural gas-fired ... more Formaldehyde is a hazardous air pollutant (HAP) that is typically emitted from natural gas-fired internal combustion engines as a product of incomplete combustion. The US Environmental Protection Agency (EPA) is currently developing national emission standards to regulate HAP emissions, including formaldehyde, from stationary reciprocating internal combustion engines under Title III of the 1990 Clean Air Act Amendments. This work investigates the effect that variations of engine operating parameters have on formaldehyde emissions from a large bore natural gas engine. The subject engine is a Cooper-Bessemer GMV-4TF two-stroke cycle engine with a 14″ (36 cm) bore and a 14″ (36 cm) stroke. Engine parameter variations investigated include load, boost, ignition timing, inlet air humidity ratio, air manifold temperature, jacket water temperature, prechamber fuel supply pressure, exhaust backpressure, and speed. The data analysis and interpretation is performed with reference to possible formaldehyde formation mechanisms and in-cylinder phenomena.

1.1 Introduction 2. Physics of Acoustic Oscillations 2.1 Modelling of Indicator Passages 2.1.1 Na... more 1.1 Introduction 2. Physics of Acoustic Oscillations 2.1 Modelling of Indicator Passages 2.1.1 Natural Frequency of the Helmholtz Resonator 2.1.2 Natural Frequency of a Prismatic Tube 2.1.3 The Bergh and Tijdeman Model 2.2 Experiment for Validation 3. Installation of Combustion Pressure Sensors in Large Bore Gas Engines 3.1 Calculated Natural Frequencies for Positions 1 to 4 4. Test Program and Results 4.1 Engine Specification and Load Conditions 5. Results 5.1 Measured Pressure Signals at Different Sensor Locations 5.2 Comparison of Experimental Results with Calculated Natural Frequencies 6. Recommendations for Sensor Installation in Large Bore Engines

Precombustion chamber (PCC) ignition is a common method for extending the lean limit and reducing... more Precombustion chamber (PCC) ignition is a common method for extending the lean limit and reducing combustion variability in large bore (36–56 cm) natural gas engines. An important component that commonly fails and requires regular replacement, besides the spark plug, is the checkvalve. The checkvalve meters fuel flow into the PCC. In this program the use of an electronic valve for monitoring fuel to the PCC instead of the checkvalve is investigated. Metering the fuel into the PCC with an electronic valve provides a number of different options for improving performance in addition to the benefit of extended valve life. PCC nozzle design is also evaluated as a means for improving PCC and engine performance. Additionally, emissions formation in the PCC is evaluated through the use of a separate pressure transducer in the PCC and a fast sample valve that extracts gas from the PCC.

Journal of engineering for gas turbines and power, 2004

The topic of this paper is the computational modeling of the gas injection process in a large-bor... more The topic of this paper is the computational modeling of the gas injection process in a large-bore natural gas fueled engine. At high injection pressures, the overall gas injection and mixing process includes compressible flow features such as rarefaction waves and shock formation. The injection geometries examined in the paper include both a two-dimensional slot and an axisymmetric nozzle. The computations examine the effect of the supply pressure/cylinder stagnation pressure ratio, with ratios ranging from 3 to 80, on the velocity and pressure profiles in the near field region. Computational fluid dynamics modeling was compared with results obtained from a two-dimensional analytical method of characteristics solution and experimental results. The comparison process evaluated factors such as pressure and Mach number profiles, jet boundary shape, and shock location.