Performance-emission Trade-off Research Articles

Study on performance-emission trade-off and multi-objective optimization of diesel-ethanol-palm biodiesel in a single cylinder CI engine: a Taguchi-fuzzy approach

ABSTRACT World energy insecurity and other issues like rapid industrialization, stringent emissions, and global warming have inspired researchers to explore the benefits of alternative fuel research for the replacement of fossil fuel. Promulgation of different advantages in non-fossil fuel helps the researcher to step forward for alternative fuel research. In the present experiment, investigation of performance and emission characteristics of different diesel, ethanol, and palm oil biodiesel blend have been studied in a signal cylinder, four-stroke direct injection CI (compression ignition) engine. The experimental results indicate almost the similar performance and emission characteristics for all test fuels. Almost equal nitrogen oxides (NOx) emission and lower brake specific energy consumption (BSEC) with some penalty of increased unburnt hydrocarbon (UHC) emission have been observed for all blends. Finally, a fuzzy-based Taguchi method has been chosen for the selection of appropriate engine operating range (load) and fuel blend for optimum performance and emission characteristics. Based on the highest MPCI value (0.676), 20% load and B4 (D75B20E5) have been found as the optimum operating range and fuel blend, respectively, for the maximum reduction of BSEC, NOx, and UHC emissions compared to other blends.

An Investigation of Diesohol-Biodiesel Mixture in Performance-Emission Characteristics of a Single Cylinder Diesel Engine: A Trade-Off Benchmark

The issue of environmental pollution and the depletion of fossil fuel are nowadays a major field of attention for the modern world. In substitution of petroleum-based diesel, biodiesel and ethanol have been explored in many studies. In this paper, diesel-palm biodiesel-ethanol has been used together at different proportion to execute performanceemission characteristics and their trade-off study at different brake power. An experimental investigation is carried out for different diesel-palm biodiesel-ethanol blends ranging by volume of 5-10% ethanol, 5-25% biodiesel and 65-90% baseline diesel. From the experimental results, comparatively, low brake specific fuel consumption (BSEC) has been observed for all 5% ethanol-blended fuels. Maximum reduction in BSEC has been observed 1.9, 2, and 3.24 % at 0.68, 2.05, and 3.42 kW respectively. At medium to high load, brake thermal efficiency (BTE) has been found higher for lower ethanol fraction. As compared to diesel, the highest nitrogen oxide (NOx) reduction have been found 13.7, 9.17, and 4.7 % at 0.68, 2.05, and 3.42 kW respectively. At last, performance-emission trade-off shows that D70B25E5 blend has a higher BTE with maximum reduction in unburnt hydrocarbon (UHC) and NOx emissions.

Multi-objective optimization of the performance-emission trade-off characteristics of a CRDI coupled CNG diesel dual-fuel operation: A GEP meta-model assisted MOGA endeavour

A meta-model based multi-objective optimization endeavor was undertaken in the present work to investigate the potential of the off-line model based calibration technique to extend the actual CRDI-CNG dual-fuel experimental investigations in determining the possibility of unearthing viable potential trade-off domains hitherto unexplored by the constraints of resources, cost and time warranted by an experimental investigation. For the ensuing optimization study, CNG energy share, fuel injection pressure and load have been used as the decision variables while PM, NHC and BSFC were chosen as the output variables to be optimized. In absence of a closed form correlation between the participating variables under study, the explicit characterization capability of the Gene Expression Programming technique was harnessed. The appropriate GEP based meta-models were adopted from a previous study correlating the identical system output responses for the same set of decision variables of interest in the present study. Genetic algorithm was chosen as the optimization routine in the present study in view of its promising potential of extremely fast convergent speed, diversity of optimal solutions and simplicity of operation. Experimental validation of the obtained solutions pertaining to the desired objectives were carried out by actual experimentation. The present optimization endeavor was able to better the best vantage in category of the desired objective of minimum fuel consumption and exhaust emissions, obtained not only as compared to baseline diesel operation comprehensively but also was superior than the actual CRDI-CNG strategy during actual dual-fuel operation corresponding to actual experimentation.

