i Jr Te 0105113117

POSTER PAPER

International Journal of Recent Trends in Engineering, Vol. 1, No. 5, May 2009

113

Influence of Injection Timing on Performance and Emission Characteristics of Naturally

Aspirated Twin Cylinder CIDI Engine Using Bio-diesel Blend as Fuel

M. Pandian1

, S.P. Sivapirakasam2 and M. Udayakumar3

1Research scholar, Department of Mechanical Engineering, National Institute of Technology, Tiruchirappalli. 620015, India. email: [email protected]

2 Assistant Professor, Department of Mechanical Engineering, National Institute of Technology, Tiruchirappalli. 620015, India. email: [email protected]

3Professor, Department of Mechanical Engineering, National Institute of Technology, Tiruchirappalli. 620015, India. email: [email protected]

Abstract---Stringent emission norms and environment degradation due to pollutants from the automotive vehicles lead us to find the suitable alternative for the petro-diesel. Among the alternatives the non-edible vegetable oil seems to be most promising one. When the vegetable oil is used as fuel in diesel engine, it does not cause any major problem if used for a short period. However in the long run it causes major problems such as injector coking, deposit build up in the combustion chamber, piston ring sticking and engine oil dilution. Hence vegetable oils are converted as biodiesels to reduce viscosity. The transesterification process has proved as one of the best method to achieve the same. It is evident from the literature that the major problem on utilization of blends of bio-diesel is the increase in NOx emission from diesel engines. To reduce the NOx emission from the diesel engines employing biodiesel blend as fuel, the injection timing of fuel is altered by either addition or removal of shims in the pump. The effect of changing the injection timing on BSEC, Brake Thermal Efficiency, CO, HC and NO emissions are studied at different injection timings such as 18°, 21°, 24°, 27° and 30° CA bTDC. From the experiments it is found that on retarding the injection to 18°CA bTDC from 24° CA bTDC, the original injection timing, the NOx emission reduced to about 35% while advancing to 30°CA bTDC, the NOx increased by 25%. The BSEC, CO, HC have been found to increase by about 3%, 12.65% and 10% respectively on retarding to 18°CA bTDC while decrease by 6.27%, 32%,and 14.44% respectively on advancing the injection to 30° CA bTDC. The brake thermal efficiency is reduced by 3.08% on retarding to 18°CA bTDC whereas it is improved by 5.09% on advancing the injection timing to 30° CA bTDC.

Keywords: Injection timing, NOx emission, CIDI engine, twin cylinder.

I. INTRODUCTION Ever increasing prices of the petro-products,

stringent emission norms and fast depletion of fossil fuel reserves forced to look for alternative fuels which

should not only be sustainable but also environment friendly. Of the several alternative fuels, non-edible vegetable oil holds good promises as an eco-friendly fuel. In India, there are several non-edible oil plants such as jatropha, pongamia, neem, mahua, simarouba, etc. Out of these plants, jatropha and pongamia have shown good promise for biodiesel production [1]. Most research works were reported on the performance and emission test of diesel engine employing pongamia biodiesel as fuel in different proportions without any engine modifications and reported that smoke, HC, CO emissions were found to be lower with higher BTE for B10, B20 and B40 biodiesel blends[3] - [7]. However in almost all the literature it was reported that NOx emission was higher for biodiesel than diesel due to higher oxygen content of the fuel [4] – [7]. Nevertheless, to improve the performance of the engine researchers also employ engine modifications such as alteration in fuel injection timing, injection pressure, nozzle specification. Lot of work had been done on alteration of injection timing for straight vegetable oils and other fuels, few work has been reported for biodiesel [8] – [13]. Therefore this paper aims to study the influence of injection timing on the performance and emission characteristics of the diesel engine using biodiesel blend of B40 as fuel.

II. EXPERIMENTAL SETUP AND PROCEDURE OF EXPERIMENTATION

The engine tests were conducted on four stroke twin

cylinder direct injection water cooled compression ignition engine. The engine was always operated at its rated speed of 1500 rev/min. The specification of the engine is given in Table. 1

Pongamia bio-diesel and diesel were used to prepare bio-diesel blend fuel. Pongamia biodiesel was

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obtained from M/s. Bannari Sugars (P) Ltd., Sathiyamangalam while diesel was purchased from a commercial supplier.

