Comparative study of thevetia peruviana seed oil with other biofuels and diesel as fuel for CI engine.

Balusamy, T. ; Marappan, R.

Introduction

World petroleum situation due to rapid depletion of fossil fuels and degradation of the environment due to the combustion of fossil fuels have caused a stimulation of interest in finding alternative fuels. Internal combustion engines, which form an essential part of the transportation as well as mechanized agricultural system, have been badly affected by the twin crisis. In this direction, many researchers have done a lot of experiment studies in the field of biodiesel to find an alternative to mineral diesel.

Naik.S.N. et.al., [1] explained various methods of preparation of biodiesel with different combination of oil and catalyst. In addition, fuel properties and specifications provided by different countries were also analyzed by them. The process of transesterification is affected by the mode of reaction condition, molar ratio of alcohol to oil, type of alcohol, type and amount of catalyst, reaction time and purity of reactants. Ramadhas.A.S. et.al, [2] reviewed the production and characterization of vegetable oil as well as the experiments carried out in various countries in this field. Also the scope and the challenges being faced in this area of research were clearly described. Barnwal.B.K. et.al., [3] reviewed the work done on biodiesel production and utilization, resources available, process developed, performance in existing diesel engines, environmental considerations, the economic aspect and barriers to the use of biodiesel. Shailendra Sinha et.al.,[4] revealed that the overall combustion characteristics were quite similar for biodiesel blend(B20) and mineral diesel. Also, reported that ignition delay is lower and combustion duration is longer for B20 compared to that of diesel. Suryawanshi.J.G et.al.,[5] conducted experiments with the bends of varying proportions of pungamia methyl ester and diesel to run a single cylinder diesel engine and reported that significant improvement in engine performance and emission characteristics were observed. Naveen Kumar et.al., [6] conducted experiments using methyl ester of palm oil, blended in different concentrations with neat diesel to find the performance and emission characteristics in order to evaluate its suitability in diesel engine. The data thus generated were compared with base line data generated from neat diesel. It was found that optimal blend of 10-20% methyl ester of palm oil with neat diesel exhibited best performance and smooth engine operations without any symptoms of undesired combustion phenomenon. Nagaraja.A.M. et.al, [7] reported that optimum blend ratio is 20% methyl ester with neat diesel. He also observed that increasing injection pressure reduce the N[O.sub.x] and improvement in thermal efficiency. The authors of this paper [89] have already established that engine performance and combustion characteristics with methyl ester of thevetia peruviana seed oil are comparable to that of diesel and CO, HC emissions are less but NOx and smoke are slightly higher than that of diesel.

The present work is to compare the properties, performance, combustion and emission characteristics of methyl ester of thevetia peruviana seed oil with other methyl esters of vegetable oils namely jatropha, pungamia, mahua, neem, corn, palm, cotton, mustard, sunflower and rice bran oils at a blend ratio of 1:5 (B20).

Transesterification

Viscosity of all eleven vegetable oils was reduced by transesterification method. The procedure involved in this method is as follows: Sodium hydroxide was added to methanol and stirred until properly dissolved. The solution thus prepared called methoxide was added to vegetable oil and stirred at a constant rate at 600C for one hour. After the reaction is over, the solution was allowed to settle for 20-24 hours in a separating flask. The glycerin settles at the bottom and the methyl ester floats at the top (coarse biodiesel). Coarse biodiesel was separated from the glycerin and it was heated to above 100 [degrees]C and maintained for 10-15 minutes for removing the untreated methanol. Certain impurities like sodium hydroxide (NaOH) etc were still dissolved in the coarse biodiesel. These impurities were cleaned two or three times by washing with 1% (by vol.) of petroleum ether and 15-20% (by vol.) of water for 1000 ml of coarse biodiesel. This cleaned biodiesel was taken up for the study. All the properties of biofuels and its blends were measured as per the ASTM standards [11] as shown in table-1.

