The Investigation into the Tribological Impact of Alternative Fuels on Engines Based on Acoustic Emission

Nasha Wei,Andrew Ball,Yuandong Xu,Zhi Chen,Fengshou Gu

doi:10.3390/en14082315

Abstract

The wide use of different alternative fuels (AL) has led to challenges to the internal combustion (IC) engine tribology. To avoid any unpredicted damages to lubrication joints by using AL fuels, this study aims to accurately evaluate the influences of alternative fuels on the tribological behavior of IC engines. Recent achievements of the acoustic emission (AE) mechanism in sliding friction provide an opportunity to explain the tribological AE responses on engines. The asperity–asperity–collision (AAC) and fluid–asperity–shearing (FAS) mechanisms were applied to explain the AE responses from the piston ring and cylinder liner system. A new adaptive threshold–wavelet packets transform (WPT) method was developed to extract tribological AE features. Experimental tests were conducted by fueling three fuels: pure diesel (PD), biodiesel (BD), and Fischer–Tropsch (F–T) diesel. The FAS–AE indicators of biodiesel and F–T diesel show a tiny difference compared to the baseline diesel using two types of lubricants. Biodiesel produces more AAC impacts with higher AAC–AE responses than F–T diesel, which occurs at high speeds due to high temperatures and more particles after combustion than diesel. This new algorithm demonstrated the high performance of using AE signals in monitoring the tribological impacts of alternative fuels on engines.

Highlights

The acoustic emission (AE) signals can reflect the dynamic information of tribology behavior of engines by asperity– asperity–collision (AAC)–AE and Fluid asperity shearing-acoustic emission (FAS–AE)
Around the middle of each stroke, significantly higher sliding speed leads to more hydrodynamic lubrication in which little AAC can occur, but high
A new adaptive threshold–wavelet packet analysis was proposed as an effective tool to extract the tribological AE from the ring

Summary

Introduction

Publisher’s Note: MDPI stays neutral with regard to jurisdictional claims in published maps and institutional affiliations. Many investigations of alternative fuels (AL) focus on the emissions and performance because of the environmental vulnerabilities and resource shortage of fossil fuels. The physical and chemical properties of alternative fuels are different from those of ordinary diesel, which inevitably lead to physical and chemical changes in the combustion chamber. The efforts to reduce fuel emissions may lead to further tribological problems such as a loss of lubricity and surface damage [1]. The influence on the friction and lubrication condition of the engines using AL fuels is still unknown. It is necessary to monitor the alternatives’ tribological behaviors on engines under the working condition

Objectives

Methods

Conclusion