Optimization of combustion, performance, and emission characteristics of a dual-fuel diesel engine powered with microalgae-based biodiesel/diesel blends and oxyhydrogen.

• Diesel engine was powered with ternary blends of biodiesel-diesel-oxyhydrogen. • Third-generation biodiesel was synthesized from biomass of Azolla Pinnata. • A low-cost device-31 plates generator generated oxyhydrogen gas. • Oxyhydrogen addition improved engine performance and lowered emissions. • Box-Behnken design coupled with desirability approach used for optimization. The current study explores and improves the effects of engine load, injection time, and oxyhydrogen fuel flow rate on the combustion and emissions characteristics of a diesel engine. Experiment with the combustion and exhaust characteristics of a medium-sized diesel engine working in tri-fuel mode using microalgae oil methyl ester-diesel blends as injected fuel and an oxyhydrogen gas combination as inducted fuel. The Box-Behnken design (BBD) was used to reduce the number of testing. The parameters and proposed attributes were calculated utilizing response surface techniques and BBD-generated quadratic models. The response surface analysis displayed the patterns of input interactions on the output using surface diagrams. The desirability-based optimization revealed the optimal engine operating parameters as 22.92° crank angles advance, 76% engine load, and 0.92 L per minute oxyhydrogen flow rate. At these optimized operating ranges, the performance and combustion output of the study was 30.8 % brake thermal efficiency (BTE), 0.3 kg/kWh brake specific fuel consumption (BSFC), and 65.6 bar peak cylinder pressure (PCP). On the emission front, the CO emission was 0.0107%, UHC was 26 ppm, and NO x was 853 ppm. The optimized values were validated through experimental testing, and all the results were within 7% of the model-predicted output. The addition of oxyhydrogen significantly improved the combustion of an algal biodiesel-diesel-oxyhydrogen-powered diesel engine in terms of fuel efficiency and fuel consumption and lower carbon-based emission levels except for nitrogen oxide emissions. [ABSTRACT FROM AUTHOR]