Government Engineering College, Jagdalpur



GOVERNMENT ENGINEERING COLLEGE JAGDALPUR, BASTAR (C.G.)-494005

LAB RECORD

OF

INTERNAL COMBUSTION ENGINE LAB

337662 (37)

DEPARTMENT OF MECHANICAL ENGINEERING

NAME OF STUDENT

SEMESTER

BATCH

ROLL NO.

ACADEMIC SESSION

LABARATORY CLASSES - INSTRUCTIONS TO STUDENTS

1. Students must attend the lab classes with ID cards and in the prescribed uniform.

2. Boys-shirts tucked in and wearing closed leather shoes. Girls’ students with cut shoes, overcoat, and plait incite the coat. Girls’ students should not wear loose garments.

3. Students must check if the components, instruments and machinery are in working condition before setting up the experiment.

4. Power supply to the experimental set up/ equipment/ machine must be switched on only after the faculty checks and gives approval for doing the experiment. Students must start to the experiment. Students must start doing the experiments only after getting permissions from the faculty.

5. Any damage to any of the equipment/instrument/machine caused due to carelessness, the cost will be fully recovered from the individual (or) group of students.

6. Students may contact the lab in charge immediately for any unexpected incidents and emergency.

7. The apparatus used for the experiments must be cleaned and returned to the technicians, safely without any damage.

8. Make sure, while leaving the lab after the stipulated time, that all the power connections are switched off.

Index

|Sr. |Name Of Experiment |Date |Signature |Remark |

|No. | | | | |

| | | | | |

| | | | | |

| | | | | |

| | | | | |

| | | | | |

| | | | | |

| | | | | |

| | | | | |

| | | | | |

| | | | | |

| | | | | |

| | | | | |

INTERNAL COMBUSTION ENGINE LAB

6th SEM. MECHANICAL

LIST OF EXPERIMENTS

|SL. |NAME OF EXPERIMENTS |PAGE |

|NO. | |NO. |

|1 |Study of working of two-stroke petrol engine and two-stroke diesel engine with help of cut section model. |01 |

|2 |Study of working of four-stroke petrol engine and four-stroke diesel engine with help of cut section model. |07 |

|3 |Study of fuel supply system of a petrol engine (simple carburetor) |12 |

|4 |Study of fuel supply system of a Diesel engine. (Fuel pump and fuel injector) |15 |

|5 |Study of Ignition system of an IC Engine (Battery and magneto ignition system) and Electronic ignition system. |18 |

|6 |Study of Lubrication system of an IC Engine (mist, splash and pressure lubrication) |26 |

|7 |Study of cooling system of an IC Engine (air cooling and water cooling) |29 |

|8 |To conduct a performance test on Four-stork Single Cylinder Diesel Engine Test Rig and to draw the heat balance sheet for given |35 |

| |load. | |

|9 |To conduct a performance test on Four-stork Four Cylinder petrol Engine Test Rig and to draw the heat balance sheet for given load|42 |

| |and performance curve. | |

| | | |

EXPERIMENT NO-01

OBJECT-

Study of working of two-stroke petrol engine and two-stroke diesel engine with help of cut section model.

THEORY:-

When working cycles of an engine is completed in two strokes of the piston or in one revolution of the crankshaft, then such an engine is called two-stroke cycle engine. Duglad Clerk devised a two-stroke cycle petrol engine in 1880. In this cycle, the suction, compression, expansion and exhaust takes place during two strokes of the piston. It means that there is one working stroke after every revolution of the crankshaft. A two-stroke engine has ports instead of valves.

[pic]

TWO STROKE PETROL ENGINE

WORKING OF TWO STROKE CYCLE PETROL ENGINE:-

All the four stages of a two stroke petrol engine are described below.

1. Suction stage- In this stage, the piston, while going down towards BDC, uncovers both the transfer port and the exhaust port. The fresh fuel-air mixture flows into the engine cylinder from the crankcase.

2. Compression stage- In this stage, the piston, while moving up, first covers the transfer port and then exhaust port. After that the fuel is compressed as the position moves upwards as shown in fig. In this stage, the inlet port opens and fresh fuel-air mixture enters into the crankcase.

