Performance, combustion and emissions of a diesel engine operated with reformed EGR. Comparison of diesel and GTL fuelling

This is the post-print version of the final paper published in Fuel. The published article is available from the link below. Changes resulting from the publishing process, such as peer review, editing, corrections, structural formatting, and other quality control mechanisms may not be reflected in this document. Changes may have been made to this work since it was submitted for publication. Copyright @ 2008 Elsevier B.V.In this work, the effects of a standard ultra-low sulphur diesel (ULSD) fuel and a new, ultra-clean synthetic GTL (gas-to-liquid) fuel on the performance, combustion and emissions of a single-cylinder, direct injection, diesel engine were studied under different operating conditions with addition of simulated reformer product gas, referred to as reformed EGR (REGR). For this purpose various levels of REGR of two different compositions were tested. Tests with standard EGR were also carried out for comparison. Experiments were performed at four steady state operating conditions and the brake thermal efficiency, combustion process and engine emission data are presented and discussed. In general, GTL fuel resulted in a higher brake thermal efficiency compared to ULSD but the differences depended on the engine condition and EGR/REGR level and composition. The combustion pattern was significantly modified when the REGR level was increased. Although the extent of the effects of REGR on emissions depended on the engine load, it can be generally concluded that an optimal combination of GTL and REGR significantly improved both NOx and smoke emissions. In some cases, NOx and smoke emission reductions of 75% and 60%, respectively, were achieved compared to operation with ULSD without REGR. This offers a great potential for engine manufacturers to meet the requirements of future emission regulations.Shell Global Solutions UK, the Government of Castilla-La Mancha (Spain) and the Royal Thai Government

Diesel exhaust-gas reforming for H2 addition to an aftertreatment unit

This is the post-print version of the final paper published in Chemical Engineering Journal. The published article is available from the link below. Changes resulting from the publishing process, such as peer review, editing, corrections, structural formatting, and other quality control mechanisms may not be reflected in this document. Changes may have been made to this work since it was submitted for publication. Copyright @ 2008 Elsevier B.V.The work described in this paper has been undertaken as part of the design of an integrated system comprising a diesel engine, an exhaust-gas fuel reformer and a NOx aftertreatment unit. The exhaust-gas reformer is used to provide hydrogen-rich reformate to the NOx aftertreatment unit, containing a hydrocarbon-SCR catalyst, in order to improve its NOx reduction activity at low exhaust-gas temperatures. The reformer configuration and operating parameters have been examined in order to optimise the performance of the hydrocarbon-SCR catalyst, which is promoted by the presence of H2 but inhibited by CO. The length of the catalyst bed inside the reformer is a key factor in determining the extent to which the water-gas shift reaction can contribute to the reforming process, and therefore strongly influences the proportions of CO and H2 in the reformate. However, it is also necessary for the reactant ratios at the reformer inlet to be controlled in response to changes in the engine operating conditions. In practice, this means that the rate of fuel addition to the reformer needs to be optimised for different exhaust gas compositions and space velocities

Application of exhaust gas fuel reforming in diesel and homogeneous charge compression ignition (HCCI) engines fuelled with biofuels

This is the post-print version of the final paper published in Energy. The published article is available from the link below. Changes resulting from the publishing process, such as peer review, editing, corrections, structural formatting, and other quality control mechanisms may not be reflected in this document. Changes may have been made to this work since it was submitted for publication. Copyright @ 2007 Elsevier B.V.This paper documents the application of exhaust gas fuel reforming of two alternative fuels, biodiesel and bioethanol, in internal combustion engines. The exhaust gas fuel reforming process is a method of on-board production of hydrogen-rich gas by catalytic reaction of fuel and engine exhaust gas. The benefits of exhaust gas fuel reforming have been demonstrated by adding simulated reformed gas to a diesel engine fuelled by a mixture of 50% ultra low sulphur diesel (ULSD) and 50% rapeseed methyl ester (RME) as well as to a homogeneous charge compression ignition (HCCI) engine fuelled by bioethanol. In the case of the biodiesel fuelled engine, a reduction of NOx emissions was achieved without considerable smoke increase. In the case of the bioethanol fuelled HCCI engine, the engine tolerance to exhaust gas recirculation (EGR) was extended and hence the typically high pressure rise rates of HCCI engines, associated with intense combustion noise, were reduced

Millimeter wave satellite communication studies. Results of the 1981 propagation modeling effort

Theoretical modeling associated with rain effects on millimeter wave propagation is detailed. Three areas of work are discussed. A simple model for prediction of rain attenuation is developed and evaluated. A method for computing scattering from single rain drops is presented. A complete multiple scattering model is described which permits accurate calculation of the effects on dual polarized signals passing through rain

Parallel Anisotropic Unstructured Grid Adaptation

Computational Fluid Dynamics (CFD) has become critical to the design and analysis of aerospace vehicles. Parallel grid adaptation that resolves multiple scales with anisotropy is identified as one of the challenges in the CFD Vision 2030 Study to increase the capacity and capability of CFD simulation. The Study also cautions that computer architectures are undergoing a radical change and dramatic increases in algorithm concurrency will be required to exploit full performance. This paper reviews four different methods to parallel anisotropic grid generation. They cover both ends of the spectrum: (i) using existing state-of-the-art software optimized for a single core and modifying it for parallel platforms and (ii) designing and implementing scalable software with incomplete, but rapidly maturating functionality. A brief overview for each grid adaptation system is presented in the context of a telescopic approach for multilevel concurrency. These methods employ different approaches to enable parallel execution, which provides a unique opportunity to illustrate the relative behavior of each approach. Qualitative and quantitative metric evaluations are used to draw lessons for future developments in this critical area for parallel CFD simulation

