Study on Combustion Performance of a Diesel Engine Fueled by Synthesized Waste Cooking Oil Biodiesel Blends

يعتبر زيت الطبخ المستعمل من مصادر تكوين البايوديزل المفيدة جدا لانها تدخل في مجال ما يعرف بـW2E حيث اننا ليس فقط نتخلص من زيوت الطبخ المستعملة و انما ننتج من النفايه وقود. في هذا البحث، تم تحضير البايوديزل من زيت الطعام المستعمل و اختبارها لتثبيت مواصفاته. من واحد لتر للزيت المستعمل حصلنا على 940 مليلتر من البايوديزل و الباقي كلسيرين و ماء. ثم تم خلط هذا البايوديزل مع الديزل بنسبه 20% من البايوديزل مع 80% من الديزل. و تشغيل محرك الديزل عنده و كما عند نسبه100% ديزل و 100 بايوديزل. حيث تم دراسه كفاءه الاحتراق من خلال الكفاءة المكبحيه و متوسط الضغط المكبحي و معدل صرف الوقود المكبحي و الكفاءهالحجميه للهواء الداخل للمحرك و العلاقه بين ضغط الاسطوانه و زاويه دوران عمود المرفق. كما ان تركيز الملوثات الكاربونيه و النتروجينيه و درجه حرارة العادم تم تحليلها. اظهرت النتائج  تطابق كبير مع البحوث الاخرى و كانت ايجابيه.


Introduction
Energy, affairs and demand remain the 21st century wide title and its mover for the advancement of technology and the promotion of peoples. Still, the fossil fuel is the most competitive energy source but its depletion energy. The challenges of diesel engines emissions, which affect the ozone layer and initiated global warming are the other axis in the importance of alternative energy and the needing to find clean and sustainable energy. (The global energy statistical yearbook, 2015) . Diesel engines have essential things made it the first choice in the world of engines such as: more desirable and most fuel-efficient engines but most polluting engine as well. Research and studies have been accelerated to find alternative fuels for conventional diesel. Biodiesel, bio alcohols, bio gases and hydrogen have all proved that they can be used instead of diesel in part or in whole in diesel engine combustion chamber without major modification in engine design as in the researches of (Sangamesh and Navindgi, 2016; Knothe and Steidly, 2015;and Jinlin et.al., 2011). (Gertz , 2000;Choe and Min, 2009;Aladedunyia et.al., 2009) studied the oil, fat, greases that might be transffered to be a biodiesel. The chemistry of those fats and the control on them are studied too. Biodiesel is one of the biodegradable and promising alternative fuels. All kinds of oils, greases, and fats from plants or animals are the source of the composition of the biodiesel. As a result of the high demand for oils that enter human food, the UN has banned the use of these types of oils in the research of bio diesel production (Rakib et.al., 2013). İn critical litera ture, there are numerous efforts to prepare, produce, synthesize, manufacture of biodiesel from different bio sources and waste cooking oil on of them as in (Carlos et.al., 2011;William et.al., 2013) The transesterification process is happening with different techniques and methods and all are depending on the catalyst, alcohol, and temperature of oil. (Carlos et.al., 2013).
The research of testing the performance of diesel engine fueled by biodiesel can be divided as the following: research of using biodiesel and biodiesel blends with net diesel such as in work of  (Rajshekhar et.al., 2015).
In this work, biodiesel is synthesized from waste cooking oil, the restruents filtered are provided the used cooking oil. From reacts of one liter of used cooking oil, 940 ml are produced while the remained is gylcerine and other impurities. Theeconomic benifit is calculated. The synethsized biodiesel is tested to recognise its chemica and physical properties. To study the compresion ignition engine performances, engine is investigated experimentally. The combustion performanc is studied in two ways, first by found the brake thermal efficiency, brake specific fuel consumption, volumetric efficiency, and mean effective pressure. Second way by analyzing the outlet emission gases constituants. A sophsticated results are obtained and good compatible in the results are obsereved as compared with critical literatures.

