Browse Topic: Fuel reformers

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Dongari, Madhukar
Considerations for Hydrogen Fuel Cells in Airborne ApplicationsAIR7765 (Current)11/18/2019
The scope of this joint EUROCAE/SAE report is to compile the considerations relating to airborne application of hydrogen fuel cells. This document provides a comprehensive analysis of the use of hydrogen as a fuel by describing its existing applications and the experience gained by exploiting fuel cells in sectors other than aviation. The use of hydrogen fuel cells in aircraft can help in meeting aviation environmental targets (including noise pollution) and can be vital to achieving efficient electrically propelled air vehicles. The experience gained with mature fuel cells in terrestrial applications and the handling of other gases in aviation, as presented herein, will help in alleviating safety concerns and in demystifying the usage of hydrogen in aviation.
AE-7F Hydrogen and Fuel Cells
Fuel Reforming and Catalyst Deactivation Investigated in Real Exhaust Environment2019-01-03154/2/2019
Increased in-cylinder hydrogen levels have been shown to improve burn durations, combustion stability, HC emissions and knock resistance which can directly translate into enhanced engine efficiency. External fuel reformation can also be used to increase the hydrogen yield. During the High-Efficiency, Dilute Gasoline Engine (HEDGE) consortium at Southwest Research Institute (SwRI), the potential of increased hydrogen production in a dedicated-exhaust gas recirculation (D-EGR) engine was evaluated exploiting the water gas shift (WGS) and steam reformation (SR) reactions. It was found that neither approach could produce sustained hydrogen enrichment in a real exhaust environment, even while utilizing a lean-rich switching regeneration strategy. Platinum group metal (PGM) and Ni WGS catalysts were tested with a focus on hydrogen production and catalyst durability. Although 4% additional hydrogen was initially produced in the EGR stream, leading to improvements in the coefficient of variation (CoV) and brake specific fuel consumption (BSFC), catalyst activity decreased within a few hours regardless of the regeneration strategy employed. With an SR catalyst, a small amount of hydrogen was produced in the EGR stream via the WGS reaction but not the SR reaction. Similar to the WGS catalyst testing, the SR catalyst deactivated quickly due to coking. While neither of these approaches displayed acceptable long-term performance, the exhaust environment still poses a significant opportunity for the production of hydrogen rich reformate to deliver improvement in engine efficiency.
Bartley, Gordon, Gukelberger, Raphael, Henderson, Robert, Henry, Cary
Effects of Low Temperature Reforming (LTR) Products of Low Octane Number Fuels on HCCI Combustion2018-01-16829/10/2018
In order to achieve high-efficiency and clean combustion in HCCI engines, combustion must be controlled reasonably. A great variety of species with various reactivities can be produced through low temperature oxidation of fuels, which offers possible solutions to the problem of controlling in-cylinder mixture reactivity to accommodate changes in the operating conditions. In this work, in-cylinder combustion characteristics with low temperature reforming (LTR) were investigated in an optical engine fueled with low octane number fuel. LTR was achieved through low temperature oxidation of fuels in a reformer (flow reactor), and then LTR products (oxidation products) were fed into the engine to alter the charge reactivity. Primary Reference Fuels (blended fuel of n-heptane and iso-octane, PRFs) are often used to investigate the effects of octane number on combustion characteristics in engines. Then PRF0 (n-heptane) and PRF50 (mixture of 50% n-heptane and 50% iso-octane by volume) were chosen as representative low octane number fuels. LTR products were quantitatively detected using online gas chromatograph (GC). High-speed imaging was conducted to illustrate the flame development. A single-zone model was used to evaluate the reactivity of LTR products. The GC measurements indicate that PRF0 and PRF50 cannot chemically react at low reformer temperature of 423 K. When the reformer temperature rises up to 523 K, LTR products mainly include hydrogen, carbon monoxides, aldehydes, alcohols, ketones, alkanes, olefins and alkynes. Due to the higher fuel reactivity, PRF0 produces more reformates than PRF50. According to the experimental engine analysis, the ignition timing is retarded significantly via LTR for both PRFs. The ignition timing difference of PRF0 due to LTR is larger than PRF50. The high-speed images reveal that LTR can lead to a slower flame development. Soot formation persists because of in-cylinder inhomogeneities, and can be lowered by LTR. The reactivity evaluation using the chemical modeling approach manifests that for PRF0 most of the LTR products inhibit mixture reactivity, while there is a large increase in the species enhancing reactivity for PRF50. The impacts of LTR products on ignition depend on both the chemical structure and the concentration in the mixture. The concentration of individual LTR product usually changes along with the reforming conditions. Thus LTR has the potential to control autoignition flexibly in HCCI engines.
Geng, Chao, Liu, Hai Feng, Fang, Xinghui, Yang, Zhi, Cui, Yanqing, Wang, Yu, Feng, Lei, Yao, Mingfa
Reformed Fuel Substitution for Transient Peak Soot Reduction2018-01-02674/3/2018
Advancements in catalytic reforming have demonstrated the ability to generate syngas (a mixture of CO and hydrogen) from a single hydrocarbon stream. This syngas mixture can then be used to replace diesel fuel and enable dual-fuel combustion strategies. The role of port-fuel injected syngas, comprised of equal parts hydrogen and carbon monoxide by volume was investigated experimentally for soot reduction benefits under a transient load change at constant speed. The syngas used for the experiments was presumed to be formed via a partial oxidation on-board fuel reforming process and delivered through gaseous injectors using a custom gas rail supplied with bottle gas, mounted in the swirl runner of the intake manifold. Time-based ramping of the direct-injected fuel with constant syngas fuel mass delivery from 2 to 8 bar brake mean effective pressure was performed on a multi-cylinder, turbocharged, light-duty engine to determine the effects of syngas on transient soot emissions. A Cambustion fNOx400 high-speed emissions analyzer and an AVL 439 opacimeter were used to quantify emissions under the load change to provide sub-cycle and cycle resolved resolution, respectively. Results show substantial soot reduction benefits with modest levels of syngas without significant increases in NOx emissions under the chosen conditions.
Dal Forno Chuahy, Flavio, Olk, Jamen, Kokjohn, Sage
System and Second Law Analysis of the Effects of Reformed Fuel Composition in “Single” Fuel RCCI Combustion2018-01-02644/3/2018
Dual-fuel reactivity controlled compression ignition (RCCI) combustion is a promising method to achieve high efficiency with near-zero NOx and soot emissions; however, the requirement to carry two fuels on board limits practical application. Advancements in catalytic reforming have demonstrated the ability to generate syngas (a mixture of CO and hydrogen) from a single hydrocarbon stream. This syngas mixture can then be used as the low reactivity fuel stream to enable single fuel RCCI combustion. The present effort uses a combination of engine experiments and system level modeling to investigate reformed fuel RCCI combustion. The impact of reformer composition is investigated by varying the syngas composition from 10% H2 to approximately 80% H2. The results of the investigation show that reformed fuel RCCI combustion is possible over a wide range of H2/CO ratios. A system level and second law analysis are performed on the highest efficiency operating points, and comparisons are made between partial oxidation reforming, steam reforming, and conventional diesel. The results show that endothermic reforming (steam reforming) can achieve comparable system level efficiency to conventional diesel operation by recovering exhaust energy at similar system-out NOx emissions and near-zero soot emissions. An autoignition integral approach combined with reformer equilibrium modeling shows that in order to achieve higher system level efficiencies, lower H/C ratios of the parent fuel are necessary. Typical H/C ratio ranges for diesel fuels limit the range of operation of the engine to high hydrogen fractions, limiting the system level efficiency due to high heat transfer rates associated with these conditions.
Dal Forno Chuahy, Flavio, Kokjohn, Sage
Demonstration of Single-Fuel Reactivity Controlled Compression Ignition Using Reformed Exhaust Gas Recirculation2018-01-02624/3/2018
A key challenge for the practical introduction of dual-fuel reactivity controlled compression ignition (RCCI) combustion modes in diesel engines is the requirement to store two fuels on-board. This work demonstrates that partially reforming diesel fuel into less reactive products is a promising method to allow RCCI to be implemented with a single stored fuel. Experiments were conducted using a thermally integrated reforming reactor in a reformed exhaust gas recirculation (R-EGR) configuration to achieve RCCI combustion using a light-duty diesel engine. The engine was operated at a low engine load and two reformed fuel percentages over ranges of exhaust gas recirculation (EGR) rate and main diesel fuel injection timing. Results show that RCCI-like emissions of NOx and soot were achieved load using the R-EGR configuration. It was also shown that complete fuel conversion in the reforming reactor is not necessary to achieve sufficiently low fuel reactivity for RCCI combustion. Overall engine brake thermal efficiency (BTE) was found to be slightly lower than for conventional diesel combustion (CDC) at the same overall fueling rate; however, increasing fumigant energy fraction (FEF) was shown to improve BTE. The presented data illustrated that further system optimization could allow R-EGR-based RCCI combustion systems to achieve BTE parity with CDC operation while maintaining extremely low engine-out soot and NOX emissions.
