03/01911 Thermokinetic interactions leading to knock during homogeneous charge compression ignition: Griffiths, J. F. and Whitaker, B. J. Combustion and Flame, 2002, 131, (4),386–399

10 Engines (power generation and propulsion, electrical vehicles) ‘The section Thermal Power Engineering of Delft University of Technology operates a 1.5 MW pressurized fluidized bed gasification rig, including a hot gas cleaning unit and a pressurized downscaled Alstom gas turbines combustor. Regarding the combustion of low caiorific value (LCV) gas, experiments are done to validate models describing turbulent steady state combustion. In this paper biomass derived LCV gas combustion experiments are described. The heating value of the gas was in the range of 2.5-4 MJ/m,’ and the process pressure was 3-8 bar. In all experiments, good combustion efficiency was observed NO, formed, resulted from NH7 fuel nitrogen conversion to NO, was in the range of 10-O%. The combustor was modelled using the CFD program Fluent. As chemical models. the chemical equilibrium, laminar flamelet and reaction progress variable model were applied. Turbulence closure Reynolds stress and K-r were used in the calculations. The fate of fuel nitrogen conversion to NO, was one of the main issues studied. The agreement between models and experiment was good for the experiments performed in the higher- pressure range. 03/01904 Method of operation of fuel cell/gas turbine combined cycle power system Labinov, S. D er ul. PCT Int. Appl. WO 02 78.109 (CI. HOIM8;06). 3 Ott 2002, US Appt. 813,714. A method for converting fuel energy to electricity includes the steps of converting a higher molecular weight gas into at least one lower molecular weight gas, supplying at least one of the lower molecular weight gases to at least one turbine to produce electricity and electrochemical oxidizing at least one of the lower molecular weight gases in fuel cells. A system for converting fuel energy to electricity includes a reformer for converting a higher molecular weight gas into at least one lower molecular weight gas, at least one turbine to produce electricity from expansion of at least one of the lower molecular weight gases, and at least one fuel cell. The system can further include at least one separation device for substantially dividing the lower molecular weight gases into at least two gas streams prior to the electromecha- nical oxidation step. A nuclear reactor can be used to supply at least a portion of the heat required for the chemical conversion process. 03/01905 Performance study of a partial gasification pressurized combustion topping gas cycle and split rankine combined cycle: Part I - Energy analysis De, S. CI crl. Internutional Journal of Energy Rcseorch. 2003, 27. (6), 549 560. The aim of this paper is to study the thermodynamic performance of a new combination of a partial gasification pressurized combustion topping gas cycle and a split Rankine bottoming steam cycle as a means of advanced clean coal power generation. Energy analysis of the conceptualized power cycle is presented in this part of the paper. The effects of design and operating parameters of both the gas and the steam cycles on the performance of the power cycle are discussed. 03/01906 Performance study of a partial gasification pressurized combustion topping gas cycle and split rankine combined cycle: Part II - Exergy analysis De, S. et al. International Journal qf Energy Resenrch. 2003, 27, (6). 561-574. In addition to the energy analysis in part I of this paper, an exergy analysis of an advanced combined cycle is presented in this part of the paper to identify the major causes of thermodynamic imperfections. The exergy loss and exergetical efficiency of each of the components of the plant are investigated for variations of design and operating parameters. This is done to explore the possible improvements in the second law performance of this plant. 03/01907 Study of using JP-6 aviation fuel and biodiesel in Cl engines Arkoudeas, P. PI crl. En~rgj~ Convrrsion uncl Managrment. 2003, 44, (7), 337 351. The first jet fuels were aviation gasoline (avgas), and the characteristics of subsequent jet fuels have evolved from this original choice, the available supply infrastructure, and the refiners’ capabilities. Earlier on, it was evident that avgas would have to be altered to operate satisfactorily in jet-powered aircraft. The present contribution outlines the various requirements that led to development of various oper- ational jet fuels, including United States Jet A (European Jet A-l), JP- 4 (NATO code, F-40), JP-5 (NATO code, F-44), JP-7 (US only), JP-8 (F-34), JP-TS (US only), and JP-X+100. To reduce this fuel logistic burden, the NATO Armed Forces are advancing the use of a single fuel for both aircraft and ground equipment. To this end, F-34 is replacing distillate Diesel fuel in many applications. In order to make this type of fuel compatible with direct injection compression engines, the Fuels and Lubricants Laboratory of the National Technical University of Athens. used a stationary Diesel engine fueled with fuel blends containing two different types of biodiesel, at proportions up to 50%. In this paper, fuel consumption and exhaust emission measurements from a single cylinder, stationary, Diesel engine are described. I‘he two types of biodiesel appeared to have equal performance. and irrespec-- tive of the raw material used for their production, their addition ro the JP-8 aviation fuel improved the particulate matter emissions. 