Leonid Tartakovsky

Performance Analysis of SI Engine Fueled by Ethanol Steam Reforming Products

The goal of the present work was to analyze the performance of a spark ignition engine fueled by ethanol steam reforming products. The highest reformer-ICE system efficiency and the lowest CO emissions were achieved with the ethanol steam reforming products obtained at reaction temperature of 1000K and water/ethanol ratio of 1.8. Fueling the SI engine with reformate gas made it possible to achieve the reformer-ICE system efficiency of 40% for the engine fed by SRE products compared with 34% for gasoline and 36% for ethanol. CO emissions were reduced by 3.5 and 10 times compared with ethanol and gasoline, respectively. NOx emissions were decreased by about 4 times compared with the gasoline fed engine.

Simulation of Wankel Engine Performance Using Commercial Software for Piston Engines

At present the market of Wankel engines is limited to some special applications. This fact explains absence of commercial software products specially developed for this engine simulation and prediction of its performance. Conversely, there are available and widely used software products for simulation of reciprocating-piston engines performance. Some attempts are known in using this software for prediction of Wankel engine performance. This paper details an approach used in these attempts. Main differences between both types of engines are summarized and principles of a virtual reciprocating-piston engine compilation are developed. A method of virtual blowing was developed for assessment of discharge coefficients for intake and exhaust ports. Comparison of simulation results with the measured performance of two UAV Wankel engines showed sufficient accuracy of the suggested approach.

Reforming Controlled Homogenous Charge Compression Ignition - Simulation Results

A computer model was built and a theoretical analysis was performed to predict the behavior of a system containing Homogenous charge compression ignition (HCCI) engine and a methanol reformer. The reformer utilizes the waste heat of the exhaust gases to sustain the two subsequent processes: dehydration of methanol to dimethyl ether (DME) and water, and methanol steam reforming (SRM) where methanol and water react to mainly hydrogen, CO and CO2. Eventually, a gaseous mixture of DME, H2, CO, CO2, water (reused) and some other species is created in these processes. This mixture is used for the engine feeding. By adding water to the methanol and fixing the vaporized fuels temperature, it is possible to manage the kinetics of chemical processes, and thus to control the products’ composition. This allows controlling the HCCI combustion. By a magnification of H2/DME ratio the ignition delay is increased and so it is possible to synchronize the ignition timing and also to control combustion duration. The simulation results prove feasibility of the suggested approach and a possibility of achieving substantially higher energy efficiency together with zero-impact NOx emissions in a wide range of engine operating modes.

Fuel Effects on Emissions from Heavy-Duty Diesel Engines – Results of Recent Research Programs

The main goal of the work presented here was to compile a review of the available literature on the effects of diesel fuel properties on emissions from heavy-duty diesel engines (HDDEs). Because of the large number of various studies that have been performed in this area, the present review is mainly based on the most comprehensive recent research programs: the European Programme on Emissions, Fuels and Engine Technologies (EPEFE), and the USA Programs EPA Heavy-Duty Engine Working Group (EPA-HDEWG) and Diesel Emission Control – Sulfur Effect (DECSE). Fuel properties that have been identified over the years as influencing emissions from HDDEs, and were considered in this work, are cetane number, density, aromatics (total and poly-), sulfur and oxygen contents and back-end distillation. The impact of fuel sulfur content on emission control systems was reviewed, based mainly on the findings of the latest DECSE Program, which was concluded in 2000. These systems include diesel oxidation catalysts, lean-NOx catalysts, NOx adsorbers and diesel particulate filters (traps). A comparison is presented between the regression models, developed in the framework of the EPEFE and EPA-HDEWG programs. Only limited data are available addressing oxygen effects on HDDE emissions. It is noted that there is still lack of data regarding the fuel effects on emissions of engines tested over the new European Transient Cycle.

Buses retrofitting with diesel particle filters: Real-world fuel economy and roadworthiness test considerations

Retrofitting older vehicles with diesel particulate filter (DPF) is a cost-effective measure to quickly and efficiently reduce particulate matter emissions. This study experimentally analyzes real-world performance of buses retrofitted with CRT DPFs. 18 in-use Euro III technology urban and intercity buses were investigated for a period of 12months. The influence of the DPF and of the vehicle natural aging on buses fuel economy are analyzed and discussed. While the effect of natural deterioration is about 1.2%-1.3%, DPF contribution to fuel economy penalty is found to be 0.6% to 1.8%, depending on the bus type. DPF filtration efficiency is analyzed throughout the study and found to be in average 96% in the size range of 23-560nm. Four different load and non-load engine operating modes are investigated on their appropriateness for roadworthiness tests. High idle is found to be the most suitable regime for PN diagnostics considering particle number filtration efficiency.

