Influence of fuel properties and composition on NOx emissions from biodiesel powered diesel engines: A review

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Abstract

Biodiesel has proved to be an environment friendly alternative fuel for diesel engine because it can alleviate regulated and unregulated exhaust emissions. However, most researchers have observed a significant increase in NOx emissions with biodiesel when compared to petrodiesel. The exact cause of this increase is still unclear; however, researchers believe that the fuel properties have been shown to effect the emissions of NOx. The present work reviews the effect of fuel properties and composition on NOx emissions from biodiesel fuelled engines. The paper is organised in three sections. The first section deals with the NOx formation mechanisms. In the following section, the reasons for increased NOx emissions of biodiesel fuel are discussed. After this, the influence of composition and fuel properties on NOx emissions from biodiesel fuelled engines has been reviewed. Finally, some general conclusions concerning this problem are summarised and further researches are pointed out.

Introduction

The most important aspect of air quality management is to control the harmful emissions from internal combustion engines. In order to improve the air quality, stringent emission norms were introduced worldwide. The limit values were lowered many times over the last decades and will be set to further lower values for the coming years. Burning biodiesel in diesel engine produces a significant reduction in emissions of particulate matter, HC and CO but in most cases also causes an increase in NOx emissions (about 10–23%) when compared to diesel fuel [1], [2], [3], [4]. This increase in NOx emissions is termed as biodiesel NOx effect. It has been a long-standing issue and yet to be satisfactorily resolved. The US Environmental Protection Agency (EPA) enlisted NOx as one of the criteria pollutants that can affect the respiratory system. The biodiesel market in the U.S alone is expected to reach 4000 million gallons in 2030 [5]. As the use of biodiesel has increased enormously, the rise in NOx emissions could become a significant barrier to market expansion. Van Gerpen et al. [6] suggested that the reason for the higher NOx emissions is mainly due to changes in the chemical composition and the physical properties of the fuel. Therefore it is necessary to understand the effect of fuel properties on biodiesel NOx emissions and to develop improved techniques for NOx abatement. The objective of this paper is to provide a complete literature review on the influence of fuel composition and properties on the NOx emissions when fuelling with biodiesel.

Section snippets

NOx formation mechanisms

NOx is a mixture of gases which consists of nitric oxide (NO), dinitrogen dioxide (N2O2), nitrous oxide (N2O), dinitrogen trioxide (N2O3), nitrogen dioxide (NO2), dinitrogen tetroxide (N2O4) and dinitrogen pentoxide (N2O5). In most high-temperature combustion processes, the majority (95%) of NOx produced is in the form of nitric oxide (NO) [7]. Understanding NO production in diesel engine combustion requires a comprehensive analysis of NOx formation mechanisms. This section deals with the

Causes of biodiesel NOx effect

There are many factors that have an impact on NOx formation from diesel engine. NOx formation is primarily a function of pressure, reaction temperature, residence time of combustion products, premixed portion of combustion, availability of excess oxygen, ignition delay period, heat removal rate and the operational parameters of the engine [14]. An overwhelming number of studies have shown that high isentropic bulk modulus of biodiesel causes an artificial advance in injection timing relative to

Effect of fuel properties on biodiesel NOx emissions

There is widespread agreement that no single factor is responsible for biodiesel NOx effect. The physical and chemical properties of biodiesel may influence combustion temperature, residence time and injection pattern and thus NOx emissions. The fuel properties such as bulk modulus, fuel bound oxygen, degree of saturation, cetane number, viscosity, density, surface tension, thermal conductivity, heat capacity, vapour diffusion coefficient all have significant impact on the engine performance

Summary and conclusions

A systematic review of the published literature on the effect of fuel properties and composition that influence biodiesel NOx emissions has been carried out and main findings are summarised.

  • 1.

    The majority of studies have shown that NOx emissions for biodiesel are significantly increased, compared with diesel.

  • 2.

    In general, thermal NO is a dominant mechanism in the combustion processes; however, prompt NO also contributes significantly in biodiesel combustion.

  • 3.

    Several factors are reported to

Acknowledgements

We wish to thank the management of Velammal Engineering College, Chennai, for encouraging and supporting this research work. We also would like to thank D.S. Pushparani, Department of Biochemistry, SRM University for providing valuable information related to this work.

References (126)

  • A. Agarwal et al.

    Particulate emissions from biodiesel vs. diesel fuelled compression ignition engine

    Renew Sustain Energy Rev

    (2011)
  • E. Varuvel et al.

    Experimental analysis of biofuel as an alternative fuel for diesel engines

    Appl Energy

    (2012)
  • K. Lin et al.

    The role of the methyl ester moiety in biodiesel combustion: a kinetic modeling comparison of methyl butanoate and n-butane

    Fuel

    (2012)
  • K. Varatharajan et al.

    Mitigation of NOx emissions from a Jatropha biodiesel fuelled DI diesel engine using antioxidant additives

    Fuel

    (2011)
  • J. Sun et al.

    Oxides of nitrogen emissions from biodiesel-fuelled diesel engines

    Prog Energy Combust

    (2010)
  • S. Hoekman et al.

    Review of the effects of biodiesel on NOx emissions

    Fuel Process Technol

    (2012)
  • E. Rajasekar et al.

