Experimental evaluation of soapberry seed oil biodiesel performance in CRDI diesel engine

Combustion study

In this combustion studies explained about the in cylinder pressure variations and the heat release rate variation on the engine during the operation at highest load with different biodiesel blends and diesel. From the Fig. 3 mentioned that the maximum pressure obtained at maximum load on the cylinder of 78.93 bar, 79.99 bar, 81 bar and 81.96 bar by 30BDSS, 20BDSS, 10BDSS and Diesel. Here increasing pressure based order maintained to mention the in cylinder pressure. Diesel have the highest peak pressure.

Cylinder Pressure differences on blending.

The individual biodiesel and their blends have lesser peak pressure than diesel. At maximum load, the fuel consumption is more, which leads to increase in the gas pressure on the cylinder¹⁶. Individual diesel have 42,000 kJ/kg of calorific value. This is highest calorific value on the fuels properties comparison. So this lead highest peak pressure during operation¹⁷. The biodiesel of soapberry seed have lesser evaporation and reduced evaporation than diesel because of their lesser calorific value and higher density. This will leads on the variations of the cylinder pressure¹⁸.

The influence of the biodiesel blends in heat release rates obviously point out in the Fig. 4. Here, 72.25 J/deg of higher heat release rate obtained by the diesel. 10BDSS blend have 68.32 J/deg, 20BDSS fuel have 65.06 J/deg, and 30BDSS fuel have 61.15 J/deg of heat release rate at greatest load. Lesser contribution of the biodiesel of soapberry seed in blending have higher heat release rate vice versa. The oxygen content available on the biodiesel of soapberry seed leads to reduction on the higher heat release rate¹⁹. The lowest heat relkease rate gained by the 30{ca2182fc8fed51dc37b95061ee48b5056cde1176732b225548c54a0c0156d303} of biodiesel blend. Because of biodiesel of soapberry seed blend’s higher density and viscosity are influence the combustion characteristics. Therefore, it lead to decrease the heat release rate²⁰.

Influence of biodiesel blends in heat release rate.

Performance analysis

In this performance analysis explained about the brake thermal efficiency and brake specific energy consumption variation on the engine during the various load condition with different biodiesel blends and diesel.

At 75{ca2182fc8fed51dc37b95061ee48b5056cde1176732b225548c54a0c0156d303} of load condition diesel have 25.98{ca2182fc8fed51dc37b95061ee48b5056cde1176732b225548c54a0c0156d303}, 10BDSS blend have 24.29{ca2182fc8fed51dc37b95061ee48b5056cde1176732b225548c54a0c0156d303}, 20BDSS fuel have 23.41{ca2182fc8fed51dc37b95061ee48b5056cde1176732b225548c54a0c0156d303}, and 30BDSS fuel have 22.52{ca2182fc8fed51dc37b95061ee48b5056cde1176732b225548c54a0c0156d303} of brake thermal efficiency. At full load, diesel have 30.10{ca2182fc8fed51dc37b95061ee48b5056cde1176732b225548c54a0c0156d303}, 10BDSS blend have 29.29{ca2182fc8fed51dc37b95061ee48b5056cde1176732b225548c54a0c0156d303}, 20BDSS fuel have 28.19{ca2182fc8fed51dc37b95061ee48b5056cde1176732b225548c54a0c0156d303}, and 30BDSS fuel have 27.82{ca2182fc8fed51dc37b95061ee48b5056cde1176732b225548c54a0c0156d303} of brake thermal efficiency. These brake thermal efficiency variations were mentioned in the Fig. 5. Efficiency increased with loads. Because of their calorific values of the blending, they produced lesser brake thermal efficiency when compared with diesel²¹. BDSS have more fatty acid²², Maximum participation of the biodiesel provide more reduction on the efficiency due to lesser viscosity, content of energy, density which lead to influence the evaporation of the fuel available in the cylinder during combustion^11,23.

Influence of biodiesel blends in BTE (Brake thermal efficiency).

Figure 6 describe about the brake specific energy consumption variations on the engine with different biodiesel blends at different loads. At 75{ca2182fc8fed51dc37b95061ee48b5056cde1176732b225548c54a0c0156d303} of load condition diesel have 8377.4 kJ/kW-hr, 10BDSS blend have 8794.49 kJ/kW-hr, 20BDSS fuel have 9628.67 kJ/kW-hr, and 30BDSS fuel have 10,462.8 kJ/kW-hr of brake specific energy consumption. Similarly at highest load, diesel have 6552.64 kJ/kW-hr, 10BDSS blend have 6917.59 kJ/kW-hr, 20BDSS fuel have 7230.41 kJ/kW-hr, and 30BDSS fuel have 7908.18 kJ/kW-hr of brake specific energy consumption.

Influence of biodiesel blends in BSEC (Brake specific energy consumption).

Diesel have the lowest brake specific energy consumption than blends. This follows the common trends of the brake specific energy consumption such as load and brake specific energy consumption are inversely proportional²⁴. These difference created by the lesser calorific values of the biodiesel of soapberry seed also higher amount of the fuel required to develop the similar amount of power^22,25.

Emissions analysis

In this emission analysis explained about the NOx emission, smoke opacity, carbon monoxide emission and hydro carbon emission on the engine during the operation at varieties of load with different biodiesel blends and diesel.

