Performance of in-use buses retrofitted with diesel particle filters

Inhalation of combustion generated nanoparticles leads to major adverse health effects. Public road transportation heavily depends on diesel fueled vehicles, which greatly contribute to air pollution in urban centers. Retrofitting polluting older buses with diesel particulate filter (DPF) is a cost-effective measure to quickly reduce particulate emissions. This study experimentally analyses the impact of DPF retrofitting on particulate emissions and engine performance aspects of in-use diesel buses. DPFs from three different major manufacturers were installed in 18 urban and intercity Euro III buses of a major Israeli bus company. Particulate number (PN) concentration and size distribution were measured both before and after DPF at different engine operating regimes. The average increase in fuel consumption due to DPF retrofitting was measured to be less than 2.5%, and backpressure increase is about one third of the acceptable limit. No deterioration of buses engine, as well as vehicle drivability were detected. The average reduction in total PN emissions was found to be higher than 97%, with no substantial difference between the different DPF manufacturers

CITY AUTOMATED TRANSPORT SYSTEM (CATS): THE LEGACY OF AN INNOVATIVE EUROPEAN PROJECT

CATS is a collaborative European project promoting driverless vehicles that ended in December 2014. This contribution explains how the project evolved, including the handling of unexpected events and concentrating on lessons learned. The constructor and vehicle had to be changed for economic reasons in the middle of the project timeline. A second constructor went bankrupt, although access to his vehicles could be secured. For security and legal reasons, part of the final demonstration was relocated at short notice to the EPFL campus in Lausanne, Switzerland, where around 1600 people were transported during 16 days of vehicle operation. Reactions to the driverless vehicle concept were overwhelmingly positive. Implications for the acceptability of driverless vehicles in Europe and elsewhere are discussed

Numerical Investigation of the Combined Influence of Three-Plug Arrangement and Slot Positioning on Wankel Engine Performance

A numerical methodology for three-dimensional fluid dynamics and chemical kinetics simulation of the combustion and gas-exchange processes in the Wankel engine was developed and validated. Two approaches of performance enhancement were studied—the addition of a slot in the rear side of the rotor recess, and installation of a third plug in the trailing side of the working chamber, in addition to the two available plugs mounted in the leading side of the baseline engine. The obtained results showed that the suggested three-plug arrangement significantly improves the engine performance. Furthermore, positioning the trailing plug further from the passage between the trailing and leading sides is of preference for higher mean in-chamber pressures. Nevertheless, for maximum performance, the distance should be brought to an optimum as during the intake stroke there is a loss of inducted charge due to backflow from the trailing plug hole. For the three-plug arrangement the presence of a slot is necessary for the prevention of early flame quenching in the trailing side, while keeping the added volume to a minimum. Moreover, positioning the slot and the trailing plug off-center, results in higher flow intensity towards the leading plugs, and accordingly, to a higher combustion efficiency. For dual-plug ignition system (two plugs in the leading side) it is preferable to maintain minimum clearance in the trailing side

Suitability of the Reforming-Controlled Compression Ignition Concept for UAV Applications

Reforming-controlled compression ignition (RefCCI) is a novel approach combining two methods to improve the internal combustion engine’s efficiency and mitigate emissions: low-temperature combustion (LTC) and thermochemical recuperation (TCR). Frequently, the combustion controllability challenge is resolved by simultaneous injection into the cylinder of two fuel types, each on the other edge of the reactivity scale. By changing the low-to-high-reactivity fuel ratio, ignition timing and combustion phasing control can be achieved. The RefCCI principles, benefits, and possible challenges are described in previous publications. However, the suitability of the RefCCI approach for aerial, mainly unmanned aerial vehicle (UAV) platforms has not been studied yet. The main goal of this paper is to examine whether the RefCCI approach can be beneficial for UAV, especially HALE (high-altitude long-endurance) applications. The thermodynamic first-law and the second-law analysis is numerically performed to investigate the RefCCI approach suitability for UAV applications and to assess possible efficiency gains. A comparison with the conventional diesel engine and the previously developed technology of spark ignition (SI) engine with high-pressure TCR is performed in view of UAV peculiarities. The results indicate that the RefCCI system can be beneficial for UAV applications. The RefCCI higher efficiency compared to existing commercial engines compensates the lower heating value of the primary fuel, so the fuel consumption remains almost the same. By optimizing the compression pressure ratio, the RefCCI system efficiency can be improved

Numerical Study of a Direct Injection Internal Combustion Engine Burning a Blend of Hydrogen and Dimethyl Ether

In the reported study, various aspects of dimethyl ether/hydrogen combustion in a Reactivity Controlled Compression Ignition (RCCI) engine are numerically evaluated using Reynolds Averaged Navier-Stokes (RANS) and Large Eddy Simulation (LES). Early direct injection and mixture propagation were also explored, along with peculiaritis of dimethyl ether combustion modeling. The numerical models are validated using available experimental results of a partially premixed dimethyl ether jet flames and an optically accessible internal combustion engine with direct hydrogen injection. LES showed more predictive results in modeling both combustion and mixture propagation. The same models were applied to a full engine cycle of an RCCI engine with stratified reactivity, to gain phenomenological insight into the physical processes involved in stratified reactivity combustion. We showed that 3D and turbulence considerations had a great impact on simulation results, and the LES was able to capture the pressure oscillations typical for this type of combustion

Biological and Environmental Research Exascale Requirements Review

The article of record as published may be found at http://dx.doi.org/10.2172/1375720An Office of Science review sponsored jointly by Advanced Scientific Computing Research and Biological and Environmental Research, March 28-31, 2016, Rockville, MarylandUnderstanding the fundamentals of genomic systems or the processes governing impactful weather patterns are examples of the types of simulation and modeling performed on the most advanced computing resources in America. High-performance computing and computational science together provide a necessary platform for the mission science conducted by the Biological and Environmental Research (BER) office at the U.S. Department of Energy (DOE). This report reviews BER’s computing needs and their importance for solving some of the toughest problems in BER’s portfolio. BER’s impact on science has been transformative. Mapping the human genome, including the U.S.-supported international Human Genome Project that DOE began in 1987, initiated the era of modern biotechnology and genomics-based systems biology. And since the 1950s, BER has been a core contributor to atmospheric, environmental, and climate science research, beginning with atmospheric circulation studies that were the forerunners of modern Earth system models (ESMs) and by pioneering the implementation of climate codes onto high-performance computers. See http://exascaleage.org/ber/ for more information.USDOE Office of Science (SC), Advanced Scientific Computing Research (SC-21)USDOE Office of Science (SC), Biological and Environmental Research (BER) (SC-23