21-10-2016, 03:23 PM
EXPERIMENTAL INVESTIGATION OF PERFORMANCE AND EMISSION CHARACTERITICS ON LHR ENIGNE WITH BIODIESEL EXTRACTED FROM WASTE COOKING OIL
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ABSTRACT:
In this investigation is to extract the biodiesel from waste cooking oil through transesterification and to assess the performance and emission characteristics of the diesel engine. In this present work, waste cooking oil methyl ester is extracted and blends with diesel to test for different varying load conditions in low heat rejection (LHR) with and without ceramic Al2TiO5 coating on piston, cylinder head and liner. Likewise, various parameters also tested such as brake thermal efficiency (BTH), brake specific fuel consumption (BSFC), emission of hydro carbons, oxides of nitrogen gases, and carbon monoxides. These tests are carried out with 3 different blends B10, B20, &B30 at different load conditions. Finally, the result shows that the performance of diesel engine with biodiesel was satisfactory increased when compared with diesel.
Key words: Biodiesel, waste cooking oil methyl ester, diesel engine, emission.
INTRODUCTION:
Major increase in motor vehicle causes large depletion in fossil fuels mainly in petroleum products. In India more than 90 million of vehicles are already sold in last decade, so there is active research in alternative fuels for petroleum products. Thereby, the diesel can be replaced with biodiesel for the diesel engines and for compression ignition engines. Here the biodiesel is used to fulfill the demand of diesel petroleum products that involves with pollution. And also it is necessary to introduce new alternative fuels for the upcoming generation especially for diesel engine. (1) At this stage it’s important to study the low heat rejection engine concepts that the effective insulation coating on the piston, cylinder head, and liner can withstand generated heat within combustion chamber so that temperature problems can be reduced for low heat rejection engines. (2) Biodiesel is only way to alter the fossil fuels which are obtained from different methods and here the process followed through transestrification. Oils like cooking oil, animal oil, and other renewable oil are used for biodiesel productions which are converted chemically from acid to ester form (Methyl ester). Ramadhas (3) experimented rubber seed oil biodiesel in LHR engine and found that increase in brake thermal efficiency for lower blends and lower specific fuel consumption rate than diesel. S.Santhanakrishan and Vijayaraj (4) investigated animal oil as biodiesel with diesel engine and found that the emissions of NOx are high than the diesel but still increases in thermal efficiency. Dalai and Kulkarni (5) tested with biodiesel taken from coconut oil which results in decrease in the HC and CO emissions and slight increase in NOx emissions. Arumugam (6) experimented with the nanoceramic Al2O3 coating on piston and cylinder head with mauha oil biodiesel that given better performance and emissions than diesel.
Therefore, in this present work the waste cooking oil biodiesel is taken for further investigation on the alternative fuel for diesel in terms of performance and emissions. Biodiesel are extracted with various methods
• Transesterification,
• Supercritical process,
• Ultra and high shear in line and batch process,
• Ultrasonic reactor method,
• Lipase-catalyzed method.
Among this listed above methods transesterification methods one of easy and inexpensive method to extract the biodiesel. Since, present work is on waste cooking oil methyl ester so free fatty acid (FFA) contents are most important to be noted. If there is increase in FFA content then the raw oil must undergo esterification process and secondly to transesterification.
TRANSESTERIFICATION:
Fats/oils are reacted with alcohol (methanol), using a strong Alkaline catalyst (sodium hydroxide NaOH or potassium hydroxide KOH). This yields mono-alkyl methyl esters (biodiesel) and glycerin.
Triglyceride + Alcohol → Glycerin + Mono-Alkyl Methyl Esters
(Waste cooking oil) (Methanol) (Soap) (Biodiesel)
The reaction is done with small quantity sample first and then it’s carried out in continuous stirrer reactor. First the optimal oil to methanol ratio and oil to NaOH ratio is investigated. The oil is pretreated by heating the oil about 50◦C for (10-15min) and then the methanol(alochol) and NaOH/KOH(strong base) is mixed with molar weight ratio with sample taken. The process is done with magnetic stirrer which heated about 55-60◦C at 450rpm for 2hours. And the separation process takes around 1 night or minimum 8 to 9 hours in the separation funnel.
MATERIALS & METHODLOGY:
In this present work the waste cooking oil methyl ester is blend with diesel with 3 proportions B10, B20, &B30.
