EXPERIMENTAL ANALYSIS OF CASTOR OIL AND DIESEL OIL MIXTURES IN A 4-STROKE COMPRESSION COMBUSTION ENGINES

The production of hydrocarbon fuels shows a downward trend which forces people to look for alternative renewable fuels such as biodiesel from vegetable oil. One solution that can be applied in the use of biodiesel mixed with castor oil. The purpose of this study was to determine the effect of using a mixture of castor oil on the performance of diesel engines. The method used in this experiment is testing it directly on a diesel engine. Experiments were carried out on machines with a load of up to 4000 watts by mixing pure diesel fuel with castor oil to produce biodiesel B10, B20, and B30 as fuel. The results showed that the use of castor oil biodiesel tends to be lower than diesel oil, the torque produced by B20 17,59 N.m is greater than diesel oil, and the thermal efficiency of B20 17,04 % and SFC B20 is 470,2 gr/kW.h more economical than diesel oil. B20 provides better performance values for diesel engines and this is the right solution to be an alternative fuel other than diesel oil .


INTRODUCTION
The territory of Indonesia which is traversed by the equator makes it a country with a tropical climate or hot and humid climate [1] and the intensity of rain and sunlight always makes the soil fertile and overgrown with various kinds of natural vegetation including jatropha [2]. The advantage of the jatropha plant is that the seeds are inedible so the development of jatropha as an alternative fuel will not cause food problems in the future, another advantage is that the seeds of the jatropha plant produce a lot of oil (about 50%) and the production costs are very cheap [3]and the most The main thing is that this oil contains much lower carbon emissions than other vegetable oils (reducing greenhouse gas emissions by up to 75%) [4].
The process of producing castor oil into biodiesel is using transesterification, this process is commonly referred to as a chemical process which aims to separate the oil and water contained in cas-tor oil so that the viscosity of the resulting oil can be lower and ultimately can be used to make bio-diesel [5]. In the transesterification process, catalysts are usually used, the use of the catalyst to speed up the reaction rate, several studies have used vegetable oils such as biodiesel production from palm oil milf effluent (pome) [6] biodiesel from corn oil [7], biodiesel from microalgal [8], biodiesel produc-tion from waste cooking oil [9], all of which use the transesterification method (using a catalyst, NaOH, and Methanol).
To test whether a fuel is feasible or not, it can be done in two ways, namely by testing the fuel properties according to those stipulated by the Ministry of Energy and Mineral Resources, such as the viscosity and density of the fuel [10] and by conducting direct testing on the engine to see the perfor-mance produced each time. variety of biodiesel fuels used [11]. By looking at the large potential of castor oil to become biodiesel, it is necessary to carry out an in-depth study related to the feasibility of biodiesel used in engines.

Characteristics of Biodiesel Castor Oil and Diesel Oil
Previously it was stated that one of the advantages of biodiesel compared to diesel oil is that the cetane number value of diesel oil is around 51 but the heating value of biodiesel is still below that of diesel oil but with the fact that the need for new energy, especially those related to fuel, is very urgent (oil prices earth tends to rise and petroleum reserves are depleting) so that this study of biodiesel with its ad-vantages and disadvantages still needs to be further developed [12]. For the references used, many scientific publications are taken from ScienceDirect [13] and Google Scholar [14,15]s which have the same scope as the research conducted.
In engine testing, data is collected that aims to determine the performance of a diesel engine. The data taken during the test includes voltage, current and time values. There are four variations of fuel used, namely diesel oil, 90% diesel oil + 10% Biodiesel Castor oil (B10), 80% diesel oil + 20% Bio-diesel Castor oil (B20), and 70% diesel oil + 30% Biodiesel Castor oil. (B30). This test uses 20 ml of fuel for each variation. Starting from setting the engine speed as many as 3 variations, namely 800 RPM, 1000 RPM, and 1200 RPM. Then it is given a load up to the maximum load (4000 Watt). After the data is obtained in the form of current, voltage and time values, calculations are carried out based on the formula previously described to obtain the value of power (kW), specific fuel consumption (kg. kW/ h), torque (Nm), and thermal efficiency (%).

Machine Test Preparation
The test was carried out using a Yanmar TF 85 MH 4-stroke diesel engine [16] with the technical specifications shown in Table 1. For schematic testing of fuel variations on the engine can be seen in Figure 1.

