Effect of Injection Pressure on the Performance and Emission Characteristics of CI Engine using Canola Bio-Diesel

Effect of Injection Pressure on the Performance and Emission Characteristics of CI Engine using Canola Bio-Diesel

1 Anbarasu. A, 2 Muturaman. V, 3 Suthan. R, 4 Poyyamozhi. N

1,2Professor, Dept. of Mechanical Engineering, Panimalar engineering college, Chennai, India

3,4Asst.Professor,Dept.of Mechanical Engineering,Panimalar engineering college,Chennai, India

Abstract- Due to the increasing demand for fossil fuels and environmental threat, a number of renewable sources of energy have been studied worldwide. An attempt is made to assess the suitability of vegetable oil for diesel engine operation, without any modifications in its existing construction. One of the important factors which influence the performance and emission of diesel engine is fuel injection pressure.The objective of this paper is to conduct the experiment to study the performance and emission characteristics of a single cylinder, 4 stroke, constant speed, and water cooled diesel engine running with diesel and blends of canola biodiesel at four fuel injection pressures of 180 bar, 200 bar, 220 bar and 240 bar. The injection pressure was changed by adjusting the fuel injector spring tension.The performance and emission characteristics were presented graphically and concluded that increase in injector opening pressure increases the brake thermal efficiency and reduces unburned hydrocarbon and Noxemissions significantly.

Key words: Diesel engine, injection pressure, canola oil, performance, emission, combustion characteristics

1. INTRODUCTION

   Developing countries are required to meet their petroleum demand on depend on other countries.Due to increase in population of vehicles the energy demand is increasing day by day. Diesel engines are chosen for transportation vehicles because of theirits

   intrinsic advantages of better fuel economy and high part load efficiency. With the rising

   cost of petroleum a major part of foreign exchange is utilized for importing petroleum. For this reason the countries are forced to search for substitute fuel for diesel engines. The straight vegetable oils can be used as a alternate fuel in diesel engines, but it have some disadvantages like gumming, sticking of piston and cylinder due to heavier hydrocarbon chain[1].The another important is viscosity of these oils

   also compared to that of diesel which leads to atomization and combustion problems. Preheating oil is the one method to reduce the viscosity [2] using straight vegetable oilsas a fuel. The results with preheating and without preheating show that with preheating of straight vegetable oil gives better

   performance compared to that of diesel. Splitting of the heavier compounds by a chemical process is the one more way of reducing the viscosity of oil. In this

   process the oil reacts with alcohol (methyl or ethyl) in presence of a catalyst (sodium hydroxide/ potassium hydroxide) and produces a product called as methyl or ethyl ester, which has properties comparable to that of diesel, and it is known as Biodiesel.This process is known transesterification. The biodiesel produced from canola with a yield of 95% using methanol and potassium hydroxide as a catalyst.The viscosity of the oilreduced to

   5.38 Cst(at 40°C) by using transesterification and the flash point was 172°C. The use of vegetable oils and their methyl esters in a single cylinder diesel engine were studied [3]. They have used raw sunflower, cottonseed, soybean oils and their methyl esters. Their results specify a reduction in NOx emission and methyl esters are better than raw oils due to their intrinsic property of high density, higher viscosity, gumming and lower cetane number. The tests on a single cylinder C.I. engine was conducted with 3 different biodiesels viz methyl esters of honge, jatropha and sesame are reported[4]. All the fuels gave a considerably lower efficiency. HC and CO emissions were slightly higher and NOx emission decreased by about 10%. They have reported that these oils can be used without any major engine modifications.The nonedible vegetable oils such as putranjiva, karanja and jatrophaare used as fuel in a single cylinder diesel engine [5]. One of the chemical process called as degumming are used to remove the impurities by using concentrated phosphoric acid to get better its viscosity, cetane number and combustion characteristics.They have reported that jatropha gives better performance. Without any engine modification the test were conducted. The forecast of biodiesel production from vegetable oils in India were discussed [6], the yield and production cost of various methyl esters also given. Compare to petroleum fuels the methyl esters of nonedible oil are much cheaper. Depending on the engine size and type of combustion system employed the fuel injection pressure varies from the range of 200 to 1700 atmin a standard diesel engine [7]. The fuel diffusion distance turns into longer and the mixture formation of the fuel andalso combustion period became shorter when air was improved as the injection pressure becomes higher [8].

   In this study, diesel oil and the blends of Canola Biodiesel at four fuel injection pressures of 180 bar, 200 bar, 220 bar and 240 bar were taken as fuels in a four-stroke single cylinder diesel engine. The engine speed was taken in a range of

   1500 rpm. The engine performances and the emissions were considered.

