Study the Effect of The Initial Temperature of Diesel Fuel Upon Engine Performance , By Using CI Engine

In my work , I investigates the effect of initial temperature of diesel fuel upon engine performance and emissions by using CI engin , with different diesel fuel cetane number ( 56 , 54 , 53 ) , from the results it showing us that the brake power is increasing with the engine speed and the increasing is (64.66 %) at maximum load with respect with brake power at minimum load ,also measuring the brake torque and it is found from the results the brake torque is increasing with the engine speed at minimum and maximum load and from the results it is found that the brake torque is increasing about (63.902 %) when compare it with brake torque at minimum load ,fuel consumption(kg/hr) is increasing with the engine speed but decreasing when increasing cetane number with the following values (6.631%,7.843%,9.15%) for cetane number ( 53,54,56 ) , and the brake specific fuel consumption also decreasing about (6.065%,6.98%,8.654%) for Cetane number (56,54,53) respectively , the thermal efficiency it is found to be increased with the engine speed and for different fuel cetane number with the following percentage (5.96%,6.837%,8.498%) for Cetane number (53, 54 , 56) respectively, The ( CO2 ) emissions is increased with the engine speed and when the Cetane number increased about (11.35%,9.457%,11.065%) for cetane number (56,54,53) respectively , The (CO) emissions is decreased when the Cetane number increased about (24.165%,20.581%,21.7%) for Cetane number (56,54,53) respectively , The (HC) emissions is decreased by increasing fuel Cetane number about (8.695%,10%,9.586%) for Cetane number (53 , 54 , 56) respectively.


Diesel Fuel.
Diesel fuel is obtainable over range of molecular weights and physical properties, various methods are used to classify it,some using numerical scales and some designating it for various uses.For convenience, diesel fuels for IC engines can be divided into two extreme categories, light diesel fuel which has a molecular weight of about (170) and can be approximated by the chemical formula ( ), and heavy diesel which has a molecular weight of about (200) and can be approximated as ( ). Most diesel fuels used in engines will fit in this range, light diesel fuel will be less viscous and easier to pump, will generally inject into smaller droplets [1].

Cetane Number.
In a compression ignition engine,self-ignition of the (air-fuel )mixture is a necessity, the correct fuel must be chosen which will self-ignite at the precise proper time in the engine cycle.It is therefore necessary to have knowledge and control of the ignition delay time of the fuel.The property that quantity this is called the (Cetane Number ), the larger the cetane number, the shorter is the ignition delay and the quicker the fuel will self-ignite in the combustion chamber environment. A low cetane number means the fuel will have a long ignition delay .cetane numbers are established by comparing the tested fuel with two standared reference fuels. The fuel component ( n-cetane) ( hexadecane ) , ( ) , is given the cetane number value (100), while heptamethylenonane ( HMN ), ( ) is given the value of (15). The cetane number (CN) of other fuels is then obtained by comparing the (Ignition delay) of that fuel with the (Ignition delay) of a mixture blend of the two reference fuels with: CN of fuel = (percent of n-cetane) + 0.15 (percent of HMN)..(1-1).
The normal cetane number range for vehicle fuel is about (40 to 60) for a given engine injection timing and rate, if the cetane number of the fuel is low , the ignition delay will be too long .When this occurs, more fuel the desirable will be injected into the cylinder before the first fuel particles ignite, causing over large, fast pressure rise at the start of combustion .This results in low thermal efficiency and a rough-running engine ( long ignition delay of fuels with E185 cetane numbers below (40) causes in a very rich fuel-air mixture in the cylinder when ignition finally occursThis results in unacceptable levels of exhaust smoke, and these fuels are illegal by many emission laws). If the [CN] of the fuel is high, combustion will start too soon in the cycle. Pressure will rise before (top dead center) and more work will be required in the compression stroke. Cetane number is the most important single fuel property which affects the exhaust emission, noise and start ability of a diesel engine. In general, the lower the cetane number, the higher are the hydrocarbon emissions and noise levels, cetane fuels increase ignition delay so that start of combustion is nearer to top dead center [2].

Ignition Delay and Cetane Number.
An increase in temperature, pressure, engine speed, or compression ratio will decrease the ignition delay time. Fuel droplet size, injection velocity, injection rate, and physical characteristics of the fuel seem to have little or no effect on the ignition delay time. At higher engine speeds, turbulence increased, wall temperature is higher and ignition delay is process. If the cetane number is low , ignition delay will be too long , and more-than desirable amount of fuel will be injected in to the cylinder before combustion starts.then, when combustion does start , a greater amount of fuel will be quickly consumed and the initial cylinder pressure rise will be greater,Then when combustion does start , a greater amount of fuel will be quickly consumed and the initial cylinder pressure rise will be greater,If the cetane number is high , combustion will start too early before (top dead center) , with a resulting loss in engine power.Ignition delay time is inversely proportional to cetane number .
( The use of a fuel with too low cetane number results in accumulation of fuel in the cylinder before combustion causing " diesel knock " , and too high cetane number will cause rapid ignition and high fuel consumption).The increasing temperature of fuel injection will cause E186 large spray droplets and incomplete combustion , fuel is injected into combustion chamber in an atomized spray at end of the compression stroke, after air has been compressed to (31-45) bar and has reached a temperature, due to compression , of at least (500 ) . This temperature ignites the fuel and initiates the pistons power stroke, the fuel is injected at high pressure (137) bar to ensure good mixing [3].
2-Literature Summury. ). The fuel ( CN ) is increased for the standard injection pressure, but the smoke value increased dramatically when the injection pressure was reduced to (100)bar in contrast with the lower pressure smoke that decreased when the injection pressure was increased to (250 bar). Increases in engine torque by (5 %) and power output by ( 4% ) were observed at the max torque speed of (2500 rpm), when the cetane number was increased from ( 46 to 54.5 ).
However when increasing ( CN ) above (54.5) no significant increase in the engine performance was observed.

