Improvement of worsened diesel and waste biodiesel fuelled-engine characteristics with hydrogen enrichment: A deep discussion on combustion, performance, and emission analyses

Abstract

Due to the strict emission policies, fuel researchers are dedicated to mitigating the tailpipe emissions from internal combustion engines (ICEs). Therefore, researchers have considered biodiesel as the best alternative to conventional diesel fuel (D) for a while. However, many scientific papers experimentally announced that the use of biodiesel significantly worsens engine behaviors. In this framework, hydrogen enrichment has become a very reasonable option in order to minimize the reverse influences of biodiesel-fuelled engine characteristics. In this direction, waste cooking of 25% (B25) was volumetrically blended to D and reference data was collected. Then, 15 and 30 Lpm hydrogen was introduced from the intake manifold by mixing with air along with B25 test fuel to observe the changes from the hydrogen effect. Tests were performed on a three-cylinder, water-cooled diesel engine at constant engine speed (2000 rpm) and variable engine loads (15, 30, 45 and 60 Nm). In the results, it is witnessed that BSFC (brake specific fuel consumption) for B25 fuel increased by 8.23% as compared D fuel. However, along with the introduction of 15 and 30 Lpm hydrogen to B25 fuel, the BSFC value dropped by 17.58%, and 30.75%, respectively. In a similar way, B25 test fuel reduces BTE (brake thermal efficiency) by 7.54% as compared to D fuel. However, the hydrogen introduction of 15 and 30 Lpm (Litre per minute) along with B25 fuel improves the BTE value by 10.19%, and 17%, respectively. On the other hand, the inclusion of 15 Lpm and 30 Lpm H2 to B25 fuel provided a reduction of 23.75% and 45.59% for HC (Hydrocarbon) emissions, and 53.1% and 62.6% for NOx (Nitrogen oxide) emissions, respectively. In conclusion, it is seen that deteriorations in combustion, performance, and emission characteristics resulting from the use of biodiesel can be minimized by using hydrogen for ICEs.