Experımental Work
The following subsection explain the experımental works:

1-The Synthesıze Of Bıodıesel
Most of critical litraure described the techniques and methods of biodiesel synthzising. Also, The author has efforts in this field, (Duraid et.al., 2008). Transesterification process is mainly depending on: the catalyst type and amount, the alcohol type and amount, the teperature of oil at reaction time.
In this work, the optimum amounts of catalyst, alcohol, and oil temperature are identified. In glass beaker 1 litre of refined waste cooking oil is heated and maintained at 60 o C. İn another glass beaker 4 gramm of NaOH are solved in 130 ml of alcohol. The transesterification reaction started when the solution of NaOH added to hot oil and stirred for one hour. The mixture is left for 24 hours. The biodiesel is separated from glycerin by gravity. The transesterification reaction shows by fig. (1). The schems of synthesized biodiesel and glycerin is schemed in fig (2). The synthesised biodiesel is tested to get its index of fuel. Table (1) represents the synthesized biodiese fuel index. As a promising fuel, biodiesel might solve the global shortage in traditional diesel and solve green house issues, the economy of biodiesel synthisized has important attention. İn this research full cost calculation is made. All prices are shifted to US $ for comparion. Table (2) illistrates the synthesized biodiesel feasibility which mentioned that one liter of synthesized biodiesel is leass price as a compare with local price of disel. The results showed that biodiesel is less prace than diesel price.

2-Combustıon Performance Utılızatıon
The performance experiments to check synthesized biodiesel combustion are carried out. Biodiesel is blended with net diesel as D100, B20, and B100. İt represents net diesel 80% diesel and 20% biodiesel, 100% biodiesel by volume respectively. The combustion performance of biodieseldiesel blends are tested in experimental setup which contains two parts: single cylinder compression ignition engine and data Acquesting for measuring. Table (3) shows the experimental engine details.
İn internal combustion laboratorydepartment of mechanical engineering / university of Babylon, single cylinder compression ignition engine is fixed on a suitable chasse with all electrical, cooling , and lubricating connections. Engine is joined to electrical dynamometer to measure its output brake power and to control and measure the load of engine. Suitable flow meters are used to messure engine intake air amount and fuel consumption amount as a function of time (rate). Pressure trancducer is connected to high speed data logger to give the combustion chamber pressure distribution along with cranck angle decoder which used to measure the cranck angle. Tachometer is utilized to find engine speed. K type thermo couples are used to find the temperatures at different positions on engine. İn addition to this, multi gas analyzer is adopted to measure the mono carbon oxides, unburned hydrocarbon, dioxide carbones, and nitrogen oxides that emitted in outlet engine exhaust gases.

