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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

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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.

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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 self-

contained 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 aninternal combustion engine's maximum intake of air

and fuel that occurs when thethrottle 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 theaccelerator 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 wide-

open 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 adiesel 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 thestoichiometric point.

If any more fuel were to be injected then black smoke would result.[2]

http://en.wikipedia.org/wiki/Internal_combustionhttp://en.wikipedia.org/wiki/Throttle_platehttp://en.wikipedia.org/wiki/Accelerator_(car)http://en.wikipedia.org/wiki/Diesel_enginehttp://en.wikipedia.org/wiki/Stoichiometrichttp://en.wikipedia.org/wiki/Stoichiometrichttp://en.wikipedia.org/wiki/Diesel_enginehttp://en.wikipedia.org/wiki/Accelerator_(car)http://en.wikipedia.org/wiki/Throttle_platehttp://en.wikipedia.org/wiki/Internal_combustion

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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 550C.

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(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 moves 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

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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

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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)

6.53 1595 1.09

6.56 1616 1.11

6.83 1676 1.2

6.99 1621 1.19

6.91 1604 1.16

7.07 1572 1.16

7.27 1520 1.16

6.88 1388 16.86 1366 0.98

7.19 1338 1.01

7.34 1325 1.02

7.15 1278 0.96

7.1 1174 0.87

7.05 1167 0.86

6.82 1107 0.79

6.88 1089 0.78

7 1084 0.79

6.9 1065 0.77

7.12 1020 0.76

6.94 906 0.66

6.84 916 0.66

7.17 923 0.69

6.93 899 0.65

6.84 856 0.61

3.58 0 0

T (Nm)

Sp

(rpm)

Pwr

(kW)

0.28 2702 0.08

0.23 2700 0.07

0.24 2703 0.07

0.4 2710 0.11

0.41 2708 0.12

0.63 2697 0.18

0.77 2693 0.22

1.12 2683 0.311.79 2664 0.5

2.56 2621 0.7

3.36 2578 0.91

3.87 2563 1.04

4.35 2545 1.16

5.71 2543 1.52

7.19 2524 1.9

8.11 2378 2.02

6.56 1627 1.12

6.69 1658 1.16

6.77 1672 1.19

6.55 1599 1.1

6.8 1697 1.21

6.51 1637 1.12

6.57 1631 1.12

6.63 1646 1.14

Continue

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Discussion

1) The results from excel were plotted in the graph shown below in graph no.1.

Graph no. 1

2)

Graph no.1 above shows the performance curve of a diesel engine by the enginesspeed 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

0

1

2

3

4

5

6

7

8

9

0

0.25

0.5

0.75

1

1.25

1.5

1.75

2

2.25

800 1000 1200 1400 1600 1800 2000 2200 2400 2600

Pwr

(kW)

Torque(N

m))

Speed (rpm)

Performance Curve

Pwr

(kW)

T

(Nm)

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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

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