Experimental Optimization of Engine Operating Parameters for Low Emissions in Diesel Engine in PCCI-DI Combustion Mode

Abstract

Researches Worldwide Are Nowadays Focusing On Finding Out More Energy Efficient And Ultra-Low Emission Engines For Automotive Applications Which Could Bridge The Gap Be Tween Conventional And Electric Vehicles. The Desire To Reduce Exhaust Emissions Particu Larly Nox (Oxides Of Nitrogen) And Pm (Particulate Matter) By Many Researchers Had Shown Promising Results Through Low Temperature Combustion (Ltc) Approaches. ThisEmerging Advanced Combustion Concept In Premixed Charge Compression Ignition (Pcci) Mode Attracted Global Attention In Maximizing Engine Efficiency And Meeting Stringent Emission Norms Compared To The Conventional. Even Though Ltc Combustion Mode Results In Prominent Advantages In Terms Of Simultaneous Reduction Of Both NoxAnd Pm In Addition To Lower Specific Fuel Consumption, It Basically Suffers From The Prob Lem Of Hc (Hydrocarbon) And Co (Carbon Monoxide) Emissions Which Make The Concept That Has Yet To Find Commercial Success. This Study Conducted Experimental Investigations For The Objective Of Finding Optimized Operating Parameters; Injection Timing, % Of Exhaust Gas Recirculation (Egr), Dieseline Ratios And Engine Load For Lower Emissions In Ltc En Gine Operating In Pcci-Di (Premixed Charge Compression Ignition-Direct Injection) Combustion Mode. The Engine Set Up Uses Dieseline Direct Injection And Methanol Port In Jection. Methanol Having High Oxygen Content And High Volatility Component Was InjectedThrough Air-Blast Port Injection Using A Workshop Air Compressor Into The Intake ManifoldWith 12cm Pfi Positions To The Intake Valves To Form A Premixed Homogeneous Mixture.For The Study A Single-Cylinder Diesel Engine Was Adapted To Pcci-Di Combustion Mode Of Operation. Emission Results Were Measured, Optimized And Analyzed. This Study Con Firmed Dieseline Direct Injection With Methanol Port Injection Is Capable Of Reducing Emis Sions And Better Nox With Hc And Co Trade-Offs Which Minimized The Drawbacks Of Pcci Combustion That Could Enable The Commercialization Of Advanced Combustion Ltc En Gines. Algorithm Applying A Hybrid Of Grey Relational Ana1ysis Together With Taguchi Method Is Used In Obtaining Optimized Results. For The Design Of Experiments And Conduct Ing Tests Taguchi?�?S L9 Orthogona1 Array Was Applied. The Taguchi?�?S S/N Ratio Which Was Found Using The Emission Results Was Used To Obtain Grey Relational Grade. 3d Surface And Contour Plots For The Control Factors Versus Emissions Were Developed And Discussed. Op Timum Combination Of The Control Operating Parameters Was Found Using The Analysis Of Grey Relation And Analysis Of Variance (Anova).Following The Multi-Response Optimiza Tion; Advanced Injection Of 25oBtdc, 25% Egr, Dieseline 90:10 In % And Load 75 % (A2b1c3d3) Is Optimal Combination Resulting Reduction Of 68.02% Nox And 62.37% In Smoke Comparing With Baseline. In Addition, In This Experimental Setup The Impact Of Dif Ferent Egr Configurations (No Egr, Cold Egr And Hot Egr) On Exhaust Emissions Of Pcci-Di Engine Were Studied. Results Showed That Both Cold And Hot Egr ConfigurationsResulted In Lower Emission Of Nox Plus Smoke At Different Loads. At Low Loads Hot Egr Showed Promising Results Of Lower Hc And Co Than Cold Egr With A Difference Of 18.33% And 33.3% Respectively. Nox And Smoke Reductions Occur Simultaneously And Better Trade-Offs Were Obtained Using Cold Egr Configuration. Further Investigation Par Ticularly On Applying Port Injection Of Alcohol Together With Better Egr Configuration On Pcci-Di (Ltc Engines) Should Be Studied In Better Equipped Laboratory Setups In Order ToMinimize The Drawbacks Of Ltc Engine For Its Commercialization.