Hwang, Jeffrey T., Kane, Seamus P., Northrop, William F.
Experimental and Kinetic Analyses of Thermochemical Fuel Reforming (TFR) with Alcohol Enrichment in Plug Flow Reactor: a Verification of In-Cylinder TFR2017-01-227810/8/2017
In-cylinder thermochemical fuel reforming (TFR) in spark ignition natural gas engine was developed to reveal that thermochemical fuel reforming could increase H2 and CO concentration in reformed gas, leading to an increase of thermal efficiency and engine performance. Moreover, ethanol enrichment has been proved to have great potential to optimize TFR performance. In order to explain TFR phenomenon chemically, methane oxidation experiments were conducted in a laminar flow reactor with addition of ethanol and methanol at equivalent ratios of 1.5, 1.7, 1.9 and 2.1 from 948K to 1098K at atmospheric pressure. Experimental results showed that methanol have great ability to facilitate the oxidation of methane than that of ethanol. Meanwhile, the degree of methane conversion became more significantly as the equivalent ratio increased. Kinetic analysis of oxidation of methane with alcohol enrichment in a plug flow model was also conducted in this study. There was good agreement between experimental and computational results. The oxidation of methanol or ethanol released plenty of radicals such as H, OH and HO2, which further reacted with CH4 more intensively in fuel rich condition. Rate of production and sensitivity analyses showed that methanol could produce more reactive radicals, which were involved in a series of initial oxidation reactions of methane. It indicated that methanol have great potential to improve in-cylinder TFR performance.
Deng, Zhiwei, Li, Ang, Zhu, Lei, Huang, Zhen
Energy Analysis of Low-Load Low-Temperature Gasoline Combustion with Auxiliary-Fueled Negative Valve Overlap2017-01-07293/28/2017
In-cylinder reforming of injected fuel during an auxiliary negative valve overlap (NVO) period can be used to optimize main-cycle auto-ignition phasing for low-load Low-Temperature Gasoline Combustion (LTGC), where highly dilute mixtures can lead to poor combustion stability. When mixed with fresh intake charge and fuel, these reformate streams can alter overall charge reactivity characteristics. The central issue remains large parasitic heat losses from the retention and compression of hot exhaust gases along with modest pumping losses that result from mixing hot NVO-period gases with the cooler intake charge. Accurate determination of total cycle energy utilization is complicated by the fact that NVO-period retained fuel energy is consumed during the subsequent main combustion period. For the present study, a full-cycle energy analysis was performed for a single-cylinder research engine undergoing LTGC with varying NVO auxiliary fueling rates and injection timing. A custom alternate-fire sequence with 9 pre-conditioning cycles was used to generate a common exhaust temperature and composition boundary condition for a cycle-of-interest, with performance metrics recorded for each custom cycle. The NVO-period reformate stream and main-period exhaust stream of the cycles-of-interest were separately collected, with sample analysis by gas chromatography used to identify the retained and exhausted fuel energy in the respective periods. To facilitate gas sample analysis, experiments were performed using a 5-component gasoline surrogate (iso-octane, n-heptane, ethanol, 1-hexene, and toluene) that matched the molecular composition, 50% boiling point, and ignition characteristics of a research gasoline. The highest total cycle thermodynamic efficiencies occurred when auxiliary injection timings were early enough to allow sufficient residence time for slow reforming reactions to take place, but late enough to prevent significant fuel spray crevice quench. Increasing the fraction of total fuel energy injected into the NVO-period was also found to increase total cycle thermal efficiencies, in part due to a modest reduction in NVO-period heat loss from a combination of fuel-spray charge cooling and endothermic fuel decomposition by pyrolysis. The effect was most pronounced at the lowest loads where larger charge mass reformate fractions increased overall specific heat ratios and main-period combustion phasing advanced closer to top dead center. These effects improved both expansion efficiency and combustion stability.
Ekoto, Isaac, Wolk, Benjamin, Northrop, William
The Effects of Charge Preparation, Fuel Stratification, and Premixed Fuel Chemistry on Reactivity Controlled Compression Ignition (RCCI) Combustion2017-01-07733/28/2017
Engine experiments were conducted on a heavy-duty single-cylinder engine to explore the effects of charge preparation, fuel stratification, and premixed fuel chemistry on the performance and emissions of Reactivity Controlled Compression Ignition (RCCI) combustion. The experiments were conducted at a fixed total fuel energy and engine speed, and charge preparation was varied by adjusting the global equivalence ratio between 0.28 and 0.35 at intake temperatures of 40°C and 60°C. With a premixed injection of isooctane (PRF100), and a single direct-injection of n-heptane (PRF0), fuel stratification was varied with start of injection (SOI) timing. Combustion phasing advanced as SOI was retarded between -140° and -35°, then retarded as injection timing was further retarded, indicating a potential shift in combustion regime. Peak gross efficiency was achieved between -60° and -45° SOI, and NOx emissions increased as SOI was retarded beyond -40°, peaking around -25° SOI. Optimal cases in terms of both gross efficiency and peak pressure rise rate (PPRR) were in the mid-range SOI timings centered about -50° SOI, while late SOI resulted in decreased gross efficiency, decreased combustion efficiency, and high NOx. To assess the effect of the premixed fuel chemistry on RCCI combustion, a representative reformed fuel referred to as syngas (50% H2, 50% CO by volume), and methane were substituted for PRF100. A reference baseline PRF condition with an SOI timing of -50° at Tin = 40°C and ϕ = 0.30 was used for comparison purposes. Matching combustion phasing to the baseline case by adjusting the premixed percent or SOI timing resulted in reduced gross efficiency (ηg) and increased NOx emissions for both the syngas and methane cases. Matching the bulk heat release rate (HRR) characteristics by fixing the DI SOI quantity and duration and adding a premixed injection of n-heptane was able to regain most of the lost efficiency while decreasing NOx emissions close to the baseline level.
DelVescovo, Dan, Kokjohn, Sage, Reitz, Rolf
Exploration of Dual Fuel Diesel Engine Operation with On-Board Fuel Reforming2017-01-07573/28/2017
Many dual fuel technologies have been proposed for diesel engines. Implementing dual fuel modes can lead to emissions reductions or increased efficiency through using partially premixed combustion and fuel reactivity control. All dual fuel systems have the practical disadvantage that a secondary fuel storage and delivery system must be included. Reforming the primary diesel to a less reactive vaporized fuel on-board has potential to overcome this key disadvantage. Most previous research regarding on-board fuel reforming has been focused on producing significant quantities of hydrogen. However, only partially reforming the primary fuel is sufficient to vaporize and create a less volatile fuel that can be fumigated into an engine intake. At lower conversion efficiency and higher equivalence ratio, reforming reactors retain higher percentage of the inlet fuel’s heating value thus allowing for greater overall engine system efficiency. The experimental work described in this paper successfully demonstrates that a thermally integrated reforming reactor using exhaust gas recirculation mixed with vaporized diesel fuel as reactants can effectively reform diesel fuel with high conversion efficiency. The engine was operated at two speed and load settings and achieved lower soot, but higher CO and THC emissions. Overall engine efficiency was decreased compared to conventional diesel combustion; loss of fuel heating value in the reforming reactor did not allow the engine to achieve efficiencies found for operation with no reforming. Additional work is required to improve diesel fuel vaporization prior to the reactor and to operate at higher reformer equivalence ratio, thereby increasing overall engine thermal efficiency.
Hwang, Jeffrey, Li, Xuesong, Northrop, William
Development of Laminar Burning Velocity Correlation for the Simulation of Methanol Fueled SI Engines Operated with Onboard Fuel Reformer2017-01-05393/28/2017
Methanol fueled spark ignition (SI) engines have the potential for very high efficiency using an advanced heat recovery system for fuel reforming. In order to allow simulation of such an engine system, several sub-models are needed. This paper reports the development of two laminar burning velocity correlations, corresponding to two reforming concepts, one in which the reformer uses water from an extra tank to produce hydrogen rich gas (syngas) and another that employs the water vapor in the exhaust gas recirculation (EGR) stream to produce reformed-EGR (R-EGR). This work uses a one-dimensional (1D) flame simulation tool with a comprehensive chemical kinetic mechanism to predict the laminar burning velocities of methanol/syngas blends and correlate it. The syngas is a mixture of H2/CO/CO2 with a CO selectivity of 6.5% to simulate the methanol steam reforming products over a Cu-Mn/Al catalyst. The simulation was exercised over syngas contents in the blend, fuel-air equivalence ratios, pressures, unburned gas temperatures and EGR ratios ranging respectively from 0% to 50%, 0.5 to 1.5, 10 to 85 bar, 550 to 800 K and 0% to 30% (by mass). The developed correlations are ready to be implemented into engine simulation tools as well as computational fluid dynamic codes. Based on the developed correlations, optimal control strategies and dilution methods have been studied. The engine is able to work with the same mass burning rate at leaner mixtures or lower intake charge temperatures with an onboard fuel reformer. If the engine is operated at stoichiometric condition, at the same mass fraction of methanol to the catalyst and the same EGR, the R-EGR concept is recommended because it provides a faster laminar burning velocity and does not require an extra tank of water for fuel reforming.
