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The need for lubrication cannot be over emphasized as far as its role in engineering is concerned. Mostly all type of the internal combustion engine will required a lubricant to protect its internal part which is known as engine lubricating oil. As we know, engine is the core of a machine that gives essential function to all operating system. This is where combustion will occur and where the engine is subjected to critical operating condition. All the part will exposed to extremely high heat and friction. The part in an engine that require lubricant including piston, cylinder, crankshaft and bearings.[V. Ganesan, 2007]
Lubricants generally can be classified into two categories which is engine and non engine.[Ilija Gawrilow, 2003]. Engine and non engine lubricants are completely different in operation. For this research purposes, engine oil will be covered detailed.
Generally lubrication system in an engine is use to prevent metal to metal contact between the moving part. If there is no lubrication, metal to metal contact will lead to friction and would result in loss of power, rapid wear and temperature rise. Oil is used as lubricant for an internal combustion engine. Lubricating oil plays an important part in the life of the engine. Lubricating oil can be considered to be the lifeblood of an engine. It is used to coat each metal surface with a film. Between the two films, other layers of the oil slide along over each other, thus replacing the high friction of metal to metal contact by the low internal friction of the oil. Additional function of lubricating oil is cushioning impact force created by combustion and cleaning the engine by picks up the foreign particles. It also protect engine against corrosion by making a barrier to oxygen and moisture from reaching the metal surface. Nowadays, there are so many type of engine oil has been produced. The engine oil being used is based on the SAE classification. The engine oil currently used is made from crude oil. [V. Ganesan, 2007]
2.2 ENGINE LUBRICATING OIL
Engine oil or known as motor oil that is used for lubrication in most internal combustion engine. These include motor or road vehicles such as cars and motorcycles, heavier vehicles such as buses and commercial vehicles and also aircraft. It is use to lubricate the moving part in an engine. Engine oils are derived from petroleum based and non petroleum synthesized chemical compounds. Motor oils today are mainly blended by using base oils composed of hydrocarbons, polyalphaolefins (PAO), and polyinternal olefins.[ G. Corsico, L. Mattei, A. Roselli and C. Gommellini, 1999]. There are two type of engine oil being used today that is mineral base and synthetic. All the engine lubricating oil used must meet SAE requirement. Figure 2.1 shows example of engine oil.
2.2.1 Crude oil
Crude Oil or Petroleum, is simply unprocessed oil found deep beneath the earth's surface. It can range in color from clear to black and can be found as a liquid or solid. Overall properties of crude oils are dependent upon their chemical composition and structure. Crude oil is pumped and stored in barrels for future refinement. The refinement process may involve filtering, addition of additives, and specialized separation techniques to create specific crude oils and crude oil products. Generally all crude oils are made up of hydrocarbon compounds. The main hydrocarbons found in crude oil are Aliphatics, Alicyclics, and Polycyclic Aromatic Hydrocarbons.
2.2.2 Synthetic oil
Synthetic oils were originally designed for the purpose of having a very pure base oil with excellent properties. Synthetic oil is an oil product that contains additional chemical ingredients that are not present in crude or petroleum oil. Synthetic engine lubricating oils are the result of a chemical reaction called synthesis, after the synthesis, result is a uniformly shaped molecules that are more resistant to heat and impossible to achieve through crude oil refining process. Oils produced by synthesis rather than by extraction or refinement. Synthetics were thus originally a reaction to the relatively poor refining processes available from about 1930 to about 1990. [Mark Lawrence, 2010]
Figure 2.1: Example of engine oil [pennzoil, 2007]
2.3 FUNCTIONS ENGINE LUBRICATING OIL
There are several function that engine lubricating oil will perform in order to keep the engine perform at its optimum level.
