Search Results

China VI emission standards (Limits and measurement methods for emissions from diesel fueled heavy-duty vehicles, China VI, GB17691-2018) have strict particle number (PN) emission standards and so the coated diesel particulate filter (DPF) technology from the EU and US market has challenge in meeting the regulation. Hence, a coated DPF with higher PN filtration efficiency (FE) is required. Currently, there are two approaches. One is from the DPF substrate standpoint by using small pore size DPF substrate. The other is from the coating side to develop a novel coating technology. Through the second approach, a layer coating process has been developed. The coated DPF has an on-wall catalytic layer from inlet side and an in-wall catalytic coating from outlet side. The DPF has improved PN filtration efficiency and can meet China VI regulation without any pre-treatment. It has lowered soot loading back pressure (SLBP), compared to the DPF with small pore size.

Despite numerous research efforts, there is no reliable and widely accepted tool for the prediction of erosion prone material surfaces due to collapse of cavitation bubbles. In the present paper an Erosion Aggressiveness Index (EAI) is proposed, based on the pressure loads which develop on the material surface and the material yield stress. EAI depends on parameters of the liquid quality and includes the fourth power of the maximum bubble radius and the bubble size number density distribution. Both the newly proposed EAI and the Cavitation Aggressiveness Index (CAI), which has been previously proposed by the authors based on the total derivative of pressure at locations of bubble collapse (DP/Dt>0, Dα/Dt<0), are computed for a cavitating flow orifice, for which experimental and numerical results on material erosion have been published. The predicted surface area prone to cavitation damage, as shown by the CAI and EAI indexes, is correlated with the experiments.

Low cost and S(sulphur)-tolerant DOCs (Diesel Oxidation Catalysts) are being demanded in emerging countries such as China and India, where Euro 4 and 5 type emission standards are going to be implemented or are being implemented. However, fuel S content is different in the metros vis-à-vis non metros in many emerging countries. In such a scenario, DOCs need to maintain catalytic performance with high S fuel as well as standard low S fuel. This paper describes the development results of S tolerant Pt-Pd based DOCs. A new washcoat technology (WT D) has been developed for EU 4 passive Pt-Pd DOC applications, in which PGM cost was thrifted by replacing part of Pt by Pd. Vehicle test results after thermal ageing and S poisoning demonstrated that the Pt-Pd DOC (Pt:Pd=4:1) prepared with WT D gave similar tailpipe CO (Carbon monoxide) and HC (Hydrocarbon) emission conversions as a commercially available EU 4 passive Pt-only DOC when 50ppm S diesel fuel was used.

This paper describes the development results of S tolerant Pt-Pd-based Diesel Oxidation Catalyst (DOC) which can be applied for passive DOC application, targeting Euro 4 and India BS4 emission standards with a view of the fact that in India the sulfur content is different in the 13 main cities compared to rest of the country. In order to develop a cost-effective DOC to meet Euro 4 and India BS4 legislation, Pt-Pd-based DOC was studied. Firstly, the effect of Pd used together with Pt in catalytic oxidation performance was studied. DOCs having different Pt to Pd ratios were evaluated in the engine exhaust. The results revealed that CO (Carbon Monoxides) and HC (Hydrocarbons) oxidation activity over Pt-Pd DOC were significantly improved as compared to Pt-only DOCs. It was also revealed that there is an optimum Pt to Pd ratio to give the best light-off performance under conditions tested. Advantage of Pd use with Pt was also confirmed in terms of thermal stability.