Marine Diesel Engine Nox Emission And Its Detection,

Against the background of Annex VI of IMO international convention MARPOL, which has come into effect recently, this paper analyses the formative mechanism and chemical reaction of diesel engine deleterious emission gases. NOx emission character of marine diesel engine is analyzed in the aspects of engine structure, fuel oil and air in-taking condition. The condition of the stand test, the standard of instruments and the measurement are described clearly. Several available measure methods of engine parameters and choose of measure devices are also studied.Direct gaseous flow measurement is a difficult task because marine diesel engine is larger in size and great in capacity of the exhaust flow. So the only method to measure NOx mass flow rate is to measure NOx concentration in the exhaust and the exhaust mass flow rate. This paper discusses the computational method to get exhaust mass flow rate with carbon/oxygen balance method based on reference [1]. This method is summarized to calculate NOx emission from the marine diesel engine .A set of formula are studied, which calculate exhaust mass flow and NOx mass emissions with simple carbon balance, general carbon balance and oxygen balance methods. Calculation formula for dry-wet coefficient and NOx ambient factor are included .On the basis of analyses and calculation mentioned above, this paper introduces the software of emission calculation with C++ language in windows 2000 environment. Owing to the superiority of object-orient, every operation function is modularized. This method makes program easily maintained and modified. Module can be used over again, which makes program easy to expend. Visual design of software interface utilizes windows resource, which makes software system a friendly and easily operated.Furthermore, the emission of marine diesel engine is more and more severe by the results of statistical comparisons between multiple engine tests by manufactures of new engine under test-bed conditions and multiple in-service engines. The major difference between on-board test and test-bed is pointed out. And the inevitability of emission measurement on-board is brought forward. This paper discusses the possible combinations of load points, the specified test cycles, steps and the special condition of NOx emission measure for on-board test.