2.3.1 Keep Moving Parts
Lubricants are typically used to make a separation between moving parts in a system. This has the benefit of reducing friction and surface fatigue together with reduced heat generation, operating noise and vibrations. [M. Afiq, 2009]
2.3.2 Reduce Friction
Typically the lubricant friction with the surface is much less than surface to-surface friction in a system without any lubrication. Thus use of a lubricant reduces the overall system friction. If the friction is reduced, it will give benefit of reducing heat generation and reduced formation of wear particles as well as improved efficiency. Lubricants may contain additives known as friction modifiers that chemically bind to metal surfaces to reduce surface friction. [M. Afiq, 2009]
2.3.3 Carry Away Contaminants and Debris
Engine lubricant circulation systems have the benefit of carrying away internally generated debris and external contaminants that get into the system to a filter where they can be removed. Lubricants for machines that regularly generate debris or contaminants such as automotive engines typically contain detergent and dispersant additives to assist in debris and contaminant transport to the filter and removal. [M. Afiq, 2009]. A variety of waste products are formed as fuel is burned in an engine. The type of fuel and the conditions of combustion will affect the nature and quantity of those waste materials. Some of the most troublesome waste materials include water, carbon, lead salts and acids. Many of these materials tend to remain in the engine and contaminate the oil. Unless these contaminants can be held in a state of dispersion so they may be removed when the oil is drained. They will contribute to the formation of harmful and deposits that reduce performance of engine. Helping to keep an engine clean is a very important function of oil. [James B. Wills,1998]
2.3.4 Protect Against Wear
Lubricating oil in an engine will prevent wear by keeping the moving parts apart. Lubricants may also contain anti wear or extreme pressure additives to boost their performance against wear and fatigue.
Immediately following the burning of fuel in the combustion chamber of the engine, the gases formed are under high pressure. It is the pressure of these gases on the piston head which is transmitted to working horsepower.[James B. Wills]. It is necessary to keep these gases from leaking past the pistons and valves. The oil will acts as a sealant. If the oil thins out too much, the gases blow by. The oil should resist excessive thinning.
2.4 PROPERTIES OF ENGINE LUBRICATING OIL
In order to accomplish all the function of engine lubrication system as mentioned earlier, the lubricating oil should have suitable viscosity, high viscosity index (VI), high flash point and low pour point.
Viscosity is resistance of an oil offers to flowing. The lower the viscosity, the more freely oil can flow above the pour point. High viscosity indicates a high resistance to flow while low indicates a low resistance. The viscosity of commercial aviation oils generally classified by numbers such as 80, 100, 120 and 140.[M. J.Kroes and T. W. Wild, 1994]
2.4.2 Viscosity Index
While viscosity is oil's internal resistance to flow, its viscosity index is simply its resistance to changing flow characteristics due to changes in temperature. Viscosity index of a lubricating oil is an important factor where extreme range of temperature is encountered. If oil's viscosity changes very little, despite significant temperature changes, the oil has a high viscosity index. Viscosity index is an arbitrary numbering system. Higher numbers mean oil's viscosity changes little with temperature and lower numbers means it changes more. [Harold tucker, 1998]
2.4.3 Flash Point
The temperature at which the oil will start burning. The higher the flash point, the more stable the oil is at high temperatures and the less oil your engine will burn. [M. J.Kroes and T. W. Wild, 1994]
2.4.4 Pour point
The temperature at which the oil stops flowing like a liquid. The lower this number is, the better protected your engine is when it is cold. It is particularly important for oil circulation for an engine in very cold climates. Pour point depressant will be added to lower the pour point in wax containing oil.[V. Ganesan, 2007]
2.5 ADDITIVES IN ENGINE LUBRICATING OIL
In order to help keep engines operating is out of trouble, it has become necessary to add a number of chemical agents in engine lubricating oil. These agents have specific jobs to do in assisting the oil to function properly. Additives use in engine oil are used for the following purposes:
Enhancing the detergency dispersancy characteristics of the oil. It is not to clean the engines that has been dirty but they are ued to ensure clean engine is keep clean. During fuel combustion, products such as soot, carbon, water, acids, lead salts and others are formed. These particles are smaller than can be seen with even a normal microscope. The additive keeps these particles dispersed so they cannot collect and form deposits on the engine parts. When the crankcase oil is drained, the contaminants are removed and the engine remains clean.[ James B. Wills, Jr, 1998]
An additive agents are added to an engine oil to improve the oxidation resistance. Acids and sludge will form because of oxidation. They help keep the oil cleaner and act as corrosion resistance of engine parts.[James B. Wills, Jr, 1998]
During the combustion of fuel, combustion acids and water are formed and in order to prevent this formation, inhibitors are added to the oil. Oil foams when churned with air. These agents break up the foam and prevent it from exceeding an acceptable level.
2.6 PALM OIL
Palm oil is produced from the fruit of the oil palm. The specific name of oil palm known as Elaeis Guinnesis which is found in Africa, South East Asia and Latin America.[Teoh C. H.,2002]. Palm can be cultivated only in tropical areas of Asia, Africa and South America. Although humans have use the oil palm for over 5000 years commercial planting and cultivation did not begin until the middle of 1990 in Malaysia.
