This paper deals with injection characteristics using different fuels at different fuel temperatures. The fuels
under consideration are neat biodiesel from rapeseed oil and some blends with diesel as well as neat mineral
diesel D2. The fuel and fuel temperature influences are investigated experimentally in the mechanically controlled
diesel fuel injection M system. At first, attention is focused on the injection characteristics, especially on
fuelling, mean injection rate, mean injection pressure, injection timing, injection delay, and injection duration,
which influence the most important engine characteristics. Furthermore, the influence of fuel temperature is
investigated. On the basis of the measurements of pressure drop through the fuel filter, the minimum fuel
temperature for safe engine operation is determined.
This paper studies the influence of biodiesel fuel on the combustion and emission formation of two different
direct-injected diesel engines, both employing different combustion processes. The research was focused on
determining the influence of the specific combustion process on measurement results to ascertain if a
generalization of the results is possible or whether they have to be interpreted as specific for specific engines.
Standard D2 diesel fuel and commercial 100% biodiesel fuel were used. Tests were executed using both fuels
under the same conditions, and exhaust emissions and engine performance were measured and compared.
In-cylinder pressure was also acquired, and the rate of heat release curves were computed by means of a
zero-dimensional, one-zone combustion model. Some macroparameters of the combustion process were obtained
from the heat-release-rate curves. The results obtained for both engines showed that findings regarding the
influence of biodiesel fuel on the combustion process and emission formation could not be generalized and
had to be interpreted as specific for the particular engine.
Turbocharging and subsequent charge cooling of the working medium usually causes increase of the mean effective pressure in an automotive diesel engine. Poor performance during the engine load increase is attributed to the nature of energy exchange between the engine and the turbocharger. Filling of the intake and exhaust manifolds, as well as consequent increase of the pressure and acceleration of the rotating components of the turbocharger require a certain period of time. Dynamic performance of the turbocharger can be substantially improved by means of an electric motor attached directly to the turbo shaft. A new concept of asynchronous electric motor with a very thin rotor was applied to support the turbocharger during the transient operation of the engine. The experimental work of matching an electrically assisted turbocharger to an engine is rather expensive; it was therefore decided to determine general characteristic of the electric motor separately through experiments, whereas transient response of the turbocharged and intercooled diesel engine was simulated by a zero-dimensional filling and emptying computer simulation method. A lot of experimentally obtained data and empirical formulae for the compressor, gas turbine, flow coefficients of the engine valves, intercooler, high-pressure fuel pump with the pneumatic control device (LDA), combustion parameters, etc., were applied to overcome deficiency introduced by the zero-dimensional simulation model. As the result a reliable and accurate program compatible with the experimental results in steady and transient engine operation was developed and is presented in the work. Faster transient response, i.e., better load acceptance of the engine was obtained by applying an adequate electric motor to assist the turbocharger; three versions of electric motors with different torque to mass moment of inertia ratios and different operating regimes were introduced in the simulation program to investigate their influence on the transient behavior of the engine.
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