heal.abstract |
Potential reduction of smoke emission of marine diesel engines is investigated through the installation of an exhaust bypass system featuring two diesel particulate filters in the Laboratory of Marine Engineering of the National Technical University of Athens. This system differs from the ones already in use in the automotive industry because it charges only during engine transient loading in order to avoid early filter contamination. The exhaust flow is controlled by the operation of two butterfly valves. When the engine is idle or operating in steady state the first valve is fully open and the exhaust gas flows through the main duct unfiltered. In case of engine transient loading, during which there is high smoke emission, the second valve gradually opens leading part of the exhaust gas into the filters. When it is almost fully open, the first one closes and the exhaust gas is being fully filtered until the engine operates in steadier conditions. Then, the valves are moved to their initial positions. The efficiency of the method, in terms of smoke emission reduction, is assessed by measuring the exhaust gas opacity after the filters. Furthermore, the differential pressure across the filters is measured, as well as the system back pressure, in order to estimate the soot load in the filters and its impact on the engine operation.
The project includes the supervision of the construction and proper installation of the exhaust bypass system in the exhaust processing unit of the laboratory, the acquisition and mounting of all sensors, the installation of the necessary subsystems and the conduction of the experiments. In the context of this project, opacity measurements on a high speed passenger vessel are also carried out in order to evaluate the opacity sensor performance, as well as to observe the smoke emission from an engine operating in real conditions. In addition, a brief description of the radio – frequency soot sensing technology is performed in order to decide whether to use this or the state of the art differential pressure in order to estimate the soot load in the filters.
The main objective is to develop a system that will reduce efficiently and in a safe way the smoke emission of diesel engines without interfering in their overall operation. Furthermore, additional issues must be considered so that the system will be suitable for retrofit in marine engines. |
en |