TABLE 1: TEST ENGINE SPECIFICATIONS

Parameters Specification

Machine supplier Niyo Engineers, Pune

Make Rocket Engineering Corporation, Kohlapur, Maharashtra

Nozzle opening pressure 200 bar

No. of cylinders 2

Fuel H.S. Diesel

Rated Power 7.5 kW

Cylinder size 80 mm Bore & 110mm Stroke

Compression ratio 17.5

Dynamometer Alternator with Heater load

Injection timing

24°CA bTDC

The properties of blend fuel B40 were shown in Table2 with the properties of diesel for comparison.

TABLE 2: PROPERTIES OF BLENDED FUEL AND DIESEL

Parameters diesel B40

Kinematic viscosity @ 40°C (cSt) 2.6 3.85

Cetane No 50 51

Iodine Value NA 41

Calorific Value (MJ/kg) 42.5 40.1

Specific Gravity @ 15° C 0.835 0.859

Flash point °C 68 81

A series of experiments were conducted using bio-diesel blend as fuel under varying load conditions at the rated speed. The fuel blend was prepared just before starting the experiment to ensure that the fuel mixture was homogenous. The engine had an original injection timing of 24° CA bTDC. The tests were carried out at five different injection timing (18°, 21°, 24°, 27°, and 30° CA bTDC) values with decreasing or increasing the advance shim [9]. In each test, the values of time for 40 cc of fuel consumption, air flow rate, voltmeter, ammeter, the ambient temperature and the exhaust gas temperature were noted from the digital display. Also the values of pollutants such as CO, HC, CO2, and NOx were recorded during the tests. For notifying the exhaust emissions, AVL 5 gas analyzer and AVL Smoke meter were used. All the data were recorded after the engine attained steady state. The experimental setup is shown in Fig. 1.

Fig. 1. Experimental Setup

III. RESULTS AND DISCUSSION

It was reported in many literature that NOx emission was higher for Bio-diesel blend fuel while CO, HC emissions were lower. One such measure to reduce the NOx emission from diesel engine is to retard the fuel injection timing. The fuel injection timing was adjusted to study its impact on Brake Specific Energy Consumption (BSEC), Brake Thermal Efficiency (BTE), CO, HC and NOx for the blend fuel of B40 from a Naturally Aspirated Twin cylinder CIDI engine.


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Fig. 2. Variation of BSEC vs. load A. Effect on BSEC

From fig. 2 it is clearly seen that BSEC increased by 3.11% on advancing the injection timing to 30°CA bTDC while reduced by 5% on retarding to 18°CA bTDC from the original injection timing of 24° CA bTDC. Because of advancing the injection of fuel to 30°CA bTDC, complete combustion would have been taken place that results in lesser BSEC. While retarding the injection to 18°CA bTDC, combustion is incomplete that results in higher BSEC.

Fig.3. BTE Vs Load

B. Effect on brake thermal efficiency (BTE) From the fig. 3, it was found that there was 5.07%

increase in brake thermal efficiency when injection timing was advanced to 30°CA bTDC but about 3.08% decrease while retarded to 18°CA bTDC. This was also due to improved combustion when advancing the injection timing and poor combustion while retarding.

C. Effect on NOx Emission Fig. 4 showed that as load increased from 0% to 100%,

the NOx emission increased at different injection timings. This is due to the fact that as the load increased to the maximum value the fuel consumption with higher oxygen content also proportionately increased which lead to the higher NOx emission.

Fig. 4. Variation of NOx Vs Injection timing. It was also found that at each load the NOx emission

increased as the injection timing was advanced to 27° CA bTDC and 30° CA bTDC from the original injection timing of 24° CA bTDC whereas on retarded to 21° CA bTDC and 18° CA bTDC the NOx emission was reduced. Because:

i) As the injection timing was advanced to 27° and 30° CA bTDC, mostly all the injected fuel is burnt before TDC. i.e during the progress of the compression stroke. Hence high peak temperature resulted which led to higher NOx emission.

ii) When the injection timing was retarded to 21° and 18° CA bTDC, only part of the fuel burnt before TDC and the remaining fuel burnt in early expansion stroke resulting in less peak temperature. Hence NOx emission lowered.


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D. Effect on CO emission Fig. 5 shows the variation of CO for various injection

timings at different loads. About 12.65 % increase in CO emissions was observed on retardation while 32% reduction was noticed on advancement of fuel injection. On advancement the fuel blend had sufficient time to undergo the combustion process whereas it had lesser time on retardation.