Visual Analysis on Trial Machine
Visual analysis is an observation made directly on the machine to pre-determine that an experiment is feasible. Visual analysis of the engine for pure diesel fuel variables where the condition of the engine is running normally about sound and vibration which is fairly reasonable. In the sample of biodiesel fuel mixed with castor oil B10, the engine condition is still running normally where sound and vibration are still within reasonable limits. Then on the B20 fuel sample, the engine condition continues to run normally at all engine speeds as in the previous fuel sample. Furthermore, in the B30 fuel sample, the engine condition was running normally, but with the addition of the occasional load, the engine detonation occurred and the vibrations were slightly more vibrating compared to the previous condition. Detonation can be interpreted as a knock or pre-ignition [17]. For testing of fuel samples to pure biodiesel, this was not continued because during the experiment on the B40 fuel sample, the engine conditions were not normal conditions where the engine stalled and an explosion occurred during combustion and the engine vibration was large and unnatural so that the test not worth doing.

Diesel Engine Performance Testing Process
The next step is to test the fuel samples on the engine, in this study using a YANMAR TF 85 Diesel engine [16]. The process of testing castor oil biodiesel is carried out by injecting fuel into the available fuel tank, the condition of the engine fuel tank must be made clean of other fuels so that the castor oil biodiesel is not mixed with other fuels. Start the engine is done manually by turning the diesel engine crank lever clockwise while raising the clutch. After the machine is turned on, wait about 5 minutes then set the engine Rpm as desired (800 Rpm, 100 Rpm, and 1400 Rpm) then sequentially set the lights on the load of 1000, 2000, 3000, and 4000 watts. Setting the amount of fuel consumption is 20 ml, and the last step is to record the amount of current obtained at each step and calculate the amount of time the fuel is consumed. The fuel testing scheme for the engine can be seen in Figure 2. Test results data and calculation of Power, SFC, Torque, and Thermal Efficiency values for each variation of fuel can be seen in table 2 for diesel oil fuel, table 3 for B10 fuel, table 4 for B20 fuel, and table 5 for B30 fuel.

Comparative Analysis Between SFC vs Load
The engine performance parameter with the ratio between fuel consumption and load at each time unit is specific fuel consumption. To show the effect of increased power on fuel consumption on the results of a comparative analysis between pure diesel fuel variations, B10, B20, and B30 at 800 RPM rotation will be presented in graphical form. for comparison of SFC vs Load on three variations of engine speed can be seen in Figure 3. ) shows a comparison between pure diesel fuel and several other fuels such as B10, B20, and B30 at 800 RPM rotation. Seen at a maximum load of 4000 watts, the largest SFC value is found in pure diesel fuel, which is 849.509 gr/KWh, while the smallest SFC value is found in the B20 fuel variation, which is 683.574 gr/KWh. Likewise, up to the minimum fuel load, biodiesel mixed with castor oil has a more efficient fuel consumption rate, especially B20, followed by B10 and B30, compared to using pure diesel fuel. Figure 3b) with the engine speed of 1000 RPM, shows the SFC value of pure diesel which is 680.689 gr/kWh at a maximum load of 4000 watts. While the biodiesel fuel mixed with castor oil variation B20 produced the lowest SFC value of 518.053 gr/kWh, followed by B10 fuel which was 542.081 gr/kWh then B30 of 547.343 gr/kWh. So that the use of biodiesel fuel mixed with castor oil has a consumption level that is still more efficient than the use of pure diesel fuel at 1000 RPM engine speed. In Figure 3c) a 1200 RPM rotation graph compares the SFC value on pure diesel fuel to produce a value of 1124.902 gr/kWh at a minimum load of 1000 watts and a maximum load of 4000 watts of 580.645 gr/kWh. Then in biodiesel fuel, a mixture of castor oil type B20 produced the lowest SFC value of 470.181 gr/kWh at a maximum load of 4000 watts, followed by B10 which was 530.460 gr/kWh, then B30 with an SFC value of 524.492 gr/kWh. It can be seen in the graph above that fuel consumption at 1200 RPM rotation of biodiesel fuel mixed with castor oil still has a more efficient consumption value when compared to the use of pure diesel fuel. The amount of loading and the amount of engine rotation greatly affects the power of the engine as a whole from the results of the SFC graph with relatively high total fuel consumption when the engine power is at the lowest value, but the greater the power, the lower the fuel consumption level so that the use of low SFC indicates high efficiency.