3. Expansion stage- Shortly before this piston reaches the TDC (during compression stroke), the charge is ignited with the help of a spark plug. It suddenly increases the pressure and temperature of the products of combustion. But the volume, practically, remains constant, Due to rise in the pressure. The piston is pushed downwards with a great force. The hot burnt gases expand due to high speed of the piston. During this expansion, some of the heat energy produced is transformed into mechanical work.

4. Exhaust stage- In this stage, the exhaust port is opened as the piston moves downwards. The products of combustion, from the engine cylinder are exhausted through the exhaust port into the atmosphere. This completes the cycles and the engine cylinder is ready to such the charge again.

USES:- The two stroke petrol engines are generally employed in very light vehicles such as scooters, motor cycles, three wheelers and sprayers.

P-V Diagrams for 2-stroke cycles petrol engine:-

[pic]

First stroke:- Suppose the piston is at TDC and the volume above the piston (clearance volume) is full of compressed charge (mixture of air-fuel for Otto and only air for diesel cycle). In an Otto cycle the fuel is ignited by means of an electric spark at constant volume, the process 2-3. The pressure of hot gases produced due to ignition, moves the piston down-wards and the work is done by the hot gases (process of expansion). This process continues till the exhaust port is open by the piston. During this process the inlet port is closed and the downward motion of the piston now compresses the charge already gone to the crankcase. Hence, the inside volume of the case decreases with increase of pressure of the charge. When the exhaust gases in the cylinder is nearly to the atmospheric value, then the inlet port opens and the fresh compressed charge from the crankcase enters the cylinder. The first stroke is completed when the piston reaches BDC.

Second stroke:-

When the piston moves upwards ad the charge is compressed, the inlet port and the exhaust port remain closed. The volume inside the crankcase increases with decrease of pressure and the charge enters into the crankcase through the inlet port. The second stroke is completed when the piston reaches TDC and the 2-stroke cycle is completed. The p-v diagrams of Otto and Diesel 2-stroke cycles.

Valve timing Diagrams for 2-stroke cycles petrol engine-

[pic]

WORKING OF TWO STROKE CYCLE DIESEL ENGINE-

During the upward movement of the piston, first the transfer port and then the exhaust port closes. As soon as the exhaust port closes the compression of the air starts. As the piston move up, the pressure in the crankcase decreases so that the fresh air is drawn into the crankcase through the open inlet port. Just before the end of the compression stroke the fuel is forced under pressure in the form of fine spray into the engine cylinder through the nozzle into this hot air. At this moment, the temperature of the compressed air is high enough to ignite fuel. It suddenly increases the pressure and temperature of the products of combustion. The rate of fuel injection is such as to maintain the gas pressure constant during the combustion period. Due to increased pressure the piston is pushed down with a great force. Then the hot products of combustion expand. During expansion some of the heat energy produced is transformed into mechanical work. When the piston is near the bottom of the stroke it uncovers exhaust port, which permits the gases to flow out of the cylinder. This completes the cycle and the engine cylinder is ready to suck the air once again.

[pic]

SCHEMATIC OF TWO-STROKE CYCLE DIESEL ENGINE

P-V Diagrams for 2-stroke cycles diesel engine: -

[pic]

Valve timing Diagrams for 2-stroke cycles diesel engine:-

[pic]

Advantages of 2-stroke cycle engine:

The advantages of 2-stroke cycles engines over the 4-stroke cycles engines are:

i) A net positive work is obtained from a 2-stroke cycle engine because it works above the atmospheric pressure.

ii) They are simple in design, manufacture and operation. Hence, they are used in small power engines such as scooters, auto-rickshaws and motorcycle.

iii) The turning moment of a 2-stroke cycle engine is more uniform and a smaller size flywheel is needed because of one working stroke for each revolution of the crankshaft.

iv) Theoretically, a 2-stroke cycle engine produces twice the power of the 4-stroke cycle engine for the same size and the same speed of the engine because one-engine wheels in 4-stroke cycle engine it is obtained in two revolutions of the crankshaft.

v) There is less friction loss due to absence of valve rockers, cams and camshafts etc in a 2-stroke cycle engine and hence higher mechanical efficiency.

vi) There is better scavenging in 2-stroke cycle engine at low speed since the burnt gases do not fill the clearance space.

vii) 2-stroke cycle engine is much lighter and more compact for the same power as compared to 4-stroke cycle engine.

