Development and application of a fully automatic troubleshooting method for large marine diesel engines

The diesel engine is the main propulsion system for marine vessels except for a small category using gas or steam turbines. This is the result of its high efficiency, power concentration and reliability that have been improved considerably during the current decade. Despite these advantages, the engineer usually has to overcome great difficulties and mainly operational problems arising during the engine's lifetime. In the case of large marine engines it is almost impossible to apply trial and error methods to solve engine operating problems. This is amplified by the fact that almost all large marine diesel engines are turbocharged ones making the problem even more severe because of the interaction between the engine and the exhaust gas turbocharger. For this reason various diagnosis methods have been proposed for diesel engine condition monitoring that are mainly statistical based on known engine operating curves. These systems provide general information only and do not reveal the actual cause for an engine fault or low performance. In the current work an advanced automatic troubleshooting method based mainly on thermodynamics is presented to monitor the engine condition and to detect the actual cause for an engine fault. The method is based on the processing of measured engine data using a simulation model and provides the current engine condition and its tuning. An application of the method on a marine vessel powered by a slow speed two stroke marine diesel engine suffering from high cylinder exhaust gas temperatures and low power output is given in the present work. The method is applied at sea under actual engine operating conditions. From the processing of measured data the diagnosis method provides the current engine condition and the cause for the low power output from which the engine suffered. After conducting the major repair/adjustments proposed by the diagnosis method a substantial improvement in engine behavior was observed providing a validation for the proposed method. (C) 1998 Elsevier Science Ltd. All rights reserved.