Elsevier

Energy

Volume 207, 15 September 2020, 118298
Energy

Combined influence of supercharging, EGR, biodiesel and ethanol on emissions of a diesel engine: Proposal of an optimization strategy

https://doi.org/10.1016/j.energy.2020.118298Get rights and content

Highlights

  • Taguchi method was applied to investigate factors affecting emissions.

  • The L16 orthogonal series was used in engine testing.

  • Direct injection diesel engine was used for the experiments.

  • Studies were done by Taguchi method, saving 70% in terms of time and cost.

Abstract

There are several abatement technologies used for emissions, especially NOx emissions, from Diesel engines. Exhaust Gas Recirculation (EGR) system and alternative blend fuels are leading among the common methods used. Although the EGR provides remarkable reduction in NOx emissions, has negative effects on other emissions and engine performance. Among the alternative fuels, biodiesel and ethanol are preferred for being renewable. Chemical properties make these fuels feasible to be used in diesel blends at various ratios. Utilizing these fuels with diesel fuel in blends on engines provide improvements in engine performance parameters and emissions characteristics. However, biodiesels with oxygen content increase NOx emissions in particular. Eventually, utilizing different methods together is beneficial to optimize for the most convenient utilization ratios and conditions regarding all the emissions from engine. In this study, utilizing supercharging, EGR, biodiesel at various ratios and introducing ethanol fumigation through intake manifold of a DI diesel, and the most convenient engine operation conditions and ratios of the factors are determined through optimization using Taguchi method regarding engine brake specific heat consumption and emissions. Experiments are conducted regarding to orthogonal series L16 (42 × 22) with the combinations of factor and levels. Effect degrees of factors are determined through variation analysis. As a conclusion, factors evaluated in combination under different engine operating conditions, and factors and levels minimizing brake specific heat consumption and emissions, NO, smoke, HC, CO and CO2, are stated.

Introduction

Global energy demand is supplied by fossil fuel resources, substantially. However, growth of world population at an increasing rate and increase in energy demand of the developing industries worldwide causes rapid depletion of resources. On the other hand, utilization of fossil fuels causes damage to the environment. Therefore, legislative regulations on emissions are changing continuously. In this situation, turning to renewable and sustainable energy resources is inevitable [1,2]. In this context, utilization of ethanol fuel, produced from vegetables or animals, stands out [3].

Biodiesel is one of the potential fuels to be used on diesel engines [1]. Utilization of biodiesels on diesel engines has become widespread [6], because vegetable oils are renewable, biologically degradable, free of toxic materials, and have low emission profile, except NOx [4,5]. In some countries, biodiesel addition into commercial diesel fuel is a legal obligation.

Ethanol is another alternative fuel used in diesel engines. Ethanol is a renewable fuel, produced by fermentation of carbohydrates using enzymes as catalysts. Corn, sugar cane, wheat, potato, rice, rye and various fruits can be used as carbohydrate sources [7]. Ethanol utilization reduces some emissions, since ethanol is free from sulfur and heavy metals, unlike diesel fuel, has a smaller molecular structure, and has oxygen content [[8], [9], [10], [11], [12]].

One of the worse problems is the negative effect of diesel engines on the environment with NOx emissions. NOx production takes place at high combustion chamber temperatures at the presence of oxygen [13]. NOx emissions can be reduced by Exhaust Gas Recirculation (EGR). By redirecting some exhaust gasses back into the cylinder, charge in the combustion chamber is diluted, and as a result, peak combustion temperatures, so the amount of NOx, are reduced [[14], [15], [16]]. But, increasing EGR ratio above a threshold worsens engine performance parameters, and so, the specific fuel consumption increases [17], [18], [19]. Therefore, to control performance and emissions, both, combined implementations can be effective and successive. Hereby, besides alternative fuel utilization, EGR and supercharging applications parameter optimization of the mentioned should be done, as a whole.

