EFFECT OF INJECTION TIMING AND INJECTION PRESSURE ON A SINGLE CYLINDER DIESEL ENGINE FOR BETTER PERFORMANCE CHARACTERISTICS FOR RICE BRAN BIODIESEL IN SINGLE AND DUAL FUEL MODE WITH CNG

Harshavardhann D

Dept. of Automobile Engineering

Hindustan University, Chennai

ABSTRACT

In the present investigation, tests were carried out to examine the performance and emissions of a direct injection diesel engine blended with rice bran biodiesel prepared with methanol to get rice bran oil methyl ester (ROME). Experiments are conducted with ROME in single and dual fuel mode with compressed natural gas (CNG) in a single cylinder four stroke diesel engine. Performance parameters such as Brake Thermal Efficiency (BTE) and Brake Specific Fuel Consumption (BSFC) are determined at two injection pressures of 190 and 200 bar and two injection timings 270btdc and 310btdc. Parameters are compared with reference line data of diesel fuel. It was found through experiments that CNG-ROME can be used as fuel with better performance at 200 bar pressure and advanced injection timing of 310btdc.

Keywords: Rice bran oil methyl ester–performance–emission characteristics–CNG–dual fuel mode, injection timing.

  1. INTRODUCTION

Petroleum resources are finite and therefore search for their alternative fuels for IC engines is continuing everywhere. Alternative gaseous fuels are used widely all over the world. Use of gaseous fuels is prompted by its cleaner nature of combustion compared to the usual liquid fuels. Natural gas has relatively high octane number and is suitable for engines with higher compression ratios [1-3]. CNG has a good potential because of its very low emissions. The use of CNG as an alternative fuel results in better economical as well as environmental impacts. It is safer than other fuels such as motor fuels in the case of a fuel spill, where natural gas is lighter than air, so it disperses quickly when leaked. Biodiesel is referred to as the mono-alkyl-esters of long-chain-fatty acids derived from renewable fatty acid sources. The principal advantages of biodiesel is that it minimizes the formation of sulphur dioxide, CO, HC, and Particulate Matter emissions during the combustion process due to low sulphur and the presence of oxygen-containing compounds. In addition, biodiesel has good ignition ability in engine due to its relatively high cetane number compared to that of conventional diesel fuel. It is found that the lower concentrations of biodiesel blends improve the thermal efficiency. As the parameters at which the engines are operating, a blend up to 20% of biodiesel with diesel works well without any modification in the engine. The potential benefits of using CNG in diesel engines are both economical and environment friendly. With reduced energy consumption, the dual fuel engine shows a significant reduction in smoke density and improved BTE. In the present study, the effect of biodiesel blends along with CNG induction over the performance and emission characteristics of a diesel engine in dual fuel mode was experimentally investigated.

  1. PROCEDURE

Engine Test

The engine running tests were conducted on Kirloskar make, single cylinder, 4 stroke, constant speed, vertical, water cooled, direct injection, 10 hp, compression ratio 17.5:1 diesel engine. Tests were conducted at different loads, with diesel, trans-esterified oil (ROME), CNG-ROME for comparative studies. The engine setup is shown in figure 1a. An electrical dynamometer was used for load measurement.

Table1. Engine Specifications

Make / Kirloskar, single cylinder
Type / Direct injection, water cooled
Bore x Stroke (mm) / 102 x 118 mm
Compression Ratio / 17.5:1
Rated Power / 10 HP
Rated Speed / 1500 rpm
Start of Injection / 180 bar

Table2. Operating Parameters

Load / 20%, 40%, 60%, 80%, 100%
Speed / Constant speed (1500 rpm)
Compression Ratio / 17.5:1
Injection Timing / 270bTDC and 310bTDC
Injection Pressure / 190 bar and 200 bar

Table3. Properties of diesel, biodiesel

Properties / Diesel / Rice Bran oil / Biodiesel
Cetane No. / 48-56 / 22/51 / 58
Density (kg/m3) / 821 / 918 / 895
Viscosity (cSt) / 3.52 / 75.9 / 5.45
Calorific Value (MJ/kg) / 43 / 40.628 / 39.5
Flash Point (0C) / 48 / 345 / 158

Test Procedure

Engine tests were conducted at 270bTDC and 310bTDC injection timings and injection pressures of 190 bar and 200 bar respectively. Engine was made to run on neat diesel, load test was done and readings were recorded. Similar procedure was done for CNG-biodiesel for which CNG has a constant flow rate of 0.5 Kg/hr at a rated speed of 1500 rpm. Load tests were taken at 20%, 40%, 60%, 80% conditions.

  1. RESULTS AND DISCUSSIONS

Engine Performance

The engine performance characteristics such as brake specific fuel consumption and brake thermal efficiency are discussed below.

