Development of Biofuel for Diesel Engines of the Fishing Vessels from Coconut Oil

: Biofuels are made from vegetable oils and animal fats, which have great potential as an alternative to traditional fuels to reduce environmental pollution. In addition to functioning as an oxygen booster for combustion, biofuels are renewable. Moreover, another advantageous characteristic of biofuels is the ease of mixing them with traditional fuel, without any need for complicated equipment. However, there are many factors affecting the application of biofuel to engines such as the geography of each country or region, its climate, and ingredients to serve human needs for food, while biofuels are developed from many different sources of raw materials. Vietnam is a country located in the tropical monsoon region, thus having great potential in developing raw materials for biofuel production. The main raw material sources, for now, are fish fat, jatropha oil, and coconut oil. Among them, coconut oil is considered one of the abundant raw materials, because the natural and social conditions in Vietnam are suitable and favorable for the growth of coconut trees. In this paper, the development of coconut oil production will be presented, as well as the method of using coconut oil (C10) as fuel for diesel engines of fishing vessels. The experimental research results show that the amount of soot emission from diesel engines using C10 fuel is lower compared to that of engines using traditional fuel (DO).


Introduction
Nowadays, the demand for fuel and petroleum products is strongly rising for internal combustion engines, leading to many problems that need to be solved such as fuel being increasingly exhausted; environmental pollution due to engine exhaust is increasing, leading to many negative consequences affecting humans' health and social development [1,3]. To overcome these limitations, many technological measures and solutions have been proposed and applied worldwide to ensure energy security and reduce environmental pollution [4,8,12]. Among the alternative energy sources to petroleum currently in use such as solar energy, wind energy, etc., research biofuels used for internal combustion engines are of primary concern, due to their suitable characteristics and the availability of raw materials. According to the forecast of the International Energy Agency (IEA), the energy development trend * Corresponding author: nghiamaiduc@gmail.com worldwide by 2050 will be made up of 23% of diesel (DO), 27% of biofuels, the rest are other fuels [5,7,13]. Biofuels are derived from vegetable oils and animal fats, which have great potential as a fuel to replace traditional fuels. In addition to functioning as an oxygen booster for combustion, biofuels are also renewable. In addition, an advantageous feature of biofuels is that it is easy to blend with conventional fuels, without the need for complicated equipment. The main sources of raw materials for biofuel production are vegetable oils, which are mainly extracted from plants with high oil content such as Soybean oil, Rapeseed oil in Europe; Sunflower oil in the USA; Coconut oil, Palm oil, Jatropha oil in Asia [3,5,9]. However, many factors affect biofuels' application to internal combustion engines, such as the geography of each country -region; climate; ingredients to serve human food needs, while biofuels are produced using different materials. Vietnam is a country located in the tropical monsoon region, with great potential in developing raw materials for biofuel production. The main sources of raw materials at present time for production are basa fat, jatropha oil, and coconut oil. Among them, coconut oil is considered one of the abundant raw materials because the natural and social conditions in Vietnam are suitable and favorable for the development of coconut trees [5,14]. According to the Asian Pacific Coconut Community (APCC), coconut trees are grown in 93 tropical countries, and the coconut growing area of the countries in the association accounts for 85.05%. In particular, Vietnam's average coconut yield is always higher than the average of APCC countries. Currently, Vietnam has grown nearly 170 thousand hectares of coconut trees and ranks high in terms of coconut oil production and coconut oil exports in the world ( Figure 1, Table 1) [6,13].  Thailand 206 1 From the advantages of Vietnam's coconut oil source, the analysis above shows that using a mixture of diesel -coconut oil as fuel for diesel engines will minimize the dependence on non-renewable fuels and reduce environmental pollution. However, some Physicochemical properties of the diesel-coconut oil mixture such as viscosity, surface tension, density, and volatility are not like those of diesel oil (DO), so when used in diesel engines, they do not achieve high efficiency and result in low mixing ratio as shown in Figure 2 [5][6]12]. Therefore, the fuel mixture will be heated to have suitable readings as fuel for fishing boats' diesel engines.

Fuel
Coconut oil has a higher viscosity than diesel oil, so when mixing coconut oil into diesel oil, it needs to be heated to about 80 0 C, to reduce the viscosity of the mixture closer to that of DO fuel. Table 2, Figure presents the chemical composition and parameters of coconut oil compared with diesel oil and the parameters of the diesel-coconut oil mixture at different mixing ratios [11]. In this study, a mixture of C10 (10% coconut oil and 90% diesel oil) was used.

Diesel engines of fishing vessels
Based on the data on diesel engines of fishing boats being used in Vietnam [2,15], the paper in this study uses the Yanmar 4CHE engine of Yanmar Company, Japan, as the testing engine. Engine parameters are given in Table 3.

Experimental setup
The article presents the experimental research method, and the experimental layout diagram is shown in Figure  4. A diagram of the equipment system which mixes diesel fuel -and coconut oil with heating by the engine's coolant water before supplying fuel to the engine is shown in Figure 5. The experimental procedures are performed according to the Japanese engine experimental cycle [10].

Measuring equipment:
The hydraulic brake Dynomite 13: The hydraulic brake Dynomite 13 of Land Sea Company -the USA and the attached measuring device ( Figure 6) are used to cause load and measure torque (load), and power. Loading the engine is done through torque adjustment in the hydraulic brake (Mb): The engine torque (Me) will be equal to the sum of the torque calculated on the dynamometer and the torque in the hydraulic brake:   3 Research results and discussion Figure 8 shows the test results of a diesel engine when using a mixture of fuel, diesel -coconut oil (C10). The engine power is reduced, leading to a higher fuel consumption rate than that of the engine using traditional diesel fuel. However, in Figure 9, the soot emission of engines using C10 is lower than that of diesel fuel. This is a favorable factor to reduce pollutant emissions from diesel engines because coconut oil contains lower sulfur and carbon mass, and it minimizes the amount of soot, resulting in reduced soot emissions. It is because the amount of soot emitted after the intake valve works is the difference between the amount of soot formed and the amount of soot oxidized.

Conclusion
When using a mixture of fuel, diesel -coconut oil (C10) for diesel engines of fishing vessels, it has higher fuel consumption and lower soot emissions compared with the engine using traditional fuel. On this basis, it is possible to figure out solutions to improve the combustion progress of diesel-coconut oil mixture to increase power, reduce fuel consumption for the engine, and contemporaneously reduce emissions (soot emissions). Hence, the development of biofuel for diesel engines of fishing vessels from coconut oil will reduce environmental pollution and the use of renewable raw materials.