Comparative Analysis Between Torque vs Load
One of the benchmarks for determining the quality of engine performance according to the fuel used is to look at the amount of torque produced, as in the previous SFC comparison analysis for the analysis results presented in graphical form in Figure 4. In Figure 4a) when the 800 RPM engine rotates, the torque value continues to increase from a minimum load of 1000 watts to a maximum load of 4000 watts, where the highest torque is at maximum load, namely fuel type B20 of 8.72 N.m and the lowest torque at maximum load is B30 of 7 .95 Nm. Likewise, up to a minimum load, affects the performance of the engine so that the power produced is different for each rotation ratio and load on the same fuel variation. Figure 4b) shows a graph of the torque comparison at 1000 RPM where the largest torque value is the B20 fuel variation of 13.91 Nm at a maximum load of 4000 watts, while the smallest torque is the pure diesel fuel variation of 4.23 Nm at a minimum load, different from the previous rotation where the lowest torque value was at the B30 fuel variation with the same maximum load, while at 1000 RPM pure diesel fuel had the lowest torque value from minimum load to maximum load.  Figure 4c) the torque comparison graph at 1200 RPM does not change significantly from the previous graph where the largest torque value is still on the B20 fuel variation, which is 19.59 Nm with a maximum load of 4000 RPM while the smallest torque value is still on a variety of fuel pure diesel of 5.15 Nm at a minimum load of 1000 RPM. It can be seen that the engine speed and the amount of load applied can affect the value of torque, the greater the rotation and the amount of load given to the engine, the higher the performance and power produced by the engine. If we look at all the comparative charts for each engine speed, it can be seen that the use of biodiesel fuel mixed with castor oil B20 is capable of producing better power and performance compared to other types of fuel.

Comparative Analysis Between Thermal Efficiency vs. Load
Thermal efficiency is one of the parameters of engine performance to determine how much power is generated from the fuel used. as in the thermal efficiency comparison graph with the load in Figure 5. Figure 5a) shows a graph of the comparison of thermal efficiency with the load at 800 RPM engine speed, it can be seen that the smallest value at a minimum load of 1000 watts is found in pure diesel fuel variations, namely 5.10% while the largest value is produced by the B20 variation, namely of 6.18% and continues to experience an increase in the value of thermal efficiency as the amount of load given to the engine increases and the B20 variation fuel still produces the largest value, namely 11.03% and the lowest value in pure diesel, namely 8.72% at the total load used. same 4000 watts. Figure 5b) shows a comparison graph at 1000 RPM engine speed, it can be seen that it is the same as in the previous graph where the value of thermal efficiency continues to increase along with the increase in the amount of load placed on the engine, namely the greatest efficiency value is found in the B20 fuel variation of 15.47% at a maximum load of 4000 watts and the smallest thermal efficiency value is found in variations of pure diesel fuel, namely 6.81 at a minimum load of 1000 watts.  Figure 5c) 1200 RPM rotation, the graph for comparing thermal efficiency with load does not show a significant difference from the graph for the previous round, where B20 fuel still produces the largest value, namely 17.04% at maximum load and pure diesel produces the smallest value. namely 6.58% at the minimum load and the value of thermal efficiency for each fuel continues to increase as the amount of load given to the engine increases. It can be seen from the previous SFC graph that pure diesel has a higher consumption level, but in comparison to the thermal efficiency value, pure diesel produces a smaller value than other fuels. After all, even though the mixture of fuel and air injected is large, it can be said that the energy of the fuel is large enough cannot be a benchmark that the energy generated in the machine will also be large because not all of the energy that is converted will become mechanical energy. And the power generated by the engine will be greater if the energy converted is good enough.

CONCLUSION
From the results of the engine performance calculation above, it can be seen that the lowest SFC is B20 fuel with a value of 470.2 gr/kW.h, which is more efficient than SFC Diesel fuel, which is 1452.4 gr/kW.h. The highest Torque can be seen in the B20 fuel sample with a value of 17.59 N.m, this is better than the Torque of Diesel fuel which is 2.98 N.m. The highest thermal efficiency (ηth) value is also found in the B20 fuel sample, which is 17.04%, far higher than the thermal efficiency (ηth) of diesel oil, which is 5.10%, so it can be concluded that mixing castor oil with diesel oil can provide better engine performance values ACKNOWLEDGMENTS I would like to send my thanks to the research partners in the Naval Architecture Department of the Kalimantan Institute of Technology and the laboratories who have helped test engine performance.