    Review of NOx reduction technologies in CI engines fuelled with oxygenated biomass fuels

    Renew Sustain Energy Rev

    (2010)
  • M. Fazal et al.

    Biodiesel feasibility study: an evaluation of material compatibility; performance; emission and engine durability

    Renew Sustain Energy Rev

    (2011)
  • L. Zhu et al.

    Experimental study on particulate and NOx emissions of a diesel engine fueled with ultra low sulfur diesel, RME-diesel blends and PME-diesel blends

    Sci Total Environ

    (2010)
  • I. Çelikten et al.

    Comparison of performance and emissions of diesel fuel, rapeseed and soybean oil methyl esters injected at different pressures

    Renew Energy

    (2010)
  • M. Nabi et al.

    Biodiesel from cotton seed oil and its effect on engine performance and exhaust emissions

    Appl Therm Eng

    (2009)
  • P. Tan et al.

    Exhaust emissions from a light-duty diesel engine with Jatropha biodiesel fuel

    Energy

    (2012)
  • A. Keskin et al.

    Usage of methyl ester of tall oil fatty acids and resinic acids as alternative diesel fuel

    Energy Convers Manage

    (2010)
  • S. Godiganur et al.

    6BTA 5.9 G2-1 Cummins engine performance and emission tests using methyl ester mahua (Madhuca indica) oil/diesel blends

    Renew Energy

    (2009)
  • M. Redel-Macías et al.

    Air and noise pollution of a diesel engine fueled with olive pomace oil methyl ester and petrodiesel blends

    Fuel

    (2012)
  • B. Kegl

    Numerical analysis of injection characteristics using biodiesel fuel

    Fuel

    (2006)
  • F. Caresana

    Impact of biodiesel bulk modulus on injection pressure and injection timing. The effect of residual pressure

    Fuel

    (2011)
  • S. Singh et al.

    Biodiesel production through the use of different sources and characterization of oils and their esters as the substitute of diesel: a review

    Renew Sustain Energy Rev

    (2010)
  • P. Glaude et al.

    Adiabatic flame temperature from biofuels and fossil fuels and derived effect on NOx emissions

    Fuel Process Technol

    (2010)
  • S. Jha et al.

    Flame temperature analysis of biodiesel blends and components

    Fuel

    (2008)
  • C. Lin et al.

    Effects of NOx-inhibitor agent on fuel properties of three-phase biodiesel emulsions

    Fuel Process Technol

    (2008)
  • C. Lin et al.

    Effects of emulsification variables on fuel properties of two- and three-phase biodiesel emulsions

    Fuel

    (2007)
  • D. Qi et al.

    Experimental studies on the combustion characteristics and performance of a direct injection engine fueled with biodiesel/diesel blends

    Energy Convers Manage

    (2010)
  • D. Hulwan et al.

    Performance, emission and combustion characteristic of a multicylinder DI diesel engine running on diesel–ethanol–biodiesel blends of high ethanol content

    Appl Energy

    (2011)
  • G. Rathore et al.

    Formation kinetics of nitric oxide of a biodiesel surrogate relative to n-heptane under comparable oxygen equivalence ratio in a homogeneous reactor

    Fuel

    (2012)
  • M. Lapuerta et al.

    Diesel emissions from biofuels derived from Spanish potential vegetable oils

    Fuel

    (2005)
  • M. Nabi

    Theoretical investigation of engine thermal efficiency, adiabatic flame temperature, NOx emission and combustion-related parameters for different oxygenated fuels

    Appl Therm Eng

    (2010)
  • H. Song et al.

    Comparisons of NO emissions and soot concentrations from biodiesel-fuelled diesel engine

    Fuel

    (2012)
  • K. Szulczyka et al.

    Market penetration of biodiesel

    Renew Sustain Energy Rev

    (2010)
  • E. Tat et al.

    The speed of sound and isentropic bulk modulus of biodiesel at 21 °C from atmospheric pressure to 35 MPa

    Am Oil Chem Soc

    (2000)
  • EPA. Nitrogen oxides (NOx), why and how they are controlled. US Environmental Protection Agency....
  • Y. Zeldovich

    The oxidation of nitrogen in combustion and explosions

    Acta Physicochim

    (1946)
  • C. Fenimore

    Formation of nitric oxide in premixed hydrocarbon flames

  • NREL, NOx solutions for biodiesel. US National Renewable Energy Laboratory. http://www.nrel.gov/docs/fy03osti/31465.pdf...
  • W. Gardiner

    Gas-phase combustion chemistry

    (2000)
  • J. Heywood

    Internal combustion engines fundamentals

    (1998)
  • A. Monyem et al.

    The effect of timing and oxidation on emissions from biodiesel-fueled engines

    Trans ASAE

    (2001)
  • M. Macías et al.

    Air and noise pollution of a diesel engine fueled with olive pomace oil methyl ester and petrodiesel blends

    Fuel

    (2012)
  • J. Szybist et al.

    NOx emissions of alternative diesel fuels: a comparative analysis of biodiesel and FT diesel

    Energy Fuel

    (2005)
  • McCormick R, Alvarez J, Graboski M. Effects of biodiesel blends on vehicle emissions. US National Renewable Energy...

    • Cited by (0)

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