Optimization of reactivity-controlled compression ignition combustion fueled with diesel and hydrous ethanol using response surface methodology. (15th November 2015)

• Record Type: Journal Article
• Authors: Fang, Wei; Kittelson, David B.; Northrop, William F.
• Is Part Of: Fuel. Volume 160(2015)
• Page Start: 446
• Page End: 457
• Publication Date: 2015-11-15
• Subjects: ANOVA analysis of variance -- ATDC after top dead center -- CA° crank angle degree -- CA5 crank angle location of 5% gross heat release -- CA50 crank angle location of 50% gross heat release -- CA95 crank angle location of 95% gross heat release -- CCD central composite design -- DoE design of experiments -- Dwell time interval between two diesel injections -- EGR exhaust gas recirculation -- FEF fumigant energy fraction -- FTIR Fourier Transform Infrared -- IMEP indicated mean effective pressure -- Inj1Fr fraction of first diesel injection -- HC hydrocarbon -- HCCI homogeneous charge compression ignition -- LTC low temperature combustion -- PFI port fuel injection -- Pint intake air pressure -- Prail diesel fuel rail pressure -- RCCI reactivity-controlled compression ignition -- RoHR rate of heat release -- RoPR rate of pressure rise -- RSM response surface method -- SOIC2 start of injection command for the 2nd injection -- TDC top dead center -- Tint intake air temperature -- TWI two-way interaction -- ULSD ultra-low sulfur diesel -- γ ratio of specific heats -- ηcomb combustion efficiency -- ηi indicated thermal efficiency; Hydrous ethanol -- Reactivity-controlled compression ignition -- Response surface methodology; Fuel -- Periodicals; Coal -- Periodicals; Coal; Fuel; Periodicals; 662.6
• DOI: 10.1016/j.fuel.2015.07.055
• Languages: English
• ISSNs: 0016-2361

Abstract

Highlights: 80% of total fuel energy can be replaced with hydrous ethanol in a RCCI engine. Engine emissions from RCCI combustion can be significantly reduced using RSM. RSM can be used to elucidate effects of engine parameters on dual-fuel combustion. Abstract: Anhydrous ethanol has been widely investigated as an alternative fuel for internal combustion engines. The use of high water content hydrous ethanol in engines has the potential to significantly improve life-cycle energy use and CO2 emissions of bio-ethanol. Our previous work showed that dual-fuel reactivity-controlled compression ignition (RCCI) combustion is a promising combustion strategy replacing up to 80% of the total fuel energy with hydrous ethanol yielding simultaneously high thermal efficiency and low engine-out NO X and soot emissions. In this work, we use response surface methodology (RSM) to experimentally optimize several key engine engine-out emissions parameters at high and low engine load with data from a single-cylinder research engine. Efficient experimental designs were developed that allowed identification of statistically significant operating parameters for optimizing emissions. Following the optimization path generated by the RSM, NO X and soot emissions were reduced by 79% and 50% at the low load condition, and by 72% and 27% at the high load condition, compared to the starting points. Indicated thermal efficiency was compromised along the optimization path due to delayed combustion phasing for both load conditions. The study also shows that different operating parameters are significant for RCCI emissions at different engine loads. A trade-off between HC and CO emissions was observed at the lower load condition, while HC and CO were both lower after the optimization process at the higher load condition. Overall, this work shows that RSM can be effectively used to elucidate interactions among multiple engine operating parameters with reduced experimentation to optimize complex dual-fuel RCCI combustion modes.