Nguyen, Duc-Khanh, Verhelst, Sebastian
Investigation of Species from Negative Valve Overlap Reforming Using a Stochastic Reactor Model2017-01-05293/28/2017
Fuel reforming during a Negative Valve Overlap (NVO) period is an effective approach to control Low Temperature Gasoline Combustion (LTGC) ignition. Previous work has shown through experiments that primary reference fuels reform easily and produce several species that drastically affect ignition characteristics. However, our previous research has been unable to accurately predict measured reformate composition at the end of the NVO period using simple single-zone models. In this work, we use a stochastic reactor model (SRM) closed cycle engine simulation to predict reformate composition accounting for in-cylinder temperature and mixture stratification. The SRM model is less computationally intensive than CFD simulations while still allowing the use of large chemical mechanisms to predict intermediate species formation rates. By comparing model results with experimental speciation data from a single-cylinder engine, the presented work provides insight into the thermodynamic and kinetic processes that occur during in-cylinder fuel reformation. Three single-component fuels (iso-octane, n-heptane and ethanol) were modeled as a function of assumed thermal stratification. Across thermal stratification levels, the modeled reformate concentrations match well with measured values though they are very sensitive to initial conditions. The relationship between thermal stratification and resulting reformed species provides insight into the effect of non-homogeneity on products and illustrates the value of SRM over homogeneous reactor models to inexpensively predict in-cylinder processes.
Kane, Seamus, Li, Xuesong, Wolk, Benjamin, Ekoto, Isaac, Northrop, William F.
A Theoretical Investigation of the Combustion of PRF90 under the Flexible Cylinder Engine Mode2017-01-10273/28/2017
On-board fuel reforming offers a prospective clean combustion mode for the engines. The flexible cylinder engine strategy (FCE) is a new kind of such mode. In this paper, the combustion of the primary reference fuel of PRF90 was theoretically investigated in a homogeneous charge compression ignition engine to validate the FCE mode, mainly focusing on the ignition delay time, the flame speed, and the emissions. The simulations were performed by using the CHEMKIN2.0 package to demonstrate the fuel reforming process in the flexible cylinder, the cooling effect on the reformed products, and the combustions of the mixture of the fresh fuel and the reformed products in the normal cylinders. It was found that the FCE mode decreased the ignition delay time of the fuel by about 35 crank angles at a typical engine condition. The reaction pathways analyses indicated that methyl peroxide (CH3OOH), ketohydroperoxides (KETs), and hydrogen peroxide (H2O2) were the key species to decrease the ignition delay time in the reformed products, while the addition of acetone (CH3COCH3) and formaldehyde (CH2O) resulted in misfire in the normal cylinders. The FCE combustion mode increased the laminar flame speed of PRF90 both at 1 atm and 50 atm, with hydrogen (H2) being the key species. Finally, the FCE combustion mode decreased the harmful emissions significantly, such as acetylene (C2H2), ethylene (C2H4), propyne (C3H4), propene (C3H6),1,3-butadiene (1,3-C4H6), and CH2O. The reaction pathway analyses indicated that the reaction pathways were altered by the addition of the reformed species. This work demonstrated that the FCE mode is a potential clean combustion mode.
Wang, Yang, Wei, Lixia, Jia, Guorui, Yao, Mingfa
Numerical Study on a High Efficiency Gasoline Reformed Molecule HCCI Combustion Using Exergy Analysis2017-01-07353/28/2017
In this study, the characteristics and the advantages on engine performance of the reformed molecule HCCI (RM-HCCI) combustion fueled with gasoline were investigated by exergy analysis. The processes of fuel reforming and the closed portion of the engine cycle were simulated integrated with chemical kinetics mechanism at varied compression ratio (CR) and constant speed conditions. Results showed the fuel reforming under high temperature and oxygen-free condition by the exhaust heat recovery and electric heating assistance could drive gasoline to transform to the small-molecule gas fuels, meanwhile enhanced the chemical exergy of the fuel. The reformed fuel contributed to extending ignition delay, so less dilution required in RM-HCCI engine when expanding high load compared with gasoline HCCI engine. Thus, RM-HCCI engine could achieve higher load than gasoline HCCI engine, with the improvements by 12%, 26%, and 31% at CR17, CR19, and CR21, respectively. Under the conditions of high compression ratio, boosting, lean burn, gasoline HCCI engine could achieve the highest exergy efficiencies of 50.2%~51.4% at CR17~CR21, which were further improved to 50.9%~52.6% at the same CR conditions when RM-HCCI combustion employed. These improvements came from chemical exergy gain of the fuel, reduction of exergy destruction, and the increase of work-extraction efficiency by fuel property changed and less exhaust dilution used improving specific heat ratio, while the extra electric heating consumption lowered some improvements. Furthermore, RM-HCCI combustion improved the flexibility to employ high CR than gasoline HCCI combustion for expanding high load more easily. The engine at CR21 employed RM-HCCI combustion to expand high load and transferred to gasoline HCCI combustion to extend low load, which achieved a wider operation range than gasoline HCCI engine at CR17, meanwhile, exergy efficiencies improved with the increases of 1.8%~2.4%-units. Overall, RM-HCCI combustion employed in the engine promoted to achieve higher load, higher efficiency, and more flexibility to high CR.
Yu, Hao, Su, Wanhua
Evaluation of Hydrous Ethanol Fuel Lubricity by HFRR2016-01-226010/17/2016
Improvement of thermal efficiency is an important problem for internal combustion engines. Fuel reforming with dehydrogenation reaction by exhaust heat is one of the measures to increase thermal efficiency using hydrogen mixed SI combustion. For this kind engine system, hydrous ethanol has a good potential. Furthermore, when the hydrous ethanol inject to combustion chamber directory, high compression combustion can be achieved by its large amount of latent heat. Therefore, fuel lubricity is an important check point for the hydrous ethanol reforming engine systems. In this study, effect of water concentrations within ethanol on the hydrous ethanol fuel lubricity has been evaluated using HFRR (High-Frequency Reciprocating Rig) test method. Wear scar diameter on 100 % of ethanol was around 700 μm which was a little better than gasoline lubricity. When the water concentration within ethanol was increased, the wear scar diameters were decreasing around 330 μm. Considering this phenomenon by the fuel viscosity, the viscosity of hydrous ethanol is growing with increasing water concentration up to 50-60 %. It seems that lubricity of hydrous ethanol can be kept by fluid film lubrication mode up to 50-60 % of water concentration.
Oguma, Mitsuharu, Matsuno, Mayumi, Kaitsuka, Masayoshi, Higurashi, Kazuaki
The Performances of a Spark Ignition Natural Gas Engine Coupled with In-Cylinder Thermochemical Fuel Reforming (TFR)2016-01-223910/17/2016
In-cylinder thermochemical fuel reforming (TFR), which involves running one cylinder rich of stoichiometric and routing its entire exhaust back into the intake manifold, is an attractive method for improving engine performances. Compared with other hydrocarbon fuels, the chemical structure of methane is more stable owing to much shorter carbon chain. As ethanol contains hydroxyl in chemical structure, it potentially generates OH radical during the combustion. Therefore, adding ethanol into natural gas (NG) might help the thermochemical reforming process in engine cylinder. This paper focused on researching the effects of ethanol-NG combined in-cylinder TFR on engine performances, before which the effect of NG in-cylinder TFR was examined in detail. Cylinder #4 (TFR cylinder) was running rich and its cooled exhaust was coupled to the intake manifold of a four-cylinder engine during the experiments. For NG in-cylinder TFR, a rapid decrease of brake specific fuel consumption was found when equivalence ratio of TFR cylinder reached about 1.2-1.3, at which substantial fraction of H2 and CO were confirmed in the reformed gas, under low load. However, compared with the case without TFR, global engine operation stability was worsened and distinct IMEP discrepancy between cylinder #2 (typical of cylinder #1, 2, 3) and TFR cylinder was resulted. For ethanol-NG combined in-cylinder TFR, results proved higher H2 and CO concentration in reformed gas and comparable fuel economy compared with NG in-cylinder TFR. Besides, more stable engine operation and lower NOx emission as well as smaller IMEP discrepancy between cylinder #2 and TFR cylinder was obtained.
