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首页> 外文OA文献 >Experimental study of SCR in a light-duty diesel exhaust to provide data for validation of a CFD model using the porous medium approach
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Experimental study of SCR in a light-duty diesel exhaust to provide data for validation of a CFD model using the porous medium approach

机译：轻型柴油机排气中SCR的实验研究，为使用多孔介质方法验证CFD模型提供数据

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Removal of NOx from a light-duty diesel automotive exhaust system can be achieved by SCR reactions using aqueous urea spray as the reductant. Measurements of emissions from such a system are necessary to provide data for CFD model validation. A test exhaust system was designed that featured an expansion can, nozzle and diffuser arrangement to give a controlled flow profile to define an inlet boundary for a CFD model and to approximate to one dimensional flow. Experiments were carried out on the test exhaust using injection of either ammonia gas in nitrogen or aqueous urea spray. Measurements were made of NO, NO 2 and NH 3 at inlet to and exit from the SCR using a CLD analyser. The NO and NO 2 profiles within the bricks were found by measuring at the exit from different length bricks. The spray and gas measurements were compared, and insights into the behaviour of the droplets upstream and within the bricks were obtained. Approximately half to three quarters of the droplets from the spray remained as droplets at entry to the first brick. Approximately 200 ppm of ammonia was released from the droplets to react in the first SCR brick. Between 10 and 100 ppm of potential ammonia passed through the first brick as droplets under conditions ranging from NOx-matched spray input to excess spray. The CFD model for the gas cases gave reasonable predictions for long bricks. For short bricks, the space velocity was high and there was breakthrough of all species. Nevertheless, the reaction kinetics used, based on a scheme published in the open literature, were shown to have some ability to describe the species profiles within the bricks.
机译：轻型柴油机汽车排气系统中的NOx去除可以通过使用尿素水喷雾作为还原剂的SCR反应进行。为了提供用于CFD模型验证的数据，必须测量此类系统的排放量。设计了一个测试排气系统，该系统具有膨胀罐，喷嘴和扩散器布置，以提供受控的流量曲线，从而定义CFD模型的入口边界并近似于一维流量。使用注入氮气的氨气或尿素水喷雾对测试排气进行了实验。使用CLD分析仪在SCR的入口和出口处对NO，NO 2和NH 3进行了测量。通过测量不同长度砖的出口处发现砖中的NO和NO 2轮廓。比较了喷雾和气体的测量值，并获得了对砖上游和砖内部液滴行为的见解。喷雾中约有一半至四分之三的液滴在进入第一块砖时仍为液滴。大约200 ppm的氨从液滴中释放出来，在第一块SCR砖中发生反应。在从NOx匹配的喷雾输入到过量喷雾的条件下，有10至100 ppm的潜在氨以液滴形式穿过第一块砖。瓦斯案例的CFD模型对长砖给出了合理的预测。对于短砖，空速很高，所有种类都有突破。然而，基于公开文献中公开的方案，所使用的反应动力学被证明具有描述砖块内物质分布的能力。

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