3-Experimental Work.
The experimental work was done on a diesel engine type ( Fiat ) .

Compression Ignition Engine.
The engine used in the experimental work is a compression ignition engine (C.I. engine) type (FIAT) model (TD313), 4 cylinders, 4 strokes; the displacement volume for this engine is (3.666L). The engine was coupled to a hydraulic dynamometer to measure the brake torque.   The following parameters are measured for the diesel engine:-1-Brake torque (N.m).

Measurement of brake torque.
The hydraulic dynamometer, Fig (1-2), type (isilingegner iadidattica) was used to measure the brake torque of (C.I. engine) by using friction fluid. Water was used as the friction fluid . The dynamometer consists of an inner rotating member or impeller coupled the output shaft of the engine. This impeller rotates in a casing filled with water. The output can be controlled by regulating the gates which can be moved in and out to partially or wholly obstruct the flow of water between the impeller and casing. The equation (1)(2)(3) in (Appendix A) was used to calculate the brake power.

Fuel consumption.
The glass tube, as shown in Figures (1-4), was used to measure the fuel consumption of the (C.I. engine). This glass tube has a constant volume (100) ml, a stop watch was used to measure the fuel consumption of this volume, and fig (1-5) shows the three tanks used in the test that contain diesel fuel with different fuel cetane numbers and, two tank for cetane number of (53, 54) and the main tank of the engine filled with cetane number (56). The equation (1-4) was used to calculate the fuel consumption.

Air consumption.
The air supplied to compression ignition engine was measured by using air box, orifice and the manometer used to measure the pressure differential between the atmosphere and pressure inside the air box. The equation (1)(2)(3)(4)(5) in was used to calculate the air consumption see fig. (1-6).

Emissions.
The exhaust gas analyzer type (Flux 2000 Italy) was used to analyze the emissions of exhaust, as shown in Fig (1-7). The analyzer detects the --HC-contents. The gases are picked up from the vehicle exhaust pipe by means of a probe. They are separated from water E193 moisture through the condensate filter, and then they are conveyed into the measuring cell. A ray of infrared light, generated by a transmitter, is sent through the optical filters on to the measuring elements. The gases in the measuring cell absorb the ray of light at different wavelengths, according to their concentration. The , gases due to their molecular composition (they have the same number of atoms) do not absorb the emitted ray.
This prevents measuring the concentration through the infrared system. The CO, and HC gases, thanks to their molecular composition, absorbs the infrared rays at specific wavelengths (absorption spectrum). However, the analyzer is equipped with a chemical kind sensor through which the oxygen which the oxygen percentage ( is measured.

4-Results and Conclusion.
4.1 Effect of engine load on the brake power of the engine. (1-9) Brake torque of the engine for different speed of the engine.  Fig. (1-10) showing the fuel consumption for different fuel cetane number Fig. (1-11) showing the brake thermal efficiency for different fuel cetane number. Fig. (1-12) showing the brake specific fuel consumption for different fuel cetane number for different engine speed.

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The conclusions from the above figs are: 1-The brake power increase with the engine speed and the increase in bp at max load is (64%) than the bp at min load and this is can be shown from fig (1-8).
2-The brake torque is increase with the engine speed and this is can be shown from fig (1-9) . (1-10) show the fuel consumption for different engine speed and for different cetane number of fuels and show us that the fuel with high cetane number have the lowest fuel consumption so fuel of cetane number (56) it is the more economically than the other fuels. From fig (1-11) show the brake thermal effeciency for different engine speed and for different cetane number of fuels and show us that the fuel with high cetane number have the highest brake thermal efficiency so fuel of cetane number (56) it is the more economically than the other fuels. fig (1-12) show the specific fuel consumption for different engine speed and for different cetane number of fuels and show us that the fuel with high cetane number have the lowest brake specific fuel consumption so fuel of cetane number (56) it is the more economically than the other fuels. fig (1-13) show the CO2 Emissions for different engine speed and for different cetane number of fuels and show us that the fuel with high cetane number have the lowest CO2 emissions so fuel of cetane number (56) it is the more economically than the other fuels. fig (1-14) show the CO Emissions for different engine speed and for different cetane number of fuels and show us that the fuel with high cetane number have the lowest CO emissions so fuel of cetane number (56) it is the more economically than the other fuels. fig (1-15) show the HC Emissions for different engine speed and for different cetane number of fuels and show us that the fuel with high cetane number have the lowest engine HC engine so fuel of cetane number (56) it is the more economically than the other fuels.