He, Zhuoyao, Xu, Zhen, Zhu, Lei, Zhang, Wugao, Fang, Junhua, Lin, He, Guan, Bin, Huang, Zhen, Hu, Junjun, Chu, Limin
Investigation of Fuel Effects on In-Cylinder Reforming Chemistry Using Gas Chromatography2016-01-07534/5/2016
Negative Valve Overlap (NVO) is a potential control strategy for enabling Low-Temperature Gasoline Combustion (LTGC) at low loads. While the thermal effects of NVO fueling on main combustion are well-understood, the chemical effects of NVO in-cylinder fuel reforming have not been extensively studied. The objective of this work is to examine the effects of fuel molecular structure on NVO fuel reforming using gas sampling and detailed speciation by gas chromatography. Engine gas samples were collected from a single-cylinder research engine at the end of the NVO period using a custom dump-valve apparatus. Six fuel components were studied at two injection timings: (1) iso-octane, (2) n-heptane, (3) ethanol, (4) 1-hexene, (5) cyclohexane, and (6) toluene. All fuel components were studied neat except for toluene - toluene was blended with 18.9% nheptane by liquid volume to increase the fuel reactivity. Additionally, a gasoline surrogate matching the broad molecular composition of RD587 gasoline was formulated using the chosen fuel palette and tested. The energy content of the injected fuel mass was kept constant for the sampled NVO cycle and the excess oxygen was relatively low (2.4%) compared to previous studies by the authors. The later injection timing studied resulted in useable recovered fuel energy near 70% and improved reformate yield of hydrogen and C1-C4 hydrocarbons compared to the earlier injection timing for all fuels except toluene/n-heptane. Analysis of the RD587 surrogate reformate compared to the individual component reformates suggests that fuel component interactions depend on injection timing, potentially through the in-cylinder equivalence ratio distribution.
Wolk, Benjamin, Ekoto, Isaac, Northrop, William
Study of an On-board Fuel Reformer and Hydrogen-Added EGR Combustion in a Gasoline Engine2015-01-09024/14/2015
To improve the fuel economy via high EGR, combustion stability is enhanced through the addition of hydrogen, with its high flame-speed in air-fuel mixture. So, in order to realize on-board hydrogen production we developed a fuel reformer which produces hydrogen rich gas. One of the main issues of the reformer engine is the effects of reformate gas components on combustion performance. To clarify the effect of reformate gas contents on combustion stability, chemical kinetic simulations and single-cylinder engine test, in which hydrogen, CO, methane and simulated gas were added to intake air, were executed. And it is confirmed that hydrogen additive rate is dominant on high EGR combustion. The other issue to realize the fuel reformer was the catalyst deterioration. Catalyst reforming and exposure test were carried out to understand the influence of actual exhaust gas on the catalyst performance. Fresh catalyst showed good performance in generating hydrogen, but an aged catalyst generated only half as compared to a fresh catalyst. So we considered measures to improve catalyst performance. According to EGR reforming performance test with single-cylinder engine using conventional catalyst and an improved catalyst, the improved catalyst showed good performance. Finally, in order to confirm the performance of hydrogen generation and the effects of real reformate gas on EGR combustion, a single-cylinder engine with the fuel reformer was developed. It is confirmed that hydrogen is generated from gasoline and EGR gas by the fuel reformer, and combustion stability under high EGR rate is enhanced by reformate hydrogen.
Ashida, Koichi, Maeda, Hirofumi, Araki, Takashi, Hoshino, Maki, Hiraya, Koji, Izumi, Takao, Yasuoka, Masayuki
Effects of Gasoline Reactivity and Ethanol Content on Boosted, Premixed and Partially Stratified Low-Temperature Gasoline Combustion (LTGC)2015-01-08134/14/2015
Low-temperature gasoline combustion (LTGC), based on the compression ignition of a premixed or partially premixed dilute charge, can provide thermal efficiencies (TE) and maximum loads comparable to those of turbo-charged diesel engines, and ultra-low NOx and particulate emissions. Intake boosting is key to achieving high loads with dilute combustion, and it also enhances the fuel's autoignition reactivity, reducing the required intake heating or hot residuals. These effects have the advantages of increasing TE and charge density, allowing greater timing retard with good stability, and making the fuel ϕ- sensitive so that partial fuel stratification (PFS) can be applied for higher loads and further TE improvements. However, at high boost the autoignition reactivity enhancement can become excessive, and substantial amounts of EGR are required to prevent overly advanced combustion. Accordingly, an experimental investigation has been conducted to determine how the tradeoff between the effects of intake boost varies with fuel-type and its impact on load range and TE. Five fuels are investigated: a conventional AKI=87 petroleum-based gasoline (E0), and blends of 10 and 20% ethanol with this gasoline to reduce its reactivity enhancement with boost (E10 and E20). A second zero-ethanol gasoline with AKI=93 (matching that of E20) was also investigated (CF-E0), and some neat ethanol data are also reported. Results show that ethanol content has little effect on LTGC autoignition reactivity for naturally aspirated operation, but it produces a large effect for boosted operation, with the reactivity enhancement with boost being reduced by an amount that correlates with ethanol content. In contrast, CFE0 showed a reactivity enhancement with boost similar to E0. Related to this autoignition enhancement, the effect of fuel-type on the increase in ITHR with boost was also investigated since it correlates with the ability to retard CA50 with good stability for higher loads without knock and to apply PFS effectively. The study showed that by adding ethanol, less EGR is required with boost, leaving more oxygen available for combustion. As a result, the high-load limit could be increased from 16.3 to 18.1 to 20.0 bar IMEPg for E0, E10, and E20, respectively, and to 17.7 bar for the high-AKI gasoline. TE vs. load curves for the various fuels at typical boosted conditions are also presented and discussed. At boosted conditions, PFS was found to be very effective for increasing the TE, with the peak TE increasing from 47.8% for premixed fueling to 48.4% with PFS, and TE improvements up to 2.8 %-units were achieved at higher loads.
Dec, John E., Yang, Yi, Dernotte, Jeremie, Ji, Chunsheng
Investigation of Negative Valve Overlap Reforming Products Using Gas Sampling and Single-Zone Modeling2015-01-08184/14/2015
Negative valve overlap (NVO) is a viable control strategy that enables low-temperature gasoline combustion (LTGC) at low loads. Thermal effects of NVO fueling on main combustion are well understood, but fuel reforming chemistry during NVO has not been extensively studied. The objective of this work is to analyze the impact of global equivalence ratio and available oxidizer on NVO product concentrations. Experiments were performed in a LTGC single-cylinder engine under a sweep of NVO oxygen concentration and NVO fueling rates. Gas sampling at the start and end of the NVO period was performed via a custom dump-valve apparatus with detailed sample speciation by gas chromatography. Single-zone reactor models using detailed chemistry at relevant mixing and thermodynamic conditions were used in parallel to the experiments to evaluate expected yields of partially oxidized species under representative engine time scales. Modeling efforts help identify physical mechanisms that further describe experimental findings with regards to anticipated fuel-fraction and temperature fields. For the NVO fueling sweep, end-cycle CO2 concentrations remained essentially flat, while intermediate species concentrations rose as fueling rates increased. The rate-of-increase was most pronounced for the C3-C4 hydrocarbons whose rate-of-increase was greater than the relative increase in fueling rate. Modeling results suggest that oxygen depleted environments coupled with lower heat release temperatures result in slower reforming rates, which yielded higher C3-C4 production. For the oxygen concentration sweep with fixed NVO fueling, CO and CO2 products increased as the amount of oxidizer likewise increased. These increases came at the expense of intermediate hydrocarbon yields.
Peterson, Brian, Ekoto, Isaac, Northrop, William
Control of Pressure-Rise Rates of Compression Ignition by Stratification of Reformed Premixture Using Pulsed DBD Irradiation2014-01-266510/13/2014
Dielectric barrier discharge (DBD) was applied to control the pressure-rise rate of homogeneous compression ignition, which is an important obstacle for homogeneous charge combustion engines. DBD can produce nonthermal plasmas and has been generated in air/fuel mixtures to reform some of the fuel molecules found in such mixtures. This generally shortens the ignition delay of compression ignition of the air/fuel premixture. Stratification of the reformed premixture in the combustion chamber was achieved by pulsed DBD irradiation during the induction process. The formation of inhomogeneous distribution of the reformed premixture is expected by the formation of discharge at the end of the intake processes. A demonstrative experiment was conducted by using a rapid compression and expansion machine. A simple plasma reactor was developed and installed at the intake tube. High-voltage, high-frequency pulses were applied to form plasmas. n-Heptane was used as fuel. Characteristic oscillation was observed at the maximum of pressure history in the compression ignition experiment without using plasma. This oscillation is supposed to be induced by the fast pressure rise initiated by simultaneous ignition in the combustion chamber. Suppression of this oscillation was observed to result from DBD irradiations. The ignition behaviors were observed by a fast-imaging camera. The possibility of using this method for combustion phasing was also examined.
