Calculation method of brake NO_x emission from marine diesel engine

In order to improve the computation precision of exhaust gas flows, a new calculation method of brake NO_x emission from marine diesel engine was deduced by chemical reaction equations based on incomplete combustion and the principle of element quality balance, CO₂ gas was ignored, iterative calculation was avoided.For meeting the requirements and characteristics of on-board measurement of NO_x emission, approximate calculation methods based on the new method and simplified measurement were discussed. The calculation result of a example shows that the exhaust gas flows calculated by the new method are more accurate by 1.1%~1.5% than by carbon balance method, brake NO_x emission is more accurate by 0.3%~0.6%, and the error of weighted brake NO_x emission caused from ignoring CO and HC is less than 0.2%. The result proves the feasibility of simplified on-board measurement of NO_x emission because of ignoring CO and HC by handy gas analyzer.