WJETWorld Journal of Engineering and Technology2331-4222Scientific Research Publishing10.4236/wjet.2017.51011WJET-74453ArticlesChemistry&Materials Science Engineering Investigation of Performance and Combustion Characteristics of DI Diesel Engine Fuelled with Ternary Fuel Blend at Different Injection Pressure PaniSharanappa1MallinathC. Navindgi1Department of Mechanical Engineering, PDA College of Engineering, Kalburgi, India091220160501125138January 9, 2017Accepted: February 25, February 28, 2017© Copyright 2014 by authors and Scientific Research Publishing Inc. 2014This work is licensed under the Creative Commons Attribution International License (CC BY). http://creativecommons.org/licenses/by/4.0/

The depletion of fossil diesel fuels, global warming concerns and strict limits on regulated pollutant emissions are encouraging the use of renewable fuels. Biodiesel is the most used renewable fuel in compression ignition (CI) engine. The majority of literature agrees that the particulate matter (PM), unburnt total hydrocarbons (THC) and carbon dioxide (CO) emission from biodiesel are lower than from conventional diesel fuel. One of the most important reasons for this is the oxygen content of the biodiesel. This induces a more complete and cleaner combustion process. In addition to this the absence of aromatic compounds in biodiesel leads to particulate matter reduction with respect to diesel fuel. The potential emission benefits induced by the presence of oxygen in fuel molecules has increased the interest in using the bio-alcohols fuel blends in CI engines such as ethanol. Although alcohols are more suitable for blending with diesel fuel, properties like lubricity, viscosity, stability, heating value and cetane number of diesel-alcohol (Diesohol) still require improvement. One of the techniques is addition of biodiesel which can improve all of these properties forming diesel-biodiesel-alcohol (ternary) blends. The blends of diesel-biodiesel-ethanol can be used in the existing CI engines without any major modifications and most significant result of using this blend is the lower emission with almost the same performance as of diesel fuel alone. The present study focused on investigation of performance and combustion characteristics of ternary fuel blend in DI diesel engine operating at different injection opening pressure (IOP). The different injection opening pressures are: 180 bar, 200 bar and 220 bar.

Diesohol Ternary Fuel Blends Aromatic Compounds Injection Opening Pressure CI Engines1. Introduction

The ongoing investigations and the already found analysis about the fractional replacement of fossil diesel fuel with the combination of biodiesel and ethanol in compression ignition engines found to be successful as this blend has the similar fuel properties like the commercial diesel fuel with high bio fuel content. Many scientists and investigators have studied this blend with different proportions of diesel, biodiesel and ethanol to study its suitability as a fuel in existing CI engines [1] . It was found from the detailed literature survey that a maximum of 20% biodiesel and 10% of ethanol can be added to the diesel fuel effectively. Many investigators have used soybean, rapeseed oil, Pongamia oil and waste cooking oil as an emulsifier in diesohol blend [2] . Little literature is available on the use of methyl esters of Rice bran oil and Mahuva oil blend with diesohol, hence these two biodiesels are chosen for analysis. However a detailed analysis of performance, combustion characteristics of diesel-biodiesel-ethanol blend in diesel engines appears to be scarce. Thus the aim of this work is to investigate the optimum engine parameters at which the ternary blends can be used effectively. The engine is also tested at different injection opening pressure. A lot of work has been carried on optimization of ternary blend using soybean, palm, rape seed, Jatropha biodiesels, but a very little information is available using mahuva biodiesel. So in this work an effort is done to determine experimentally the performance and combustion characteristics of the direct injection diesel engine fuelled with diesel-mahuva biodiesel blend with ethanol as an additive. The engine is also tested at different injection opening pressure.

1.1. Scope of Biodiesel as an Alternative Fuel

Biodiesels can be defined as “the mono alkyl esters of long chain fatty acids derived from lipid feed stock, such as vegetables and animal fats, for its use in diesel engines” [3] . Neat vegetable oils are not ideally suitable for compression ignition engines as a fuel because of durability and operational problems. The durability problems such as deposit formation, lubrication oil dilution and choking of injector tip. The Operational problems such as ignition, combustion and ability to start may restrict the use of neat vegetable oils [4] . These problems are mainly due to higher viscosity and density, which leads to poor atomization, bigger droplets, longer jet spray penetration, and low volatilities. Many efforts have been carried out to reduce the viscosity of the vegetable oils. Two different methods are used to reduce the viscosity of the oils:

1) Engine modification: Heating the fuel line, injection system modification, duel fuelling.