Takahashi, Eiichi, Kojima, Hirokazu, Furutani, Hirohide
A Demonstration of Dedicated EGR on a 2.0 L GDI Engine2014-01-11904/1/2014
Southwest Research Institute (SwRI) converted a 2012 Buick Regal GS to use an engine with Dedicated EGR™ (D-EGR™). D-EGR is an engine concept that uses fuel reforming and high levels of recirculated exhaust gas (EGR) to achieve very high levels of thermal efficiency [1]. To accomplish reformation of the gasoline in a cost-effective, energy efficient manner, a dedicated cylinder is used for both the production of EGR and reformate. By operating the engine in this manner, many of the sources of losses from traditional reforming technology are eliminated and the engine can take full advantage of the benefits of reformate. The engine in the vehicle was modified to add the following components: the dedicated EGR loop, an additional injector for delivering extra fuel for reformation, a modified boost system that included a supercharger, high energy dual coil offset (DCO) ignition and other actuators used to enable the control of D-EGR combustion. In addition, the compression ratio of the engine was increased to 11.7:1 to take advantage of the improved knock resistance from reformate and EGR. The engine conversion and the development of the control system for the engine are the subject of this paper. The conversion to D-EGR configuration resulted in an improvement in engine efficiency of at least 10% across the performance map, with some operating conditions seeing substantially higher improvements. For example, the brake specific fuel consumption (BSFC) at 2000 rpm 2 bar BMEP improved from 385 g/kW-h in the series production state to 330 g/kW-h and the lowest BSFC for the engine was 212 g/kWh compared to 236 g/kW-h for the series engine. The addition of 2-stage boosting also allowed the engine to meet its torque targets of at least 17 bar BMEP from 1500-5500 rpm while maintaining good transient response and low engine-out emissions.
Chadwell, Christopher, Alger, Terrence, Zuehl, Jacob, Gukelberger, Raphael
Negative Valve Overlap Reforming Chemistry in Low-Oxygen Environments2014-01-11884/1/2014
Fuel injection into the negative valve overlap (NVO) period is a common method for controlling combustion phasing in homogeneous charge compression ignition (HCCI) and other forms of advanced combustion. When fuel is injected into O2-deficient NVO conditions, a portion of the fuel can be converted to products containing significant levels of H2 and CO. Additionally, other short chain hydrocarbons are produced by means of thermal cracking, water-gas shift, and partial oxidation reactions. The present study experimentally investigates the fuel reforming chemistry that occurs during NVO. To this end, two very different experimental facilities are utilized and their results are compared. One facility is located at Oak Ridge National Laboratory, which uses a custom research engine cycle developed to isolate the NVO event from main combustion, allowing a steady stream of NVO reformate to be exhausted from the engine and chemically analyzed. The other experimental facility, located at Sandia National Laboratories, uses a dump valve to capture the exhaust from a single NVO event for analysis. Results from the two experiments are in excellent trend-wise agreement and indicate that the reforming process under low-O2 conditions produces substantial concentrations of H2, CO, methane, and other short-chain hydrocarbon species. The concentration of these species is found to be strongly dependent on fuel injection timing and injected fuel type, with weaker dependencies on NVO duration and initial temperature, indicating that NVO reforming is kinetically limited. Further, NVO reforming does not require a large energy input from the engine, meaning that it is not thermodynamically expensive. The implications of these results on HCCI and other forms of combustion are discussed in detail.
Szybist, James P., Steeper, Richard R., Splitter, Derek, Kalaskar, Vickey B., Pihl, Josh, Daw, Charles
Development and Demonstration of LNT+SCR System for Passenger Car Diesel Applications2014-01-15374/1/2014
The regulations for mobile applications will become stricter in Euro 6 and further emission levels and require the use of active aftertreatment methods for NOX and particulate matter. SCR and LNT have been both used commercially for mobile NOX removal. An alternative system is based on the combination of these two technologies. Developments of catalysts and whole systems as well as final vehicle demonstrations are discussed in this study. The small and full-size catalyst development experiments resulted in PtRh/LNT with optimized noble metal loadings and Cu-SCR catalyst having a high durability and ammonia adsorption capacity. For this study, an aftertreatment system consisting of LNT plus exhaust bypass, passive SCR and engine independent reductant supply by on-board exhaust fuel reforming was developed and investigated. The concept definition considers NOX conversion, CO2 drawback and system complexity. The passive SCR significantly contributes to the total NOX conversion over a broad temperature range. In contrary to conventional LNT applications, the LNT NOX slip does not directly reduce the system NOX conversion but can be converted over the passive SCR. Thereby, the NOX adsorption duration might be prolonged, resulting in lower LNT regeneration frequency and less fuel consumption, resp. CO2 emissions. Additionally, the engine independent LNT enrichment is beneficial regarding fuel consumption in comparison to conventional engine internal enrichment. The system has been tested in a vehicle in combination with a highly efficient Diesel engine. Results regarding CO2 and NOX as well as their dependency on temperatures are shown here.
Wittka, Thomas, Holderbaum, Bastian, Maunula, Teuvo, Weissner, Michael
GDI Engine Performance and Emissions with Reformed Exhaust Gas Recirculation (REGR)2013-01-05374/8/2013
Exhaust Gas Fuel Reforming has potential to be used for on-board generation of hydrogen rich gas, reformate, and to act as an energy recovery system allowing the capture of waste exhaust heat. High exhaust gas temperature drives endothermic reforming reactions that convert hydrocarbon fuel into gaseous fuel when combined with exhaust gas over a catalyst - the result is an increase in overall fuel energy that is proportional to waste energy capture. The paper demonstrates how the combustion of reformate in a direct injection gasoline (GDI) engine via Reformed Exhaust Gas Recirculation (REGR) can be beneficial to engine performance and emissions. Bottled reformate was inducted into a single cylinder GDI engine at a range of engine loads to compare REGR to conventional EGR. The reformate composition was selected to approximate reformate produced by exhaust gas fuel reforming at typical gasoline engine exhaust temperatures. The decision was guided by data from experimental work carried out by Johnson Matthey using a reforming catalyst developed for the fuel reforming application. The engine test results show improved combustion stability with REGR; this allows for higher recirculation rates and increased combustion mixture dilution. This is significant as it could allow for a higher fraction of fuel to be reformed, and therefore waste energy captured. REGR results in a large NOx reduction and a reduction in HCs relative to EGR. The effects of REGR on Particulate Matter (PM) emissions were also analysed, concluding that REGR reduces PM mass compared to conventional EGR.
Fennell, Daniel, Herreros, Jose M., Tsolakis, Athanasios, Xu, Hongming, Cockle, Kirsty, Millington, Paul
Identification of Optimal CNG -Hydrogen Enrichment Ratio in the Small SI Engines2012-32-001510/23/2012
A study on the overall performance of an engine powered with hydrogen-enriched NG at stoichiometric condition, for different hydrogen shares have been described in this paper. The research has been carried on a General Motors Company X16SZR 4-cylinder, 4-stroke 1600 cm3 engine. Engine dynamometer tests were complemented with mathematical model calculations. Tested engine has been equipped with an aftermarket CNG feeding system where fuel is being injected into intake manifold simultaneously under low overpressure. Research program provided analysis for fuel blends with variable methane/hydrogen volume proportion (%): 100/0, 95/5, 90/10, 85/15, 80/20, 70/30, 60/40 and 50/50. Ignition timing and all other strategies, excluding EGR, remained unvaried. Testing procedure provided three different steady-state engine operation points for each of 8 different fuels: idle, high speed without load and full power at speeds in range of 1500-3500 rpm. The main aspect of the analysis was to identify the influence of hydrogen share on engine parameters such power, fuel consumption, in-cylinder pressure, temperature and exhaust gas composition. Very significant possibility of CO₂ emission reduction has been identified. Authors do also attempt to identify optimal blend for applications without any significant changes into engine construction and ignition/timing calibration. All possible negative effects of increasing hydrogen share have also been taken into consideration - like knocking. Analysis carried out on the basis of results allowed it to the point on methane/hydrogen proportion in fuel blend considering a total efficiency, emission and heat flux in parts of combustion chamber in engine. The results provide a basis for further studies on optimization of the process of managing the process of combustion in car engines fuelled by CNG and equipped with fuel reformer or using natural gas and hydrogen mixtures prepared at a filling station.