Modifying catalytically the soot morphology and nanostructure in diesel exhaust: Influence of silver De-NOx catalyst (Ag/Al2O3)

The influence of an Ag/Al2O3 HC-SCR catalyst on the morphological and nanostructural aspects of the exhaust particulate matter (PM) generated during the combustion of diesel fuel and a glycol ether–diesel fuel blend was addressed in this research work. In addition, the impact of in-cylinder fuel post injections (FPI) on the particulate formation pathway and on the catalytic de-NOx efficiency was also studied. The tests were carried at low exhaust temperatures in the absence and presence of small amounts of hydrogen (H2). It is concluded that in the absence of H2, the catalyst does not modify the primary particle size (dp0) of the soot aggregates, while the aggregation of the soot particles throughout the catalyst channels is the main governing mechanism. The catalyst influence on the particulate structure was evident when H2 was introduced, with smaller dp0 seen downstream of the catalyst, indicating that despite the short residence time of the PM within the catalyst bed, the soot particles were partially oxidised. The use of late FPI reduces the exhaust PM level and delivers sufficient HC:NOx ratios that improves the catalyst activity up to a maximum of 80% NOx conversion, with no sign of catalyst deactivation when H2 (500 ppm) was injected. Furthermore, it is suggested that along with oxidising part of the particles produced during the main fuel injection phase, late FPI can also produce, to a lesser extent, some additional soot with a less matured structure, resulting on average in less ordered particles being emitted into the exhaust stream. This work shows that in modern diesel engines, a silver catalyst can alter the soot structure in the exhaust in a way that can ease the diesel particulate filter (DPF) regeneration cycles, improve its filtration efficiency and help in effectively reducing the tailpipe NOx emissions. For the catalyst to perform these functions, multiple in-cylinder fuel injection strategies (late FPI) combined with small amounts of hydrogen addition to the exhaust are required

Thermochemical recovery technology for improved modern engine fuel economy – part 1: analysis of a prototype exhaust gas fuel reformer

Exhaust gas fuel reforming has the potential to improve the thermal efficiency of internal combustion engines, as well as simultaneously reduce gaseous and particulate emissions.</p

Extending the environmental benefits of ethanol–diesel blends through DGE incorporation

The research focuses on the potential use of DGE (diethylene glycol diethyl ether), as a high-cetane number oxygenated additive to diesel-like fuels. Apart from evaluating its individual effects an investigation of how DGE can facilitate the use of bio-ethanol in diesel engines was conducted; which faces many technical difficulties, but can provide environmental advantages over biodiesel and conventional diesel fuel. Four partly renewable fuel blends with varying contents of DGE and ethanol were designed with overall diesel-replacement rate of 20%. DGE was found to reduce gaseous emissions, achieving a simultaneous reduction in both soot and NOx which highlighted the beneficial effects of its high cetane number and oxygen content. In ethanol–diesel blends small additions of DGE significantly enhanced blend stability and blend auto-ignition properties. Improvements in the NOx/soot trade-off characteristics were obtained for all blends. All tested blends produced lower particulate matter number concentrations and soot with characteristics that reduced their oxidation temperatures, hence providing benefits for diesel particulate filter (DPF) regeneration. Overall it was found that DGE fuel provides considerable energy and environmental benefits if used both as a single oxygenate with diesel or in multicomponent blends with ethanol and diesel

Reducing CO2 footprint through synergies in carbon free energy vectors and low carbon fuels

Carbon-footprint from transport and power generation can significantly be improved when carbon free or reduced carbon energy carries are utilised that are compatible with the current technology of the internal combustion (IC) engines. The current study focuses on the reduction of diesel engine CO2 emissions by improving ammonia and hydrogen combustion through the incorporation of alternative fuel, diethyl glycol diethyl ether (DGE) as an oxygenated fuel blend and combustion enhancer. The aim of the work is to study the potential synergies between DGE and two carbon free energy vectors H2 and NH3 in reducing the environmental effects and contribute in decarbonising internal combustion engines. DGE's ignition properties (i.e. high cetane number) improved the H2 and NH3 combustion efficiencies via counteracting their high auto-ignition resistances, and also contributing in lowering the unburnt H2 and NH3 emissions to the atmosphere. This led in the reduction of CO2 by up 50% when 60–70% of diesel fuel is replaced with DGE, H2 and NH3. Synergetic effects were also found between DGE and the gaseous fuels (i.e. hydrogen and ammonia) simultaneously decreasing the levels of PM, NOx, HC and CO emitted to the atmosphere; thus mitigating the health and environmental hazards associated to diesel engines.NOTICE: this is the author’s version of a work that was accepted for publication in Energy. Changes resulting from the publishing process, such as peer review, editing, corrections, structural formatting, and other quality control mechanisms may not be reflected in this document. Changes may have been made to this work since it was submitted for publication. A definitive version was subsequently published in Energy VOL 112, (2016) DOI: 10.1016/j.energy.2016.07.010© 2016, Elsevier. Licensed under the Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International http://creativecommons.org/licenses/by-nc-nd/4.0/<br/