Fig. 5 CO vs. Injection Timing

E. Effect on HC emission

From the Fig. 6, it was found that HC emission

also reduced by about 14.44% on advancing the injection timing to 30°CA bTDC but increased about 10% on retarding the fuel injection to18°CA bTDC. Advancing the injection timing caused earlier start of combustion relative to TDC. Hence the cylinder charge had relatively higher temperatures and thus lowered the HC emissions.

Fig. 6 Variation of HC vs. injection timings

IV. CONCLUSIONS The BSEC increased by 3.11% on advancing the

injection timing to 30° CA bTDC and got reduced by 6.27% while retarding the injection timing to 18° CA bTDC. Also it was found that the brake thermal efficiency (BTE) improved by 5% on advancing the fuel injection and reduced by 3.08% during retardation. On advancing the injection timing by 6° CA bTDC from the original injection timing, the NOx emission increased by 25% while the NOx emission reduced by 35% when retarded by 6° CA bTDC. The CO and HC emissions were reduced by 32% and 14.44% respectively when advancing the injection timing to 30°CA bTDC and increased by 12.65% and 10% respectively on retardation to 18°CA bTDC.

REFERENCES

[1] M.Lapuerta, O. Armas, J. Rodriguez- Fernandez. “Effect of

bio-diesel fuels on diesel engine emissions”, Progress in Energy and Combustion Science. Vol 34,2008 pp198 – 223.

[2] G. Lakshmi Narayana Rao, S.Sampath, K. Rajagopal. “Experimental Studies on the combustion and Emission Characteristics of a Diesel Engine fuelled with used cooking oil methyl ester and its diesel blends” International journal of Applied science, Engineering and Technology, vol. 4, 2007, pp 64 – 70.

[3] M.M. Azam, A. Waris, N.M. Nahar, “Prospects and

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[4] P.K. Srivastava, Madhumita Verma, “Methyl ester of karanja oil as alternative renewable source energy”, Fuel, vol. 87, 2008, pp. 1673 – 1677.

[5] K. Sureshkumar, R. Velraj, R. Ganesan, “Performance and Emission characteristics of a CI engine fuelled with Pongamia Pinnata methyl ester and its blends with diesel”, Renewable Energy, vol. 33, 2008, pp. 2294 – 2302.

[6] H. Raheman, A.G. Phadatare, “Diesel Engine emissions and performance from blends of karanja methyl ester and diesel”, Biomass and Bioenergy, vol.27, 2004, pp. 393 – 397.

[7] T. Venkateswara Rao, G. Prabhakar Rao, K. Hema Chandra Rao, “Experimental Investigation of Methyl esters of Non-edible oils as bio-diesel on CI engine”, Jordan Journal of Mechanical and Industrial Engineering.

[8] M. Senthil kumar, A. Ramesh, “An experimental comparison of methods to use methanol and Pongamia oil in a compression ignition engine”, Biomass and Bioenergy, 2003.

[9] Cenk Sayin, Kadir Uslu, Mustafa Canakci, “Influence of injection timing on the exhaust emissions of a dual fuel CI engine”, Renewable Energy, 2007.


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[10] Ekrem Buyukkakaya, Muhammet Cerit, “Experimental Study of NOx emissions and injection timing of a low heat rejection diesel engine”, International journal of thermal sciences, vol. 47, 2008, pp. 1096- 1106.

11] Ke Zeng, Z. Huang et al. “Combustion characteristics of a direct injection natural gas engine under various fuel injection timings”, Applied Thermal Engineering, vol. 26, 2006, pp. 806 – 813.

[12] G.H. Abd Alla, H.A. Soliman, O.A. Badr, M.F. Abd Rabbo, “Effect of injection timing on the performance of a dual fuel engine”, Energy conversion and Management, vol. 43, 2002, pp. 269 – 277.

[13] S. Bari, C.W. Yu, T.H. Lim, “ Effect of fuel injection timing with waste cooking oil as a fuel in a direction injection diesel engine”, Proc. Instn. Mech.Engrs. vol. 218, part D: J. Automobile Engineering, pp. 93 – 104.

[14] John B. Heywood, “Internal Combustion Engine Fundamentals”, McGraw Hill International Edition, 1988.


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