Study on On-board Measurement of NOx Emission Value

概要

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The on-board NOx monitoring method is one of the three ways for the periodical survey, which demonstrates compliance by means of the measurement of the NOx emission value on in-service conditions. In this study of the NOx emission measurement, made on the same two-stroke engine, and with the same gas analyzer, was carried out on three occasions. That is a shop test, an at sea trial and during in-service. The effects on the NOx emission value are discussed with regard to the derivation methods of the exhaust gas flow rate. They are gas concentrations in UOB (universal oxygen balance) and UCB (universal carbon balance) method, compositions of the sampled fuel, stability of engine output power in operation, and the temperature & humidity correction factor KHdies. The coefficient of humidity term, for the factor KHajes, should be larger than that of KHdiesas specified in the NOx technical code. This correlates the NOx emission values measured at sea trial and during in-service. The temperature and humidity should be measured in the engine room rather than in the steering house. The stability of the engine power can be evaluated alternatively by using the C.O.V. of the oxygen concentrations. The NOx emission values on an actual vessel do not agree to those at a test-bed due to the effect of the derived exhaust gas flow rate and the temperature of the intercooler outlet air.
社団法人日本マリンエンジニアリング学会の論文