Energies, Vol. 18, Pages 5502: Response Surface Analysis of the Energy Performance and Emissions of a Dual-Fuel Engine Generator Using Biodiesel and Hydrogen-Enriched Biogas

Energies, Vol. 18, Pages 5502: Response Surface Analysis of the Energy Performance and Emissions of a Dual-Fuel Engine Generator Using Biodiesel and Hydrogen-Enriched Biogas

Energies doi: 10.3390/en18205502

Authors:
Danilo Simon
Samuel N. M. de Souza
Doglas Bassegio
Willian C. Nadaleti
Juliano de Souza
Reinaldo A. Bariccatti
Reginaldo F. Santos
Carlos E. C. Nogueira
Waldir M. Machado Junior
Jair A. C. Siqueira

In this study, we investigate the dual-fuel operation of compression ignition engines using biodiesel at varying concentrations in combination with biogas, with and without hydrogen enrichment. A response surface methodology, based on a central composite experimental design was employed to optimize energy efficiency and minimize pollutant emissions. The partial substitution of diesel with gaseous fuel substantially reduces the specific fuel consumption, achieving a maximum decrease of 21% compared with conventional diesel operation. Enriching biogas with hydrogen, accounting for 13.3% of the total flow rate, increases the thermal efficiency by 0.8%, compensating for the low calorific value and reduced volumetric efficiency of biogas. Variations in biodiesel concentration exhibits a nonlinear effect, yielding an additional average efficiency gain of 0.4%. Regarding emissions, the addition of hydrogen to biogas contributes to an average reduction of 5% in carbon monoxide emissions compared to the standard dual-fuel operation. However, dual-fuel operation leads to higher unburned hydrocarbon emissions relative to neat diesel; hydrogen enrichment mitigates this drawback by reducing hydrocarbon emissions by 4.1%. Although NOx emissions increase by an average of 26.6% with hydrogen addition, dual-fuel strategies achieve NOx reductions of 11.5% (hydrogen-enriched mode) and 33.3% (pure biogas mode) relative to diesel-only operation. Furthermore, the application of response surface methodology is robust and reliable, with experimental validation showing errors of 0.55–8.66% and an overall uncertainty of 4.84%.