Performance-Emission Trade-off Analysis of Luffa Cylindrica Biodiesel Diesel Blends in a Single Cylinder Direct Injection Compression Ignition Engine

The growing demand for sustainable energy and the environmental impacts associated with fossil fuel combustion have intensified research into alternative fuels such as biodiesel. Biodiesel derived from non-edible feedstocks has gained attention due to its potential to reduce emissions while maintaining engine performance. However, limited studies have explored the performance emission trade-offs of underutilized feedstocks such as Luffa cylindrica, particularly across varying engine operating conditions.This study investigates the performance and emission characteristics of Luffa cylindrica biodiesel diesel blends (B5–B100) in a single-cylinder, four-stroke, direct injection compression ignition engine. Engine performance was evaluated under variable load conditions, while emission characteristics (NOx, CO, CO₂, and HC) were analysed at engine speeds of 1200 rpm, 1500 rpm, and 1800 rpm.The results show that brake power increased with engine load for all fuels, with conventional diesel exhibiting the highest performance. Among the biodiesel blends, B5 demonstrated performance characteristics closest to diesel, making it the most suitable blend for maintaining engine output. In contrast, higher blends resulted in reduced performance due to lower calorific value and higher viscosity. Emission analysis revealed that biodiesel blends significantly reduced carbon monoxide and hydrocarbon emissions, with B20 exhibiting the most favourable emission profile. However, nitrogen oxides emissions increased with increasing biodiesel concentration due to higher combustion temperatures.The findings highlight a clear performance emission trade-off in the use of Luffa cylindrica biodiesel blends. While B5 is optimal for performance, B20 offers better emission reduction, indicating that blend selection should be based on specific operational and environmental priorities. This study demonstrates the viability of Luffa cylindrica as a sustainable biodiesel feedstock for compression ignition engines.