Flekiewicz, Bartosz, Flekiewicz, Marek, Kubica, Grzegorz
Meeting Nonroad Final Tier 4 Emissions on a 4045 John Deere Engine Using A Fuel Reformer and LNT System with An Optional SCR Showing Transparent Vehicle Operation, Vehicle Packaging and Compliance to End-of-Life Emissions2011-01-22069/13/2011
The nonroad Final Tier 4 US EPA emission standards require 88% reduction in NOx emission from the Interim Tier 4 standards. It is necessary to utilize aftertreatment technologies to achieve the required NOx reduction. The development of a fuel reformer, lean NOx trap (LNT) and optional selective catalytic reactor (SCR) on a John Deere 4045 nonroad engine is described in this paper. The paper discusses aftertreatment system performance, catalyst formulations and system controls of a fuel vaporizer, fuel reformer, LNT and SCR system designed to meet the nonroad Final Tier 4 emission standards. The 4045 John Deere engine was calibrated and integrated with the aftertreatment system. The system performance was characterized in an engine dynamometer performance test cell, durability test cell and on a vehicle. The catalyst performance was evaluated using aged catalysts and a detailed description of the LNT, DPF and SCR catalysts is provided. Test results show that the system performance met Final Tier 4 emission standards under a range of test conditions including limited vehicle operation. System performance was characterized under the nonroad transient cycle (NRTC), ramped eight-mode cycle, steady state modal points and not-to-exceed regulations. LNT regeneration, LNT desulfation and DPF regeneration were demonstrated in these test cycles while maintaining repeatable and consistent aftertreatment temperature control. The LNT system regeneration fuel consumption ranged between 1.4% to 3.1%. The system consistently demonstrated 85% NOx reduction in a performance and durability test cell, and on a vehicle. The downstream SCR catalyst can be removed as an option for tighter vehicle packages while still meeting Final Tier 4 emission standards.
McCarthy Jr, James, Yue, Yong, Mahakul, Budhadeb, Gui, Xinqun, Yang, Hanlong, Ngan, Evan, Price, Kenneth
Fuel-Cell Power Source Based on Onboard Rocket PropellantsTBMG-81717/1/2010
The use of onboard rocket propellants (dense liquids at room temperature) in place of conventional cryogenic fuel-cell reactants (hydrogen and oxygen) eliminates the mass penalties associated with cryocooling and boil-off. The high energy content and density of the rocket propellants will also require no additional chemical processing.
RENEWABLE AND ENVIRONMENT FRIENDLY OXYGENATED BIOMASS FUEL BLENDS FOR DIESEL ENGINES2009-28-003612/13/2009
Owing to the great interest in biodiesel fuels around the world, the Department of Science and Technology (DST), Government of India has sponsored this research work to study the performance and emission characteristics of Jatropha Methyl Ester (JME) and Diesel-JME-Ethanol hybrid fuel blends in a direct injection diesel engine. Detailed experiments are carried out in a single cylinder CI diesel engine to study the performance, emissions and combustion characteristics of JME and hybrid fuel blends. The results reveal that 100% JME can be used as a complete replacement fuel for fossil diesel. A slight increase in BTE, considerable reduction in NOx emissions and moderate smoke reduction at all loads were observed for the hybrid fuel blends. With suitable surfactants ethanol can be blended up to 15% in diesel - biodiesel fuel blends to fuel existing CI engines without any hardware modifications to reduce engine out emissions.
RAJASEKAR, E., SUBRAMANIAN, R., NEDUNCHEZHIAN, N.
Characteristics of Syngas Combustion Based on Methane at Various Reforming Ratios2007-01-36308/5/2007
Characteristics of syngas combustion at various reforming ratios were studied numerically. The syngas was formed by the partial oxidation of methane to mainly hydrogen and carbon monoxide and cooled to ambient temperature. Stiochiometric and lean premixed flames of the mixtures of methane and the syngas were compared at the atmospheric temperature and pressure conditions. The adiabatic flame temperature decreased with the reforming ratio. The laminar burning velocity, however, increased with the reforming ratio. For stretched flames in a counterflow, the high temperature region was broadened with the reforming ratio. The maximum flame temperature decreased with the reforming ratio for the stoichiometric case, but increased for the lean case except for the region of very low stretch rate. The extinction stretch rate increased with the reforming ratio, implying that the syngas assisted flame is more resistance to turbulence level. Fuel reforming can reduce EINO as compared to the case of unreformed fuel for the case of stoichiometric combustion.
Choi, S. K., Kim, M. K., Chung, S. H., Song, Y. H.
Supporting next-gen propulsionAEROAPR07_014/1/2007
The need for advanced computational and communication systems on board military aircraft make fuel cells an attractive propulsion alternative, and ample access to hydrogen a necessity. Fuel-cell power systems are conceptually more attractive than combustion-based systems for the generation of electricity due to higher efficiencies, fewer emissions, and less maintenance. There are efforts to incorporate fuel-cell power systems as auxiliary power for the increased electrical demands on both commercial and military aircraft as well as for UAVs and other applications. However, direct inclusion of these power systems into an aircraft can be extremely difficult due to requirements that each aircraft may have, and how the auxiliary power system will affect the performance of the aircraft. To gain the information needed to afford the adoption of fuel-cell power systems into onboard aircraft systems, alternate applications must be considered that do not have difficult requirements such as power density. Researchers from Nu Element, Boeing Phantom Works, and NAVAIR have identified the ground cart as a potential intermediate target for the incorporation of fuel cells into the aviation market.
Hydrogen Fuel Production from Propane in Gliding Arc Discharge2007-01-00171/23/2007
Reforming characteristics and optimal operating condition for hydrogen-rich gas production were studied by using gliding arc plasma with a catalytic reactor. Parametric screening studies were carried out for variations of the following variables: vapor flow ratio, CO2 flow ratio, reactant flow rate and input electric power. When these variables were 0.65, 0.14, 14 L/min and 1.37 kW, respectively, the production of hydrogen-rich gas was maximized with an optimal propane conversion rate of 62.6-. Under these optimal conditions, the following syngas concentrations were determined: H2, 44.4%; CO, 18.2%; CH4, 11.2%; C2H2, 2.7%; C3H6, 1.9%; C2H4, 0.6%; and C3H4, 0.4%. The carbon dioxide conversion rate was 29.2% and the H2/CO ratio was 2.4.
Chun, Y. N., Song, H. W., Kim, S. C., Lim, M. S.
Reformation of Jet Fuels for Navy Ground Cart Applications2006-01-309511/7/2006
Fuel cells have been under considerable interest for both commercial and military aviation applications for power generation needed for advanced computational and communication systems on board aircraft, as well as for other power requirements needed both while in flight and on the ground. However, in order to power the fuel cells, hydrogen must be generated at some point, the ideal source being the logistic fuels such as JP-5 or JP-8 that is already used for propulsion. This process is not trivial, as several potential issues can arise from processing logistic fuel, the two primary concerns being the effect of sulfur within the fuel on the processing and fuel cell components, and the longevity issues resulting from coke formation during fuel processing. In the first part of this paper, we look as work that we have performed that addresses some of these issues for the steam reforming of JP-5 to produce pure hydrogen for fuel cell use. Specifically, we have identified a means to separate the reforming process into several steps in order to minimize the amount and cost of maintenance that must be done on the system. This separation can potentially lead to other optimizations in the reforming pathway. Results from bench-scale demonstrations of these processing steps will be presented based on the conversion of JP-5 fuel. In considering applications for this technology, a ground cart would likely be the first large scale target that can then be used to plan for other application areas. Present ground carts ranging from 90 to 300kVA power output are a critical tool for aviation support, but are presently based on the inefficient conversion of logistic fuels to power through internal combustion. It may be possible to replace the internals of a ground cart to use fuel cell to improve the efficiency of the energy conversion process, however, certain decisions will need to be made as to what processes will be retained on board the ground cart and which can be done at a central facility to support multiple ground carts. Three possible arrangements of equipment for ground carts based on logistic fuels can be identified: The use of a hydrogen storage medium with hydrogen directly feed to the fuel cell. This option would require a stationary plant to generate hydrogen, most likely through the desulphurization and reforming of logistic fuels. The use of on-board reforming of sulfur free logistic fuel, with the output sent to the fuel cell. A central plant to handle the sulfur removal of the fuel would be required. The use of both on-board desulphurization and reforming of as-delivered logistic fuels, with the resulting output feed to the fuel cell. In this case, no additional support facilities would be needed. In the second part of this paper, we examine each of the above scenarios in the consideration of replacing a current 90kVA combustion-based unit. System models have been built for fuel processing of JP-5 in order to size the individual processes within the ground cart and provide representative mock-ups of each arrangement. Other factors such as environmental, maintenance, and longevity have also been considered as part of this study. We have also considered the prospect of using other fuel cells besides PEM-based units as to determine if improvements in thermal and mass integration can be performed for each configuration. Additionally, we consider what the size of the off-board support systems would be to support a number of ground carts.
Neylon, Michael K., Yu, Xioachen, Fleckner, Karen, Trela, John A., Iya, Sri K., Field, Sean A.
