Biodiesel Production Process Using Plasma Method on Engine Performance and Exhaust Gas Emissions

Crude Palm Oil is one of the renewable energy sources that is widely used as an environmentally friendly energy source, one form of utilization is by processing crude palm oil into biodiesel. However, biodiesel has drawbacks in terms of performance which is less good than fossil fuels. This study aims to improve the performance of the engine produced by biodiesel and maximize the utilization of crude palm oil in biodiesel. In improving the performance of diesel engines, the treatment method used in producing biodiesel affects the physical properties of the biodiesel produced. This study uses a mixture of Dexlite fuel with plasma biodiesel in a ratio of 1:1, which produces B50 biodiesel. To measure the performance using a TV1 diesel engine and a gas analyzer OPA 100 with a compression ratio of 1:18, 1:14, and a load of 1 kg, 3 kg, 5 kg, 7 kg, and 9 kg. The results showed that the maximum effective power (BP) occurred at a load of 9 kg with a ratio of 1: 14, which was 2.38 kW, and the minimum specific fuel consumption (SFC) occurred at a compression ratio of 1: 18 and loading 9 which is 0.240 Kg/kWh, the maximum volumetric efficiency (ηvo) occurs at 9 kg loading with a compression ratio of 1: 14 with the addition of 0% methanol solvent which is 70.61%, and thermal efficiency (ηth) maximum loading occurred at 9 kg loading with a compression ratio of 1: 18 using 0% methanol solvent, which is 44,74%.


Introduction
The traditional methods of producing biodiesel (esterification and transesterification) often include microwaves and, more recently, the plasma process [1].The production of biodiesel using conventional techniques takes a long time.The process of transesterification is one of the most used ones for making biodiesel.While the microwave approach produces biodiesel quickly, the transesterification process results in a mixture of mono-alkyl esters from high fatty acids.[2][3] Plasma, often recognized as the fourth state of matter after solids, liquids, and gases, is estimated to constitute more than 99% of the visible matter in the universe.Plasma is an ionized gas composed of numerous reactive species, including positive ions, negative ions, electrons, free radicals, gas atoms, excited and ground state atoms or molecules, and photons (visible and UV).[4] The properties of the so-called positively charged ions and negatively charged electrons in the plasma are very different from those of ordinary gases and matter [5][6].
The performance of a plasma dielectric barrier discharge reactor for biodiesel production from palm oil using a 3:1 methanol/palm oil ratio resulted in the highest yield value of 89.9% and the highest acid value, cetane number, iodine number, and saponification value [7].It has met SNI biodiesel standards with FAME, aldehydes, alkynes, alcohols, esters, and carboxylic acids.The plasma pyrolysis results of a mixture of palm oil (crude palm oil) and methanol have been characterized, yielding a yield value of 83.74% and a viscosity value that meets SNI biodiesel standards with methyl/ethyl, ester, and carbonyl content [8].Corona discharge plasma method has been applied to produce biodiesel from fatty acid using a waste product of the food industry as the raw material.This method confirmed the acceleration of the esterification reaction, easy separation of the biodiesel, and the elimination of waste generation [9].Previous studies also discussed gas emissions from the use of biodiesel produced conventionally by producing more environmentally friendly emissions from the use of biodiesel with a higher fuel ratio and a decrease in engine power produced by the engine.Biodiesel produced from the non-thermal plasma technology (NTP) reported reductions in THC and CO emissions of 62% and 80% [10].Particulate matter was also significantly reduced in biodiesel with NTP treatment [11].In this study, biodiesel was produced from crude palm oil and then applied to a diesel engine to observe the engine performance and emission as well.

Materials and Methods
This research used 50% biodiesel from crude palm oil (CPO) as fuel in a plasma generator operating at a frequency of 2.45 GHz.

