Reliability of renewable oxygenated fuels in engines: A comprehensive review of long-term testing

Abstract

Long-term testing is crucial for evaluating renewable and non-carbon fuels for engines, ensuring compatibility and assessing their performance for extended periods. This is especially pertinent as researchers explore the addition of higher ethanol, hydrogen and ammonia content in gasoline as potential fuel additives. The paper extensively reviews the long-term effects of various fuels on engine deposits, wear, and lubricating oil. Studies indicate that biofuel blends can pose challenges in the long run, leading to increased deposits, engine wear, and lubricating oil degradation. However, some studies highlight the favorable impact of biofuel blends, due to their oxygenated nature. For instance, deposit formation in diesel-fuelled constant-speed engines was significantly lower than in JO5 and JO10-fuelled engines (512 h duration). Similarly, KB20-fuelled engines exhibited approximately 15.3 % higher deposit formation than diesel-fuelled engines (274 h duration). The oxygen content and superior lubrication properties of biodiesel blended fuels help in better combustion process and reduce engine deposits. The deposit formation on the fuel-injector affects the fuel pattern and engine performance. The performance and combustion characteristics degrade and emissions increase with time. The application of biodiesel observed to enhance corrosive behavior due to inherent oxygen, leads to increased wear and friction in engine components and fuel pump plunger. The formation of metal debris increases and lubrication oil degrades with respect engine operation time. This study provides insights into the long-term impact of various renewable biofuels and their blends on engine performance and discusses future prospects on engine tribological characteristics.