Andrzej Sobiesiak

Modeling operation of HCCI engines fueled with ethanol

A mathematical engine model is developed to study the operation process in homogeneous charge compression ignition (HCCl) engines. Ethanol is used as an alternative fuel for testing in this model. Two-step reaction mechanisms are implemented to model combustion process for which Arrhenius reaction rates are used and heat transfer process is also included. The simulation results are then compared with experimental data from a modified heavy-duty diesel engine which is used to imitate HCCI operation. Results from this model show good correlation with experiment with respect to combustion phasing, pressure rise and peak pressure. Some control strategies could be potentially developed to stabilize HCCI combustion based on this model.

Multi-Dimensional Engine Modeling Study of EGR, Fuel Pressure, Post-Injection and Compression Ratio for a Light Duty Diesel Engine

For copious levels of exhaust gas recirculation (EGR) (>30 %), oxides of nitrogen (NOx) emissions can be reduced from Euro V to Euro VI regulated levels at the expense of fuel economy and soot emissions. The Lifted-Flame Concept (LFC) has been demonstrated by several researchers to be successful in reducing NOx, while minimizing soot emissions and impact to fuel economy. By simultaneously applying increased EGR and fuel pressure the LFC extends the lift-off length of a diffusion flame and enhances fuel-air entrainment leading to improved fuel and oxygen utilization. When combined with advanced turbocharging and EGR systems the LFC applied to a modern light duty (LD) diesel engine can result in improved fuel economy and lower soot emissions and shows good potential for meeting low soot engine-out targets.In the proposed paper a computational study was conducted using a multi-dimensional engine model. A modified 3D CFD KIVA code with detailed chemistry solver was used to model the diesel fuel spray, droplet breakup, vaporization, mixing, auto-ignition and subsequent heat release and emissions. The model uses inputs from 1D Amesim electro-hydraulic solver to generate the rate of injection (ROI) profile to raise pressure of 1800 bar to 2500 bar as well as to include a simulated post-injection. A 1D model using GT-Power was developed and utilized to provide air system boundary conditions for the 3D CFD model. Post-processing optimization was conducted using Matlab to identify minimum fuel economy and soot emissions for the study of several parameters.The objective of the study was to demonstrate Euro VI emissions levels on a 3.2 L LD diesel engine without NOx aftertreatment and minimal impact to fuel economy using the lifted flame concept. The engine-out NOx emission level was targeted at 0.4 g/kWh and the soot levels were targeted at 0.2 g/kWh assuming diesel particulate filter would be used for after-treatment. The results of the computational study successfully demonstrate the potential of the lifted flame concept to meet Euro VI without the use of NOx aftertreatment technology.Copyright

An Aerodynamic Study and Design Methodology for the 2009 Supermileage Body

Computational Fluid Dynamics (CFD) has gained recognition as a valuable simulation tool for many industrial applications, creating immense opportunities for introducing CFD into standard undergraduate curriculum. This paper is focused on an extensive aerodynamic CFD study related to the 2009 Supermileage Vehicle. Supermileage Competition is a trademark competition conducted by the Society of Automotive Engineers (SAE). This paper provides an aid for future undergraduate students and young researchers interested in designing low drag vehicles. The major part of this study includes airfoil selections and three dimensional CFD iterations to optimize the body design. The methodology focuses on an inside-out approach to optimization of body shape through computation of aerodynamic forces on a low mass vehicle. The 2008 Supermileage car, after four design iterations, had a drag coefficient of 0.16. The 2009 body, in its final full body design, has a drag coefficient equal to 0.12, which is the lowest drag coefficient ever calculated for a University of Windsor Supermileage car. Due to the current economic state and reduced funding, an additional low budget vehicle was also designed and extensive aerodynamic studies were conducted to validate the design. The new low budget design includes a scoop at the leading edge of the vehicle and the CFD model included a driver model for accuracy. After several design iterations the low budget design yielded a drag coefficient of 0.14. Due to the weight savings, conforming to SAE rules, and considering the current economic conditions, the low budget design was finalized for the 2009 Supermileage Vehicle.Copyright

Steady and unsteady modeling of single PEMFC with detailed thermoelectrochemical model

A steady and unsteady water and thermal model was developed to consider the effects of local pressure on the cell performance, pressure drop, open-circuit voltage variation with stack temperature, and water-vapor effects on membrane conductivity. These considerations made the model physically more reasonable as well as more suitable for various operating conditions. Additionally, this model combined the along-flow-channel model and catalyst layer model, which represent a significant improvement to proton exchange membrane fuel cell (PEMFC) modeling. The model could predict the distributions of a series of important parameters along the flow channel and in the catalyst layer. Furthermore, the transient performance of the fuel cell can be simulated with this model. The modeling results agreed reasonably with the available experimental results from the literature. The results show that the humidification of both anode and cathode is very important for the performance of PEMFC which could also be improved by increasing the flow inlet temperatures within a reasonable range. Pressure loss is one of the important parameters that affect total system efficiency and optimization. This model could be used as part of a PEMFC stack or entire system modeling.

CONTROL-ORIENTED MODEL OF ISOOCTANE HCCI COMBUSTION

Abstract A mathematical engine model is developed in this paper to study the operation process in HCCI engines. Isooctane is used as fuel for testing in this model. Two-step reaction mechanisms are implemented to model combustion process and heat transfer process is also included. Results from this model show good correlation with experiment with respect to combustion phasing, pressure rise and peak pressure. Some control strategies could be potentially developed to stabilize HCCI combustion based on this model.