2. MATERIALS AND METHODS

   2.1 Preparation of biodiesel

   Transesterification process is one of the method to convert canola oil into its methyl ester. In this process involves the triglycerides of Canola oil is allowed to react with methyl alcohol along with NaOH catalyst to produce glycerol and fatty acid ester. The ester has lower viscosity because the molecular weight of ester molecule is approximately one third that of oil molecule [9]. Due to low cost and physicochemical advantages with triglycerides and alkalies the methanol is used and also it is easily dissolved in it. When compare to acid catalyzed transesterification process the Alkali catalyzed transesterification process is faster one and it is most commonly and commercially used. a known value of (800 ml) canola oil mixed with 200 ml methanol along with 1.5g of sodium hydroxide and this solution was poured in a round bottom flask. This mixture were stirrer well until the ester formation began at the same time the mixture is heated to 70oc.

   Then it was allowed to cool overnight without stirring. Two layers are formed. The bottom layer consists of glycerol and top layer was the ester.

   2.2. Experimental Setup and Procedure

   The performance tests for the stable Diesel-biodiesel are carried out on a computerized single cylinder four stroke direct injection variable compression ratio engine. The Table shows the specification of the engine. No modification or alteration has been made in the engine. The experimental setup consists of a variable compression ratio engine is coupled to an eddy current dynamometer.The specification of the engine is shown in Table1. During the engine test in order to collect, store and analyze the data a computerized data acquisition system is used. To measure cylinder gas pressure and the corresponding crank angleKistler piezoelectric pressure transducer and a crank angle encoder are used. A load cell is connected to eddy current dynamometer to measure the apply load on the engine. To measure the fuel flow two infra red optical sensors fixed to a burette used and an air flow sensor measure the inlet air flow rate, to measure inlet air and exhaust gas temperatures thermocouples are used. the exhaust gas constituents such as CO, HC, NOare measure by a AVL DIGAS analyzer and the smoke is measured using the AVL smoke meter.The experiments are conducted at the compression ratio of 17.5 and the results are recorded under steady state conditions.

   Table 1.Specification of the engine.

   The fuels which have been used in this study are: Commercial diesel (D) and a blend of 20% biodiesel (B20), 40% biodiesel (B40), 60% biodiesel (B60) and 100% biodiesel (B100). The main properties of the test fuels are given in Table2.

   Table 2. Properties of Canola biodiesel

   Acidity as mg of KOH/gm	0.01
   Density (kg/m3)	886.5
   Viscosity at 40 ºC in cst	5.38
   Gross calorific value (KJ/kg)	38758
   Cetane number	48
   Sulfur content (mg/L)	< 50ppm
   Flash point	172oc
   Fire point	186oc

   The investigation was conducted at constant speed of 1500 rpm. The load applied to engine is through eddy current dynamometer and strain gauge was used to measure the load. The fuel injection pressure was set to 180 bar, 200 bar,220 bar and 240 bar. By adjusting the injector spring tension the Injection pressure was changed. The air flow was measured with an air manometer surge tank set which has orifice diameter of 20 mm.A blend of 20% biodiesel and 80% diesel (by volume) is denoted by B20. The performance parameters, efficiency and brake specific fuel consumption (BSFC) are compared.

3. RESULTS AND DISCUSSIONS

   3. 1. Performance characteristics

   1. Brake Thermal Efficiency (BTE)

      At full load it was found that the highest brake thermal efficiency was obtained at 240 bar but this was decreases for lower pressure due to its lower calorific value.at higher injection pressure more quantity of fuel was injected so that the brake thermal efficiency is increased. The value of BTE is maximum at 240bar because during injectionfine spray formed and improvedatomization is shown in Figure 1.The brake thermal efficiency at all loads in injection pressure of 180, 200, 220 and 240 bar are shown in Figure-1.The reason for increasing BTE when increasing the injection pressure due to the reduction in the viscosity, improvedatomization and bettercombustion. the highest value of brake thermal efficiency for canola oil at240 bar pressure is 31.3% and it is close to diesel fuel efficiency (31.26%) at full load condition [13][14]

      40

      BTE in %

      30

      20

      Brake Power	3.7 kW
      Speed	1500 rpm
      mpression ratio	17.5 (Variable)
      Bore	80 mm
      Stroke	110 mm
      Ignition	Compression ignition
      Cooling	Water cooled
      oading System	y current dynamometer

      10

      0

      0 Bra2ke Power in4kW

      180b

      ar

      6

      Figure 1. Load VsBrake Thermal Efficiency for differentinjection pressures of biodiesel

