Search Results

Spark plugs with integrated pressure transducer, also called measuring spark plugs, are suitable for measuring cylinder pressure in gasoline and gas engines without the need to provide an additional bore in the cylinder head. Various changes to the original spark plug occur when a pressure sensor is integrated in the body of the spark plug such as the spark position and the maximum diameter of the isolator. This article shows the results that can be achieved in respect of the spark and measurement function on a state-of-the-art, turbocharged, directly-injected gasoline engine with homogeneous mixture operation by comparing the original spark plugs with measuring spark plugs. To this end, various engine operating points were carried out at full and partial load by varying the lambda and spark ignition timing, which were assessed as a reference based on water-cooled pressure sensors.

A new approach within the well-known trade-off in combustion process simulations between computational efforts (and thus the capability for engine operating map calculations) on the one hand, and accuracy of predictions on the other, has been developed and applied successfully to diesel combustion, in particular to energy release and pollutant formation. Using phenomenological models in combination with bio-inspired algorithms (for parameter identification), it is now possible to predict thermal, chemical and injection related engine characteristics over an entire operating map including different types of fuel (e.g. diesel, water-in-diesel emulsions and oxygenated diesel).

In this paper we investigate the effect of the introduction of water in the combustion chamber of a DI-diesel engine on combustion characteristics and pollutant formation, by using water-diesel fuel emulsions with three distinct water amounts (13%, 21% and 30%). For the measurements we use a modern 4-cylinder DI-diesel engine with high-pressure common rail fuel injection and EGR system. The engine investigations are conducted at constant speed in different operating points of the engine map with wide variations of injection setting parameters and EGR rate. The main concern refers to the interpretation of both measured values and relevant thermodynamic variables, which are computed with analytical instruments (heat release rate, ignition delay, reciprocal characteristic mixing time, etc). The analysis of the measured and computed data shows clear trends and detailed evaluations on the behavior of water-diesel fuel emulsions in the engine process are possible.

At the Internal Combustion Engines and Combustion Laboratory of the Swiss Federal Institute of Technology in Zurich we are currently developing low emission strategies for heavy duty diesel engines that engine manufacturers can implement to meet stringent emissions regulations. The technologies being studied include high-pressure fuel injection (with common-rail injection system), multiple injection strategies (with pilot or post injections), turbo charging, exhaust gas recirculation (cooled EGR), oxygenated fuels and the optimization of the air management system. This paper focuses on the effects of exhaust gas recirculation (cooled EGR) in combination with very high injection pressure. Measurements were carried out on a heavy-duty diesel single-cylinder research engine equipped with a modern common rail fuel injection. The engine investigations were conducted in different operating points in the engine map covering wide speed and load ranges.

The findings presented in this paper result from a collaboration between two Federal Laboratories in Switzerland. In this research project the characteristics of the particulates from internal combustion engines were investigated in detail. Measurements were carried out on a single-cylinder research engine focusing on exhaust particulate matter emissions. The single-cylinder diesel engine is supercharged and features a common-rail direct injection system. This work analyzes the influence of fuel properties and injection parameters on the particulate number size distribution. For the fuel composition, five different fuels including low sulfur diesel, zero-sulfur and zero-aromatics diesel, two blending portions of oxygenated diesel additive and rapeseedmethylester were used. For the injection parameters the injection pressure, the start of injection and the fuel amount in the pilot- and in the post-injection phases were varied.

Oxygenated fuel additives are currently an important research topic for particulate emissions reduction in diesel engines with direct injection (DI) to meet future emission regulations. In this work more than twenty oxygenated hydrocarbons from the literature were considered as diesel fuel additives. Butylal (an acetal compound, chemical formula C9H20O2) offers significant advantages over most other oxygenates in that its physical properties are very close to those of common diesel fuel. Wear scar measurements were conducted to evaluate the lubricity characteristics of diglyme (C6H14O3), ethyldiglyme (C8H18O3), butylal and different diesel-butylal mixtures. The results reveal the low lubricity of all oxygenated compounds. Thus, for the engine tests, a lubricity improver has been added to the diesel-butylal mixtures.