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In this study, biogas was generated by anaerobic co-digestion process of pig manure and corn straw. The biogas was used as an alternative gaseous fuel in a DI (direct injection) turbocharged diesel engine, in the dual fuel mode with diesel as pilot fuel. Three compositions of biogas generated from pig manure and corn straw: 45BG55CO2, 50BG50CO2 and 60BGCO2 (containing 45%, 50% and 60% of methane (CH4) by volume respectively) and two compositions of enriched biogas: 75BG25CO2 and 85BG15CO2 (containing 75% and 85% of CH4 by volume) were used. The effects of carbon dioxide (CO2) ratio in biogas on combustion, performance and emission characteristics of the engine in the dual fuel operation were numerically analyzed at four various engine loads (0.425, 0.85, 1.275 and 1.7MPa), and compared with that of diesel fuel operation. The numerical simulations were carried out using GT-Power commercial package. The results showed that the BTE values for biogas-diesel fuel operations were found to be higher compared to that of diesel fuel operation. The BTE was not considerably impacted by CO2 ratio. The highest BTE value of 38.22% was recorded for 45BG55CO2 (45% methane and 55% CO2). The exhaust gas temperatures (EGT) of the biogas-diesel fuels were found to be 8.5-20.3% lower than that of the diesel fuel operation at higher load condition. With respect to emissions, The NOX (Nitrogen oxides) and carbon monoxide (CO) emissions in the dual fuel operation were found to be lower by about 55.3-83.3% and 73.1-97.4%, compared to that of diesel operation. However, the unburned hydrocarbons (HC) and carbon dioxide (CO2) discharges of dual-fuel operation were found to be higher by average of 349.7% and 39.8% respectively. The utilization of biogas with diesel by all accounts is attractive to cut down discharges and improve performance of the engine. The engine performance did not deteriorate with up to 45% CO2 content biogas. [ABSTRACT FROM AUTHOR]

In recent years, due to stringent emission regulations vehicle manufacturers have been compelled to cut down noxious pollutants released from diesel engines. Different alternative solutions have been recommended to achieve this challenging task. One of these alternative solutions is the utilization of biogas in addition to the use of liquid diesel. In this regard, the current study investigates the combustion characteristics and exhaust emissions of a turbocharged, direct injection, diesel engine operating at constant speed (1800 rpm) and under dual fuel mode with diesel as the pilot fuel and biogas (generated from pig manure and corn straw) and methane enriched biogas. Simulations were carried out at four various engine loads corresponding to brake mean effective pressure (BMEP) of 0.425, 0.85, 1.275, and 1.7 MPa using GT-Power package. The BTE values of biogas-diesel were higher as compared to diesel fuel. The CO2 ratio of biogas did not impact BTE considerably. The highest BTE value of 38.22% was recorded for BG45. However, the Brake specific fuel consumption (BSFC) values for the biogas-diesel fuels were higher than that of diesel fuel operations. With respect to emissions, compared to diesel fuel operation, the hydrocarbon (HC) and CO2 of the biogas-diesel were higher, but NOx and CO pollutants were much lower. The utilization of biogas with diesel by all accounts is attractive to cut down discharges and improve performance of the engine. The engine performance did not deteriorate with up to 45% CO2 proportion in biogas. [ABSTRACT FROM AUTHOR]

The available energy can be effectively upgraded by adopting smart energy conversion measures. The biodegradability of biomass can be improved by employing pretreatment techniques; however, such methods result in reduced energy efficiency. In this study, microwave (MW) irradiation is used for green algae (Enteromorpha) pretreatment in combination with iron oxide nanoparticles (NPs) which act as a heterogeneous catalyst during anaerobic digestion process for biogas enhancement. Batch-wise anaerobic digestion was carried out. The results showed that MW pretreatment and its combination with Fe3O4 NPs produced highest yields of biogas and hydrogen as compared to the individual ones and control. The biogas amount and hydrogen % v/v achieved by MW pretreatment + Fe3O4 NPs group were 328 mL and 51.5%, respectively. The energy analysis indicated that synergistic application of MW pretreatment with Fe3O4 NPs produced added energy while consuming less input energy than MW pretreatment alone. The kinetic parameters of the reaction were scientifically evaluated by using modified Gompertz and Logistic function model for each experimental case. MW pretreatment + Fe3O4 NPs group improved biogas production potential and maximum biogas production rate. [ABSTRACT FROM AUTHOR]