10 Engines (power generation thermal efficiency. The newly developed capacitor system, since it has high energy and power density, is able to regenerate almost all the braking energy of a 14-ton bus at over 90% charging efficiency. The internal resistance of the capacitor system is minimized by the capacitor itself and a new capacitor connection. Furthermore, the voltage dispersion of the capacitor cells is minimized by the capacitor charging control system. The fuel economy was improved by 166% compared with the CNG low-floor bus and the vehicle efficiency reached over 4Sq in the Ml5 mode test.
Discrete-time nonlinear control scheme for small 03/00788 synchronous generator Sanchez-Orta, A. E. et 01.Jntc~r.turtiorlcrl Jourrd of’Elrt~tric~ctl Powr & Enrrgt
24. (9). 751 764.
a class of discrete-time non-linear systems was In this paper, considered for which the control design is based on singular perturbation and sliding-mode techniques. In addition, a discrete-time observer is designed to estimate the non-measurable states required in the control law. The proposed controller-observer scheme is applied to a small synchronous generator. Simulations are carried out to show the performance of the controller-observer scheme. 03/00789 Effects of diesel fuel characteristics on spray and combustion in a diesel engine Lee, S. rt cd..JSd4E Revim,. 2002. 23. (4). 407- 414. Fuel properties play a dominant role in the spray, mixture formation and combustion process, and are a key to emission control and efficiency optimization. This paper deals with the influence of the fuel properties on the spray and combustion characteristics in a highpressure and temperature chamber. Light diesel fuel spray and combustion images were taken by using a high-speed video camera and analysed by their penetration and evaporation characteristics in comparison with current diesel fuel. Then, a single-cylinder DI engine was used to investigate combustion and exhaust characteristics. The mixture formation of the light diesel fuel is faster than that of the current fuel depending on physical properties like boiling point, density, viscosity and surface tension. Engine test results show that smoke is reduced without an increase in other emissions. 03/00790 Engine-fault diagnostics: an optimisation procedure Sampath. S. ct c/i.Appl/c>rl Er~orq~ . 3002, 73, (1):. 47 -70. .4 diagnostic process capable of providing an early warning of a fault in a gas turbine is of tremendous value to the user and can result in substantial financial savings. The approach in the Genetic Algorithm based technique adopted is to treat the problem of engine diagnostics as an optimization exercise using sensor-based and mathematical behavioural model based information. The engine performance model would simulate a range of possible combinations of potential faults (i.e. the effects of model-based information) and a comparison would be made with values of the actual (sensor-based) parameters obtained from an engine. The difference between the actual and simulated values of would be converted into a suitable objective-function and the aim of the optimization technique such as the genetic algorithm would he to minimize the objective function. The technique has given promising results for simple cycle engines.
03/00791 Entropy generation in a diesel engine turbocharging system Nakonieczny, K. Energy, 2002, 27, (1 I), 1027 1056. The paper describes a model of entropy production In a diesel engine the processes occurring in the turbocharging system, discussing compressor, turbine, piping system, charge-air cooler and valves with the exclusion of combustion. The charging efficient!) of the system is studied in two distinct engine operating states, conforlning to maximum torque and nominal power conditions. Unlike i,n the standard approach, where the irreversibilities are derived from the balance equation for exergy and thus are addressed inexactly, the criterion function based on the notion of entropy generation, Introduced in this paper, improves second law analysis of turbocharged engines by accounting for a direct description of the system internal irreversibilities. This function is used for the examination of an impact of the system design parameters on its efficiency. Computations based on the unsteady one-dimensional flow model show that. untler the variations of the inlet pipe length, the timings of inlet valve opening and exhaust valve closure, and the valve overlap period. a favourablc correlation can be found between the decrease of entropy production and the increase in amount of air charged into the engine cylinders. The other variables under study. including the turbine equivalent area, temperature decrease in intercooler and wastegate effective area ratio, show an opposite correlation. and thus, can hc viewctl a\ constraints in the system optimization. 03/00792 Fischer-Tropsch process for the production of hydrocarbon products and the generation of electric power Price, J. G. PCT Int. Appl. WO 02 60,841 (Cl. CO7Cl/OO), 8 Aug 2002, ZA Appl. 20011909, 1 Feb 2001. 31. An integrated process for producing hydrocarbon products and energy includes reforming a hydrocarbonaceous gaseous feedstock (e.g. natural gas) into synthesis gas, and exothermally reacting the synthesis gas at elevated temperature and pressure, and in the presence of a Fischer-Tropsch catalyst, to produce a range of hydrocarbon products of differing carbon chain lengths. The reactlon temperature is controlled by the indirect heat exchange of a reaction medium, comprising synthesis gas and hydrocarbon products, with water, with the water being converted to Cteam (FT steam). The process includes burning a combustible gas in a combustion chamber of a gas turbine generator. to form combusted gas, and expanding the comhusted gas through an expansion chamber of the gas turbine generator to form hot flue gas. The gas turbine generator generate\ electri:: energy. The FT steam is superheated by means of hot flue pas. thereby producing superheated FT steam. 03/00793 Fuel conversion in vehicles: dimethyl ether from methanol for diesel motors Armbruster, H. nor-t.rchritt-Be~i~llt~~ C’DJ. Rc~hc~ 3 I .c,~fuhrc~rlstr~hnik, 2002, 734. (i xv). 1 -194. (In German) The conversion of fuels onboard a vehicle is the cenjtral theme of this investigation. As an example of a catalytic conversion reaction the production of methanol to di-Me ether (DME) and water was studied. Alcoholic fuels (methanol or ethanol) have Interesting advantages with respect to emissions and, since they can be producc:d from biomass, represent one possible way of introducing renewable fuels into transportation applications. The disadvantage of methanol is its bad ignition behaviour in compression ignition engines. ,2 system analysis carried out as a part of this work shows that fumigation of DME is an interesting option for using methanol as a fuel in compression ignition engines. In this concept, a fraction of the methanol u\ed as a fuel is catalytically converted onboard to DME and water, and the products of the conversion are introduced into the engine via tht: combustion air. Emission investigations show that the EURO-V limit values are kept with an oxidation catalyst. The main issue of this thesis is the development of a catalytic reactor for the fumigatilon concept. The methanol conversion was tested with different catalysts under various conditions such a$ temperature from 100 to 3OO’C. WhSV from 3 to 30 l/h, pressure from 0.5 to 5 bar, particle size from 11.063 to 1.00 mm and mass of catalyst from 0.41 to 1.25 g. Because of its superior thermal stability and low costs. ?-Al203 has been \electcd as the most promising catalyst for converting methanol to DMF in sufficient rates for an onboard application. The chemical kinetics and the mass transfer limitations of the ?-Al103 catalyst used for the methanol dehydration were evaluated. The rate-detecting step of the cat,llytic reaction is found to be the reaction of adsorbed intermediates (LangmuirHinshelwood mechanism) and mass transfer I\ limited by Knudsen diffusivity. The model parameters were adapted to experimental data. For the activation energy a value of 123 kJ/mol resulted. The kinetic data was used to design a catalytic converter for fuel processing onboard. A pilot conversion reactor loaded with 110 g of catalyst was built to study the transient behaviour, i.e. cold start and cllanges of load of the catalytic system. The most important result is that the reactor shows stable operation as soon as wall temperatures exceeding 250°C are maintained. Models describing the transient hehaciour of the Fuel and Energy Abstracts