An Analytical Model of a Two-Phase Jet with Application to Fuel Sprays in Internal Combustion Engines

The paper presents an analytical two-dimensional model of two-phase turbulent jets with focus on fuel sprays in internal combustion engines. The developed model allows prediction of the fuel spray parameters including local fuel concentration and mixture velocity. The model proposed in this paper is based on the single-phase steady-state laminar axisymmetric jet flow field solution by Schlichting. This solution is amended to include transport of the discontinuous fuel phase in a stagnant air in the limit of a dilute fuel concentration. This two-phase jet flow model admits a closed form analytical solution for the fuel concentration distribution. This solution is then applied to turbulent jet flow as per the approach described by Schlichting and in other studies, and used to predict point-wise properties of fuel sprays in internal combustion engines. The results of model simulations are compared with the available experimental data. It was found that the analytical model predicts satisfactorily spray properties without additional assumptions or fitting coefficient.

Thermo-Chemical Recuperation as an Efficient Way of Engine's Waste Heat Recovery

It is known that about 30% of fuel energy introduced to an internal combustion engine (ICE) is wasted with engine exhaust gases. One of the promising ways of waste heat recovery is thermo-chemical recuperation (TCR). For the purpose of TCR realization, in principle any fuel may be used. However, utilization of renewable bio-alcohols, especially ethanol or methanol is the most favorable. The advantages of TCR over turbocharging are in the fact that its energy transfer is not limited by isentropic expansion and that the reforming process improves the fuel properties. A comprehensive theoretical analysis of the ICE with TCR was carried out using the developed model for simulation of the joint operation of ICE with alcohol reformer, when the ICE is fed by the alcohol reforming products and the energy of the exhaust gases is utilized to sustain endothermic reforming reactions. Simulation results show that it is possible to sustain endothermic reforming reactions with a reasonable reactor size. Modeling results point out a possibility of engines efficiency improvement by up to 13% in comparison with ICE feeding by gasoline together with achievement of zero-impact pollutant emissions.

Theoretical and Experimental Study of Remote Sensing for Measuring Transport Emissions

The problem of air pollution by motor vehicles is b ecoming more severe in the world. The standard methods for measuring the concentrations of pollutants emitted by vehicles may be performed only for very limited vehicle samples because of their cost and complexity. A novel method of “Remote Sensing” (RS) is developed to enable measurements of pollutants emitted by passing vehicles. The resu lts of RS experiments, carried out in Israel and in the world, show that 10% of the gasoline veh icles fleet are responsible for about half of the total emissions. These results indicate that identifying these big polluters and repairing them could lead to significant improvement of the air quality. The remote sensing method for measuring pollutants concentrations is based on the attenuation of electromagnetic (or laser) beams, which are radiate d from a source, traverse through the exhaust gas plume and detected by a sensor. Infra ‐ Red (IR) and Ultra ‐ Violet (UV) radiation absorption is applied to monitor the NO, HC, CO and CO 2 concentrations. The RS measurement is still in the development stage, and not yet accurate and reliable enough. Thus it cannot be used now to determine emission standards or to enforce them. The main objective of this work was to develop a theoretical model for the interpretation of RS measurements of gaseous pollutants and Particulate Matter (PM) emissions. A new method was developed for calculating the Optical Thickness (OT) of participating media containing exhaust gas mixture with scattering particles. The medium considered here is anisotropic and has wavelength dependent properties. The radiation absorption and scattering efficiencies of the particles were calculated accor ding to Mie or Rayleigh theories and the gaseous absorption coefficients by the Line-By-Line (LBL) method. It is assumed that the concentration of each component in the plume can be calculated according to Gaussian dispersion model. A new analytical solution for the General Dynamic Equation (GDE) is employed in this algorithm. RS experiments were carried out, where emissions of about 14,000 vehicles were monitored and analyzed. The calculated results for the OT were fitted to the RS measurement results in order to obtain th e gaseous pollutants concentrations and particles emission rates in the tailpipe outlet. Nu merical results (for OT) compare favorably with experimental data. This model may be applied in current RS technologies as a supplement tool for monitoring PM.

Results of electric vehicle demonstration program

Many countries and companies around the world are supporting and developing zero emission vehicles (ZEVs). These efforts reflect legislative and other government actions that result from the growing public awareness of the damaging effects of air pollution caused by automotive emissions. In spite of developments, the most significant technology barrier postponing the manufacturing of commercially acceptable electric vehicles is the development of a suitable energy source. The zinc-air battery that is being developed by Electric Fuel Ltd. is one of the advanced technologies under development. In December 1996, the Israel Electric Corp. (IEC) signed an exclusive license agreement to utilize the electric fuel zinc-air battery technology in the Middle East. The first stage of implementing this agreement was the development of and carrying out a demonstration program based on a Mercedes Benz MB 410 van that was converted to EV operation. The vehicle was equipped with a computerized data acquisition system. The battery data is collected via the battery controller, the data concerning the regeneration of the zinc anodes is collected via the control computer of the regeneration plant. The purpose of the work presented in this paper was to evaluate road performance of the demonstration electric vehicle powered by zinc-air battery under typical conditions of Israeli traffic.