Palm oil is extracted and refined through pressing and crushing rather than through using chemical solvents such as hexane. Palm oil can be further refined into palm olein (liquid) and palm stearine (solid). Among the food uses, refined, bleached and deodorised (RBD) olein is used mainly as cooking and frying oils, shortenings and margarine while RBD stearin is used for the production of shortenings and margarine.[Prof.Noor Azian & Prof. Mustafa Kmal, 2006]. Palm oil resists oxidation and rancidity, which means products made using palm oil have extended shelf lives. Oil palm wil produce two different types of oil at the same time which is palm oil and palm kernel oil. Palm oil is produce from mesocarp of the fruit. Figre 2.2 shows the cross section of palm oil fruit. In unprocessed state, it is red in colour due to carotenoid content. Palm kernel oil is produce from fruit kernel and has creamy colour. Palm kernel oil has very similar characteristic to coconut oil.
Figure 2.2: Cross section of Palm oil fruit. [Prof.Noor Azian & Prof. Mustafa Kamal, 2006]
2.6.1 Palm oil Processing
The process to produce the oil involves the reception of fresh fruit bunches from the plantation, sterilizing and threshing of the bunches to free the palm freit, mashing it and pressing out the crude palm oil.[Teoh C. H.,2002]. The crude palm oil then treated to purify and dry for storage.
Process of crude palm convert into refined oil involves removal of the products of hydrolysis and oxidation, colour and flavour. After refining, oil will be frationate into liquid and solid phases by thermo mechanical means. This is where the palm olein is produced. Oil extraction from the palm kernels is generally differ from palm oil extraction and will often be carried out in mills that process other oilseeds. The stage of this process comprise grinding the kernel into small particle, heating and extracting the oil. The oil will requires clarification in a filter press by sedimentation.
2.6.2 Usage of palm oil
Over centuries palm oil is being used for varies industry. 80% of palm oil is used for human consumption which is cooking oil, margarine, biscuit, cake and confectionary. The other 20% is used in soaps and also detergents. [Pahl, G.,2005]
2.6.3 Advantage of palm oil
There are many advantage of palm oil that is undeniable. From the price aspect, palm oil that used as cooking oil is cheaper than normal engine oil currently used. Palm oil is rich in beta carotenes and is considered as the richest natural source of carotenoid, which are known to be an effective antioxidant. Palm oil also has a high melting point. [Pahl, G.,2005]
2.6.4 Disadvantage of palm oil
Unprocessed of palm oil will have higher pour point (the temperature at which dissolved solids in the oil begin to form and separate from the oil). So, the oil must therefore be kept at a temperature that is above the pour point. [Pahl, G.,2005]
2.7 COCONUT OIL
Coconut oil is produce from the fruit of coconut palm. Coconut Palm or its scientific name Cocos Nucifera is a member of the Family Arecaceae which is from palm family. It is the only species in the genus Cocos. It can growing up to 30m tall. The term coconut refers to the seed of the coconut palm. In some areas of the tropics, the palm grows with a minimum of attention through a lifespan of more than 50 years. The coconut palm is grows throughout the tropical world, for decoration as well as for culinary and non-culinary uses. Virtually every part of the coconut palm has some human uses. Propagation of the coconut palm starts from the collection of fully matured nuts (11-12 months old) from selected palms. [Elias C. Canapi, Yvonne T. V. Agustin, Evangekube A. Moro, 2005] Figure 2.3 shows a 9 month old seedling of the Cocos Nucifera.
Figure 2.3: A 9 month old seedling
[Elias C. Canapi, Yvonne T. V. Agustin, Evangekube A. Moro, 2005]
2.7.1 Coconut fruit
The fruit common mature coconut weight is more that 1 kg. It is ovoid in shape and green or yellow in color. The nut has a smooth epidermis over a fibrous mesocarp which is husk that covers the hard endocarp or shell. Within the shell is the kernel or meat approximately 1-2 cm thick. A thin brown layer called testa separates the kernel from the inner surface of the shell. [Elias C. Canapi, Yvonne T. V. Agustin, Evangekube A. Moro, 2005]. The cross section of mature Coconut fruit is shown in figure 2.4.
Figure 2.4: Cross section of mature coconut fruit
[Elias C. Canapi, Yvonne T. V. Agustin, Evangekube A. Moro, 2005]
The kernel is the origin of the coconut oil, desiccated coconut, coconut skim milk, coconut cream, coconut flour, protein powder, and copra meal. Copra is the dried kernel of the coconut. Fresh kernel contains approximately 50% of moisture as shown in figure 2.5.