Disadvantages of 2-stroke cycle engines:

The following are the disadvantages of 2-stroke cycle engines over 4-stroke cycle engines:

i) The effective compression ration is lower in a 2-stroke cycle engine for the same stroke and clearance volume.

ii) An effective cooling arrangement is needed since there is one working stroke in each revolution and less dissipation of heat than the 4-stroke engine.

iii) A 2-stroke cycle engine is noisier because of sudden release of burnt gases in the exhaust port.

iv) Mass of lubricating oil needed is more in 2-stroke cycles engines.

v) Scavenging pump absorbs power.

vi) Loss of fuel at the time of admission of charge in the 2-stroke cycles S.I. engine is observed.

vii) Thermal efficiency of 2-stroke engines is generally less due to the fact that some amount of charge escapes without burning and poor scavenging due to short period opening of the exhaust port.

QUESTIONS FOR VIVA-

1. What do the terms T.D.C. and B.D.C. stand for?

2. Define piston stroke?

3. What is clearance volume?

4. What is piston displacement in an engine?

5. How do you define compression ratio?

6. What is mean effective pressure?

7. What is the function of an engine flywheel?

***********

EXPRIMENT NO-02

OBJECT-

Study of working of four-stroke petrol engine and four-stroke diesel engine with help of cut section model.

THEORY-

In four-stroke cycle S.I. engine one cycle of operation is complete in four strokes of the piston in two revolutions of the crankshaft. Each stroke is completed with half rotation of crankshaft i.e.1800 of rotation.

[pic]

FOUR-STROKE PETROL ENGINE

WORKING OF FOUR- STROKE CYCLE PETROL ENGINE (S.I. ENGINE): -

The sequence of the four operations i.e. suction, compression, expansion (power), and exhaust.

i) Suction stroke- Process o-a is the suction stroke and it starts when the piston is at TDC and is about to move downwards. At this time the exhaust valve is closed and the inlet valve is open. Due to the motion of the piston towards BDC (bottom dead center0 vacuum or suction is created and hence the mixture of air and fuel (the charge) is drawn into the cylinder. The inlet valve is closed at the end of the suction stroke.

ii) Compression stroke- The mixture of air and fuel (the charge) taken into the cylinder during the suction stroke of the piston gets getting compressed when the piston starts its return stroke upwards from BDC to TDC (top dead center) during the process a-b. During the compression is compressed up to the clearance volume (vc) and just before the compression stroke is completed the spark plug ignites the charge. Burning of mixture occurs when the piston is at TDC spark gives to temperature up to about 20000c and pressure of the mixture considerably high. The chemical energy of the fuel is liberated and is transformed into thermal energy.

iii) Expansion (power) stroke- The gases at high pressure force the piston to move towards the BDC (expansion processes c-d). During this process the inlet valve and exhaust valve remain closed. Mechanical power is obtained during this process (stroke). The pressure and the temperature of the burnt gases decrease during expansion stroke.

iv) Exhaust stroke- The exhaust valve opens at the end of the expansion stroke and the inlet valve remain closed. The piston moves towards TDC and the gases exhaust from the cylinder (process d-o) to the atmosphere. At the end of the exhaust stroke the exhaust valve closes. The residual gases remain in the clearance volume of the cylinder of the S.I. engine.

