Enhancing combustion performance and emission profiles using Citrullus colocynthis biodiesel blends with hydrogen

This study was performed to explore the potential use of a combination of two alternative fuels such as hydrogen and biodiesel . A Citrullus colocynthis biodiesel blend with a proportion of 10 % or 20 % biodiesel was chosen. The hydrogen gas flow rate was controlled using a rotameter to maintain a constant supply of hydrogen at 3 L per minute (LPM) for all test fuels throughout the run. The fuels used for conducting the experimental tests were D100, B10 (Diesel 90 % + 10 % Citrullus colocynthis ), B20 (Diesel 80 % + 20 % Citrullus colocynthis ), D100 + H3L (Diesel 70 % + 30 % Citrullus colocynthis ), B10 + H3L (Diesel 90 % + 10 % Citrullus colocynthis with 3 LPM) and B20 + H3L (Diesel 90 % + 10 % Citrullus colocynthis with 3 LPM). Test blends were allowed to run in the direct ignition diesel engine and the performance, combustion, and emission characteristics were determined and the results were compared. All tests were conducted at full load condition with varying engine speed from 1500 rpm to 3000 rpm with 500 rpm intervals. Use of the 10 % and 20 % biodiesel blends reduced the brake thermal efficiency of the engine due to lower cetane number and calorific value . Due to the higher viscosity, fuel consumption was higher for both blends. The results obtained from the fuel blends without and with hydrogen showed that the addition of hydrogen significantly improved performance and combustion efficiency. Further, the addition of hydrogen and use of Citrullus biodiesel reduced emission of the greenhouse gases CO and CO 2 . Presence of excess oxygen content in the biodiesel ensured superior combustion, which eventually led to lower emission of exhaust emissions. However, there is no evidence of reduction in the NOx emission for all the blends compared to diesel. • Potential use of hydrogen and Citrullus colocynthis biodiesel blends (B10 and B20) in a direct ignition diesel engine. • Brake thermal efficiency and brake power increased with higher proportions of biodiesel when hydrogen was added. • Reduced emission of CO and CO 2 due to the higher oxygen content in the biodiesel. • Slight increases in CO 2 and NO emissions noted due to high cylinder temperature as a result of hydrogen.