2) Fuel modification: Blending, Pyrolysis and micro emulsion.

Biodiesel are chemically high biodegradable, it can be mixed with any diesel at any ratio. It emits no sulphur oxides, a pollutant that causes acid rain and burns the lungs, eyes and throat. Global warming can be reduced by reducing the emission of carbon dioxide by using the biodiesel. Some of the advantages of using biodiesel are, absence of sulphur, absence of aromatics, lower hydrocarbon emissions, reduction of smoke and soot and reduction i carbon monoxide [5] .

Biodiesel can be mixed with diesel fuels in any proportion; the blend can stable even at low temperatures. It is advisable that biodiesels can’t be stored more than six months, similar to fossil diesel fuel. It can be stored in a closed container with air tight heading protecting from direct sun light, moisture and cold weather. Biodiesel separates from diesel fuel at lower temperatures and it can clog the fuel flow line, but as it warms up it liquidates [6] .

Even though it has got many more advantages, it cannot be used as a sole fuel for compression ignition engine, because of its lower heating value, higher density and higher emission of NOx. The higher emission of NOx is due to higher exhaust gas temperature. Due to lower heating value of biodiesel the efficiency of the engine reduces.

1.2. Scope of Alcohols as an Alternative Fuel

Alcohol is a bio-product extracted with the help of chemical process. Raw material for alcohol is; grains, agricultural wastes, starch, sugar and wood. Ethanol and methanol are two important alcohols. Ethanol has been used in Germany and France as early as 1894 and Brazil has utilized ethanol as a fuel since 1925 [7] .

Ethanol consists of carbon, hydrogen and oxygen, since it consists of oxygen ethanol burns cleaner than fossil fuels. Emissions from ethanol are very less, particularly NOx emission which is not possible with biodiesel. Ethanol can be produced from agricultural wastes, grains, dated soda, cheese whey, grains or any other material which contains starch or sugar. Ethanol can be called as renewable fuel as it is produced from crops. Use of ethanol in the compression ignition may cause some problems such as:

1) More amount of ethanol is required to produce the rated power.

2) Low boiling point and high vapour pressure may cause vapour lock.

3) High latent heat of ethanol leads to poor mixing with air, hence need heating of intake manifold.

4) Low cetane number leads to poor combustion.

The above problems can be overcome by blending the ethanol with diesel fuel. The blend of diesel and ethanol is called as diesohol, which is the best alternative fuel for dual fuel engines. Anhydrous ethanol makes homogeneous mixture with diesel fuel but hydrous ethanol with diesel makes phase separation. This can be solved by adding emulsifier or surfactants. The maximum percentage of ethanol in the diesel fuel blend is around 15% [8] .

2. Experimental Work

Experiment was conducted on DI diesel engine to determine the performance and combustion parameters. The performance parameters like brake thermal efficiency (BTE), brake specific fuel consumption (BSFC), exhaust gas temperature (EGT) were determined. The combustion parameters like, cylinder pressure, mass fraction burn, cumulative heat release rate and net heat release were determined. The engine was run at different injection opening pressure. Different injection opening pressure: 180 bar, 200 bar and 220 bar, injection opening pressure was set by adjusting the compression of the spring and calibrated. Table 1 gives detailed Engine specifications:

3. Materials and Methodology

The various materials used for conducting experiment are, pure diesel fuel (D100), pure biodiesel (B100), ternary fuel blends; ternary fuel blends were prepared by blending different proportion of diesel fuel, Mahuva biodiesel and ethanol by volume. The different prepared ternary fuel blends are: D70B20E10 (B20), D60B30E10 (B30) and D50B40E10 (B40). E10 indicates 10% of ethanol is used as an additive in the blend. The basic fuel properties of fuels were determined according to ASTM standards in Bangalore test house, Bangalore and IISC, Bangalore. The engine was run with different injection pressure (IOP) 180 bar, 200 bar and 220 bar; IOP was set by adjusting the spring pressure and was calibrated in the lab.

4. Results and Discussions4.1. Performance Characteristics

The performance characteristics discussed in this section are brake thermal efficiency (BTE), brake specific fuel consumption (BSFC) and exhaust gas temperature (EGT).

4.1.1. Brake Thermal Efficiency

Figure 1 shows the variation of brake thermal efficiency of pure diesel (D100),

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