Efe et al. [22] investigated effects of using blends of biodiesel, from corn, sunflower, soybean, canola and hazelnut oils, and diesel fuel on Diesel engine, experimentally. Experiment resulted in 20% biodiesel fraction blend fuel giving the best engine performance and for hazelnut oil. Also, testing various oil biodiesel-diesel fuel blends, increase in specific fuel consumption in comparison to standard engine data is stated. Ayhan et al. [20] tested diesel and sunflower oil methyl ester blend fuel on a Diesel engine and studied engine brake power, specific fuel consumption and emissions. And, indicated, B20 blend giving the optimum results compared to standard engine data among B10, B20 and B50 blends. Also pointed, significant decrease in HC, CO and smoke emissions, but increase in NO emission. And added, increasing biodiesel fraction in blend fuel caused increase in specific fuel consumption compared to standard engine data. Karabas [21] experimentally investigated the effect of using tobacco seed oil biodiesel blend fuels, B10, B20 and B50, on a Diesel engine for engine performance and emission characteristics. And reported, higher specific fuel consumption and NOx emissions, and lower HC, CO and smoke emissions, in comparison to diesel fuel. Manigandan et al. [20] conducted experimental studies using blend fuel, consist of corn oil methyl ester, pentanol and titanium at various fractions, at various speeds and loads. Significant reductions in CO, HC and smoke emissions are reported for using blend fuel consist of 25% corn oil methyl ester, 50% diesel fuel, 20% pentanol and 5% titanium, namely M25D50P20T5, compared to diesel fuel.

Jamrozik [12] conducted experimental studies on a direct injection Diesel engine to investigate effects of using ethanol and diesel fuel blend fuels on performance and emissions. Alternating alcohol fractions in the blend between 0 and 40%, reported improvements in engine performance by using diesel ethanol blend fuels throughout the mentioned range, CO emissions were reduced by 38%, whereas THC and CO2 emissions remained virtually unchanged, but NOx emissions increased. Ghadikolaei et al. [23] analyzed comparatively performance and emissions on a Diesel engine using diesel-biodiesel-ethanol blend using fumigation. To compare different fuel modes, a blend with constant fractions by volume of 80% diesel, 5% biodiesel and 15% ethanol is used. To the test results, in fumigation mode, CO2, CO and HC emission increased, but NOx and NO emissions decreased. And, in general, smoke emission is determined to be increased in comparison to standard engine. Pradelle et al. [24] studied experimentally performance and combustion characteristics of a Diesel engine using diesel-biodiesel-ethanol blend fuels. In engine tests, blend fuels used are obtained by adding ethanol in fractions of 0% up to 20% into B15 fuel. The test results of the various blend fuels are presented in comparison to B7E0, consisting of 7% biodiesel, 0% ethanol and 93% diesel, blend fuel. A 2% increase in specific fuel consumption is reported corresponding to each 5% increase in ethanol fraction. It is suggested to be caused by the decrease in blend fuel volume and the decrease in heating value. Shamun [25], testing on a Diesel engine using ethanol in high amounts, 30% ethanol fraction, reported significant decrease in NOx emissions. And, added HC and CO emissions to be higher than diesel fuel for using ethanol at low loads.

In Exhaust Gas Recirculation (EGR) applied studies, worsening in engine performance and increase in HC, CO and smoke emission, but decrease in NOx emissions are observed [14,[26], [27], [28]]. He et al. [27] added alcohol at different fractions, 15% ethanol, 15% butanol and 40% butanol, into diesel fuel, and also applied EGR on a Diesel engine, and to investigate combustion properties and changes in emissions at high load conditions, experimentally. And concluded that, at moderate alcohol fraction and EGR ratios improvements in engine performance and emissions can be achieved, in common. Verma et al. [28], using dual fuel (diesel and biogas) on a Diesel engine at different EGR ratios and compression ratios studied engine performance and emissions experimentally. During testing, 5%, 10% and 15% EGR ratios are used. Inducing EGR into engine at low loads resulted in a slight increase in engine efficiency and decrease in NOx emissions. Also, at high loads and increasing EGR ratios decrease in engine efficiency is reported.

In this study, engine tests are designed as suggested in Taguchi method. In this method, instead of conducting all the test in the factorial combination, just a factorial combination of orthogonal series is determined for the optimal emission characteristics and tested [41]. Reviewing the literature within this context, Taguchi design of experiments method is chosen by many researchers [29,[33], [34], [35], [36], [37], [38], [39]] to reduce time and costs. In the literature [[29], [30], [31]] optimization of various engine input parameters to sustain the best engine emissions are performed by Taguchi method. Ansari et al. [32] investigated engine performance and emissions of a Diesel engine using various biodiesel blend fuels by Taguchi method. As a result, input parameters are optimized for the best engine performance and emissions. Wu et al. [33] studied combustion characteristics by Taguchi method on an EGR applied Diesel engine run on Liquefied Petroleum Gas (LPG) and diesel-biodiesel blend fuel and stated the optimum operating factors. Wu and Wu [34] investigated engine emissions and combustion properties on a single cylinder engine using diesel and biodiesel blends and induction of H2 at various fractions and EGR into inlet manifold at various fractions, and determined the best combinations of input parameters by Taguchi method. Also, time savings of 67% is pointed out during tests by using L9 orthogonal series of Taguchi method.

