【作者】

Sun Shaowei

【摘要】

该论文已在赫尔辛基举行的第28届CIMAC大会上发表，论文的版权归CIMAC所有。ABSTRACT With the introduction of IMO Tier 3 NOx-emissions from Marine Diesel Engines have to be reduced dramatically. In Emission Controlled Areas (so called ECAs) an emission of approximately 2 g/kWh must be achieved. Several technologies have been investigated to reach this target. With EGR it is possible to realize the required reduction. This has been demonstrated successfully in automotive engines. Operation of Marine Engines however poses some difficulties which do not exist in the automotive sector. These are high sulfur content of the fuel and the necessity to switch off the EGR outside the ECAs. Therefore Selective Catalytic Reduction (SCR) has turned out to be the mainstream solution, at least with Medium Speed Engines. For this technology the supply of urea solution is necessary, which represents an additional operating fluid and therefore additional cost. This results in the task to minimize the operation cost while keeping the emission limits and all operational boundaries of the engine and the aftertreatment system. For this purpose a simulation model of the engine and the aftertreatment system is used. The basis is the commercial simulation package GT-Suite. The engine cylinder is computed with an in house model. For the calculation of heat release a quasisteady jet model is used. Engine out NOx emissions are calculated with an empirical model taking into account inter alia characteristics of the rate of heat release, gas temperature in the cylinder and oxygen concentration representing EGR rate. Good agreement between measurements and calculations is demonstrated. The chemical reactions in the SCR catalyst are simulated with an Artificial Neural Network which is trained with data from a laboratory gas test bench. With this toolbox a systematic parametric study is carried out. Engine parameters like injection timing, injection pressure, compression ratio, valve timing, charge air pressure, charge air temperature etc. are varied. All these have an influence on specific fuel consumption, engine out NOx emission and exhaust temperature. The latter influences the conversion rate in the catalyst. The limitations of the engine like maximum cylinder pressure and maximum temperatures are taken into account. NOx emission after catalyst is kept below the IMO Tier 3 limit. As a result a matrix of fuel and urea consumption is obtained. From this the cost optimum can be calculated with the fuel and urea prices.

【会议名称】

第28届CIMAC会议

【会议地点】

芬兰 赫尔辛基

【下载次数】

3

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