It is important that marine diesel engines run in their normal condition in order to maintain correct efficiency, low pollution and high reliability. The record of in-cylinder pressure pattern and its evaluation is one of the most powerful sources for experimental based analysis of internal combustion engines. In addition, collected data and calculated values expand the engine diagnostic system capabilities. From the other hand reliable calculation of mean indicated pressure and other performance data requires accurate measurement of cylinder pressures and detection of the crankshaft position. It is necessary to ensure correct synchronization of recorded pressure shape with crankshaft position. For this purpose magnetic pick-up to measure the rotational speed from flywheel is usually used as a source of sampling pulses. The instantaneous piston speed can be investigated using the linear movement sensor located inside the crankshaft box. For this purpose marine propulsion testing engine was equipped with optic fiber sensor to perform permanent piston position measurement. Test bed with examined engine is equipped additionally with: optoelectronic in-cylinder pressure transducer, magnetic pick-up to measure rotational speed from flywheel, optic fiber sensor to measure the rotational speed and angular increments from propeller shaft and strain gauge arrangement designed to provide effective torque measurement.
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High demand to improve exhaust gas emission characteristics while keeping fuel economy requires a new technology for engine control. One of the methods used to meet these requirements is a convenient and real-time cylinder pressure monitoring. The final aim is balanced combustion and reliable, emission-compliant operation. Excluding the direct exhaust emission measurement, easily accessible indicators come from the in-cylinder pressure combustion data. The aim of this paper is to establish combustion model variables for use in transient condition analysis. The model should be able to predict cylinder-averaged quantities such as NOx emission. To overcome the exhaust analyzers problem, a set of engine operating conditions was tested at steady state to provide a wide range of combustion conditions with their associated emissions. Multi-zone models are the simplest and most suitable to observe the effects of empirical variations in the engine operating parameters. The obtained results are unlikely to be as detailed as those of a good CFD model, but the ease of changing characteristics makes such models useful for cheap and easy means of analyzing. Successful prediction of the NOx emission in engines varies in operating conditions. The NOx emission levels for different operating conditions are calculated for large bore, slow speed marine engine. The agreement between calculated and measured results is discussed. Cylinder pressure based model has the broad ability to predict NOx emissions in steady state.
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