Results And Dıscussıon
Tested of combustion performances are divided in two parts, engine thermal characteristic analyzing and find out the emission constituent ratios. Fig (3) represents the variation of cylinder pressure vs. crank angle in full load and no load at different blend ratio. At no load and full load, its observed that peak pressures of B20 and B100 are advanced than the peak pressure of D100 by 8 to 10 degrees. At full load, this trend is noticed clearly. This combustion behaviour means that the blends of biodiesel-diesel enhanced the combustion performance process and the power stroke is becaming more long to give enough time to convert most of producing thermal power to break power.   (4) gives the relation between the brake thermal efficiency and engine brake power. The brake thermal efficiency of diesel fuel is marginally higher than the efficiency of B20 and biodiesel respectively. Due to the decrease in the caloric value of biodiesel. B20 has decrease in brake efficiency as a compareison with efficiency at net diesel or D100.  (5) provides the relation of brake mean effective pressure vs. brake power at different blend ratio. The brake mean effective pressure is generally has same trends and no big difference is observed. The difference in values due to sensable difference in engine brake power at D100, B20, and B100 respectively. Fig (6) posses the relation of specific fuel consumption vs. brake power at different blend ratio. The specific fuel consumption is decreased with load increment. These trends are reflected in this figure. İt is noticed that fuel consumption of diesel less amount than B20 or B100 to produce power. Due to caloric value 1 kg of D100 genrate more brake power than B20 and B100. The curves give a clear view to that diesel engine produce more much energy or power than B20 and B100. Specific fuel consmption for B20 is closed to specific fuel consumption of B100 and both have clear difference than fuel consumption at D100. Again, this is due to the caloric value difference between biodiesel and diesel. Fig (7) shows the relation between the volumetric efficiency and brake power of engine at different blend ratio. For D100, B20, and B100, volumetric efficiency is slightly decreased with brake power increment. The blends of biodiesel leaves more residual gases in cylinder which is meaning less cylinder volum available ton fresh air. Scintific interpretation of this can be explained as at D100 cylinder volume is occupied by less fuel volume. The B20 showed higher value as compare with B100. Fig (8) provides the relation between the exhaust temperature and brake power at different blends ratio. İt observed that exhaust gas temperatures are increased with engine brake power increasing. Whereas more amount of fuel is burned. Due to caloric value the D100 gives the high exhaust gas temperature. The significant observation is the combustion of B20 blends gave low exhaust temperature as a comparison with D100 and B100. The rate of fuel burned is increasing with load increment to keep speed constant. This released more heat and raised the temperature. There is a margin decreased in exhaust gas temperature of B20 flue gases due to enhacement in combustion. Fig (9) represents the relation between the monoxide and brake power at different blends ratio. İts observed that biodiesel emitted low amount of carbon monoxide. The low carbon content and combustion enhancement due to oxygen exsistence, the carbon monoxide is reduced almost by 50% at B100. Fig (10) represents the relation between the dioxide carbon and brake power at different blends ratio. The main indicator of combustion efficiency is the CO 2 forming. At low load the forming of CO is higher than the forming of CO 2 as shown in fig (9) and (10). At high load most of burning carbon forms CO2. The blending of biodiesel is reducing the CO 2 widely. Two reasons stand behand this reduction: first the biodiesel contains less carbon than net diesel D100. Second reason is biodiesel contains oxygem which led to improve the combustion. B20 and B100 reduced the CO 2 by 19 and 27% respectively. Fig (11) represents the relation between the unburned hydrocarbon HC and brake power at different blends ratio. The blend of biodiesel with diesel decreased the emission of HC. Due to low carbon in chemical structure of biodiesel and oxygen exsitence, the combustion is run efficiently. The B20 and B100 decreased the HC of diesel fuel emission by 37 and 68 respectively.  (12) gives the relation between the NO X and brake power at different blends ratio. The formation of NO X is a function to excess air in combustion chamber and the temperature inside combustion chamber. With increasing of load, the NO X formation increased due to increase of sucking air. The rate of NO X formation is increased rapidly due to the increase temperature inside combustion chamber. Biodiesel has low Sulphur and aromatic. Biodiesel reduced the NO X due to less sufficient air. Fig (13) represents the relation between the smoke opocity and brake power at different blends ratio. The smoke is most big trouble in running diesel engines. Smoke is increasing with load increment. At full load, the smoke is decreased 3 times than D100 and nearly 2 times at B20. This is due to high viscosity and complicated molecular stractures.

Conclusion
In present work, the following points it can be concluded: -One of efficient solution to treat polution is transfering gram g the waste to energy W2E. -Four grams of NaOH with 130 ml of alcohol are optimum amounts to synthesize biodiesel from waste cooking oil at 60 oC. -The economic calculation gives that one liter of biodiesel synthesized in laboratory is cheaper than one liter of diesel. -Blends of biodiesel with diesel decreases the polutants. -B20 (20%biodiesel +80% of diesel) is the best to copromize between thermal efficiency and exhaust emissions.