Bryan Willson's research while affiliated with Colorado State University and other places

Publications (46)

Article
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....
Conference Paper
Many modern engine systems are designed using one-dimensional computational fluid dynamics (1D CFD). This same technique can be used to model these systems in real time. This real-time model can be used to create virtual sensors in places where due to environmental or cost reasons physical sensors would not be practical. Achieving real-time perform...
Article
Biomass fuels are used by nearly half the world's population on a daily basis for cooking. While these stoves often look simple in appearance they are notoriously difficult to test. By their very nature biomass stoves are typically fairly uncontrolled devices which often exhibit a large amount of variability in their performance. In order to charac...
Article
Full-text available
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. Na-tional air toxic standards are r...
Article
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 us...
Article
Full-text available
Interest in algae as a feedstock for biofuel production has risen in recent years, due to projections that algae can produce lipids (oil) at a rate significantly higher than agriculture-based feedstocks. Current research and development of enclosed photobioreactors for commercial-scale algal oil production is directed towards pushing the upper limi...
Conference Paper
Closed photobioreactors (PBRs) facilitate the cultivation of specific strains of algae and allow optimal growth conditions to be maintained. To date, however, the high capital and operating costs of PBRs have prohibited their use for low-valued products such as biofuels. Since its founding in 2006, Solix Biofuels has maintained a sustained effort t...
Conference Paper
Micro-algae have the potential to produce enough bio-fuels to meet the current US fuel demands. In order to achieve this potential, photo-bioreactors (PBRs) need to be developed that are efficient, scalable, and affordable. Models are an analytical tool that can be used to evaluate various PBRs. In this article, a dynamic model is developed for gro...
Article
Full-text available
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 wi...
Article
Past research has shown that laser ignition provides a potential means to reduce emissions and improve engine efficiency of gas-fired engines to meet longer-term DOE ARES (Advanced Reciprocating Engine Systems) targets. Despite the potential advantages of laser ignition, the technology is not seeing practical or commercial use. A major impediment i...
Conference Paper
Full-text available
Past research has demonstrated the feasibility of using optical sparks for engine ignition, and has shown potential benefits associated with reduced cyclic variability and increased rate of cylinder pressure rise, thus extending the lean operating limit of natural gas engines. This contribution details the design and bench-top testing of a fiber-op...
Article
This work expands the knowledge base concerning the formation of oxides of nitrogen (NO x ) in the precombustion chamber (PCC) of a four-stroke lean burn (4SLB) industrial gas engine. Two analysis methods were used to characterize specific exhaust constituent concentrations formed in the PCC. The first method extracted gas from the PCC and the over...
Conference Paper
The acoustic resonances in indicator passages are often modeled using either a Helmholtz or a so called organ pipe acoustical model. However, in practice these models often indicate natural frequencies which are too high. This paper proposes the Bergh and Tijdeman model [1] which is more accurate and which was originally developed for pressure meas...
Conference Paper
Past research has shown that laser ignition is capable of operating high bmep engines at high efficiency and with low emission levels. However, for laser ignition systems to be adopted by industry, one requires a practical (and economical) mode of beam delivery other than the conventional open-path beam delivery that has been used in much of the pa...
Conference Paper
Laser ignition is viewed as a potential future technology for advanced high-efficiency low-emission natural gas engines. However, in order to make laser ignition systems more practical, thereby enabling them to transition from the laboratory to industrial settings, there is a need to develop fiber optically delivered ignition systems. Recent work a...
Article
Full-text available
We report what is to our knowledge the first delivery of nanosecond laser pulses through flexible fibers to produce optical sparks in atmospheric-pressure gases. Our work employs a Nd:YAG laser beam (1.064 microm) delivered through a cyclic olefin polymer-coated silver hollow fiber. We studied the beam properties at the fiber exit as a function of...
Article
In this work fuel and ignition control techniques are developed for articulated rod, largebore, two-stroke, natural-gas-fuelled engines. A Cooper-Bessemer GMV-4TF engine is utilized for the experimental investigation. Due to the articulation of the connecting rods, the even bank cylinders have different piston position and port opening profiles and...
Conference Paper
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 t...
