Investigating the microstructures of piston carbon deposits in a large-scale marine diesel engine using synchrotron X-ray microtomography. (15th February 2015)

• Record Type: Journal Article
• Authors: Zhang, Xusheng; Peng, Guanyun; Du, Guohao; Sun, Xiucheng; Jiang, Guohe; Zeng, Xiangming; Sun, Pengfei; Deng, Biao; Xie, Honglan; Wu, Zhijun; Xiao, Tiqiao
• Is Part Of: Fuel. Volume 142(2015)
• Page Start: 173
• Page End: 179
• Publication Date: 2015-02-15
• Subjects: Piston carbon deposit -- Microstructure -- Marine diesel engine -- Synchrotron radiation -- X-ray microtomography; Fuel -- Periodicals; Coal -- Periodicals; Coal; Fuel; Periodicals; 662.6
• DOI: 10.1016/j.fuel.2014.11.005
• Languages: English
• ISSNs: 0016-2361

Abstract

Highlights: We study the 3D structure of piston carbon deposits using X-ray microtomography. We find clear pore structure adjacent to the piston surface in carbon deposits. We find the thickness threshold is around 150 μm for carbon deposit density. The top morphology of piston carbon deposit relies on the gas condensation. Abstract: The three-dimensional structures of carbon deposits on piston surfaces in a large-scale two-stroke marine diesel engine have been nondestructively investigated using synchrotron X-ray microtomography. The results indicate that the piston carbon deposit (PCD) has a flat bottom surface where many irregular structures accumulate. Based on the microtomography, cross sections of the carbon deposit sample can be obtained in the direction perpendicular to the piston surface. A uniform deposition is found on the bottom surface of piston, where many tiny pores appear, which implies that a liquid film first forms on the piston surface and subsequent nucleation boiling occurs due to the high surface temperature. A significant decrease in the PCD density is observed when the PCD thickness is below a threshold of approximately 150 μm. However, the PCD density remains almost unchanged from 150 to 1800 μm. This result suggests that there should be different dominant formation mechanisms at these two stages. The local morphology, especially the approximately circular structure and the smooth boundary on the PCD surface, indicates that condensation should be the major factor controlling the formation of the PCD surface. However, the internal pores and minimal swelling on the surface could result from other mechanisms.