Experimental Setup and Measurement

Experiments were conducted in a fully automated single-cylinder, four-stroke, naturally aspirated, direct injection diesel engine (Fig.1) using these biofuels. The specification of the engine is given in table-2. Two separate fuel tanks with a fuel switching system were used, one for diesel and the other for biodiesel. The fuel consumption was measured with the aid of optical sensor. A differential pressure transducer was used to measure air flow rate. The engine was coupled with an eddy current dynamometer which is used to control the engine load through computer. Engine speed and load were controlled by varying excitation current to the eddy current dynamometer using dynamometer controller. A piezoelectric pressure transducer was installed in the engine cylinder head to measure the combustion pressure. Signals from the pressure transducer were fed to charge amplifier. A high precision crank angle encoder was used to give signals for TDC and the crank angle. The signals from the charge amplifier and crank angle encoder were supplied to data acquisition system. An AVL-five gas analyzer and AVL-Smoke meter were used to measure the emission parameters and smoke intensity respectively. Thermocouples (chrommel alumel) were used to measure different temperatures, such as exhaust temperature, coolant temperature, and inlet air temperature. Load was changed in eight levels from no load to the maximum load. The engine was operated at the rated speed i.e., 1500 rpm for all the tests. The performance, combustion and emission parameters like brake thermal efficiency, specific fuel consumption, volumetric efficiency, P-[theta] curves, instantaneous heat release, cumulative heat release, exhaust gas temperatures, CO, C[O.sub.2],HC, NOx, and smoke intensity were measured for diesel and all eleven methyl esters mentioned in this study. Then all the results were compared and analyzed.

Results and Discussion

The following comparative results were taken at the maximum load and the diesel fuel operation has been taken as the reference for all other methyl esters of non-edible and edible oils.

[FIGURE 1 OMITTED]

Brake Thermal Efficiency

Fig.2. shows deviation of thermal efficiency for different methyl esters at the maximum load operation. It is observed that brake thermal efficiency of all biofuels blends is less than that of the diesel. The brake thermal efficiency of diesel was 28.73% at the maximum load which was considered as reference line for making comparison. Among the biofuels, the maximum deviation of brake thermal efficiency was obtained for neem oil (2.6%) where as, the minimum deviation was 0.6% for TPSO. This is due to higher energy content of the methyl ester of TPSO blend compared to other bio-diesel blends.

[FIGURE 2 OMITTED]

Brake Specific Fuel Consumption

The percentage variation of bsfc for different methyl ester of non-edible and edible oils is shown in fig.3 at maximum load with respect to diesel operation. It is observed that bsfc for all biofuel blends were higher than that of the diesel. The maximum and minimum percentage variation of bsfc among the biofuels blend were 9.66% and 3.45% for neem and TPSO respectively. Even though methyl esters of TPSO and rice bran oil have shown equal bsfc, the advantage of TPSO is that it is non-edible oil. The reason behind lesser bsfc of TPSO is again its higher energy content compared to that of other biofuels blend.

[FIGURE 3 OMITTED]

Volumetric Efficiency

Variation in volumetric efficiency for various biofuels blend is as shown fig.4 It was observed that for all biofuels blend the volumetric efficiency is slightly less than that of diesel. The maximum variation in volumetric efficiency among the biofuels blend were 4% for methyl ester of corn oil compared to that of diesel. But, the methyl ester of TPSO has only 1% lower than that of diesel.

[FIGURE 4 OMITTED]

Peak Pressure

Fig-5 shows the percentage variation of peak pressure developed at injection pressure of 210bar (230 before TDC) in the engine for various biofuels blend at the maximum load. It was observed that peak pressure was somewhat less than that of the diesel. The maximum and minimum deviation in peak pressure among the biofuels blend were 11.76% and 2.35% for methyl ester of neem oil and TPSO respectively. The reason behind higher in peak pressure of TPSO is its higher energy content and better combustion character as evidenced by the low value of crank angle(fig.6) at which peak pressure is developed.

[FIGURE 5 OMITTED]

Crank Angle for Peak Pressure

At the maximum load operation, the variation of crank angle for peak pressure for different biofuels blend is shown in fig.6. It is clearly observed that the crank angle for peak pressure is moved ahead few degrees towards top dead center compared to that of diesel. For methyl ester of TPSO, peak pressure is obtained 10 earlier than that of the diesel at the maximum load. This is due to the fact that combustion starts earlier during the premixed combustion period in comparison to diesel.

[FIGURE 6 OMITTED]

Exhaust Gas Temperature

Fig.7 shows the percentage variation in exhaust temperature for various biodiesel blends at the maximum load. It was observed that exhaust gas temperature of all biofuel blends was higher than that of diesel. This is due to the fact that biofuels have higher flash point and fire point compared to that of diesel and hence heat release is slightly delayed leading to higher exhaust gas temperature. Among the biodiesel blends, the maximum and minimum deviations in EGT were 34.72% and 3.37% for methyl ester of mustard oil and TPSO.

Carbon Monoxide

The percentage variation in carbon monoxide present in the exhaust gas for the various biofuels blend at the maximum load is shown in fig.8. It was observed that carbon monoxide content for all biodiesel blends was lower than that of the diesel (0.013% of vol.). Among the biofuels, methyl ester of palm oil (edible) has lower CO content (46.15%). In particular, CO content of methyl ester of TPSO was 23.08% lower than that of diesel which is due higher oxygen content of biodiesel leading to better combustion.