03/01906 The effect of ocean waves on offshore wind turbines Thorsen, T. and Naeser. H. In~wncrrio~~ul .Jowwc~l o/ E~I~I~~WIWII Sustnindh Dew/o~nmt, 2002. 1. (4), 146 355. The ocean has a varying surface roughness where the roughness length is determined by the characteristics of the waves. In this paper a method is established, where the roughness length of the ocean is calculated from the wind speed and the fetch length. The fetch length depends on the wind direction and a case study is performed for a wind turbine exposed to wind blowing in two opposite directions; from the shore and the sea. For each case, the vertical wind speed distribution is calculated in order to study the influence that the direction of the wind has on the annual energy production. The potential for using a site specific offshore turbine design, dependent on the prevailing wind direction. is also explored. 03/01909 The sources of polycyclic aromatic compounds in diesel engine emissions Rhead, M. M. and Hardy, S. A. Fuel, 2003, 82. (4), 3X5-3Y?. The application of a radiotracer technique to investigate the sources of polycyclic aromatic hydrocarbons (PAI+] d’ m lesel exhaust emissions is described. In separate experiments, C radiolabelled naphthalene, fluorene, fluoranthene and pyrene were each added to diesel fuel which was combusted in a 2L direct injection Perkins Prima diesel engine run at steady state under a series of speed (1000-3200 rpm) and load (20-80 N m) conditions. Each PAH was recovered in the exhaust emissions, using a novel sampling system, and its specific activity used to reveal the extent of its survival and pyrosynthesis of the PAH from other fuel fragments. Survival of the PAH varied from below detection limit for fluoranthene at low speed and load to 1.25% for fluorene at high speed and low load. For mid-speed and mid-load conditions, a linear relationship was observed between the extent to which individual PAH survived combustion and the energy level of the lowest unoccupied molecular orbital (LUMO) of the molecule calculated from Hiickel molecular orbital theory. LUMO is an indirect parameter related to gas phase oxidation rates of PAH. Linearity was not so apparent at other speeds and loads. Resynthesis of the PAH varied from less than 0.1% for pyrene at mid-speed and mid-load to 4.93% for naphthalene at high-speed and high-load. Probable mechanisms for the production of some of the pyrosynthetic PAH were discussed. 03/01910 Thermoqravimetric analysis of soot emitted by a modern diesel engme run on catalyst-doped fuel Stratakis. G. A. and Stamatelos. A. M. Cnmhusfion and Flame. 2003. 132,(1-i). IS7 169 Understanding the mechanisms that affect catalytic activity in porous ceramic diesel particulate filters (DPF) at the temperature range 200- 400°C is impoitant for the successful’modelling df the initiatcon and evolution of catalytic regeneration by use of fuel additives. This refers not only to the dry carbon particulate. but also to the volatile hydrocarbons adsorbed on it. In this paper, a detailed analysis of the hydrocarbon adsorption-desorption and oxidation behaviour of diesel particulate emitted by a modern diesel engine and collected on a SIC diesel filter is performed by use of thermogravimetric and differential scanning calorimetry analysis (TGA-DSC). Non-isothermal tests were performed with samples collected directly from a ceramic filter connected to the exhaust system of the diesel engine running under low and medium speed and load operating conditions with and without fuel additive. Fuel additive concentration was varied to investigate its effect on the soot oxidation behavior. Based on the TGA data, the kinetic parameters of the soot oxidation reaction were calculated. The effect of volatile adsorbed hydrocarbons on the soot oxidation reaction was evaluated by comparing the calculated activation energies for samples collected from the centre and the periphery of the filter at various exhaust temperatures prevailing at filter loading phase. In particular it was seen that the catalytic activity of the fuel additive is enhanced by the presence of the volatile organic components. 03/01911 Thermokinetic interactions leading to knock during homogeneous charge comprasslon ignition Griffiths. J. F. and Whitaker. B. J. Cornhurtion and Flame. 