A comprehensive review of exergy analysis in biodiesel-powered engines for sustainable power generation

Exergy analysis, along with its extensions, plays a pivotal role in understanding and improving the efficiency and sustainability of energy systems. In the realm of renewable energy, diesel engines fueled by biodiesel have received significant attention through exergy-based analyses. This paper aims to comprehensively investigate the effects of integrating biodiesel into diesel engines, focusing specifically on their exergetic, exergoeconomic, and exergoenvironmental parameters. The exploration begins with an overview of biodiesel production, followed by an assessment of its impact on diesel engine characteristics. The methodology for applying exergy-based analyses to diesel engines is then detailed. Subsequently, the paper thoroughly examines the influence of biodiesel on diesel engine exergy parameters, drawing insights from the available literature. Generally, the literature reveals a lack of consensus regarding the impact of biodiesel on diesel engine exergy parameters. More specifically, the increase in biodiesel content in fuel blends is associated with a negative correlation with both exergy efficiency (r = -0.09) and exergy destruction (r = -0.08). Engine speed shows a weak negative correlation with exergy efficiency (r = -0.23) and a weak positive correlation with exergy destruction (r = +0.22). On the other hand, engine load exhibits a weak positive correlation with exergy efficiency (r = +0.19) and a relatively strong negative correlation with exergy destruction (r = -0.42). Additionally, biodiesel usage contributes to heightened specific exergoeconomic cost and exergoenvironmental impact of shaft work. The article further explores the strengths and limitations of exergy analysis in the context of diesel engines while also outlining potential avenues for future research.