Carbon Dioxide

The percentage variation in carbon dioxide for the various biofuels blends at the maximum load is shown in fig.9. It was observed that carbon dioxide content for all biodiesel blends was higher than that of the diesel (2.4 % of vol.). For the biofuels, deviation of C[O.sub.2] content ranges from 4.7% to 20.83% higher than that of diesel. In particular, C[O.sub.2] content of methyl ester of TPSO was 8.33% higher than diesel. This is again reconfirming the complete combustion of biodiesel blends.

[FIGURE 7 OMITTED]

[FIGURE 8 OMITTED]

[FIGURE 9 OMITTED]

Unburnt Hydrocarbon

The percentage variation in unburnt hydrocarbon for the various biofuels blends at the maximum load is shown in fig.10. It was observed that HC emission in the exhaust gas for all biodiesel blends was lower than that of the diesel (12 ppm). For the biofuels, deviation of HC emission ranges from 8.33% to 33.33% lower than that of diesel. In particular, HC emission for methyl ester of TPSO was 12.5% lower than diesel which is again due to higher oxygen content of biodiesel leading to better combustion.

[FIGURE 10 OMITTED]

Oxides of Nitrogen

In a naturally aspirated four stroke diesel engine N[O.sub.x] emissions are sensitive to [O.sub.2] content, adiabatic flame temperature and spray characteristics. Higher combustion chamber temperatures incase of biofuels has resulted in N[O.sub.x] formation, which is evident from higher exhaust temperature. The percentage variation in N[O.sub.x] for various biofuels blends at maximum load is shown in fig.11. It was observed that N[O.sub.x] emission for all biodiesel blends was higher than that of the diesel (537 ppm). Among the biofuels, maximum deviation of N[O.sub.x] emission was 13.97% for methyl ester of mahua oil. In particular, N[O.sub.x] emission of methyl ester of TPSO was 2.79% higher than diesel which was lower than that of other biofuels blends.

[FIGURE 11 OMITTED]

Smoke Number

The variation in smoke emission for the various biofuels blends at the maximum load is shown in fig.12. It was observed that smoke in the exhaust gas for all biodiesel blends was higher than that of the diesel (16 BSU). For the biofuels, deviation of smoke emission ranges from 21.50 BSU (Palm oil) to 80.70 BSU (Neem oil) higher than that of diesel. In particular, smoke emission for methyl ester of TPSO was 29.10 BSU only higher than diesel. This is due to its slightly heavier molecular structure and high viscosity compared to that of diesel.

Oxygen Content

The percentage variation in oxygen content in the exhaust gas for the various biofuels blends at the maximum load is shown in fig.13. It was observed that [O.sub.2] in the exhaust gas for all biodiesel blends was higher than that of the diesel (16.81%of vol.). For the biofuels, deviation of [O.sub.2] content ranges from 1.37% to 10.65% higher than that of diesel. In particular, [O.sub.2] content for methyl ester of TPSO was 3.81% higher than diesel.

[FIGURE 12 OMITTED]

[FIGURE 13 OMITTED]

Conclusion

Based on the above experiments, performance and emission characteristics of methyl ester of TPSO compared to that of diesel are summarized as follows:

* Brake thermal efficiency was only 0.6% lower.

* bsfc was only 3.45% higher.

* Volumetric efficiency was slightly lower (1%).

* Peak pressure was only 2.35% lower.

* EGT was 3.37% higher.

* CO emission was 23.08% lower.

* C[O.sub.2] emission was 8.33% higher.

* HC emission was 12.5% lower.

* N[O.sub.x] emission was 2.79% higher

* Smoke emission was 29.10 BSU higher than diesel.

Based on the above points, performance and emission characteristics of methyl ester of TPSO were significantly better than other biofuels blends considered in this study.

Hence, it is concluded that blend of 20% methyl ester of thevetia peruviana seed oil and 80% diesel could be used as a fuel for diesel engine for better performance with less emission when compared to other methyl esters considered in this study.

Acknowledgment

The authors gratefully acknowledge the equipment support extended by the World Bank under Technical Education Quality Improvement Programme (TEQIP). The authors also thank all faculty and supporting staff of Department of Mechanical Engineering for wholehearted support to complete this experiment in the Internal Combustion Engine Laboratory.

References

[1] Naik S.N., Meher.L.C, and Vidya Sagar.D., 2006, "Technical aspects of biodiesel production by transesterification--a review," Renewable and Sustainable Energy Reviews., 10, pp.248-268.

