Effects of exhaust gas recirculation on the particulates structure characteristics of diesel engine fueled with diesel/biodiesel blend

ABSTRACT

Exhaust gas recirculation (EGR) is a type of mature technology used to reduce NOx emissions from diesel engines. However, the use of EGR causes diesel engines to produce more particulates. In this paper, the particulates of diesel, diesel/biodiesel blend (50% biodiesel) and biodiesel were collected and measured at different EGR rates. High-resolution transmission electron microscopy (TEM) and thermogravimetric (TG) analyses were used to study the effects of EGR on the microstructure, composition and oxidation characteristics of particulates. The results showed that with the increase of biodiesel content in the diesel/biodiesel blend, the accumulation of diesel/biodiesel particulates was denser, the particle size of particulates for the diesel/biodiesel blend was smaller, the soluble organic fractions (SOF) content in particulates was increased and the surface activation energy of the particulates was reduced. With the increase of the EGR rate, the boundary of multiple particulate overlap areas was difficult to distinguish, the particle size of the particulates increased, and the SOF content in the particulates increased, while the soot content decreased gradually. When the EGR rate was increased from 0% to 15% and 30%, the activation energy of particulates for biodiesel was decreased by 15.59% and 26.63%, respectively.

KEYWORDS:

• Diesel engine
• EGR
• biodiesel
• particulate
• structure characteristics

Additional information

Funding

This study was financially supported by the National Natural Science Foundation of China under Grant [No. 51776089] and China Postdoctoral Science Foudation Project [2019M651732].