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Recently, after-treatment techniques for diesel engine emission reduction have made a remarkable progress. Owing to new techniques such as the diesel particulate filter (DPF), the total amount of particulate matter (PM) collected on filter is rapidly reducing. It is significantly important for an engine operation to control the amount of PM or PM component ratio for high efficient after-treatment operation. Though a conventional gravimetric method is required by regulations, an alternative method, a combustion method, is focused on because of its simple and quick measurement. However it turned out that the combustion method has some difficulties to measure the low mass PM below 0.5mg. Then improvement methods were considered in this paper. Finally the modified instrument showed good correlation with gravimetric results below 0.5mg.

Recently, after-treatment techniques for diesel engine emission have made remarkable progress with the development of suitable De-NOx catalysts. The urea-injection SCR system is one of the candidates for a high efficiency De-NOx method for diesel engine emissions. This system reduces NOx through a reaction with ammonia (NH3) that is generated from injected urea. In this system, it is very important to control the amount and timing of the urea injection so as to minimize the NH3 gas slip. Therefore, NH3 gas measurement is becoming important during the development of NOx after-treatment systems even though NH3 is not a target component of the current emission regulations. In this paper, a new NH3 gas analyzer utilizing a chemi-luminescence detection (CLD) method has been developed. The new NH3 analyzer consists of dual detectors (DCLDs) and a furnace for a NH3 oxidization catalyst. Real-time concentration of NH3 can be calculated from the difference of NOx readings of two detectors.