current RESEARCH
brief description from home page
3-D Modeling of the CFR Engine Toward the Development of a High Efficiency Controlled End Gas Auto-ignition Natural Gas Engine
This work is part of a project where an on-road Natural Gas (NG) Spark-Ignited (SI) engine has been under development to achieve Diesel-like efficiencies. Engine knock and misfire are barriers to pathways leading to high-efficiency NG engines. The general tendency to knock is highly dependent on engine operating conditions and the fuel reactivity. The problem is further complicated by low emission limits and the wide range of chemical reactivity in pipeline quality NG (65< MN<95). In order to realize diesel-like efficiencies, spark-ignited NG engines must be designed to operate at high BMEP near knock limits over a wide range of fuel reactivity. This requires a deep understanding of combustion-engine interactions significant in flame propagation and end-gas autoignition. This work aims to develop a three-dimensional computational fluid dynamics (CFD) model of the Cooperative Fuel Research (CFR) engine to investigate knock behavior with NG. The CFR engine model is used to investigate fuel-engine interactions that lead to knock with NG, including effects of fuel reactivity, engine operating parameters, and exhaust gas recirculation (EGR).
Related Publications:
- Investigation of the end-gas autoignition process in natural gas engines and evaluation of the methane number index
- Multi-Dimensional Modeling of the CFR Engine for the Investigation of SI Natural Gas Combustion and Controlled End-Gas Autoignition
- 3-D Modeling of the CFR Engine for the Investigation of Knock on Natural Gas
The Role of Spray Processes and the Physical and Chemical Properties of Single and Multicomponent Liquid Fuels on Flame Stability and Behavior
This project aims to understand the coupling between the physical and chemical properties of single and multicomponent liquid fuels (e.g., jet fuels) on flame stability. More specifically, we are investigating the role of these properties on the spray process, e.g. atomization and subsequent evaporation processes of multi-component fuels, including preferential vaporization effects, on flame stability and behaviors, and how these phenomenons should be considered in the surrogate fuel formulation activities and model-based design approaches. To achieve these goals, we have designed and built a new spray burner to simulate the environment that liquid fuel goes through in gas turbine engines. The experimental apparatus, which is used for this project, is illustrated in the figure below. The specifications of the Annular Co-Flow Spray Burner (ACF – Spray Burner) are:
- Delivering high air co-flow up to 3000 L/min using flow mass controller (Alicat, MCR-3000SLPM-D-PAR).
- Ability to heat the air co-flow to ~500K.
- Delivering a high liquid fuel flow rate up to 107 mL/min using a syringe pump (ISCO, Model 260D).
- Ability to use different nozzle sizes (different injector diameter sizes) to control the droplet sizes for different fuels.
In collaboration with the United States Air Force Academy, we are investigating the behaviors of surrogate fuels developed to model the behavior of real jet fuels. Due to the complex nature of jet fuels, which will contain hundreds of different hydrocarbon species, researchers have developed surrogate fuels – mixtures of a small number of well-understood compounds such as dodecane, toluene, iso-cetane, and others – which can be used as stand-ins for the more complicated jet fuels in simulation and testing. We study the performance of these surrogates in real spray flames to determine the degree to which they accurately emulate jet fuel in varying conditions, and using various laser diagnostic and imaging techniques, we can identify spray and flame characteristics that affect the fuel performance.
The development of a high power laser-based combustion imaging and the diagnostic facility is underway to study turbulent flame stability and dynamics. The facility will utilize a unique seeded high power YAG laser to carry out a suite of combustion diagnostic techniques, including, Planar Laser Induced Fluorescence (PLIF), Rayleigh Light Scattering/Thermometry, Mie droplet scattering/PIV, Raman spectroscopy, as well as, fundamental laser plasma ignition studies.