Reviewing the literature, the following information is concluded. Biodiesel utilization in engines improves engine performance parameters and emissions, but NOx, at different amounts, instead increases NOx emissions. And, ethanol decreases CO emissions, but increases NOx emissions, while do not effect HC and CO2 emissions. EGR decreases NOx emissions, significantly, but deteriorates rest of the engine parameters, particularly under high EGR rates. However, differences in test results are observed regarding differences in testing conditions in the studies. In the literature, in any study using different fuels and emission reductions techniques, comprehensively, like in this study is reported. In this study, factors are chosen considering improvements provided by different alternative fuels, supercharging and EGR. With EGR utilization, NO emission reduction is predicted. And with biodiesel, ethanol and supercharging utilization, improvements on deteriorated emissions remaining and specific fuel consumption are aimed. In comparison to standard engine data, reductions in all the emissions and specific fuel consumption are intended. For this reason, the effects of using alternative fuel blends and ethanol fumigation as alternative fuels and EGR at various rates and supercharging on specific fuel consumption and emissions for a diesel engine operating at various loads and engine speeds are investigated experimentally. Taguchi method is used for the design of experiments. The optimum factor levels of parameters are evaluated using the Signal/Noise (S/N) ratios suggested by Taguchi method. Variation analysis is used to evaluate the effect of different factor levels on specific fuel consumption and emissions characteristics.

Section snippets

Biodiesel production

The biodiesel fuel used in experiments was produced from corn oil by transesterification method in laboratory. Alcohol, and catalyst used in transesterification process were methyl alcohol and KOH (potassium hydroxide), respectively. At first, KOH catalyst was dissolved in alcohol. In the meanwhile, corn oil was placed in a mixing container and its temperature was brought to 60 °C, constant. Afterwards, alcohol and catalyst mixture was transferred into a closed reaction container. And, corn oil

Brake specific heat consumption

In Fig. 2, Changes in S/N values of factors and levels for brake specific heat consumption is presented. Optimum BSHC is obtained at 80% load, for B10 biodiesel blend fuel and E20 ethanol ratio, EGR0 (without EGR), at 1600 rpm and SC2.1 (supercharging at 2.1 bar). And, the best combination corresponds to A3-B2-C4-D1-E1-F2 (Load:80%-Biodiesel:10%-Ethanol:20%-EGR:0%-Speed:1600rpm-SC:2.1 bar).

Engine load increases with the fuel quantity delivered. Brake specific heat consumption is defined as

Conclusion

In this study, using Taguchi design of experiments method, changes in engine parameters, specific fuel consumption and emission characteristics at various biodiesel fractions, ethanol fractions, EGR ratios and charging pressure, are investigated for a Diesel engine running at various loads and speeds. In conclusion, as determined, engine load and engine speed at various biodiesel, ethanol, EGR and supercharging levels have influence on SFC and emission characteristics. Overall results are

Credit author statement

We would like to inform you that all authors have contributed to the preparation of the manuscript. The study was prepared with the contribution of all authors, both in the conduct of experimental studies and in the writing of the manuscript, literature research, drawing and interpretation of the figures, writing and editing.

Declaration of competing interest

The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.

References (54)

  • F. Pradelle et al.

    Performance and combustion characteristics of a compression ignition engine running on diesel-biodiesel ethanol (DBE) blends - potential as diesel fuel substitute on an euro III engine

    Renew Energy

    (2019)
  • T. He et al.

    The influence of alcohol additives and EGR on the combustion and emission characteristics of diesel engine under high-load condition

    Appl Therm Eng

    (2018)
  • S. Verma et al.

    The effects of compression ratio and EGR on the performance and emission characteristics of diesel-biogas dual fuel engine

    Appl Therm Eng

    (2019)
  • D.H. Lee et al.