Exploration of PROMETHEE II and VIKOR methodology in a MCDM approach for ascertaining the optimal performance-emission trade-off vantage in a hydrogen-biohol dual fuel endeavour

In order to meet the challenges of global energy insecurity and the increasing obligation of complying with the environmental legislation, a paradigm shift from the reliance of conventional fossil fuel resources in IC engine domains are being increasingly witnessed. Exhaustive research has been carried out with non-conventional and alternative fuels resources in the off-road and transportation sector to meet the challenges of exploring a potential alternative to conventional diesel fuel with the additional objective of meeting the ever increasing stridency of the emission mandates. Among various alternative fuels, hydrogen whose clean and green burning characteristics has proven to be viable, sustainable fuels in IC engine domains with the premium quoting as one of the significant low emission signature than conventional fuels. Biodiesel, on the other hand, presents itself as a ready-to-use sustainable alternative in diesel powertrains in the environment of its National agricultural and rural economic development potential. As hydrogen is deemed to increase NOx emission when it is used with biodiesel, ethanol (20% v/v) blend with biodiesel has been used as a viable NOx suppression measure owing to its superior miscibility in methyl ester in comparison to conventional diesel. To this end, single cylinder diesel engine has been made to operate in a dual fuel mode with hydrogen as the dual fuel and mahua methyl ester with ethanol in blend as pilot fuel. The present aims of the study are to choose the best suitable fuel combination among the alternatives, in relation to various attributes chosen especially with an eye to address the performance-emission trade-off potential of the dual fuel operation. The most appropriate duel fuel combination out of ten alternatives has been discerned through distinct multi-criteria decision making (MCDM) methodologies.Analytic Hierarchy Process (AHP) has been applied for finding the weightage of each criterion and ranks of the alternatives investigated have been calculated by using VIKOR and PROMETHEE II methods.The alternative which signified biodiesel under hydrogen enrichment, at hydrogen injection duration of 9000µs at a constant engine speed of 1500RPM, was discerned as the the most appropriate alternative fuel combination at 75% load since it has been ranked first by both the MCDM methods. At full load for PROMETHEE II it was alternative A4, and for VIKOR it was observed as alternative A3 which signified biodiesel under hydrogen enrichment at hydrogen injection duration of 7000µs at 1500RPM. Alternatively, A10 strategy which indicate biodiesel ethanol blend along with hydrogen enrichment at hydrogen injection duration of 13,000µs at 1500RPM was observed to be the least preferential amongst the alternative for both the MCDM methods, at both 75% and 100% loads. Since there was consistency in the ranking, in order to judge the performance of both the methods Spearman’s Rank Correlation Coefficient was calculated and was observed to be within acceptable levels lending an index of robustness of the optimal choices of the strategies advocated by the MCDM methodologies adopted in the present case study.

Experimental study on the role of ethanol on performance emission trade-off and tribological characteristics of a CI engine

An experimental study of engine combustion, performance and emission characteristics using diesel–ethanol blends along with investigation of tribological effects of ethanol on engine oil was done in present work using 1-butanol as emulsifier. Thorough observations of diesel–ethanol miscibility resulted that 25% v/v ethanol is miscible with diesel using only 3% v/v emulsifier. Tribological effects of ethanol on engine oil were investigated by analyzing the engine oil samples through FT-IR (Fourier Transform Infrared Spectroscopy). Overall experimentation re-evaluated the potential of ethanol in reduction of NOx, Soot and in-cylinder temperature with slight penalty for HC, CO and BSEC prominently at low load. All fuels produced more NO but lesser NO2 at higher load satisfying Zeldovich mechanism. A comparative trade-off analysis was done in between NHC, Soot and BSEC to reflect the performance and emission characteristics at a time. Trade-off study revealed D78E20B02 (78% diesel 20% ethanol 2% butanol) as optimal blend among all fuels used in present work. FT-IR analysis depicted negligible variation in the compounds in engine oil samples for the specified operational period. Statistical analysis showed larger Coefficient of variation for D78E20B02 blend due to higher absorbance of a particular compound.

An experimental investigation of performance-emission trade off characteristics of a CI engine using hydrogen as dual fuel

The investigation carried out in this research work concerns the effect of the addition of H2 on performance and emission characteristics of a single cylinder, 4-stroke diesel engine. The tests were performed using diesel as a pilot fuel, with hydrogen addition at varying load condition using a Timed Manifold Injection (TMI) system has been developed using ECU (electronic control unit) with varying injection strategy to deliver hydrogen on to the intake manifold. The results showed a significant increase in BTE with appreciable decrease in BSEC of the engine when compared to conventional diesel-fueled operation. The emission of CO2 and NOx was found to increase with enhancement of H2 addition. The emission of UHC was found to be very high at low load conditions, but it enhanced as the load increased for all hydrogen injection while Soot emissions decreased. Thus, this paper provided a potential to investigate the effect of the addition of H2 on the performance and emission characteristics of a diesel engine and how to get a best ratio of H2 addition. The tradeoff study also consolidated the verity that Diesel–H2 dual fuel operation was instrumental in resolving the high performance – low emission paradox.