Lubricant dilution with high pressure natural gas and impact on natural gas compressor lubrication
Colorado State University is partnering with the Gas Machinery Research Council to investigate the relation between oil lubricity and the time the oil is exposed to natural gas. Natural gas (composed mostly of methane, ethane, and propane) is oil soluble. As the natural gas components are dissolved into an oil, the viscosity of the oil decreases. This decrease in viscosity can prevent the oil from lubricating a compressor properly. Currently, natural gas compressors are over lubricated to prevent expensive equipment failures. However, this excess oil, entrained with natural gas, must be removed downstream, which can also result in costly system downtime. The goal of this research is to find a relation between oil lubricity and oil-gas exposure time. This relation will then be used to estimate optimal lubricant feed rates for industrial natural gas compressors.
Modeling of Ablative and Regenerative Cooling System for Liquid Fuel Rocket Engine
This project focuses on determining the most effective cooling system for a non-cryogenic bi-propellant liquid-fuel rocket engine. Rocket engines create extreme conditions for any material to withstand; moreover, materials lose integrity well below their melting points, and the temperatures in rocket engines typically surpass the melting points of metals by a substantial quantity. This necessitates an effective cooling system for the rocket engine to be able to endure the required burn durations. Two common cooling systems for rocket engines are ablative and regenerative. Ablative cooling is a process that utilizes a sacrificial liner which cools the engine through chemical reactions and enthalpy of vaporization. The chemical reactions decrease temperatures in the boundary layer, while charring creates an insulating layer on the chamber walls. Regenerative cooling incorporates the flow of pressurized propellants in channels on the exterior surface of the regions of the rocket which experience the highest heat flux, typically the throat and combustion chamber. Flowing liquid through cooling channels along the outside of the engine wall acts as a heat exchanger by absorbing heat. Liquid rockets enable the potential use of the fuel as a coolant; however, liquid fuels have a relatively small temperature gradient before a phase change occurs. Reserving this small gradient for the sections nearest the nozzle allows for the greatest benefit. In collaboration with Pioneer Astronautics, these two cooling methods are being modeled and compared using both analytical and numerical CFD-FEA methods to simulate the fluid dynamics and heat transfer within the rocket engine.
Natural Gas -Water Vapor Liquid Equilibrium Measurements Using NMR Spectroscopy
In collaboration with the Gas Machinery Research Council and the National Institute of Standards and Technology, Colorado State University is measuring high pressure vapor-liquid equilibrium of methane and water mixtures to improve natural gas transportation. Natural gas transportation utilizes well-established pipelines and compressors across the United States. In order to maintain compressor lifetime and optimize the efficiency of the entire transportation process, operators utilize equation of state software to determine operating conditions. The high-quality data collected will be implemented into NIST’s REFPROP equation of state software to improve the predictive capabilities for the compressor station operators.
Poly-oxymethylene ethers with extended alkly end groups as an optimized bio-derived diesel fuel blend stock
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High Efficiency Direct Injection LPG Engine – LPG Spray Characterization
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High Efficiency Fuel Cell/IC Engine Hybrid Power Generation System: Simulation and Design of High Efficiency Dilute Syngas Fueled Engine
This study deals with the utilization of low heating value mixtures, like dilute hydrogen syngas mixtures, as fuel in conventional IC engine. These kinds of gases are usually used in the synthesis of other products like urea or are produced as products of reactions such as biomass gasification or hydrocarbon reforming. General Syngas is mostly composed of hydrogen and carbon monoxide with varying levels of dilution by many other gases such as carbon dioxide or water. The goal of the current project is to develop a virtual combustion model of the CFR engine using such dilute low LHV fuels. The model should be able to predict the performance of the engine and also operating conditions that can cause knock in the engine when using the dilute syngas. CAE software, GT-Power, and Chemkin are being used to develop the combustion model. The tasks involved in this project include gathering experimental data from the CFR engine while running on the dilute syngas mixture, selection of a chemical mechanism suitable to model the syngas combustion, using the Three Pressure Analysis (TPA) on the model using the experimental data and then finally optimizing the combustion model to allow for predictive results. The long term goal of the project is to replicate the predictability of engine performance and operating envelope for different IC engines.
