How to improve the combustion efficiency and reduce harmful emissions has been a hot research topic in the engine field and related disciplines. Researchers have found that nano-additives to diesel-biodiesel fuel blends have achieved significant results. Many research results and both current and previous studies on nanoparticles have shown that nano-additives play an essential role in improving the performance of internal combustion engines and reducing the emission of harmful substances. This paper summarizes the recent research progress of nanoparticles as additives for diesel-biodiesel fuel blends. Firstly, the excellent properties of nanoparticles are described in detail, and the preparation methods are summarized and discussed. Secondly, the effects of several commonly used nanoparticles as diesel-biodiesel fuel blends on combustion performance and harmful substances emissions in terms of combustion thermal efficiency, brake specific fuel consumption, CO, UHC and NOx, are reviewed. Finally, the effects of nano-additives on internal combustion engines, the environment and human health are discussed. The work carried out in this paper can effectively contribute to the application of nanomaterials in the fuel field. Based on our work, the researchers can efficiently select suitable nano-additives that enable internal combustion engines to achieve efficient combustion and low-emission characteristics.
TaB 2-SiC coating modified by different content of MoSi 2 was fabricated on graphite substrate with SiC inner coating by liquid phase sintering to elevate the anti-oxidation capability of the TaB 2-SiC coatings. As compared to the sample with the TaB 2-40wt%SiC coating, the coating sample modified with MoSi 2 exhibited a weight gain trend at lower temperatures, the fastest weight loss rate went down by 76%, and the relative oxygen permeability value reduced from about 1% to near 0. More importantly, the large amount of SiO 2 glass phase produced over the coating during oxidation was in contact with the modification of MoSi 2 , which was proved to be beneficial to the dispersion of Ta-oxides. A concomitantly formed continuous Ta-Si-O-B compound glass layer showed excellent capacity to prevent oxygen penetration. However, when the TaB 2 content was sacrificed to increase the MoSi 2 content, the relative oxygen permeability of the coating increased instead of decreased. Thus, on the basis of ample TaB 2 content, increasing the MoSi 2 content of the coating is conducive to reducing the relative oxygen permeability of the coatings in a broad temperature region.
The NH3 uniformity and conversion rate produced by the urea–water solution spray system is an essential factor affecting de-NOx efficiency. In this work, a three-dimensional simulation model was developed with the CFD software and was employed to investigate the effects of two typical injection methods (wall injection and center injection) and three distribution strategies (pre-mixer, post-mixer, pre-mixer, and post-mixer) of two typical mixers on the urea conversion rate and uniformity. The field synergy principle was employed to analyze the heat transfer of different mixer flow fields. The results show that the single mixer has instability in optimizing different injection positions due to different injection methods and injection positions. The dual-mixer is stable in the optimization of the flow field under different conditions. The conclusion of the field synergy theory of the single mixer accords with the simulation result. The Fc of the dual-mixer cases is low, but the NH3 conversion and uniformity index rate are also improved due to the increase in the residence time of UWS.
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