Effect of Diesel–Ethanol–PPME (Pongamia piñata Methyl Ester) Blends as Pilot Fuel on CNG Dual-Fuel Operation of a CI Engine: A Performance-Emission Trade-Off Study

The major portion of today’s natural gas dual-fuel engines use pilot amounts of diesel as the igniter fuel. However, it is found that dual-fuel operation of natural gas with pilot diesel poses problems, such as reduced brake thermal efficiency and increased hydrocarbon emission. The present experimental work explores the potential of compressed natural gas (CNG) under dual-fuel operation by utilizing two blends of diesel–ethanol–Pongamia piñata methyl ester (PPME) as pilot fuel. The blends, namely, D45E15B40 (45% diesel, 15% ethanol, 40% PPME) and D30E20B50 (30% diesel, 20% ethanol, 50% PPME) are selected on the basis of biodiesel-assisted miscibility of ethanol in diesel. It is found from the study that the pilot operation of D45E15B40 blend increases the brake thermal efficiency by 43.5% and 26.4% at 80% and 100% load conditions with CNG injection for 23 000 μs, whereas D30E20B50 produces an increase of 51.7% and 46.5% under the same conditions in comparison with pilot diesel operation. The NOx emission from the engine is also decreased by 37.3% and 21.6% at 80% and 100% load conditions by D45E15B40 and 33.9% and 15.9% by D30E20B50 blend, as compared to pilot diesel operation. The trade-off study in the present work reveals encouraging aspects of D45E15B40 and D30E20B50 blends as it is found that pilot operation with these blends can stretch the usability range of CNG injection duration to 9000 μs.

ANN metamodel assisted Particle Swarm Optimization of the performance-emission trade-off characteristics of a single cylinder CRDI engine under CNG dual-fuel operation

The encouraging potential of a CRDI coupled CNG application in providing superior PM–NOx–BSFC trade-off footprint as compared to the BDO of a single cylinder diesel engine, provided a strong motivation to undertake an in-depth exploration of the parametric design space to investigate the possibility of obtaining superior emission-performance trade-off characteristics as compared to the experimental endeavour. To obviate the infeasibility of a full factorial based experimental approach to the intended exploration, an offline metamodel assisted optimization study within the same experimental range of the input/control variables was considered as a viable strategy. FIP, CES and engine load were chosen as the control variables for the optimization study. An Adaptive Merit Function (AMF) was constituted as the objective function to be optimized encapsulating the simultaneous necessity to meet the EPA Tier 4 PM–NHC emission mandates and lower BSFC expectations of the consumer. An ANN based metamodel was developed to correlate the objective function with the chosen control variables while Latin-Hypercube was chosen as the DoE scheduler to provide the initial population sample for the optimization iteration sequence. PSO was chosen as the optimization algorithm due to its inherent simplicity and efficiency in yielding an ensured convergence of the objective function at significantly less computational cost. Validation of the obtained optimal solutions at the experimental load steps of 25%, 50%, 75% and full load yielded 9.9%,16.4%, 10.5%, 2.7% higher AMF than that yielded by the best CRDI–CNG operation at the corresponding load steps respectively during actual experimentation. The inherent design of the AMF objective function ensured that all such optimal trade-off values simultaneously honoured the expectations of the EPA Tier 4 PM and NHC mandates.

An experimental investigation of performance-emission trade off of a CI engine fueled by diesel–compressed natural gas (CNG) combination and diesel–ethanol blends with CNG enrichment

In order to comply with the ever-stringent emission norms throughout the world and crunch in petroleum reserves, the modern day automobile industry is compelled to hunt for new and alternative means of fuel sources to keep the wheels spinning globally. Paradoxical objectives of attaining simultaneous reduction in emission along with high performance has provided with a few alternatives. The present study deals with one such approach in which the potential of diesel ethanol blending and subsequent CNG (compressed natural gas) enrichment have been investigated. The study starts with a miscibility test of ethanol in diesel, which paves the way for an experimental comparison between performance and emission characteristics of Diesel–Ethanol blends, Diesel–CNG combinations and Diesel–Ethanol blends with CNG enrichment. The results indicates that diesel ethanol blend D95E5 (95% diesel 5% ethanol) with low CNG enrichment produces a better performance-emission characteristics as compared to base diesel operation as well as diesel–ethanol blend operation. Results also portrayed ethanol's potential in reducing NOx emission, BSEC and smoke opacity.