Influence of Cissus quadrangularis as biofuel additive on the performance of VCR diesel engine fueled with palm oil

Although many bio-fuels (neat vegetable oils) including palm oil, were found suitable for diesel replacement in internal combustion engines, none of them ever tested so far had better performance than diesel and therefore bio-fuels are commercially not viable to date. Hence in this research work, a novel bio-fuel additive derived from naturally available herbal species known as Cissus quadrangularis (Vajravalli) has been proposed. This herbal juice in liquid form is added with palm oil in different volumetric proportions and is used as fuel to test the performance of single-cylinder, 4-stroke, compression-ignition water-cooled, direct-injection, variable compression ratio engine. The experimental results witness a significant advancement in the brake thermal efficiency of the engine operating with palm oil using Cissus quadrangularis as an additive when it is compared to neat palm oil fuel operation. At rated load with an engine compression ratio of 18, the fall in brake thermal efficiency for palm oil operation is 7% in comparison to diesel operation. This reduction in BTE has been improved to only 3% for 2V98P fuel. Also, there is a decrease in brake specific fuel consumption. Furthermore, the performance characteristics of 2V98P fuel are in close concurrence with diesel operation. The maximum mechanical efficiency obtained at rated load for palm oil, 1V99P, 2V98P, 3V97P, and 4V96P fuels is respectively 7%, 5.8%, 4.8%, 4%, and 3% greater than that of diesel. Also, the exhaust gas temperatures obtained for 2V98P, 3V97P, and 4V96P are less than that of diesel operation while for palm oil and 1V99P it is greater than that of diesel. The maximum BTE and minimum BSFC obtained for 2V98P fuel is 32.05% and 0.3255 kg/kWh respectively as against 32.8% and 0.3126 kg/kWh for the diesel operation at a rated load with a compression ratio of 20.