Figure 1. Research Scheme
Figure 1 shows that the engine used in this research is a TV1 model diesel engine (vertical 1 cylinder type).The diesel engine has a power of 3.50 kW with a constant rotation of 1500 rpm.It has 1 cylinder, four-stroke, water-cooled, cylinder diameter 87.50 mm, stroke length 110.00 mm, connecting rood length 234.00 mm, compression ratio 1 to 18, cylinder volume 661.45 cc.The machine is run for 4-5 minutes with no load before the desired conditions are examined.Then, operating conditions are gradually attained by applying loads to the engine of 3 kg, 5 kg, 7 kg, and 9 kg.At each loading, data recording is completed after the machine has stabilized.An Opa-100 directly linked to the engine exhaust line is used to monitor exhaust emissions, while a test dynamo directly attached to the engine is used to assess engine performance.The IC-Engine application is used for reading and recording test result data.Torque, effective power, specific fuel consumption, volumetric efficiency, thermal efficiency, exhaust gas temperature, and percentage of opacity are among the measured parameters.Torque is a measure of an engine's ability to generate power.When a load is applied to the engine shaft, torque from the engine can help overcome resistance.As a load is applied to a diesel engine, torque increases.The engine's maximum torque with plasma-produced B50 fuel is 16.4 Nm at a compression ratio of 14 and a load of 9kg.This is because the torque value is influenced by engine speed, which is determined by the given load; the higher the load, the greater the torque produced.

Figure 3. Engine effective power
The power on the shaft that will be used to lift the engine load is referred to as effective power.The effective power is calculated by multiplying the torque on the shaft by the angular speed of rotation.Because of the increased torque generated by the engine, the effective power generated by the engine using plasma produced B50 fuel has increased.As a result, the engine produces the most effective power at a compression ratio of 14 with a load of 9kg and the least effective power at a compression ratio of 14 with a load of 3kg.The increase in effective power in plasma produced B50 fuel is more  stable when a low compression ratio is used; specifically, the compression ratio of 18 is caused by the increased cylinder pressure, which increases the heat released and produces more power.

Figure 4. Engine specific fuel consumption
Specific fuel consumption is a comparison between fuel consumption and the effective power produced by the engine.Specific fuel consumption is an indicator of the effectiveness of a fuel motor in the use or consumption of fuel consumption to produce motor power.The lower the specific fuel consumption value, it can be said that the motor is more efficient in fuel consumption.Therefore, the fuel consumption produced by the engine using plasma B50 fuel has decreased.The smallest specific fuel consumption produced is 0.24 kg/kWh at a compression ratio of 18 with a loading of 9, while the largest is 0.59 at a compression ratio of 18 with a loading of 3. Specific fuel consumption has decreased due to the engine's increased thermal efficiency when using plasma generated B50 fuel, which requires less fuel to generate heat, which is then converted to power.

Figure 5. Engine volumetric efficiency
Figure 5 shows that volumetric efficiency refers to the engine's ability to perform the work of mixing fuel efficiently.For example, the engine with plasma fuel b50 produces the highest volumetric efficiency (70.61%) at a compression ratio of 18 at a load of 9.The lowest is 67.82% at a compression ratio of 18 to a load. 5.When fuel is injected into the combustion chamber, volumetric efficiency will affect the pressure generated in the cylinder, affecting combustion.The more compressed the air in the cylinder, the higher the pressure in the cylinder, so that when fuel is injected, the heat released is greater, increasing the engine's thermal efficiency.

Thermal Efficiency
Figure 6.Engine thermal efficiency An engine's thermal efficiency (ƞth) is defined as the amount of heat converted from burning fuel into mechanical work.The amount of heat the fuel provides can be determined by fuel consumption and the calorific value of the fuel.In contrast, the amount of mechanical work can be determined by the motor's power.At a compression ratio of 18 and a loading of 9, the highest thermal efficiency produced is 44.74%.The lowest thermal efficiency, 18.47%, is produced at a compression ratio of 18 at a loading of 3. Thermal efficiency is influenced by the injection of compressed air and fuel into the combustion chamber.When there is too much air in the combustion chamber, efficiency suffers.When the combustion chamber lacks air, in addition to compressed air in the combustion chamber, thermal efficiency is influenced by the calorific value of the fuel, the fuel's density, and the compression ratio based on the fuel's characteristics.The compression ratio of 18 best suits the resulting thermal efficiency in this case.Figure 7 shows the temperature of the exhaust gas produced by the engine after combustion is channeled from the exhaust valve.At a compression ratio of 14 loadings, the highest exhaust gas temperature produced by a diesel engine using plasma B50 fuel is 191.6 °C.At a compression ratio of 18 loadings 3, the smallest temperature produced is 109.8°C.The amount of heat released in combustion and the thermal efficiency produced by the engine to be converted into mechanical energy influence exhaust gas temperature; any remaining heat that is not utilized is discharged through the exhaust valve.