[2] Ramadhas A.S., Jayaraj.S, and Muralidharan.C., 2004, "Use of vegetable oils as IC engine fuels- a review," Renewable Energy., 29, pp.727-742.

[3] Barnwal B.K., and Sharma.M.P., 2005, "Prospects of biodiesel production from vegetable oils in India," Renewable and Sustainable Energy Reviews., 9, pp.363-378.

[4] Shailendra Sinha., and Avinash Kumar Agarwal., 2005, "Combustion characteristics of ricebran oil derived biodiesel in a transportation diesel engine," SAE Paper No. 2005-26-354.

[5] Suryawanshi.J.G., and Despande.N.V., 2004, "Experimental investigations on a pungamia oil methyl ester fuelled diesel engine," SAE Paper No.2004-280018.

[6] Naveen Kumar., and Abhay Dhuwe., 2004, "Fuelling an agricultural diesel engine with derivative of palm oil," SAE Paper No.2004-28-0039.

[7] Nagaraja, A.M., and Prabhukumar.G.P., 2004, "Characterization and optimization. of rice bran oil methyl ester for CI engines at different injections pressures," SAE Paper No.2004-28-0039.

[8] Balusamy,T., and Marappan,R., 2007, "Performance evaluation of direct injection diesel engine with blends of thevetia peruviana seed oil and diesel," Journal of Scientific and Industrial Research, 66, pp.1035-1040.

[9] Balusamy,T., and Marappan,R., 2008, "Focus on combustion characteristics of thevetia peruviana seed oil fueled in a direct injection diesel engine," International Journal of Energy Sources--Part (A)--2008--Accepted for publication.

[10] John B Heywood, Internal Combustion Engine Fundamentals, Automotive Technology Series (McGraw--Hill International Editions), Singapore, 1988.

[11] Annual Book of ASTM Standards (American Society for Testing and Materials, Philadelphia) 1994.

T. Balusamy* (1) and Dr. R. Marappan**

*Lecturer, Department of Mechanical Engineering, Government College of Engineering, Salem--636 011, Tamilnadu, India

** Director, Paavai Institutions, Pachal, Namakkal, Tamilnadu, India E-mail: [email protected]

(1) Corresponding author: E-mail: [email protected]

Table. 1. Properties of methyl ester of biofuels of various origins and
diesel

                         Methyl ester of oil (Biodiesel)

PROPERTY        Diesel               Nonedible Oil

                         TPSO    Jatropha   Pangumia   Mahua   Neem

Calorific       43200    42652   42250      42334      42062   41905
Value(KJ/Kg)

Specific        0.804    0.828   0.8157     0.8212     0.815   0.829
Gravity

Viscosity (at   3.9      6.5     4.84       6.4        4.8     6.8
40 [degrees]

Cetane number   49       51      48         50         47      50

Flash point     56       88      92         95         85      87
[degrees]C

Fire point      64       95      96         98         92      93
[degrees]C

Cloud point     -8       -6      -3         -5         -4      -6
[degrees]C

Pour point      -20      -18     -16        -17        -14     -16
[degrees]C

                         Methyl ester of oil (Biodiesel)

PROPERTY                         Edible Oil

                Corn    Palm    Cotton   Mustard   Sunflower

Calorific       41905   42857   42150    42102     41260
Value(KJ/Kg)

Specific        0.82    0.826   0.838    0.823     0.825
Gravity

Viscosity (at   4.5     5.3     5.87     5.6       52
40 [degrees]

Cetane number   51      48      50       47        48

Flash point     78      81      88       86        79
[degrees]C

Fire point      85      87      95       90        82
[degrees]C

Cloud point     5       8       -1       3         5
[degrees]C

Pour point      -2      -3      -7       -5        -3
[degrees]C

PROPERTY        Edible Oil   ASTM code

                Rice brain

Calorific       42125        D4809
Value(KJ/Kg)

Specific        0.828        D445
Gravity

Viscosity (at   5.8          D2217
40 [degrees]

Cetane number   47           D4737

Flash point     87           D92
[degrees]C

Fire point      96           D92
[degrees]C

Cloud point     2            D97
[degrees]C

Pour point      -8           D97
[degrees]C

Table 2: Engine Specifications

Particulars               Specifications

Make & Model              Kirloskar--TV1
BHP& Speed                5 Hp & 1500 rpm
Type of Engine            Direct Injection & 4S
Compression Ratio         16.5:1
Bore & Stroke             80 mm & 110 mm
Method of Loading         Eddy current dynamometer
Method of Starting        Manual Cranking
Method of Cooling         Water
Orifice diameter          20 mm
Type of ignition          Compression Ignition
Nozzle opening pressure   210 bar
Lube Oil                  SAE40