Lehmann U, Niemelä V, Mohr M
Laboratory for Internal Combustion Engines, EMPA (Swiss Federal Laboratories for Materials Testing and Research), CH-8600 Dübendorf, Switzerland.
Environ Sci Technol. 2004 Nov 1;38(21):5704-11. doi: 10.1021/es035206p.
The Dekati mass monitor (DMM; Dekati Ltd., Finland), a relatively new real-time mass measurement instrument, was investigated in this project. In contrast to the existing gravimetric filter method also used as a standard for regulation purposes, this instrument provides second-by-second data on mass concentration in the engine exhaust gas. The principle of the DMM is based on particle charging, inertial and electrical size classification, and electrical detection of aerosol particles. This study focuses on the instrument's practical performance. Details on calibration and the theory of operation will be published elsewhere. The exhaust emissions of two heavy-duty engines complying with the Euro III emission standard were measured on a dynamic engine test bench. We looked atthe particle number and mass emissions of the engines in different transient test cycles and steady-state conditions. The ability to follow transient test cycles and the response times of the DMM were investigated. The aerosol mass concentration measured by the DMM was compared with the mass concentration obtained by the standard gravimetric filter method with Teflon-coated glass fiber filters. The total mass concentration (integral over the whole cycle) measured by the DMM is about 20% higher than that measured by the standard gravimetric filter method. The total mass concentration from the DMM was also compared with the volume concentration calculated from the electrical low-pressure impactor (ELPI) measurements. Correlations were made with other particle measuring systems. The DMM correlates very well with the particulate mass (R2 = 0.95) and exhibits good linearity and repeatability. The response time to a well-defined change in exhaust concentration was observed to be fast and stable. The DMM was able to follow transient test cycles and provides good results on a second-by-second basis. The instrument used in this study was still under development, and there is therefore no complete scientific background reference for the DMM. This study therefore focuses more on the measurements than on the scientific background. The measurements have shown thatthe DMM is an adequate instrument for measuring the mass concentration of engine exhaust, with results comparable to those from the standard gravimetric filter method. In addition, the DMM provides real-time second-by-second data of the mass concentration during transient test cycles.
本项目对一种相对较新的实时质量测量仪器——德卡蒂质量监测仪（DMM；芬兰德卡蒂有限公司）进行了研究。与同样用作监管标准的现有重量法过滤法不同，该仪器能提供发动机废气中质量浓度的逐秒数据。DMM的原理基于颗粒充电、惯性和电尺寸分级以及气溶胶颗粒的电检测。本研究聚焦于该仪器的实际性能。校准及操作理论的详细内容将在其他地方发表。在动态发动机试验台上测量了两台符合欧Ⅲ排放标准的重型发动机的废气排放。我们考察了发动机在不同瞬态试验循环和稳态条件下的颗粒数量和质量排放。研究了DMM跟踪瞬态试验循环的能力及其响应时间。将DMM测量的气溶胶质量浓度与采用涂覆特氟龙的玻璃纤维滤膜的标准重量法过滤法获得的质量浓度进行了比较。DMM测量的总质量浓度（整个循环的积分）比标准重量法过滤法测量的结果约高20%。DMM的总质量浓度还与根据电低压冲击器（ELPI）测量结果计算出的体积浓度进行了比较。与其他颗粒测量系统建立了相关性。DMM与颗粒质量的相关性非常好（R2 = 0.95），并表现出良好的线性和重复性。观察到对废气浓度明确变化的响应时间快速且稳定。DMM能够跟踪瞬态试验循环，并能逐秒提供良好的结果。本研究中使用的仪器仍在开发中，因此对于DMM没有完整的科学背景参考资料。因此，本研究更多地关注测量结果而非科学背景。测量结果表明，DMM是一种用于测量发动机废气质量浓度的合适仪器，其结果与标准重量法过滤法的结果相当。此外，DMM在瞬态试验循环期间提供质量浓度的实时逐秒数据。