Where,
B10 = 90 % Diesel + 10 % Biodiesel,
B20 = 80 % Diesel + 20 % Biodiesel,
B30 = 70 % Diesel + 30 % Biodiesel.
This waste cooking oil was collected from the local restaurant in Coimbatore. Since, the oil was used more than twice for cooking purpose the oil is seemed to be not healthy for third time so the oil cannot give more minerals for the human beings and also free fatty acid content will increases in that oil which causes more trouble for living beings. And so the oil is taken for this investigation for the preparation of biodiesel. Then, it is tested in the LHR engines with and without ceramic Al2TiO5 coating and to compare with the diesel according to the performance and emissions characteristics.
BRAKE THERMAL EFFICIENCY (BTHE):
The brake thermal efficiency (BTHE) done for varying load conditions for three different blends of biodiesel in the normal (conventional) and LHR (non-conventional) engine. In both cases the brake thermal efficiency increases with increase in load. Thereby, it also shows that biodiesel have higher BTHE in both cases. Compare to the normal engine the LHR engine gives more efficiency in both diesel and biodiesel. This is due to the lower calorific value and specific gravity of the fuel.
SPECIFIC FUEL CONSUMPTION (SFC):
The variations between brake power (BP) and specific fuel consumption (SFC) shown in figure 4. SFC is higher for LHR engine than conventional engine with both fuels diesel and biodiesel. It’s mainly due to heat rejection through the cooling water is reduced by coating with the Al2TiO5. By varying the load condition the SFC is increased in LHR engine than conventional engine because of the cylinder wall temperature and the mixture of high gas temperature inside the engine. Since more quantity of fuel required in the case of biodiesel than diesel for producing the same output power in both conventional and LHR engine.
CARBON MONOXIDE EMISSION (CO):
The variation between the CO emission and brake power is shown in the figure 5. The carbon monoxide emissions are the less than diesel in case of biodiesel when increasing the load conditions in the both conventional and LHR engines. This is due to the more available oxygen content in the biodiesel than diesel. Here, the LHR engine is less polluted than conventional engine with both biodiesel and diesel.
HYDROCARBON EMISSIONS (HC):
The variations of hydrocarbon emissions and brake power are shown in the figure 6. Hydrocarbons are less in the LHR engine when compared to conventional engine and it’s reasoned by excessive oxygen in biodiesel assess the combustion to be complete combustion. And also the low heat rejection by coating ceramic Al2TiO5. At maximum loading conditions the unburnt HC emission in LHR engine with both diesel and biodiesel blends. Therefore, the hydrocarbons emissions are less in LHR engine which also by increase in after combustion temperature
OXIDES OF NITROGEN GASES:
The variations between NOX emission and brake power is shown in figure 7. The NOX emissions are more in case of both the conventional and LHR engines. At the increasing loading conditions the NOX emissions are increased. Compared with diesel fuel the biodiesel is having high NOX for the conventional engine and the LHR engine has some closure and similar emissions like the diesel fuel when compared with biodiesel. This is due to the high oxygen content in the biodiesel than diesel and also the ceramic coating on the cylinder piston and liner.
CONCLUSION:
In this experimental investigation the conventional and LHR engines were tested with the pure diesel and the biodiesel blends. The Al2TiO5 coating is done in the piston head liner and cylinder head through plasma spray coating. The coated engine is known as LHR engine and its well observed for the low heat rejection through the coolant and heat rejection to atmospheric air is decreased due the Al2TiO5 coating.
The following conclusions were drawn from the experimental investigation:
1. The brake thermal efficiency (BTHE) is gradually increases with increasing the loading conditions. In case of biodiesel the BTHE is increased in both conventional and LHR engine. But, still there is improved BTHE in LHR engine while compared with diesel fuel.
2. SFC is higher for LHR engine than conventional engine with both fuels diesel and biodiesel. It’s mainly due to heat rejection through the cooling water is reduced by coating with the Al2TiO5. The increased after temperature during combustion in LHR engine makes the combustion process to nearly a complete combustion.
3. Due to excess oxygen present in the biodiesel and high combustion temperature the CO and HC emissions are reduced in LHR engine than the conventional engine.
4. The NOX emissions are more in case of both the conventional and LHR engines. At the increasing loading conditions the NOX emissions are increased. Compared with diesel fuel the biodiesel is having high NOX for the conventional engine and the LHR engine has some closure and similar emissions like the diesel fuel when compared with biodiesel. This is due to the high oxygen content in the biodiesel than diesel and also the ceramic coating on the cylinder piston and liner.