FACULTY OF ENGINEERING & TECHNOLOGY
LAB SHEET
Internal Combustion Engine EME 4096
TRIMESTER 3 (2013/2014)
Experiment 1:
Test Engine Bed (Single Cylinder 4-Stroke CI)
Name
Mohammed Islam
ID
1112702923
Table of Contents
Abstract………………………………………………………………………………………………………….….…….3
Objective………………………………………………………………………………………………..……….……….4
Introduction………………………………………………………………………………………….………………….4
Procedures……………………………………………………………………………………………………………….6
Result……………………………………………………………………………………………………………………….7
Discussion and Data Analysis…………………………………………………………………………………….9
Conclusion…………………………………………………………………………………………………..………….11
References…………………………………………………………………………………………………..………….11
Abstract
A diesel engine performance test was conducted on an an Engine Test Bed (SOLTEQ, Model: TH 03). Torque (Nm) and Power (kW) of the engine was analysed with increasing Speed (rpm) of the engine and from the results acquired performance curves were plotted to better observe the results and hence determine the factors leading to the performance of a diesel engine. The results were acquires due to the help of a computer software hence the results were easy to collect and plot in excel.
Objective
To determine the engine performance at full throttled condition and to prepare the engine performance curve Introduction
This experiment is conducted on an Engine Test Bed (SOLTEQ, Model: TH 03) which is a selfcontained compact unit designed for easy installation and bench mounting. The test set is supplied with, as standard, a diesel engine which is a single cylinder, four -stroke; spark ignited and air cooled. The engine and dynamometer are carried on a solid steel base plate resiliently mounted within a steel framework. Included within the framework are the fuel system, which incorporates a fuel tanks and valves, and the air induction system. The instrumentation and control panel are mounted on the front frame. The engines are supplied with proper adaptors for measuring of temperature at exhaust and lubrication oil tank. Wide open throttle (WOT) refers to an internal combustion engine's maximum intake of air and fuel that occurs when the throttle plates inside the carburettor or throttle body are "wide open", providing the least resistance to the incoming air. In the case of an automobile, WOT is when the accelerator is depressed fully, sometimes referred to as "flooring it".
[2]
Wide-Open Throttle (WOT) Engine operated with throttle valve fully open when maximum power and/or speed is desired. Typical values of volumetric efficiency for an engine at wideopen throttle (WOT) are in the range 75% to 90%, going down to much lower values as the throttle is closed. Restricting air flow into an engine (closing the throttle) is the primary means of power control for a spark ignition engine.
[1]
In the case of a diesel engine, which does not have a throttle valve, WOT is the point at which the maximum amount of fuel is being injected relative to the amount of air pumped by the engine, generally in order to bring the fuel-air mixture up to the stoichiometric point. If any more fuel were to be injected then black smoke would result.
[2]
An engine that completes one cycle with four strokes of the piston, or two revolutions of the crankshaft is called a four-cycle diesel engine. An engine that completes one cycle with two strokes of the piston, or one revolution of the crankshaft, is called a two-cycle diesel engine.
Figure no.1
Figure no.1 above shows a visual explanation of the process in a diesel engine cylinder. (1) Intake Stroke
Clean air is drawn into the cylinder as the piston descends from its top-dead-center. At this time, the intake valve opens slightly before the piston reaches its top -dead-center in order to facilitate the intake of air. It remains open for a while even after the piston has passed its bottom-dead-center and has started ascending again.
(2) Compression Stroke
After the piston moves past its bottom-dead-center and starts to ascend, the intake valve closes, causing the air that was drawn into the cylinder to become compressed with the ascent of the piston. Because a diesel engine creates combustion by igniting the injected fuel with the heat of the compressed air, the compressive pressure is much higher than in a gasoline engine. Even when the engine speed is low, such as during starting, there is a compressive pressure of approximately 20 to 30 kg/cm2, and the compressive temperature reaches 400 to 550°C.
(3) Combustion Stroke
Near the end of the compression stroke, fuel is injected in a spray form by a nozzle that is provided in the cylinder head. The compressive heat causes the mixture to self-ignite, resulting in a sudden combustion and the expansion of the combustion gas pushes the piston down.
(4) Exhaust Stroke
Slightly before the piston reaches its bottom-dead-center in the combustion stroke, the exhaust valve opens, and the resulting difference in pressures starts the discharge of the exhaust gas. Then, as the piston ascends from the bottom-dead-center, the exhaust gas is pushed out of the cylinder. As described thus far, the engine effects the four strokes of intake, compression, combustion, and exhaust while the piston move s in the cylinder from its top-dead-center to bottom-dead-center, or vice-versa.
