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On Calculation Method and Simplified on-board Test of NOX-emmission from Marine Diesel Engine
Zibin Yin, Defeng Wu and Haito Ma

This paper proposes a new calculation method of exhaust gas flow, namely a new calculation method of brake NOX-emission from marine diesel engine through the chemical reaction equations based on incomplete combustion and the principle of element quality balance. The new method has some advantages compared with the two methods in Annex VI to MARPOL73/78, such as less parameters of exhaust gas components for calculation, avoidance of iterative calculation and higher accuracy. To meet the requirements and the characteristics of the on-board measurement of NOX-emission from marine diesel engine, the approximate calculation methods based on the new method and simplified measurement are also discussed. The calculation example proves the correctness of the new method and shows that the exhaust gas flows calculated by the new method are more accurate by 1.0% ∼1.5% than those calculated by carbon balance, and that the brake NOX-emission are more accurate by 0.4% ∼ 0.6%, and that the error on brake NOX-emission caused by ignoring CO and HC in the exhaust gas components based on the new method less than 0.2%. The calculation example and error analysis prove the feasibility of simplified on-board measurement of NOX-emission ignoring CO and HC. Thus, the on-board measurement of NOX-emission becomes more practical and feasible by using handy gas analyzer.

Keywords: Marine diesel engine, NOX-emission, On-board test, Calculation method

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