Testing and Evaluation of Fuel Cell Vehicle Technology in the United States Postal Service2006-01-329510/16/2006
As the owner of the largest non-military vehicle fleet in the world, the United States Postal Service (USPS) has been a pioneer and a leader among all federal agencies in adopting alternative fuel initiatives, continuing to work in cooperation with the vehicle industry to develop new ways to reduce fuel consumption and air pollution. Given that hydrogen can be produced from a variety of energy sources, it is considered by most to be the ultimate energy carrier for relieving the U.S. of its dependence on imported oil. Hydrogen fuel cell vehicles operate via an electro-chemical process that converts pure hydrogen into water and electricity, producing zero emissions and potentially doubling the energy efficiency seen in today's gasoline-powered vehicles. This paper describes the USPS experiences gained during operational testing and evaluation of a hydrogen fuel cell vehicle at Fort Belvoir, Virginia. Included in the discussion are lessons learned-specifically regarding fuel cell vehicle operation in a delivery environment- and USPS future testing plans.
Dinh, Han
A Fast Start-Up On-Board Diesel Fuel Reformer for NOx Trap Regeneration and Desulfation2004-01-268410/26/2004
This paper describes recent progress in our program to develop an emissions technology allowing diesel engines to meet the upcoming 2007/2010 regulations for NOx. At the heart of this technology is the ArvinMeritor Diesel Fuel Reformer that reforms the fuel, on-demand, on-board a vehicle. The fuel reformer uses plasma to partially oxidize a mixture of diesel fuel and air creating a highly reducing mixture of Hydrogen and Carbon monoxide. In a previous publication, we have demonstrated that using a reformate rich in H2 and CO to regenerate a NOx trap is highly advantageous compared to vaporized diesel fuel used conventionally. In this paper we present results and a strategy for performing desulfation of the traps using the fuel reformer. In contrast to vaporized diesel, which requires very high temperatures that fall outside the normal exhaust operating temperatures for diesel engines, desulfation was achieved at temperatures lower by more than 100 °C using the Plasma Fuel Reformer. This is likely to provide substantial durability benefits for the NOx traps, a major hurdle remaining in the commercialization of that technology. A lower temperature that falls within the normal engine operating range also provides an effective desulfation strategy including the possibility of some desulfation occurring simultaneously with regeneration. In this paper, we also present experimental results on the fuel reformer including hydrogen yield, soot production, start-up time and durability. The fuel reformer is capable of reaching up to 90-100% of the theoretically possible hydrogen yield at a range of fuel flow rates when used in conjunction with a downstream catalyst. The soot production is minimal both upstream (<20 mg/m3) and downstream (<5 mg/m3) of the catalyst, while the start-up time required to reach 90% of the maximum hydrogen output is around 10 seconds. The system has been operated for more than 3000 cycles without any noticeable performance degradation.
Khadiya, Navin, Crane, Sam, Huffmeyer, Chris, Taylor, Bill
Knock Behavior of a Lean-Burn, H2 and CO Enhanced, SI Gasoline Engine Concept2004-01-09753/8/2004
Experiments were performed to identify the knock trends of lean hydrocarbon-air mixtures, and such mixtures enhanced with hydrogen (H2) and carbon monoxide (CO). These enhanced mixtures simulated 15% and 30% of the engine's gasoline being reformed in a plasmatron fuel reformer [1]. Knock trends were determined by measuring the octane number (ON) of the primary reference fuel (mixture of isooctane and n-heptane) supplied to the engine that just produced audible knock. Experimental results show that leaner operation does not decrease the knock tendency of an engine under conditions where a fixed output torque is maintained; rather it slightly increases the octane requirement. The knock tendency does decrease with lean operation when the intake pressure is held constant, but engine torque is then reduced. When H2 and CO are added to the mixture, the knock susceptibility is reduced, as illustrated by a decrease in the measured octane number of the primary reference fuel resulting in knock. Experiments conducted with the addition of H2 and CO separately show similar trends, but to a lesser degree; therefore, both H2 and CO act as octane enhancers when added to a hydrocarbon-air mixture. The extent to which H2 and CO improve the knock resistance of a mixture can be estimated by finding the bond-weighted octane numbers for these non-traditional blends of fuels. To understand these results better, a reduced chemical kinetic model was also used to predict autoignition of the end-gas for various conditions and fuel-air mixtures. Predicted model trends of knock onset of primary reference fuels agree with experimental observations. A comprehensive isooctane chemistry mechanism was used to demonstrate that H2 and CO are effective in lengthening the ignition delay, thereby reducing knock tendency.
Topinka, Jennifer A., Gerty, Michael D., Heywood, John B., Keck, James C.
Synthetic Hydrocarbon Fuel for APU Application: The Fuel Processor System2003-01-02673/3/2003
Fuel cell Auxiliary Power Units (APUs) can use a variety of fuels as a hydrogen carrier. Projects showing the use of hydrogen as a fuel for an APU have been completed and the prospects of using methanol as an alternative fuel has been discussed before. Despite the success of the previous fuel cell APU demonstrations, potential military and commercial customers desire a single on-board fuel for the main propulsion engine and for the APU. Such an application would require a fuel processor that can produce sufficiently pure hydrogen for utilization in a fuel cell from prevailing hydrocarbon fuels. The position of the U.S. Army's National Automotive Center (NAC) is to address this challenge by first using a synthetic diesel fuel as part of a phased fuel reformation program. This paper presents an analysis of the use of a synthetic fuel as a hydrogen carrier. The paper focuses on the fuel processor system, main results achieved during the two phase program and the challenges that remain to be faced during the technology development.
Venturi, Massimo, zur Megede, Detlef, Keppeler, Berthold, Dobbs, Herb, Kallio, Erik
Automotive Engineering International 2002-07-01AUTOJUL027/1/2002
Drivetrains: Challenging the design philosophy A researcher from the Southwest Research Institute focuses on one of the most immediate and dramatic changes of powertrain design: the introduction of CVTs. Elastohydrodynamic lubricants for CVTs In metal-to-metal continously variable transmissions, EHLs momentarily become part of the machinery, allowing for a much higher traction coefficient than is possible with hydrodynamic fluids. Hybrid vehicle dynamics Toyota engineers combined electronic control of the Estima minivan's breaking and driving functions to create its new Vehicle Dynamics Management system, resulting in improved environmental and vehicle performance. Jeep Commander 2 Chrysler Group engineers provide an inside look at one of the pioneering methanol fuel reforming fuel-cell concept vehicles. Improving SUV fuel economy Delphi is pursuing a strategy of engine shutdown and adding torque from an electric motor with its new 42-V integrated starter-generator. Hardtop convertibles Retractable metal roofs are replacing fabric tops on some convertible passenger cars to provide the comfort, quietness, styling, and solid structure of coupes in vehicles with open-air capabilities.
Environmental Evaluation of Direct Hydrogen and Reformer-Based Fuel Cell Vehicles2002-01-00943/4/2002
Fuel cells have attracted a great deal of attention in the last few years as potential replacements for conventional gasoline- or diesel-powered internal combustion engines. This study evaluated the potential life-cycle environmental impacts of a fuel cell vehicle (FCV) using a 50 kW proton exchange membrane (PEM) fuel cell system (both with and without a fuel reformer), and compared them with those of a gasoline-fueled internal combustion engine vehicle (ICEV). The fuels considered for the fuel cell systems were direct hydrogen (without reformer), and methanol and gasoline (with reformer). Exclusive of the propulsion systems, the rest of the vehicle was assumed to be the same across all the profiles. The hydrogen FCV is found to have the lowest impact scores in 12 of the 14 impact categories evaluated (see Appendix A for impact category definitions), mainly because of zero air emissions from driving and the lowest total lifetime quantity by mass of fuel (hydrogen) required during use. In 5 of these 12 categories, the gasoline FCV is a close second. An additional long-term scenario for the gasoline FCV assumed a much lower platinum content and reduced overall weight (reduced by ∼ 220 kg). This vehicle has the lowest impact scores in 3 categories (nonrenewable resource use, energy use, and smog formation), while the hydrogen FCV still leads in the other nine impact categories. Also, the long-term gasoline FCV's scores are much closer to the hydrogen FCV's scores. The hydrogen FCV, however, still remains the most environmentally preferable vehicle.