P-V Diagrams for 4-stroke cycles petrol engine:-

[pic]

Valve timing Diagrams for 4-stroke cycles petrol engine:-

[pic]

WORKING OF FOUR- STROKE CYCLE DIESEL ENGINE( C.I. ENGINE)-

i) Suction stroke- During this stroke, the inlet valve opens and only air is sucked into the engine cylinder. The exhaust valve remains closed. This stroke is completed when the piston reaches the bottom dead center position.

ii) Compression stroke- During this stroke the piston starts moving upward from the bottom dead center position. In this stroke, both the inlet and exhaust valve remain closed. As the piston moves up, the air is compressed to a high pressure (about 60 bar) and temperature (6000c). Just before the end of the compression stroke, a fine spray of diesel is injected into the high temperature compressed air. The fuel ignites instantaneously. The injection of fuel takes place at constant pressure.

iii) Expansion stroke- During this strokes both inlet and exhaust valve remain closed. Due to increased pressure of the products of combustion, the piston is pushed down with a large force. Expansion of the gases takes place and work is down during this stroke. The expansion stroke is completed as the piston reaches its bottom dead center (BDC) position.

iv) Exhaust stroke- During this stroke the inlet valve remain closed while the exhaust valve remain open. The piston moves up from BDC to TDC position and pushes out the burnt gases from the engine cylinder. The stroke is completed as the piston reaches the TDC position and is ready for the next cycle.

[pic]

FOUR-STROKE DIESEL ENGINE

P-V Diagrams for 4-stroke cycles diesel engine:-

[pic]

Valve timing Diagrams for 4-stroke cycles diesel engine:-

[pic]

COMPARISON OF S.I. AND C.I. ENGINE-

|SL. NO. |Description |SI Engine (Petrol engine) |CI Engine (Diesel engine) |

|1 |Basic cycle |Otto cycle |Diesel cycle |

|2 |Fuel used |Gasoline |Diesel oil |

|3 |Introduction of fuel |Carburetor is used |Fuel pump & injector is used |

|4 |Ignition |Spark ignition |Self ignition due to high compression |

|5 |Compression ratio |6 to 10 |16 to 20 |

|6 |Speed |High speed engine |Low speed engine |

|7 |Thermal efficiency |Lower |Higher |

|8 |Weight |Lighter |Heavier |

QUESTIONS FOR VIVA-

1. What is an Otto cycle?

2. How does diesel cycle differ from Otto cycle?

3. What is difference between internal external combustion engines?

4. How is the fuel ignition in a diesel engine?

EXPERIMENT NO-03

OBJECT-

Study of fuel supply system of a petrol engine (simple carburetor)

CARBURETTOR-

PRINCILPE OF CARBURETION-

The carburetor works on Bernoulli’s principle; the fact that moving air has lower pressure than still air, and that the faster the movement of the air, the lower the pressure. The throttle or accelerator does not control the flow of liquid fuel. Instead, it controls the amount of air that flows throws the carburetor. Faster flows of air and more air entering the carburetor draws more fuel into the carburetor due to the partial vacuum that is created.

FUCTION OF A CARBURETOR-

A carburetor has been defined as a mechanical device to produced mixture of fuel and air in accordance with the requirements of the engine. It is always expected from carburetor that it will fulfill all the requirements as desired.

PARTS OF A SIMPLE CARBURETOR

[pic]

A simple carburetor

FLOAT CHAMBER-

The level of the petrol in the chamber should be maintained constant and slightly below the top of the spray nozzle. The level of the fuel in the float chamber is maintained constant with the help of float and needle valve. The main function of the float chamber assembly is to maintain the fuel level constant in the float chamber under variables loads on engine.

VENTURI-

The fuel flows through the fuel nozzle and mixes with the air as the air flows through the venturi. The suction is created inside the engine as the engine starts and the air sucked into the engine through the venturi.

THROTTLE VALVE-

The basic control element is the throttle valve. It controls the velocity of the mixture supplied to the engine through the intake manifold and therefore the head under which the fuel flows.

[pic]

Venturi

CHOKE VALVE-

It is necessary to provide an extra rich mixture to the engine during starting or warm up in cold weather.

The extra rich mixture ensures enough fuel availability in vaporized from for combustion. This is done by introducing the chock valve in the air passage before the venturi.