Conference Paper
Full-text available
A practical impediment to implementation of laser ignition systems has been the open-path beam delivery used in past research. In this contribution, we present the development and implementation of a fiber-optically delivery laser spark ignition system. To our knowledge, the work represents the first demonstration of fiber coupled laser ignition (u...
Article
Full-text available
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 d...
Article
Cycle-resolved NO data were acquired from a Cooper-Bessemer GMV 4TF two-stroke engine to better understand and quantify large bore natural gas engine NO x emission. The cycle resolved NO data were extracted separately from the engine's cylinder two and four exhaust ports and taken simultaneously with cycle resolved pressure traces, conventional ste...
Article
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 eff...
Article
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-d...
Conference Paper
A student design team at Colorado State University (CSU) has developed an innovative snowmobile to compete in the Clean Snowmobile Challenge 2003 competition. This engine concept was originally developed for the CSC 2002 competition and demonstrated the lowest emissions of any engine that competed that year. The team utilized a 3-cylinder, 594cc, l...
Article
A thermodynamic two-stroke-cycle engine simulation with a quasi-steady scavenging model was developed and used to mass-integrate cycle-resolved NO measurements made with a fast-response NO analyser. The engine tested was a Cooper-Bessemer GMV-4TF large-bore natural gas engine and the fast NO measurements were made in cylinders 2 and 4 using a Cambu...
Article
One cylinder of the Colorado State University large-bore test engine was instrumented with fast-response surface thermocouples for heat-transfer analysis. Probes were installed at several locations progressively farther from the ignition source and their outputs were recorded along with combustion pressure using a high-speed data-acquisition system...
Article
This investigation assesses the benefits of retrofitting a diesel micro-pilot ignition system on a Cooper-Bessemer GMV-4TF two-stroke cycle natural gas engine with a 14" (36 cm) bore and a 14" (36 cm) stroke. The pilot fuel injectors are mounted through an adaptor in one of the spark plug holes in a set of dual-spark plug heads. A high pressure, co...
Article
The tracer gas method is investigated as a means to study scavenging in fuel-injected large-bore two-stroke cycle engines. The investigation is performed on a Cooper-Bessemer GMV-4TF natural gas engine, with a 36-cm bore and a 36-cm stroke. Two important parameters are evaluated from the tracer gas measurements, which are scavenging efficiency and...
Article
In this work the tracer gas method using nitrous oxide as the tracer gas is implemented on a stationary two-stroke cycle, four-cylinder, fuel-injected large-bore natural gas engine. The engine is manufactured by Cooper-Bessemer, model number GMV-4TF. It is representative of the large bore natural gas stationary engine fleet currently in use by the...
Conference Paper
Investigations of fuel jet penetration and fuel and air mixing are performed in a static piston, pressurized optical engine. The pressure in the cylinder that the gas is injected into is varied to study the effect of the compression process. The engine has the same piston and cylinder geometry as a Cooper-Bessemer GMV-4TF two-stroke cycle natural g...
Conference Paper
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...
Conference Paper
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 in...
Article
This research addresses the growing need to better understand the mechanisms through which engine-out formaldehyde is formed in 2-stroke cycle large bore natural gas engines. The investigation is performed using a number of different in-cylinder sampling techniques implemented on a Cooper-Bessemer GMV-4TF 4-cylinder 2-stroke cycle large bore natura...
Article
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 inclu...
Article
An investigation was performed to try to quantify the relative importance of large-scale mixing and turbulence in a multi-valve spark-ignited automotive engine converted to use natural gas fuel. The role of mixing was examined by comparing single-point versus multi-point combustion performance at several operating conditions. The fuel-air mixture p...
Conference Paper
Full-text available
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 deve...
Conference Paper
A study was conducted to determine the ability of neural networks to extract high level control information from cylinder pressure data. Various experiments were performed using neural networks for pattern recognition on a series of data files consisting of cylinder pressure versus crank angle. The goal of these experiments was to estimate spark ti...
Article
There are an estimated 70-100 million 2-stroke cycle engines in Asia, powering motorbikes, mopeds, three- wheelers, tuk-tuks, and tricycles. These 2-stroke engines are characterized by very high levels of hydrocarbon (HC), carbon monoxide (CO), and particulate (PM) emissions. These high emissions levels are primarily caused by "scavenging losses" p...