   2. Brake Specific Fuel Consumption

   1000

   Nox in ppm

   The The deviation of brake specific fuel consumption at different loads at different injection pressure 180, 200, 220 and 240 bar are given in Figure-2. The effect of injection pressure on brake specific fuel consumption was found decreasing at the full loadin the order 180-200-220-240 bar. When fuel injection pressure is increased the BSFC decreases and BTE increases .It is found that specific fuel consumption deteriorating with increasing injection pressure for a heavy duty direct injection diesel engine [10].Also that the brake specific fuel consumption found increasing with injection pressure both in fixed load-variable engine speed and fixed engine speed-variable load tests [11]

   BSFC (Kg/KWhr)

   0.8

   0.6

   1500

   180bar

   0

   0

   1 Brake2Power3in kW 4

   5

   500

   Figure 4. Load VsNOx emission for differentinjection pressures of biodiesel

   0.4

   0.2

   0

   0

   180bar

   200

   Brak2e Power i4n kW 6

   3.2.3 HC emissions

   The HC emission for canola biodiesel is found lower than the diesel fuelfrom Fig.5,this is because due the heavier hydrocarbon particles that are present in diesel fuel increase HC emissions. The HC emission deviation in the exhaust gases at various injection pressure of 180,200,220 and 240 bar at all the loads are shown in fig.5 and it was found that increasing trend in the order 200-180-240-220 bar injection

   Figure 2. Load VsBrake specific fuel consumptionfor differentinjection pressures of biodiesel

   1. Emissions characteristics

      1. CO2 emissions

         co2 emision (%)

         The percentage of CO2 in the exhaust gas was lower in the injection pressure 240 bar shown in figure3. From the graph it was observed that the percentage of CO2 is in decreasing trend at all the loads in the order of 220-180- 200-240 bar fuel injection pressure.

         10

         8

         6

         4

         2

         180bar

         200 bar

         0

         0

         Bra2ke Power in4kW

         6

         Figure 3. Load VsCO2 emission for differentinjection pressures of biodiesel

      2. NO emissions

   The main reason for NOX development isdependent upon the availability of oxygen during combustion and cylinder gas temperature. In The NOX emission for the light duty direct injection diesel engine was found lowest at 200 bar injection pressure from this study and it was found that decreasing in the order 240-220-180-200 bar injection pressure[12] at all loads as shown in Figure-4.

   pressure.

   25

   20

   HC in ppm

   15

   10

   180bar

   5 200 bar

   220 bar

   0

   0 Bra2ke Power in4kW 6

   Figure 5. Load VsHydro carbon emission for differentinjection pressures of biodiesel

4. CONCLUSIONS

For electrical power generation and agricultural water pumping the light duty diesel engines ar normally used. From this experimental study, the effect of injection pressure on the engine performance parameter such as brake thermal efficiency found increasing trend and brake specific fuel consumption found decreasing trend in the order of 180-200-220-240 bar injection pressure at full load. On the other hand at 240 bar injection pressure has higher brake thermal efficiency and lower brake specific fuel consumption was obtained and the percentage of improvement was very less.

The increasing injection pressure gave insignificant effect on engine performance.

At full load CO and NOx emissions were found the lowest

2

at 240 bar and 200bar and HC emission were found lowest at 200 bar.

Fuel economy is essential for engine andthe environmental protection is more important than fuel economy. Due to this reason the decreasing emission is the primary concern which demands moderate injection pressure for a light duty diesel engine.

REFERENCES

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[2]. A.K. Agarwal, K. Rajmanoharan: Experimental investigations of performance and emissions of Karanja oil and its blends in a single cylinder agricultural diesel engine, Applied Energy 86 (2009) pp106112.

1. RecepAltin, SelimCetinkaya, HuseyinSerdarYucesu: The Potential of UsingVegetable Oil Fuel as Fuel for Diesel Engine, Energy Conversion & Management 42(2001) 529538.

2. N.R.Banapurmath, P.G.Rewari, R.S.Hosmath :Performance and emissioncharacteristics DICompression Ignition engine operated on Honge, Jatropha andsesame oil methyl esters, Renewable Energy 33(2008) 19821988.

3. S.K.Haldar, B.B.Ghosh, A.Nag: Studies on the comparison of performance andemission characteristics of a diesel engine using three degummed nonediblevegetable oils,

   Biomass and Bioenergy 33 (2008) 10131018

4. B.K.Barnwal, M.P. Sharma: Prospects of BiodieselProduction from Vegetable Oilsin India,

   Renewable & Sustainable Energy Reviews 9 (2005) 363378

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6. Seang-wock Lee, Daisuke Tanaka, Jin Kusaka, YasuhiraDaisho. 2002. Effects of diesel fuel characteristics on spray and combustion in a diesel engine. JSAE Review. 23: 407-414.

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   :A review , BioresTechnol, 70, pp.1-15.

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