WORKING OF A SIMPLE CARBURETOR-

[pic]

Carburetor

The main function of the carbonator is to vaporize the petrol by means of engine suction and to supply the required quantity of the mixture (air and petrol) in proper proportion.As the engine is started, the suction is created inside the cylinder and airflows atmosphere into the cylinder. As the air passes through the venturi, the pressure of the air falls bellows the atmosphere and that is equivalent to hw, cm of water. The pressure of the nozzle tip is also hw, cm of water below, atmosphere because the pressure on the fuel surface in the fuel tank is also atmospheric. This pressure difference causes the flow of the fuel through the fuel jet into the air stream. As the fuel and air pass ahead of the venturi, the fuel gets vaporized and uniform mixture is supplied to the engine. The quality of the mixture supplied to the engine depends upon the opening of the throttle valve. In case of stationary engine, the opening of the throttle valve is controlled by the governor according to the load on the engine, in case of automobile engine on road; the opening of the throttle valve is controlled by the driver through thre accelerator pedal.

QUESTIONS FOR VIVA-

1. What is meant by carburetion?

2. What are the functions of a carburetor?

3. Why do are require a rich mixture even for idling?

4. What is a Stoi-chiometric air-fuel mixture?

5. Why is the carburetor float made hollow?

6. What is the function of venturi in a carburetor?

7. What is the function of choke valve in the carburetor?

EXPERIMENT NO-04

OBJECT-

Study of fuel supply system of a Diesel engine. (Fuel pump and fuel injector)

THEORY-

One of the most important parts of the ignition engine is its fuel supply system. The performance of engine depends on the proper functioning of this system. In fact it plays such an important part in the operation of the engine that it can be considered as the ‘heart’ of the engine.

FUEL FEED PUMP-

Fuel has to be fed to diesel engines of vehicles under pressure of about 1 atm.(gauge) as the quantity of fuel delivered would otherwise be inadequate. Only in stationary engines and in some tractors a gravity feed tank can be placed at so high a level as to provide sufficient pressure. Hence in diesel driven vehicles, fuel has to be pumped to the injection pump. The fuel feed pump has been designed to meet this demand. Fig. Shows fuel injection equipment with feed pump.

[pic]

Diagram of a fuel circulation in the injection system

DESIGN-

The fuel feed pump is constructed as a single acting or double acting plunger pump, and is usually provided with a hand priming devices and preliminary filter.

DRIVE-

The fuel feed pump is attached to the injection pump and driven by its camshaft that is either by a cam also driving a pump element of the injection pump, or by an eccentric mounted between two cams. It is advisable to use an eccentric for driving at higher speeds.

FUEL INJECTION PUMP-

INLINE ENCLOSED CAMSHAFT FUEL INJECTION PUMP-

To deliver accurately measured amounts of fuel at high pressure to the injectors. The amount of fuel delivered should be controlled precisely with regard to the timing, rate and duration and must satisfy the work the engine is required to do.

GENERAL DESIGN-

All our in-line fuel injection pumps are of cam-operated, spring return, plunger type, using one pumping unit for each engine cylinder, and incorporates its own camshaft tappet gear.

Each pumping unit comprises the following, essential components;

1. Pumping element, (barrel and plunger).

2. Delivery valve and seating.

OPERATION-

The system of operation of the pump elements, which is comprised have the plunger and barrel. When the plunger is at BDC as at oil can enter through the barrel ports either by gravity flow from an overhead tank, or force-feed from a fuel feed pump. As the pump plunger rises, a certain amount of fuel is pushed back through the barrel ports, until the plunger reaches the piston where the top land of the plunger has closed both parts. The fuel above the plunger is then trapped, and its only outlet is via the delivery valve, which is mounted on the top of the pump barrel. The pressure exerted by the rising plunger upon the oil causes this to lift the valve and to enter the pipe, which connects the pump to the injectors.

[pic]

Fuel injection pump pe type with generator for 6- cylinder

As this itself already full of oil, the extra oil that is being pumped in at the pump end, causes arise in pressure throughout the line and lifts the nozzle needle.