Article
A spark delivery system for generating a spark using a laser beam is provided, the spark delivery system including a laser light source and a laser delivery assembly. The laser delivery assembly includes a hollow fiber and a launch assembly comprising launch focusing optics to input the laser beam in the hollow fiber. In addition, the laser deliver...

Citations

... Data for three different fuel injection poppet valves are presented in this paper. The geometries of these valves are described in elsewhere [11]. The fuel injection pressures for the low pressure mechanical, low pressure electro-hydraulic, and high pressure electro-hydraulic are 25, 45, and 500 psig (0.17, 0.31, and 3.4 MPag), respectively . ...
... However, publications on high performance two-stroke engine simulations are limited. Hull et al [6] reported limited success on modeling a 600 cm 3 snowmobile. With regards to motorcycle road-racing grand prix engines, attempts were made by Cartwright [7] and McEntee [8], both with inadequate accuracy. ...
... The associated results could be used to calibrate and validate NO x kinetics models as well as to correlate NO produced by individual cycles with other bulk parameters associated with the cycle, such as peak-combustion pressure, crank angle location of peak pressure or indicated mean effective pressure. Such correlations could lead to new or improved parametric-based emissionmonitoring systems that predict emission levels based on measured engine operating parameters and can presumably be implemented more economically and more reliably than direct emission measurement [4]. ...
... The air blast direct injection system, pioneered by Orbital Engine Company (Huston et al. 1998), has successfully been applied as a retrofit to small twostroke engines for the purpose of improving emissions via reduction of fuel short-circuiting (Willson 2002). In the ABDI system (figure 1), fuel is injected into a cavity in an air rail, which is separated from the combustion chamber by an outwardly opening, solenoid actuated, poppet valve called the "blast valve". ...
... Few studies have been published on the effects of injection timing on the charge preparation dynamics and the combustion process in CNG engines. [26][27][28] This research investigates the impact of injection timing on engine performance and combustion behaviour for gasoline and CNG engine at 25% throttle and 1700 engine speed. Moreover, the effect of injection timing on gasoline and CNG combustion performance was reported for further understanding. ...
... Some works related to this topic are (Prapas, Baumgardner, Marchese, Willson, & DeFoort, 2014), where they investigated the influence of the draft caused by the expansion of gases in the chimney of a biomass cookstove, using CFD and experimental validation. The results presented by the authors were similar to (Pundle, Sullivan, Means, Posner, & Kramlich, 2019) and concluded that the draft created by the expansion of gases, leads to an excessive amount of air coming into the system, of between [300 − 1250]% higher than the stoichiometric. ...
... A retrofit DI system in the form of a kit has also been developed to replace the existing carburettor system on the motorcycle engine. For example, a retrofit DI system has been developed for Kawasaki HDIII in [44,45]; a 125 cc, 2-stroke motorcycle from Philippines that is commonly used as a taxi. The system incorporates the air blast direct injection (ABDI). ...
... In this contribution, Yalin et al. [89][90][91] have shown the possibility of using coated hollow fibers for spark delivery and have demonstrated laser ignition and operation of a single engine cylinder using hollow fiber delivery. The work represented the first demonstration of fiber coupled laser ignition (using a remote laser source) of a natural gas engine. ...
... The signal at DP2 represents a more complex pattern, which has a high-amplitude wave in one period and a lowamplitude wave in the next period. The acoustic resonance in the long recess passage seems to influence pressure measurements at DP2 [23]. The amplitude of the pressure fluctuations in the fuel manifold was approximately four times higher than that in the oxidizer manifold, since the fuel mass flow rate was three times larger than the oxidizer one. ...
... Subsequently, a standard pre-combustion chamber was modified by designing a new nozzle and an electronic valve that replaced the check valve for fuel metering in a large-bore natural gas engine (Fig. 5a). It was found that the electric valve and new nozzle design reduced NO x and brake-specific fuel consumption (BSFC) by 20% and 4%, respectively ( Fig. 5b) [40]. ...