2002. I3 I. (4) X6:399. Experiments have been performed in a rapid compression machine to investigate the conditions for and the origins of ‘knock’ in controlled autoignition (CAI), or homogeneous charge compression ignition (HCCI). The combustion of n-pentane in air at the composition $ = 0.5 and a gas density of 217 mol rn. ’ was studied in the compressed gas temperature range 720 to 820 K. This corresponds to the region in which a transition from non-knocking to knocking reaction occurred in the two-slage ignition regime. clo\e to the minimum of the ignition 320 Fuel and Energy Abstracts September 2003 11 Process heating, power and incineration (energy applications in industry) delay before the negative temperature dependence is encountered. High-resolution pressure records, combined with image intensified, natural light output (with spectral resolving filters in some exper- iments) were used to characterize the reaction and to identify the behavior in terms of chemical activity associated with chemilumines- cence and spatial variations in temperature, respectively. It appears that the knock observed in a rapid compression machine (and hence during CAI) originates from the localized development of the hot stage of ignition, often from near the combustion chamber walls. Exceedingly rapid development of ignition centres may be attributed to the onset of vigorous chain branching via 0 atoms. In conditions where knock does not occur, there is a much more spatially uniform and slower overall development of ignition, which may be restricted by the persistence of reactions involving HO2 radicals to a very late stage of the combustion. The distinctions of these modes of behavior are traced to the way in which the early stages of two-stage ignition interact with the temperature field set up by the compression stroke. 03/01912 Two-stage ignition in HCCI combustion and HCCI control by fuels and additives Tanaka, S. et al. Combustion and Flame, 2003, 132, (l-2), 219-239. A Rapid Compression Machine (RCM) has been used to study the effects of fuel structure and additives on the Homogeneous Charge Compression Ignition (HCCI) of pure hydrocarbon fuels and mixtures under well-determined conditions. Such information is needed for understanding ignition delays and burning rates in HCCI engines, and ‘knock’ in spark-ignition engines. It is also valuable for validating basic chemical kinetic models of hydrocarbon oxidation. The pure fuels used in the study include: paraffins (n-heptane, iso-octane), cyclic paraffins (cyclohexane, methylcyclohexane), olefins (1-heptene, 2-heptene, 3- heptene), cyclic olefins (cyclohexene, 1,3-cyclohexadiene), and an aromatic hydrocarbon (toluene). The additives were 2-ethyl-hexyl- nitrate and di-tertiary-butyl-peroxide. It was found that fuels which contained the structure -CHz-CHz-CHz- showed two-stage ignition with relatively short ignition delays and that the ignition delay depended strongly on the energy released during the first-stage. For primary reference fuel mixtures (n-heptane + iso-octane), the ignition delay depended only on the molar ratio of n-heptane to oxygen and was independent of the octane number (percent iso-octane). On the other hand, the burn rate depended on both these parameters, which uniquely determine the equivalence ratio. When additives were included in the air/fuel mixtures, the ignition delay was reduced but the burn rate was not affected. These results indicate that for HCCI combustion, the ignition delay and the burn rate can be independently controlled using various fuel mixtures and additives. 03lO1913 Unsteady flow evolution and combustion dynamics of homogeneous solid propellant in a rocket motor Apte, S. et al. Yang, V. Combustioti and Flame. 2002, 131, (l-2). 1 IO-- 131. A time-resolved numerical analysis of combustion dynamics of double- base homogenous solid propellant in a rocket motor is performed by means of a Large-Eddy Simulation (LES) technique. The physiochem- ical processes occurring in the flame zone and their influence on the unsteady flow evolution in the chamber are investigated in depth. A five-step reduced reaction mechanism is used to obtain the two-stage flame structure consisting of a primary flame, a dark zone, and a secondary flame in the gas phase. It is observed that, for homogeneous solid propellant combustion, the chemical time scale is much greater than the smallest turbulence time scale, rendering a highly stretched and thickened flame. The chemical reactions proceed at a slower rate than turbulent mixing, and propellant combustion may be locally treated as a well-stirred reactor. The flowfield in the chamber consists of three regions of evolution: the upstream laminar regime, the central transitional section, and the fully developed turbulent regime further downstream. A theoretical formulation exploring the chamber flow and flame dynamics is established to study the intriguing phenomenon of combustion instability. The work done by Reynolds stresses, vorticity- flame interactions, and coupling between the velocity field and entropy fluctuations may cause resonance effects and excite pressure oscil- lations leading to self-sustained unsteady motions within the chamber. 