Figure 2.5: Composition of coconut kernel
[Elias C. Canapi, Yvonne T. V. Agustin, Evangekube A. Moro, 2005]
The thin brown layer between the kernel and shell is the testa. This layer is pared off from the kernel's outer surface to eliminate colored bodies in the production of desiccated coconut.
22.214.171.124 Shell and Husk
The shell that encloses the kernel is a hard spherical covering 3-5 mm thick. It is used mainly for fuel in copra making. Other products derived from coconut shell are charcoal, activated carbon, filler for synthetic resin and glues.
2.7.2 Coconut oil extraction process
According to Sonia Nair, the coconut shell and husks are removed and coconut water is being kept in any container. After that, coconut meat will be grated by using a nifty tool that consist of a board sprouting of nails and fill the grated meat into a net bag. Then the bag is tightly press to extract the coconut milk. The bag will be dip into the coconut water in order to produce more milk.
There are two different process of extracting coconut oil. First method is by natural fermentation. Using this method, the coconut water will be mix with the milk and put it in a transparent container or jar. It will left remain for about 20 hours at ambient temperature. After 20 hours, it will be indicate 3 layer in the jar. Top layer is the protein and the oil is under the protein layer. Bottom layer will be the water. Second method is by heating. The coconut milk is heated over a low flame. After some times, water will evaporate and leaving the oil behind. [Sonia Nair, 2010]
2.7.3 Usage of coconut oil
Coconut oil has benn used in a wide range of food and nonfood products. It is a raw material for the production of medical foods and infant food formulations. In industry, the fatty acids of coconut oil provide a versatile feedstock for an array of products from diesel fuel substitute to hygienic products. [Indonesia export news, 2009]
2.7.4 Advantage of coconut oil
Based on Tiffany Windhurst in an article, the advantage of using coconut oil is it does not irritate sensitive skin and differ from normal engine oil that tend to make human skin itchy. It is also better in thermal and oxidative stability.[Tiffany Windhurst, 2010]
2.7.5 Disadvantage of coconut oil
Disadvantage of coconut oil is same as palm oil which is unprocessed coconut is have high pour point.
2.8 CASE STUDY
Based on the study of lubricating properties of palm oil by John Jiya Musa, the properties of the palm oil and bleach palm oil are almost the same as normal engine oil. The lubricating properties of palm oil are compared with SAE 30 and SAE 40 engine oil. The properties that have been test on the study is flash point, fire point, and pour point. It was also observed that the viscosity of the samples decreased with increase in temperature. But among the three specimens examined, the bleached palm oil exhibited the best lubricating features. This implies that the caroteneous content of palm oil has a negative effect on its lubricating properties. On increasing the operating temperatures from 40Â°C to 100Â°C, all the samples analyzed showed various percentage decrease in their viscosities. The result of the study is shown on figure 2.6.[ John Jiya MUSA, 2010]
Figure 2.6: Result of the lubricating properties[John Jiya MUSA, 2010]
From the study of palm oil as base stock for engine oil carried by Department of Chemical Engineering, King Mongkut's Institute of Technology, wear scar and sulfate ash is tested. Wear scar test is carried out based on ASTM D4172.Wear scar diameter of palm oil is insignificantly different from that of commercial oil. Sulfate ash test is follow ASTM D874. From the test, it shows that pure palm oil is extremely low sulfate ash than commercial engine oil. [Kraipat Cheenkachorn and Isarawat Udornthep, 2006]
2.9 METHOD FOR TESTING
The oil properties will be test according to standard of ASTM and the performance of the engine is tested using dynamometer.
2.9.1 Properties of oil testing
Tests are designed to measure such physical and chemical properties of oils like Viscosity, Viscosity index, Pour point, Flash point and Density.
126.96.36.199 Materials & Equipment
The materials and equipment used in carrying out this research work include oil sample, Ice block, Water, Open cup Viscometer, Stop watch, Beakers, Retort Stand, Ohous Weighing Equipment, Cleavland open cup apparatus, Thermometer, Gas burner, Viscometer bath, Holding cylinder, Heater, Flask (flat bottom), Torch nozzle. [A. B. Hassan, M. S. Abolarin, A. Nasir, and U. Ratchel, 2006]
188.8.131.52 Viscosity (ASTM D 445)
Objective: To know the flow ability of the samples
1. A sample of oil was poured into the viscometer cup.
2. The cup was inserted into the viscometer bath which contained water.
3. The viscometer bath was switched on to attain the experimental temperature of 40Â°C and 100Â°C.
4. The sample was slowly ran into the viscometer and allowed for 15 minutes to attain bath temperature.
5. The sample was sucked up the capillary tube above the upper mark.
6. The stop watch was started when the sample dropped to the upper mark and it was stopped when the sample reached the lower mark.