    Development of a highly efficient low-emission diesel engine-powered co-generation system and its optimization using Taguchi method

    Appl Therm Eng

    (2013)
  • M.K. Balki et al.

    Optimization of the operating parameters based on Taguchi method in an SI engine used pure gasoline, ethanol and methanol

    Fuel

    (2016)
  • T. Ganapathy et al.

    Performance optimization of Jatropha biodiesel engine model using Taguchi approach

    Appl Energy

    (2009)
  • N.A. Ansari et al.

    Performance and emission analysis of a diesel engine implementing polanga biodiesel and optimization using Taguchi method

    Process Saf Environ Protect

    (2018)
  • Z.Y. Wu et al.

    Applying Taguchi method to combustion characteristics and optimal factors determination in diesel/biodiesel engines with port-injecting LPG

    Fuel

    (2014)
  • H. Wu et al.

    Using Taguchi Method on combustion performance of a diesel engine with diesel/biodiesel blend and port-inducting H2

    Appl Energy

    (2013)
  • P.K. Bose et al.

    Multi objective optimization of performance parameters of a single cylinder diesel engine running with hydrogen using a Taguchi-fuzzy based approach

    Energy

    (2013)
  • H.W. Wu et al.

    Combustion characteristics and optimal factors determination with Taguchi method for diesel engines port-injecting hydrogen

    Energy

    (2012)
  • P. Bhowmick et al.

    Effect of fuel injection strategies and EGR on biodiesel blend in a CRDI Engine

    Energy

    (2019)
  • M. Pan et al.

    Reduction in PM and NOX of a diesel engine integrated with n-octanol fuel addition and exhaust gas recirculation

    Energy

    (2019)
  • M. Tongroon et al.

    Combustion and emission characteristics investigation of diesel-ethanol biodiesel blended fuels in a compression-ignition engine and benefit analysis

    Fuel

    (2019)
  • A. Sharma et al.

    Effect of biogas on the performance and emissions of diesel engine fuelled with biodiesel-ethanol blends through response surface methodology approach

    Renew Energy

    (2019)
  • S.K. Kandasamy et al.

    Experimental investigations of ethanol blended biodiesel fuel on automotive diesel engine performance, emission and durability characteristics

    Renew Energy

    (2019)
  • S. Dong et al.

    Investigations on the effects of fuel stratification on auto-ignition and combustion process of an ethanol/diesel dual-fuel engine

    Appl Energy

    (2018)
  • Cited by (18)

    • Comprehensive optimization of a diesel-E85 engine over the full operating range using the Taguchi method in intelligent charge compression ignition (ICCI) mode

      2023, Fuel
      Citation Excerpt :

      Uslu et al. [19] studied the effect of operating parameters using the Taguchi method, and the results showed that the Taguchi method effectively reduced the experiment cost and supplied a reliable assessment of the factor importance. Ayhan et al. [20] researched multiple factors together using the Taguchi method, and the experiment cases were reduced from 1024 cases to 16 cases to obtain optimum levels of factors. Therefore, the Taguchi method offered the best design of the experiment to reduce the experiment cost, which also promoted the training of prediction models and shortened the computing time by reducing the simulation cases.

    • Research on diagnosis of pre-ignition of hydrogen engine based on SOM-MAS

      2022, International Journal of Hydrogen Energy
      Citation Excerpt :

      Numerous researchers have analyzed the backfire problem of hydrogen engines and proposed some solutions. For example, delayed hydrogen injection [15–18], increased compression ratio [19,20], use of water-cooled spark plugs [21], reduced piston-cylinder clearance volume [22], use of charge dilution, exhaust gas recirculation (EGR) [23,24] and water injection [25,26]. In addition, Liu et al. [27] analyzed the correlation between the concentration of residual hydrogen in the intake manifold and the possibility of backfire based on CFD simulation.

    • Application of methanol and optimization of mixture design over the full operating map in an intelligent charge compression ignition (ICCI) engine

      2022, Fuel Processing Technology
      Citation Excerpt :

      EGR rate became more important when operating the ICCI combustion under over 9 bar IMEP, as in Fig. 6(c). The purpose of using EGR in ICCI mode was to delay the combustion phase not too early, though this might deteriorate the CO emission [36]. The maximum EGR rate had over 50% to reach 15 bar IMEP despite the inevitable sacrifice of the thermal efficiency.

    View all citing articles on Scopus
    View full text