With the emergence of the problems such as air pollution and greenhouse gases over the world, IMO realized the seriousness of air pollution caused by ship and they established MARPOL 73/78 Annex VI in 1997. Annex VI includes several emission controls on air pollution. Especially, in NOx case, marine diesel engines should be certified by standard of emission controls and NOx technical codes detailed guidelines. NOx emission intensity is regulated by the output according to speed of marine diesel engines. Therefore, exact calculation of engine output is very important as well as the technique to reduce NOx.
In recent years, measuring power of marine diesel engine has been obtained by using electronic pressure indicator. However, measured output has been known to be different from the one that engines generate. A device that measures the movement of piston cannot read an accurate location of the TDC, which makes it difficult to measure an accurate output of diesel engines. This fact has been confirmed through various materials. One degree difference between the location of measured TDC and that of physical TDC causes 10 percent of differences in IMEP and 25 percent of differences in heat release rate. and thus, many researchers recommend that the range of differences between the location of measured TDC and that of physical TDC should be within 0.1 degree.
These days, various engines installed in ships are equipped with injection devices that inject fuels after TDC in the way to meet NOx emission controls. In this case, two pressure peak points are shown in a cylinder pressure graph.
However, compression TDC on operating is indicated prior to physical TDC by heat loss and blow-by gas. The difference between compression TDC and the location of physical TDC is defined as loss angle. And if we consider loss angle, not only can measure the location of accurate TDC, but also obtain the accurate output.
In this paper, loss angle is analyzed by simulation and experiment. Through a simulation, the influences of heat loss and blow-by gas had on loss angle is investigated. And confirming the value of loss angle by experimenting with an engine installed in a ship. Finally, the result of simulation with that of experiments is compared and analyzed.