7. The time in seconds was multiplied with the viscometer constant to obtain viscosity.
Figure 2.7: Viscometer bath.[Raj scientific company, 2011]
184.108.40.206 Flash/Fire Point ( ASTM D92)
Objective: To determine the temperature at which the vapour of the sample will ignite.
1. The Sample of palm oil was poured into the cleveland open cup.
2. The cup was placed on the heating element.
3. Heat was applied at constant rate.
4. Flame from the torch nozzle was directed over the heated sample at regular intervals.
5. The flash point was reached when the torch flame ignited the vapour of the sample which is the first spark.
6. As heat was continuously applied and flame was continuously passed over the heated sample, a further spark was observed that lasted for 5 seconds which dictated the fire point. [A. B. Hassan, M. S. Abolarin, A. Nasir, and U. Ratchel, 2006]
Figure 2.8: Cleveland open cup flash tester.[Paul N. Gardner, 2010]
220.127.116.11 Pour Point (ASTM D 97)
Objective: To determine the minimum temperature at which the oil can flow
1. Oil sample was poured into a holding cylinder.
2. The oil sample was heated above its pour point in the holding cylinder
3. The heated sample was cooled gradually by adding ice block into the cooling bath.
4. The holding cylinder was tilted at regular intervals to check the movement of the oil.
5. A temperature was reached when the oil did not show any movement after 5 seconds of tilting the holding cylinder.
6. 5Â°C was added to the temperature at which the oil solidified to indicate the pour point.
[A. B. Hassan, M. S. Abolarin, A. Nasir, and U. Ratchel, 2006]
Figure 2.9: Cooling bath.[Petrolab, 2001]
Objective: To determine the compatibility of the samples
1. The beaker was weighed on the ohous weighing apparatus
2. The weight of the breaker was deleted from the screen
3. A known volume of the oil sample was poured into the beaker and weighed
4. The reading on the screen was taken which indicated the density of the sample
5. Specific gravity was obtained from the relation: Density of Substance/ Density of Water.
[A. B. Hassan, M. S. Abolarin, A. Nasir, and U. Ratchel, 2006]
2.9.2 Engine performance
Test Stands and Dynamometers are used to test and characterize rotating equipment. A dynamometer is a load device which is generally used for measuring the power output of an engine. If the dynamometer is connected to the engine's output shaft it is referred to as an Engine Dynamometer. When the dynamometer is connected to the vehicles drive wheels it is called a Chassis Dynamometer.
18.104.22.168 Engine Dyno Test
Engine dynamometers are usually contain within a small room call a test cell. The engine is control by an operator from another room. Dyno test will identify the horsepower and torque that produce by the engine using different type of engine oil. Dyno test will measure the engine efficiency in 3 types measurement which is mechanical efficiency, volumetric efficiency and thermal efficiency. [Tim Gilles, 2010]
22.214.171.124 Chassis dyno test
A chassis dynamometer is used to simulate driving on a road inside a laboratory under controlled conditions. The vehicle is driven on rolls, while a dynamometer simulates the inertia of the vehicle as well as the drag and friction on the vehicle it is also known as road load in the vehicle testing community.
Because an entire vehicle is tested instead of just an engine, and a driver controls the vehicle instead of a computer, the use of a chassis dynamometer allows the assessment of real world emissions. This allows a better assessment of the benefits of new fuels and vehicle technologies, and is absolutely essential to assessing the performance of heavy hybrid trucks and buses. [Tim Gilles, 2010]
2.9.3 Chassis Dyno test operation
Chassis dyno test is carried out by a vehicle or chassis is driven onto a chassis dynamometer. The vehicle that will be test is secured using straps or chains typically provided with the dynamometer system. The vehicle then performs a series of tests that mimic the operating conditions the vehicle would face during its intended use or actual operation. These tests can be performed by an operator either inside, outside of the vehicle or through an automated test depending on the control system supplied with the chassis dynamometer. All the information including RPM, horsepower and torque of the engine will be shown by the computer. [Sarah Simmon, 2010]
Figure 2.10: Motorcycle on chassis dynamometer.[GGB bikers, 2011]