03/01914 Using Monte Carlo simulation in life cycle assessment for electric and internal combustion vehicles McCleese, D. L. and LaPuma, P. T. International Journal of Life Cycle Assessment, 2002, I, (4), 230-236. The US government has encouraged shifting from internal combustion engine vehicles (ICEVs) to alternatively fueled vehicles such as electrical vehicles (EVs) for three primary reasons: reducing oil dependence, reducing greenhouse gas emissions, and reducing Clean Air Act criteria pollutant emissions. In comparing these vehicles, there is uncertainty and variability in emission factors and performance variables, which cause wide variation in reported outputs. A model was developed to demonstrate the use of Monte Carlo simulation to predict life cycle emissions and energy consumption differences between the ICEV vs the EV on a per km (km) traveled basis. Three EV technologies are considered: lead-acid, nickel-cadmium, and nickel metal hydride batteries. Variables were identified to build life cycle inventories between the EVs and ICEV. Distributions were selected for each of the variables and input to Monte Carlo Simulation software called Crystal Ball 2000. All three EV options reduce US oil dependence by shifting to domestic coal. The life cycle energy consumption per km (km) driven for the EVs is comparable to the ICEV; however, there is wide variation in predicted energy values. The model predicts that all three EV technologies will likely increase oxides of sulfur and nitrogen as well as particulate matter emissions on a per km driven basis. The model shows a high probability that volatile organic compounds and carbon monoxide emissions are reduced with the use of EVs. Lead emissions are also predicted to increase for lead- acid battery EVs The EV will not reduce greenhouse gas emissions substantially and may even increase them based on the current US reliance on coal for electricity generation. The EV may benefit public health by relocating air pollutants from urban centers, where traffic is concentrated, to rural areas where electricity generation and mining generally occur. The use of Monte Carlo simulation in life cycle analysis is demonstrated to be an effective tool to provide further insight on the likelihood of emission outputs and energy consumption. 03/01915 Viability of LPG use in low-power outboard engines for reduction in consumption and pollutant emissions Murillo, S. et al. Internationul Journal of Energy Research, 2003, 21, (5), 4677480. This study presents the viability of the use of liquified petroleum gases (LPG) dosage systems in order to solve the fuel supply in four-stroke outboard engines in compliance with regulations concerning emissions of immediate application pollutants. Results obtained show an important decrease in specific fuel consumption (nearly 20%) provok- ing a small power loss (about 5%), with an extra saving when making use of bottled fuel, which does not suffer spills in the bunkers and maintenance operations. Laboratory tests have been carried out on 8 and 15 HP Yamaha outboard engines, obtaining reductions in pollutants (CO, HC and NO,) of 60% and of 95% for each power, respectively. These trials have been contrasted with tests carried out in the Vigo estuary and the river Mirio waterways, both located in the South of Galicia (Spain). 11 PROCESS HEATING, POWER AND INCINERATION Energy applications in industry 03101916 A new image reconstruction method for tomographic investigation of fluidized beds Liu, S. et al. AZChE Journal, 2002, 48, (8), 1631-1638. It is important to investigate the behaviour of circulating fluidized beds (CFB) for efficient coal combustion. Electrical capacitance tomography (ECT) was applied to the measurement of gas/solids distribution in square CFBs. An iterative method was used to achieve improved image reconstruction over the commonly used linear back-projection algor- ithm. The solids concentration profile, temporal variation of average solids concentration, and frequency spectra, which were obtained from the ECT data, are presented. 03/01917 A rotor position estimator for switched reluctance motors using CMAC Mese, E. Energy Conversion and Management, 2003,44, (8), 122991245. This paper presents an approach to rotor position estimation in switched reluctance motors (SRMs) by using a cerebellum model articulation controller (CMAC). Previous research has shown that an artificial neural network (ANN) forms an efficient mapping structure through measurement of the flux linkages and currents for the phases. A CMAC is investigated in this paper in order to overcome the high computational power requirement problem that is encountered in a feedforward ANN based rotor position estimator. The CMAC structure does not contain neurons with activation functions, and all mathematical operations are performed without multiplication. These simplicities increase the throughput in real time implementation Fuel and Energy Abstracts September 2003 321