QUESTIONS FOR VIVA-

1. What is the principle of individual pump system?

2. What is the function of a fuel feed pump?

3. Where is feed pump usually located?

4. What is the function of nozzle?

5. Describe the function of a fuel injection pump?

6. What are the functions of a fuel injection system for a diesel engine?

7. What is the principle of a individual pump system?

EXPERIMENT NO-05

OBJECT-

Study of Ignition system of an IC Engine (Battery and magneto ignition system) and Electronic ignition system.

THEORY-

The operator of a spark ignition engine expects the ignition system to fire thousands of consecutive cycles in cylinders full of fuel air mixture without “miss” although the manifold pressure may vary from 0.35 to 2.7 kg/cm2, the air-fuel ratio may vary from 0.06 to 612 and the r.p.m. From 400 to 5000. In addition, the ignition must occur at the proper crank angles so that the time losses are held at a minimum.

BATTERY IGNITION SYSTEM-

Most of the modern spark ignition engines use battery ignition system. In this case, the energy required for producing spark is obtained from a 6 or 12-volt battery. Essential components of a battery ignition system are:

a) Battery,

b) Induction coil,

c) Distributor,

d) Contact Barker,

e) Condenser

f) Spark plug,

BATTERY-

To provide electrical energy for ignition, battery is used as an accumulator. It is charged by a dynamo driven by the engine. Owing to electro-chemical reactions, it is able to convert chemical energy into electrical energy. The battery must be mechanically strong to withstand the strains to which it is constantly subjected. Given reasonable care and attention two years or more of trouble – free life may be obtained.

[pic]

Cell connections for 12 volts battery

Two types of batteries are used for spark ignition engines the lead acid battery and the alkine battery. The former is used in private cars and light commercial vehicles and latter on heavier commercial vehicles and sometimes on motorcycles.

INDUCTION COILS-

Induction coil consists of a number of soft iron rods or strips bounded by an insulating materials, which constitutes laminated central core. Over this center are wound several turns of comparatively heavy enameled wire forming the primary winding. The secondary winding is wounded over or under the primary and consist of up to 20,000 turns of the fine enameled wire, the ratio between the two (secondary and primary) being about 50 to 1. Each layer of wire is insulated from the other during the winding process.

[pic]

Battery ignition system

DISTRIBUTOR-

The distributor unit usually includes the contact barker for reason of compactness and convenience, both driven by a single spindle. Additionally, most modern distributor contains mechanism for automatically advancing or retarding the duration of the spark plug, in accordance with the engine sped.

Each of the segments of the distributor is connected to a sparking plug and as the rotor presses it, the contact breaker opens, the high tension current is passed through the rotor and brass segment via high tension wiring to the appropriate spark plug.

[pic]

Details of distributor

CONTACT BREAKER-

This is mechanical device for braking (and making) the primary circuit and it consist essentially of a fixed metal point against which, another point bears, this second point being on a spring loaded pivoted arm. The metal used is invariably one of the hard metal, usually tungsten, and each point has a circular flat face of about 3 mm dia. The mounting of the fixed point and the arm to which the movable points is attached are insulated from each other, but both points are connected in series in the circuit so that when the point are in contact current may flow, when thy are separated the circuit is broken and the flow of current stops. The pivoted arm has, generally at the opposite end to the tungsten point, a heel or rounded part of some hard plastic material, and this heel bears on a cam, which is driven by the engine.

[pic]

Contact breaker

CONDENSER-

This consists of sheets of metal foil, separated by sheets of insulating material such as mica, termed the dielectric. Suitable papers are also used for this purpose. One sheet of the metal foil is connected to the condenser terminal, the next to the metal case of the condenser and so on, alternatively.

He terminal is connected to one side of the contact breaker and the casing is connected to the other, usually earth so that the condenser is in parallel with the contact breaker and the whole condenser forms a small cylindrical unit.

The function of the condenser is to provided a reserver for current include in the primary circuit of the uncoil as the contact breaker points are separated, bur for the condenser these current tends to cause sparking at the contact breaker point which, in a comparatively short time, would mean away or pitting at of the point, and, in consequence, misfiring and stopping of the engine.