Figure 8. Engine exhaust gas emission
Opacity or smoke density indicates whether or not the combustion system in diesel vehicles is working properly.The compression ratio influences the opacity produced by diesel engines, with higher compression ratios producing more opacity because combustion occurs at low pressure, resulting in incomplete combustion.

Conclusion
In this study, the engine's maximum torque with plasma-produced B50 fuel is 16.4 Nm at a compression ratio of 14 and a load of 9kg.In contrast, the engine's smallest torque at a compression ratio of 14 and a loading of 3 kg is 5.57 Nm.The largest effective power produced by the engine is 2.35 kWh at a ratio of 14 with a load of 9kg, and the smallest effective power produced is 0.79 kWh at a compression ratio of 14 with a load of 3kg.The fuel consumption produced by the engine using plasma B50 fuel has decreased.The smallest specific fuel consumption produced is 0.24 kg/kWh at a compression ratio of 18 with a loading of 9, while the largest is 0.59 at a compression ratio of 18 with a loading of 3. The decrease in volumetric efficiency was produced at a compression ratio of 14 loads of 9 kg 70.61%, and the smallest volumetric efficiency was produced at a compression ratio of 14 loads of 5 kg 67.82%.At a compression ratio of 18 and a loading of 9, the highest thermal efficiency produced is 44.74%.The lowest thermal efficiency, 18.47%, is produced at a compression ratio of 18 at a loading of 3. The largest exhaust gas temperature produced by a diesel engine using plasma-produced B50 fuel is 191.6 °C at a compression ratio of 14 loadings 9, and the smallest is produced at a compression ratio of 18 loading 3, which is 109.8°C.The compression ratio that is appropriate for the characteristics of plasma-produced B50 fuel is appropriate for the performance of the diesel engine; based on the performance produced by a diesel engine with plasma-produced B50 fuel, it can increase effective

Figure 7 .
Figure 7. Engine exhaust gas temperature , volumetric efficiency, thermal efficiency, and reduce fuel consumption.There are specific fuel and exhaust emissions produced.References[1] Secretariat General of the National Energy Council 2019 Indonesia Energy Outlook.[2] Government Regulation 2015 Biodiesel Mandatory Program (B30).[3] Patil P D Gude V G Mannarswamy A Cooke P Nirmalakhandan N Lammers P and Deng S 2012 Comparison of direct transesterification of algal biomass under supercritical methanol and microwave irradiation conditions Fuel 97 822-831 [4] Shaw A Shama G and Iza F 2015 Emerging applications of low temperature gas plasmas in the food industry Biointerphases 10(2) [5] Nur M 2011 Plasma Physics and Its Applications Diponegoro University Semarang.[6] Rahim I Amaliyah, N Mandra M A S Nomura S 2022 Spectroscopic Measurement of High Argon Jet Plasma Flow Rate for Methane Hydrate Decomposition Int.Journal of Design & Nature and Ecodynamics 17 6 973978 [7] Bashir M A Wu S Zhu J Krosuri A Khan MU and Aka R J N 2022.Recent development of advanced processing technologies for biodiesel production: A critical review Fuel Processing Technology 227 107120 [8] Istadi I Yudhistira A D Anggoro D D Buchori L 2014 Electro-catalysis system for biodiesel synthesis from palm oil over dielectric-barrier discharge plasma reactor Bulletin of Chemical Reaction Engineering & Catalysis 9111-120 [9] Cubas A L V Machado M M Pinto C R S C Moecke E H S and Dutra A R A 2016.Biodiesel production using fatty acids from food industry waste using corona discharge plasma technology Waste management 47 149-154.[10] Cubas A L V Moecke E H S Ferreira F M and Osório F D S 2022.THC and CO Emissions from Diesel Engines Using Biodiesel Produced from Residual Frying Oil by Non-Thermal Plasma [11] Wang P Cai Y X Zhang L and Tolksdorf C 2010 Physical and chemical characteristics of particulate matter from biodiesel exhaust emission using non-thermal plasma technology Energy & fuels 24(5) 3195-3198.