Absorption of fuel containing esters on iron surface based on molecular simulation and its effects on lubricity

ABSTRACT

Appropriate amount of methyl myristate (C₁₄), methyl palmitate (C₁₆), methyl stearate (C₁₈), methyl oleate (C_18:1), methyl linoleate (C_18:2), and methyl ricinoleate (C_18:1OH) were blended into low-sulfur diesel to conduct the lubrication experiment on four-ball friction tester. Then, based on Materials Studio software, adsorption models of n-tetradecane with various esters on the iron surface were built up. The lubrication performance of diesel blends with 1.0%, 2.0%, 3.0%, and 5.0% (volume fraction) of different esters was improved with the increase of the esters’ fraction. Meanwhile, it is revealed by molecular simulation that the adsorption energy in the film was augmented greatly with the increase in the volume fraction of C₁₄ ester; however, the cohesive energy varied slightly. Therefore, the ester fraction puts more influence on the adsorption energy. Moreover, lubrication experiment of low-sulfur diesel with a given fraction of different esters indicated that the diameter of worn scars decreased with the increase in the length of carbon chain and the number of unsaturated C = C double bond, and at the presence of polar group as well. While via the molecular simulation, the adsorption energy in the films of n-tetradecane with 5% various esters was roughly comparable, but the cohesive energy changed with the carbon chain length, the degree of unsaturation, and the polar group. Namely, the variation of ester composition causes a significant difference in the cohesive energy. Consequently, both the increase of ester fraction and the change of ester composition are effective measures to improve the lubricity of low-sulfur diesel fuel.

KEYWORDS:

• Low-sulfur diesel
• biodiesel
• fatty acid ester
• lubricity
• molecular dynamics
• absorption

Acknowledgments

Authors wish to express their sincere appreciation for funding provided by the National Natural Science Foundation of China (No. 51761145011 and No. 51876133) and the Priority Academic Program Development of Jiangsu Higher Education Institutions (PAPD).

Additional information

Funding

This work was supported by the the National Natural Science Foundation of China [51761145011,51876133]; the Priority Academic Program Development of Jiangsu Higher Education Institutions.

Notes on contributors

Deqing Mei

Deqing Mei is a professor in Jiangsu University, and mainly engages in the research of biomass alternative energy, engine exhaust emissions and so on.

Shengchao Dai

Shengchao Dai is a graduate student in Jiangsu University, and studies the catalytic cracking of vegetable oils.

Tiaotiao Chen

Tiaotiao Chen is a doctor student in Jiangsu University, focusing on the research of gearbox.

Hengquan Wang

Hengquan Wang is an engineer in Nanjing Bangqi Automatic Transmission Co., Ltd., working on the development of tansmission.

Yinnan Yuan

Yinnan Yuan is a professor in Suzhou University, and mainly engages in the research on the operation and emission control of internal combustion engine, and alternative fuels.