[3]
Procedure:
1. The position of all the sensors and the presence of fuel in fuel tank were checked 2. The power was switched on and left to idle for 20 minutes to warm up 3. The lude (p) and the speed (n) is is set to zero 4. Slowly turn the knob the controls the speed (rpm), until the engine shuts doen automatically 5. The data stored in the computer is acquired and later tabulated in excel software
Results
The results were acquired from the computer attached to the sensors, the figure below shows a part representation of the data acquired from the software
Figure no.2
The results were transferred to notepad which was again imported into the excel software. Our main variables to focus upon are Speed(rpm), Torque(Nm) and power(kW). The results below show the main variables.
T (Nm)
Sp (rpm)
Pwr (kW)
Sp (rpm)
T (Nm)
Pwr (kW)
0.28
2702
0.08
6.53
1595
1.09
0.23
2700
0.07
6.56
1616
1.11
0.24
2703
0.07
6.83
1676
1.2
0.4
2710
0.11
6.99
1621
1.19
0.41
2708
0.12
6.91
1604
1.16
0.63
2697
0.18
7.07
1572
1.16
0.77
2693
0.22
7.27
1520
1.16
1.12
2683
0.31
6.88
1388
1
1.79
2664
0.5
6.86
1366
0.98
2.56
2621
0.7
7.19
1338
1.01
3.36
2578
0.91
7.34
1325
1.02
3.87
2563
1.04
7.15
1278
0.96
4.35
2545
1.16
7.1
1174
0.87
5.71
2543
1.52
7.05
1167
0.86
7.19
2524
1.9
6.82
1107
0.79
8.11
2378
2.02
6.88
1089
0.78
6.56
1627
1.12
7
1084
0.79
6.69
1658
1.16
6.9
1065
0.77
6.77
1672
1.19
7.12
1020
0.76
6.55
1599
1.1
6.94
906
0.66
6.8
1697
1.21
6.84
916
0.66
6.51
1637
1.12
7.17
923
0.69
6.57
1631
1.12
6.93
899
0.65
6.63
1646
1.14
6.84
856
0.61
3.58
0
0
Continue →→→→
Discussion
1) The results from excel were plotted in the graph shown below in graph no.1.
Performance Curve
2.25
9
2
8
1.75
7
1.5
6
1.25 ) ) m N 1 ( e u q r 0.75 o T
5
0.5
2
0.25
1
4
) W k ( r w P
3
0
0 800
1000
1200
1400
1600
1800
2000
2200
2400
2600
Speed (rpm)
Graph no. 1 2) Graph no.1 above shows the performance curve of a diesel engine by the engine’s speed to its toque and power. According to the readings, the increase in the power of the engine is proportional to the speed of the engine till it reaches a maximum of 2.02kW at 2378rpm. After this point the power of the engine shows a rapid decrease to a point of shut down at 2702rpm.This is probably due to the friction losses at higher speeds. Similarly the readings show that initially the torque is quite stable with slight fluctuations between 6.5Nm to 7.3Nm until the engine increases rapidly to its maximum of 8.11Nm at 2378rpm. After this point the power of the engine shows a rapid decrease to a point of shut
Pwr (kW) T (Nm)
down at 2702rpm.This is probably due loss in volumetric efficiency in the engine at high speed hence leading to loss of torque. The similarity between both the curves is that the maximum for both occur at the same speed of 2378rpm. The representation of the results can be visually observed in graph no.1 shown above. 3)
(⁄) [ *+] According to the thermal efficiency formula shown above, the values of compression ratio and the cut off ratio are required to calculate the efficiency of the engine. This experiment was not elaborate enough to get the cut off ratio and the compression ratio. So it is not possible to calculate the efficiency of this experiment by conducting a limited experiment. 4) It is clear from graph no.1 that all the variables; brake power, torque and engine performance increases with an increase in the engine speed. But after a point all the variables start decreasing even though the engine speed keeps increasing, until the engine suddenly shuts down due to overheating. Each variable have their own reasons for the decrease. The Torque is low at high speeds because the volumetric efficiency decreases at high speeds. The brake power decreases at higher speeds because the mechanical efficiency decreases at high speeds due to friction and other minor losses. Therefore the indicated power continuously increases. Indicated power = friction power + brake power
Conclusion
In this introductory practical of internal combustion engine lab it is observed as to what the diesel engine test bed is and how it works. Not only modern technology is fast and reliable but its versatility has helped in the acquiring of lab data which were easily collected and plotted. This experiment shows that diesel engine is capable of producing a reasonable amount of torque even if the speed is less and can maintain this torque to high speeds too hence making it very useful for large truck and Lorries and for uphill driving. It is noted that the brake power increases linearly with increasing engine speed until the engine is operated at very high speed. A downfall of using diesel engine is that a diesel engine requires large space to be operated and it creates high noise distur bance in the nearby areas while running.
References
1. Willard W. Pulkrabek, “Engineering fundamentals of the internal combustion engine”, 2nd addition, Prentice hall, 2004.
2. http://en.wikipedia.org/wiki/Wide_open_throttle 3. http://www.kovsh.com/media/library/228/AAC02VD.pdf
