High efficiency ethanol-diesel dual-fuel combustion: A comparison against conventional diesel combustion from low to full engine load. (15th October 2018)

• Record Type: Journal Article
• Authors: Pedrozo, Vinícius B.; May, Ian; Guan, Wei; Zhao, Hua
• Is Part Of: Fuel. Volume 230(2018)
• Page Start: 440
• Page End: 451
• Publication Date: 2018-10-15
• Subjects: ATDC after firing top dead centre -- CA10 crank angle of 10% cumulative heat release -- CA10–CA90 combustion duration or 10–90% cumulative heat release -- CA50 crank angle of 50% cumulative heat release -- CA90 crank angle of 90% cumulative heat release -- CAD crank angle degree -- CDC conventional diesel combustion -- CH4 methane -- CO carbon monoxide -- CO2 carbon dioxide -- CO2eq CO2 equivalent -- COV_IMEP coefficient of variation of IMEP -- COV_Pmax coefficient of variation of Pmax -- DAQ data acquisition -- ECR effective compression ratio -- ECU engine control unit -- EF ethanol energy fraction -- EGR exhaust gas recirculation -- EGT exhaust gas temperature -- FID flame ionisation detector -- FSN filter smoke number -- GHG greenhouse gas -- GWP global warming potential -- HC hydrocarbons -- HD heavy-duty -- HRR apparent net heat release rate -- iEGR internal EGR -- iLUC indirect land use change -- IMEP net indicated mean effective pressure -- ISCO net indicated specific emissions of CO -- ISCO2 net indicated specific emissions of CO2 -- ISHC net indicated specific emissions of actual unburnt HC -- ISNOx net indicated specific emissions of NOx;LHVdiesel, lower heating value of diesel -- LHVethanol, lower heating value of ethanol -- LHVfuel, lower heating value -- ṁair fresh air mass flow rate -- ṁdiesel diesel mass flow rate -- ṁethanol ethanol mass flow rate -- ṁurea estimated consumption of aqueous urea solution in the SCR system -- MCO2 normalised molar mass of CO2 -- Mdiesel normalised molar mass of diesel;Methanol, normalised molar mass of ethanol -- Mfuel normalised molar mass -- MFB mass fraction burnt -- N2O nitrous oxide -- NetIndicatedEff.SCRcorr. SCR corrected net indicated efficiency -- NOx nitrogen oxides -- O2 Oxygen -- Pind net indicated power -- PFI port fuel injector -- Pmax peak in-cylinder gas pressure -- PRR pressure rise rate -- RON research octane number -- SCR selective catalyst reduction -- SOC start of combustion -- SOI_main actual start of main diesel injection -- SOI_mai–SOC ignition delay -- SOI_pre actual start of diesel pre-injection -- TDC firing top dead centre -- TTW tank-to-wheels -- VVA variable valve actuation -- WTT well-to-tank -- WTTdiesel WTT CO2eq emissions for fossil diesel -- WTTethanol WTT CO2eq emissions for ethanol -- WTW well-to-wheels -- %Cfuel carbon mass content -- %Hfuel hydrogen mass content -- %Ofuel carbon mass content -- γ ratio of specific heats -- ρfuel density -- ρdiesel diesel density -- ρethanol ethanol density -- Φ global fuel/air equivalence ratio; Ethanol -- Low carbon fuel -- Dual-fuel combustion -- Diesel engine -- Greenhouse gas emissions; Fuel -- Periodicals; Coal -- Periodicals; Coal; Fuel; Periodicals; 662.6
• DOI: 10.1016/j.fuel.2018.05.034
• Languages: English
• ISSNs: 0016-2361

Abstract

Highlights: High efficiency dual-fuel combustion was demonstrated between 0.3 and 2.4 MPa IMEP. Up to 4.4% higher net indicated efficiency than conventional diesel combustion. Up to 90% lower nitrogen oxides emissions using identical engine testing conditions. The use of ethanol as a substitute for diesel can reduce CO2eq emissions by up to 57%. Dual-fuel operation with sugarcane ethanol achieved the lowest WTW CO2eq emissions. Abstract: Comparisons between dual-fuel combustion and conventional diesel combustion (CDC) are often performed using different engine hardware setups, exhaust gas recirculation rates, as well as intake and exhaust manifold pressures. These modifications are usually made in order to curb in-cylinder pressure rise rates and meet exhaust emissions targets during the dual-fuel operation. To ensure a fair comparison, an experimental investigation into dual-fuel combustion has been carried out from low to full engine load with the same engine hardware and identical operating conditions to those of the CDC baseline. The experiments were executed on a single cylinder heavy-duty diesel engine at a constant speed of 1200 rpm and various steady-state loads between 0.3 and 2.4 MPa net indicated mean effective pressure (IMEP). Ethanol was port fuel injected while diesel was direct injected using a high pressure common rail injection system. The start of diesel injection was optimised for the maximum net indicated efficiency in both combustion modes. Varied ethanol energy fractions and different diesel injection strategies were required to control the in-cylinder pressure rise rate and achieve highly efficient and clean dual-fuel operation. In terms of performance, dual-fuel combustion attained higher net indicated efficiency than the CDC mode from 0.6 to 2.4 MPa IMEP, with a maximum value of 47.2% at 1.2 MPa IMEP. The comparison also shows the use of ethanol resulted in 26% to 90% lower nitrogen oxides (NOx) emissions than the CDC operation. At the lowest engine load of 0.3 MPa IMEP, the dual-fuel operation led to simultaneous low NOx and soot emissions at the expense of a relatively low net indicated efficiency of 38.9%. In particular, the reduction in NOx emissions introduced by the utilisation of ethanol has the potential to decrease the engine running costs via lower consumption of aqueous urea solution in the selective catalyst reduction system. Moreover, the dual-fuel combustion with a low carbon fuel such as ethanol is an effective means of decreasing the use of fossil fuel and associated greenhouse gas emissions.