Dhingra, Rajive, Overly, Jonathan G., Davis, Gary A., Das, Sujit
Fuel-Flexible, Fuel Processors (F3P) - Reforming Infrastructure Fuels for Fuel Cells2001-01-13413/5/2001
Fuel cells will undoubtedly be a part of the next generation of power supply technology. The gap that prevents fuel cells from entering into wide spread service is the lack of a hydrogen infrastructure, but fuel reformers can bridge that gap. A fuel reformer is a device that takes a hydrocarbon fuel (natural gas, gasoline, diesel, etc.) and processes it into a hydrogen rich, proton exchange membrane (PEM) fuel cell ready gas stream. Hydrogen Burner Technology's (HBT) process approach is to use an auto-thermal reformer (ATR), low temperature shift bed (LTS), preferential oxidation reactor (PROX), and an anode off gas oxidizer (AGO). These technologies will be explained and discussed in detail. As important as the specific process is how each are tied together and packaged into a commercially viable product. At this stage of fuel cell and fuel reformer development, HBT sees this package as a fully independent device that can seamlessly be coupled with any PEM fuel cell. Direct attention was paid to manufacturing ease, tight packaging, required periodic maintenance, and most importantly cost. The packages were designed to be fully automated and required only minimal communication from the fuel cell to start up, run at various loads, and shut down. Creating this type of fuel reformer package is a quicker path to real use durability testing with integrated fuel cells, determining unforeseen integration problems sooner, and giving valuable data to the potential manufacturing costs. The progress of this project and the initial results will be discussed. Finally, the goals of the reformer packaging project as well as the planned progress for the next generation of production units will be addressed.
Barge, Shawn, Woods, Richard
Transient Measurement in a Gasoline Fuel Cell Fuel Processor2001-01-02323/5/2001
Fuel cell powered vehicles offer the potential of ultra-low or zero emissions along with very high efficiency. The major practical barrier to wide-spread introduction has been the need to provide hydrogen to the fuel cell. On-board hydrogen storage is not practical at the current time, leading to a large research and engineering effort in developing fuel processors that convert a hydrocarbon fuel such as gasoline, methanol or methane into a hydrogen-rich reformate. A key component of these systems, all of which have multiple catalytic reactors, is the processor response to transient operation that is inherent to vehicle use. This paper reports on a research reactor system designed to measure the transient response of fuel processors, and reports preliminary measurements of transient response for the primary reformer reactor of a gasoline fuel processor.
Berlowitz, Paul J., Hershkowitz, Frank, Carter, Robert N., Pettit, William
Removal of CO from Reformed Fuel by Shift Reaction and Selective Oxidation2000-01-20086/19/2000
Cu-based and noble metal catalysts for CO removal from methanol reformed gas were investigated for application to polymer electrolyte fuel cells. Over Cu-based catalysts, Oxygen-assisted low-temperature CO shift reaction (combined shift reaction and CO oxidation) enhanced CO removal considerably by the addition of a small amount of oxygen. While the Cu/Al2O3-ZnO catalyst exhibited a comparable activity with noble metal catalysts at low CO concentration, it demonstrated a higher activity than Pt/Al2O3 at high CO concentration.
Utaka, Toshimasa, Eguchi, Koichi, Sekizawa, Koshi, Sasaki, Kazunari
Fuelsfor Fuel Cell-Powered Vehicles2000-01-00013/6/2000
While it is generally agreed that the PEM fuel cell technology is best for road vehicles, the need for a source of relatively pure hydrogen poses significant challenges. There are two distinct options that are currently being considered: On-board processing of gasoline or methanol Fueling with hydrogen gas made in an off-board facility Each option has different implications for the fueling infrastructure and for the technologies required both on- and off-board the vehicle. In addition, various fueling strategies shift the balance of risk between fuel providers and vehicle manufacturers. Generally speaking, alternative fueling options can be seen to trade off technical risk (e.g., will it work?) for commercial risk (e.g., will anyone buy it?). In seeking a satisfactory business solution, a key issue is the balance between these two risks on the part of the vehicle manufacturer and the fuel provider. Only when this balance is struck will the industry be able to move forward and the number of vehicles grow to a reasonable proportion of the total fleet. This paper will address the options and the implications associated with them. It will illustrate that decisions cannot be made independently between the different players in the industry.
Casten, Sean, Teagan, Peter, Stobart, Richard
Demonstration of Natural Gas-to-Liquids (GTL) Light Paraffin Fuel in an Integrated Fuel Processing System2000-01-00043/6/2000
Key to broad commercialization of fuel cells is development of fuels that are not only fuel cell reformer compatible, but are also power technology neutral and able to use the existing fuel distribution system with minimal investment. These fuels must permit the transition from present power technologies to ultra-clean power technologies approaching commercialization, including both fuel cell and advanced internal combustion engines. Tests of cobalt-based Fischer-Tropsch (FT) light synthetic paraffin in an integrated fuel cell power system demonstrate the feasibility of a natural gas-to-liquid (GTL) fuel for fuel cell applications. This paper discusses both experimental data that verifies the suitability of such fuels for fuel cell applications, and the broader ability of these fuels to support a commercial transition to clean power technologies.
Russell, B. J., Tomlinson, H. L, Prabhu, S. K., Mitchell, W.
Fuel-cell concepts and technologyAUTOMAR00_083/1/2000
Cost reduction and fueling options are the two major issues facing auto industry OEMs and suppliers as they develop vehicles and systems for production beginning in 2003. Auto manufacturers around the globe are placing their bets on fuel cells as major long-term energy-conversion solutions because they offer high fuel economy and substantially lower emissions, particularly of CO2. Though it is very early in the automotive fuel-cell R&D cycle, fuel cells as energy providers are not new. Utilities use fuel cells to generate electricity for normal industrial and consumer use and for emergency back-up power. The Gemini and Apollo space programs were powered by fuel cells. The primary transportation application to date has been on city buses engineered for low exhaust-emissions demonstrations. Like batteries, fuel cells rely on chemical reactions at electrodes to convert energy from chemical to electrical form. Specifically, fuel cells electrochemically combine oxygen from the air with hydrogen from a hydrocarbon fuel to produce electricity. Unlike batteries, fuel cells store the reactants outside of the electrodes. They are fed to the cell as “fuel” for the reaction.
Jost, Kevin
The Automotive Industry and the Global EnvironmentR-2638/20/1999
This book presents an analysis on the potential effects of globalization on the automotive industry and the environment. Energy challenges, market economy growth, and population dynamics are considered. The authors also present future scenarios for transportation technologies to meet the ever growing global demand for transportation of goods and services while minimizing energy and environmental impacts and maximizing cost, value and widespread acceptance.
Glaze, William, Schuetzle, Dennis
The Role of Alternative Fuels in the New Generation of Vehicles95237910/1/1995
The Partnership for a New Generation of Vehicles (PNGV) is linking the research efforts of a broad spectrum of U.S. Federal agencies and laboratories with those of the domestic auto manufacturers in pursuit of three specific, interrelated goals: 1) reduce manufacturing production costs and product development times for all car and truck production; 2) pursue advanced technologies for near-term vehicle improvements that increase fuel efficiency and reduce emissions of standard vehicles; and 3) within the next decade, develop a new class of vehicle that will achieve up to three times the fuel efficiency of today's comparable vehicle, and, at the same time, cost no more to own and drive than today's automobile, maintain performance, size, and utility of comparable vehicles, and meet or exceed safety and emission requirements. This paper focuses on the potential role of alternative fuels in meeting the challenges faced by the PNGV in developing and implementing advanced technologies that are capable of meeting these goals. Hybrid vehicle and fuel cell technologies targeted by the PNGV are potentially capable of using alternative fuels such as natural gas, hydrogen, methanol, and ethanol. Of particular interest are fuel cells, which offer considerable fuel flexibility in addition to high efficiency, low or zero emissions, and low noise levels. They are also readily adaptable for use with natural gas, the most widely available non-petroleum-based fuel. Achieving PNGV goals will support national efforts to reduce the consumption of petroleum fuels and increase the use of clean, domestic, alternative fuels, which will lower transportation emissions and decrease the nation's dependence on imported petroleum.
Patil, Pandit G.
Simulated Performance of Solid Polymer Electrolyte Fuel-Cell-Powered Vehicles8303512/1/1983
Fuel cells offer a number of attractive features as alternate power sources for transportation applications. Potential advantages include high efficiency, good performance operation on nonpetroleum fuel and negligible pollution. General Electric (GE) assessed solid polymer electrolyte (SPE) fuel cells specifically for automotive applications. The results of this assessment are used to calculate the performance and fuel consumption of the GM X Car and of the GE Chrysler Electric Test Vehicle 1 (ETV-1). The X car was calculated to have good performance, negligible emission, and substantially reduced energy consumption. The calculated performance of the ETV-1 with an SPE fuel cell is comparable to that of a present day, small gasoline-powered passenger car. In addition, the calculated fuel consumption is 33 mpg of methanol, equivalent to 66 mpg of gasoline on an engery basis.
Lynn, David K., Murray, Hugh S., McCormick, J. Byron, Huff, James R.
Cost of Fuels for Fuel Cell Automobiles7703802/1/1977
The cost of operation projected for a fuel cell automobile could be as much as 1-2¢/mi less than for a comparable internal combustion engine car or an all-battery car, assuming energy raw material cost equilibrated at 10$/bbl crude oil equivalent. Fuel cost is a small but significant element in total operating cost. Therefore, the projected cost advantage of the fuel cell automobile increases with increasing cost of fossil fuel, because of the higher energy efficiency projected for the fuel cell automobile.
Bush, Warren V.
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