Figure 7 clearly express the influence of biodiesel blends for the NOx emission The temperature on the cylinder and supplied oxygen to the cylinder are the preferable response for the NOx emission. At 75{ca2182fc8fed51dc37b95061ee48b5056cde1176732b225548c54a0c0156d303} of load condition diesel have 1045 ppm, 10BDSS blend have 1080 ppm, 20BDSS fuel have 1108 ppm, and 30BDSS fuel have 1139 ppm of NOx emission produced. In the same way at 100{ca2182fc8fed51dc37b95061ee48b5056cde1176732b225548c54a0c0156d303} of load condition diesel have 1258 ppm, 10BDSS blend have 1286 ppm, 20BDSS fuel have 1300 ppm, and 30BDSS fuel have 1348 ppm of NOx emission produced. 30BDSS fuel have produced more NOx than other fuels because of the higher oxygen content available on the fuel. At higher loads increase in the pressure leads to the increase in the combustion temperature²³. During the phase of premixed combustion, more heat generated cause the more NOx emission^16,26.

Influence of biodiesel blends in NOx emissions.

The major influence on the smoke opacity by the various biodiesel blends and diesel clearly mentioned in the Fig. 8. At 75{ca2182fc8fed51dc37b95061ee48b5056cde1176732b225548c54a0c0156d303} of load condition diesel have 14.53{ca2182fc8fed51dc37b95061ee48b5056cde1176732b225548c54a0c0156d303}, 10BDSS blend have 13.39{ca2182fc8fed51dc37b95061ee48b5056cde1176732b225548c54a0c0156d303}, 20BDSS fuel have 12.50{ca2182fc8fed51dc37b95061ee48b5056cde1176732b225548c54a0c0156d303}, and 30BDSS fuel have 11.39{ca2182fc8fed51dc37b95061ee48b5056cde1176732b225548c54a0c0156d303} of smoke opacity. At full load, diesel have 18.52{ca2182fc8fed51dc37b95061ee48b5056cde1176732b225548c54a0c0156d303}, 10BDSS blend have 17.46{ca2182fc8fed51dc37b95061ee48b5056cde1176732b225548c54a0c0156d303}, 20BDSS fuel have 16.44{ca2182fc8fed51dc37b95061ee48b5056cde1176732b225548c54a0c0156d303}, and 30BDSS fuel have 15.38{ca2182fc8fed51dc37b95061ee48b5056cde1176732b225548c54a0c0156d303} of smoke opacity. From these observation produced that the smoke opacity have reductions at lesser loads and rises gradually in maximum loads. At greater load, fuel supplied to the system is higher which create rich mixture in the chamber, these cause the smoke in the tail pipe²¹. Because of the oxygen content supremacy in the 30BDSS blend produce healthier combustion; these will reduce the smoke opacity than other considered fuels^10,27.

Influence of biodiesel blends in smoke opacity.

The most important effect on the CO emission through the different biodiesel blends and diesel at different load clearly mentioned in the Fig. 9. At 75{ca2182fc8fed51dc37b95061ee48b5056cde1176732b225548c54a0c0156d303} of load condition diesel have 0.77{ca2182fc8fed51dc37b95061ee48b5056cde1176732b225548c54a0c0156d303}, 10BDSS blend have 0.73{ca2182fc8fed51dc37b95061ee48b5056cde1176732b225548c54a0c0156d303}, 20BDSS fuel have 0.70{ca2182fc8fed51dc37b95061ee48b5056cde1176732b225548c54a0c0156d303}, and 30BDSS fuel have 0.66{ca2182fc8fed51dc37b95061ee48b5056cde1176732b225548c54a0c0156d303} of CO emission. Similarly at 100{ca2182fc8fed51dc37b95061ee48b5056cde1176732b225548c54a0c0156d303} of load condition diesel have 0.92{ca2182fc8fed51dc37b95061ee48b5056cde1176732b225548c54a0c0156d303}, 10BDSS blend have 0.89{ca2182fc8fed51dc37b95061ee48b5056cde1176732b225548c54a0c0156d303}, 20BDSS fuel have 0.84{ca2182fc8fed51dc37b95061ee48b5056cde1176732b225548c54a0c0156d303}, and 30BDSS fuel have 0.81{ca2182fc8fed51dc37b95061ee48b5056cde1176732b225548c54a0c0156d303} of CO emission. These CO emission created by the incomplete combustion by reason of higher viscosity, spray penetration in untimely, temperature inside the cylinder, applied fuel involvement and the ratio of the hydrocarbon involved in the combustion²⁸. Blending have lesser CO emission. Especially 30BDSS have lowest CO emission than other fuels at highest load. These all are because of the temperature of the combustion, incomplete mass burnt rate in maximum load^22,29.

Influence of biodiesel blends in CO emissions.

Figure 10 noticeably express the influence of biodiesel blends for the HC emission. At 75{ca2182fc8fed51dc37b95061ee48b5056cde1176732b225548c54a0c0156d303} of load condition diesel have 12 ppm, 10BDSS blend have 11 ppm, 20BDSS fuel have 11 ppm, and 30BDSS fuel have 10 ppm of HC emission produced. In the same way at 100{ca2182fc8fed51dc37b95061ee48b5056cde1176732b225548c54a0c0156d303} of load condition diesel have 13 ppm, 10BDSS blend have 12 ppm, 20BDSS fuel have 12 ppm, and 30BDSS fuel have 11 ppm of HC emission produced. Increase in load lead to decrease in HC emission through the enhancing of the combustion efficiency with load augmentation. 30BDSS blend have lower HC emission than other fuels in all loads. The presence of more biodiesel not much affect the HC emission in tail pipe because of the better air fuel ratio obtained during the combustion in combustion chamber at the time of combustion³⁰. Higher fatty acid¹⁵ contain biodiesel have more oxygen content it help to improve the combustion with lesser HC emission²³.

Influence of biodiesel blends in HC emissions.