Brake Specific Fuel Consumption

At 270bTDC

Fig 1. BSFC vs BP at 190 bar Fig 2. BSFC vs BP at 200 bar

Figures 1 and 2 show variation of brake specific fuel consumption with brake power curves for diesel, biodiesel and CNG-biodiesel operation of the engine at 27 deg bTDC and 190barand 200bar injection pressures respectively. BSFC of diesel at standard injection pressure of 190 bars and injection timing of 27 deg bTDC is 0.6 Kg/KWh at low loads of operation. At higher loads of operation BSFC is 0.31 Kg/KWh.

The values for CNG-biodiesel for low load and higher loads are 0.81 Kg/KWh and 0.32 Kg/KWh. For CNG-biodiesel at all the two injection pressures at low loads it is 0.78 Kg/KWh with very little variations and it is nearly equal to that of diesel at higher loads.

It occurs because of better mixing and atomization of fuel at higher injection pressures.

At 310bTDC

Fig 3. BSFC vs BP at 190 barFig 4. BSFC vs BP at 200 bar

Figures 3 and 4 show variation of brake specific fuel consumption with brake power curves for diesel, biodiesel and CNG-biodiesel operation of the engine at 31 deg bTDC and 190 bar and 200 bar respectively. BSFC of diesel at standard injection pressure of 190 bar and injection timing of 31 deg bTDC is 0.6 Kg/KWh at low loads of operation. At higher loads of operation BSFC is 0.37 Kg/KWh. The values of CNG-biodiesel for low loads and higher loads are 0.82 Kg/KWh and 0.35 Kg/KWh. For CNG-biodiesel at all the two injection pressures at low loads it is 0.8 Kg/KWh with very little variations and it is nearly equal to that of diesel at higher loads.

Brake Thermal Efficiency

At 270bTDC

Fig 5. BTE vs BP at 190 barFig 6. BTE vs BP at 200 bar

Figures 5 and 6 show variation of brake thermal efficiency with brake power curves for diesel, biodiesel and CNG-biodiesel operation of the engine at 27 deg bTDC and 190 bar and 200 bar injection pressures respectively. BTE of diesel at standard injection pressure of 190 bars and injection timing of 27 deg bTDC is 13% at low loads of operation. At higher loads of operation BTE is 27%. The values of CNG-biodiesel for low loads and higher loads at 190 bars are 7.5% and 27.5% and for 200 bars are 7% and 27% respectively.

At 310bTDC

Fig7. BTE vs BP at 190 barFig 8. BTE vs BP at 200 bar

Figures 7 and 8 show variation of brake thermal efficiency with brake power curves for diesel, biodiesel and CNG-biodiesel operation of the engine at 31 deg bTDC and 190 bar and 200 bar injection pressures respectively. BTE of diesel at standard injection pressure of 190 bars and injection timing of 31 deg bTDC is 13.5% at low loads of operation. At higher loads of operation BTE is 28%. The values of CNG-biodiesel for low loads and higher loads at 190 bars are 9.5% and 27.5% and for 200 bars are 12% and 29.5% respectively.

  1. CONCLUSION

In this investigation, the diesel engine have been set to run at compression ratio 17.5:1, advanced injection timing 31 deg bTDC and injector pressure 200 bar to arrive at the optimum for rice bran oil ethyl ester (ROEE). In CNG-ROEE dual fuel operation of the engine at 31 deg bTDC, BSFC of 0.82Kg/KWh, 0.8 Kg/KWh were obtained at low loads of operation at 190 bar and 200 bar respectively. At higher loads, the values are 0.32 Kg/KWh and 0.35 Kg/KWh for 190 bar and 200 bar pressures respectively. BSFC at higher loads is even less than diesel operation at all pressures with advanced injection timings due to lesser flame velocities and clean burning of fuel. An increase in brake thermal efficiency of 1.5% is obtained at higher loads when compared to reference diesel fuel operation due to the advancement in injection timing. Finally, it could be concluded that CNG-ROEE dual fuel mode could be used as alternative fuel for compression ignition engine at a compression ratio of 17.5:1, higher injector operating pressure of 200 bar and advanced injection timing of 31 deg bTDC for better engine performance.

REFERENCES

[1] Agarwal.A.K. & Das.L.M., (2001), “Biodiesel development and characterizationfor use as a fuel in compression ignition engines”, Transactions of ASME, 123,pp 440-447.

[2] N.R.BanapurmathV.S,Yaliwal., ”Experimental Studies on Manifold Injected CNG-Biodiesel Dual Fuel Engine”, International Journal of Emerging Technology and Advanced Engineering”, Feb 2013, pp 77-83.

[3] Subhan Kumar Mohanty., “A production of biodiesel from rice bran oil and experimenting on small capacity diesel engine”, International Journal of modern Engineering Research, Mar 2013, pp 920-923.

[4] Venkatesan.M.,(2011), “Performance and Emission Characteristics of Jatropa biodiesel in dual fuel mode with CNG in a single cylinder four stroke diesel engine”, International Journal of Applied Engineering Research.

[5] Ranbir Singh., “Performance and Exhaust Gas Emissions Analysis of Direct Injection CNG-Diesel Dual Fuel Engine”, International Journal of Engineering Science and Technology.