Hydrogen enhanced biodiesel production from Botryococcus braunii algal oil for sustainable fuel development

Abstract

The growing demand have made researchers look into algae-based biodiesel, which is precisely a type of algae called Botryococcus braunii, as an alternate to sustainable fuel source. The feature of this alga is that it has high oil content and is determined as user friendly. The study made an attempt to explore the effectiveness and efficiency of adding hydrogen with Botryococcus braunii at 2 different rates, viz., 4LPM and 8LPM respectively in a Common Rail Direct Injection (CRDI) diesel engine and compared its performance with the pure diesel. This assessment approach of testing hydrogen (H₂) with 30% Botryococcus braunii biodiesel + 70% diesel blend combination (A30) and comparing the same with pure diesel is regarded as the primary creativity and uniqueness of this research investigation. The analysis of the study revealed the fact that adding hydrogen to 30% Botryococcus braunii biodiesel + 70% diesel blend enhanced the performance of the engine substantially. It further demonstrated that the Brake Thermal Efficiency improved to 37% from 31% with the addition of A30 + H₂ (8 LPM) against the pure diesel, marking a rise of 19.35%. Similarly, specific fuel consumption dropped to 0.24 kg/kWh from 0.30 kg/kWh, illustrating a reduction of 20%, in comparison with pure diesel. Volumetric efficiency surged to 91% (with a rise of 10.98%) from 82%. This is because of the presence and availability of more content of oxygen in 30% Botryococcus braunii biodiesel + 70% diesel blend, facilitating a better and a clean process of combustion. The study focused on the properties of combustion improved with the in-cylinder pressure at the utmost load, where it was found rising to 77.3 bar from 70.2 bar, indicating a marginal surge of 10.11% against the net heat release rate, demonstrating a steep rise of 18.26% (increased to 48.63 kJ/m³deg from 41.11 kJ/m³deg). Besides the above, the Carbon Monoxide (CO) emissions reduced by 69.46% (0.334% to 0.102%), Hydrocarbons decreased by 43.24% (148ppm to 84ppm), CO₂ dropped by 7.77% (10.3% to 9.5%), smoke opacity diminished by 14.18% (69.1% to 59.3). It was evidently observed that the hydrogen blend algae biodiesel enhanced a better combustion process by the removal of incomplete combustion areas and enhancing the overall performance and efficiency of the engine. It is noted that while the outcomes of the emissions reveal substantial enhancements, Nitrogen oxides (NO_X) emissions do increase by 47.64% (from 1503ppm to 2220ppm). The exhaust gas temperature is decreased marginally from 520 °C to 498 °C, marking a reduction of 4.23%. In a nutshell, the study apparently reveals the fact that A30 + H₂ (8 LPM) significantly improves the performance of the engine, enhances the characteristics of combustion and minimizes most emissions leading to a very high and an efficient sustainable fuel in contrast to the pure diesel.