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In order to address the increasing energy and environmental concerns, China and the US both launched the fuel economy regulations and aim to push the development of technology. In this study, the stringency of CAFC and CAFE regulations and the technology development of two countries are compared. Besides, the optimal technology pathways of America and automakers for the compliance of CAFE regulations are calculated based on the modified VOLPE model, and the results are used as reference for China. The results indicate that the annual regulation improvement rates of China is higher than America and the AIR of China 2015-2020 regulation reaches 6.2% and is the most stringent phase in 10 years from 2015 to 2025. From the perspective of technology, there are still big gaps between China and the US in the applications of advanced fuel saving technologies.

The homogeneous charge, compression-ignition (HCCI) combustion process has the potential to significantly reduce NOx and particulate emissions, while achieving high thermal efficiency and the capability of operating with a wide variety of fuels. This makes the HCCI engine an attractive technology that can ostensibly provide diesel-like fuel efficiency and very low emissions, which may allow emissions compliance to occur without relying on lean aftertreatment systems.

To meet more stringent emission regulations for diesel engines, diesel particulate filters (DPF) have been widely used for diesel engines. However, the DPF regeneration is a great challenge for fuel economy. In this paper, a mathematical model characterizing the microwave regeneration process of a wall-flow particulate filter is introduced to better understand the process. Based on this model, important parameters such as evolutions of the energy stream densities of microwaves, wall temperature, regeneration efficiency and the pressure drop in the filters, both cordierite and SiC, are investigated. These results can provide an important theoretical guide for optimizing and controlling the microwave regeneration process.