[pic]

Condenser

ADVANTAGES OF BATTERY SYSTEM-

• Current is obtained from the battery.

• Sparking is good even at low speed.

• Starting of engine is easier.

• If the battery is discharge, the engine cannot be started.

• Occupies more space.

• Complicated wiring.

• Less costly.

• Spark intensity falls as the engine speed rises.

• Used in cars, buses trucks etc.

MAGNETO IGNITION SYSTEM-

The magneto is a generator of electric current mounted on and driven by the engine, and it may give either low tension or high tension current. Unless stated otherwise, magneto ignition today invariably means the high-tension magneto, which generates adequate voltage to jump across the gap at the sparking plug, and the magneto itself replace all the components of a coil ignition system, except the sparking plugs.

[pic]

Magneto ignition system

By eliminating the unreliability and trouble of early coil ignition system the high tension magneto first made possible the reliable engines that today we take for granted; although, something of a paradox, modern engine mostly employ the coil ignition system vastly improved, of course, over that which was ousted by the magneto. It is however, significant that where the last gram of the performance and reliability are demanded that is in aircraft, the magneto still holds the field. Otherwise also for engines developing more than 500 horsepower, magneto ignition engine system is invariably used.

ADVANTAGES OF MAGNETO IGNITION SYSTEM-

• Current is generated by the magneto.

• Poor sparking at low speed.

• Difficult starting.

• No such difficulty as battery is not needed.

• Occupies less space.

• Simple wiring.

• More costly.

• Sparking intensively improved as the engine speed rises.

• Used in motorcycles, scooters, racing cars etc.

ELECTRONIC IGNITION SYSTEM-

Points/coil ignition was near universal in petrol engine road vehicles for many years and steadily improved in the detail of design and construction. A careful owner carried out the necessary maintenance or had it dine for him, there by keeping his engine in s good state of tune. Not-so-careful owners ignored the engine so long as it still ran tolerated the poor fuel economy, degraded performance and difficult starting caused by their neglect. Today at the end of twentieth of century, quit ordinary family cars have electronic engine management system, which have done away with the familiar distributor and carbonator entirely and allow previously unheard of performance and fuel economy.

ADVANTAGES OF ELECTRONIC IGNITION SYSTEM-

To overcome the defects of the contact point ignition system, engineers have design two type of transistor ignition system-

1) Contact-trigger,

2) Magnetic pulse type.

[pic]

A-Standard system. B- Transistor system

The first advantages of the transistor system over the standard contact-point ignition system is that available output voltage can be increased substantially, because the contact point do not have to carry high currents.

The second advantages are that service problems are minimized because of the lower current passing through the points.

[pic]

Magnetic pulse type

The magnetic –pulse type transistor system has a further advantage is that there are no contact point-this eliminates rubbing block wear and resulting ignition timing problem of the former system and should, therefore, eliminate most of the ignition service problems.

QUESTIONS FOR VIVA-

1. What is the voltage of the batteries generally used in the automobile ignition system?

2. What is the voltage causing the spark at the plug electrodes?

3. What is the function of an ignition coil?

4. What does the condenser do in the ignition system?

5. What is the function of distributor and where is located on the engine?

6. Why does an electronic ignition system have a longer life than the conventional electrical system?

************

EXPERIMENT NO-06

OBJECT-

Study of Lubrication system of an IC Engine (mist, splash and pressure lubrication)

THEORY-

The lubrication system is an internal part of the engine and the operation of one depends upon the operation of the one depends upon the operation of the other. Thus the lubrication system, in actual practice, cannot be considered as a separate and independent system; it is part of the engine.

The parts of engine which require the lubrication these are-

• Cylinder walls, piston rings, gudgeon pin and crankshaft main and big end bearing.

• Camshaft-bushes arms, and its drive.

• Valve guides, rocker arms, valve, etc.

• Exhaust, compressor, blower etc.

OBJECTS OF LUBRICATION SYSTEMS-

The primary objects of lubrication are as follows: -

• To reduce the friction of moving parts.

• To reduce the wear of the moving parts.

• To act as a cooling medium for removing heat.

• To keep the engine parts clean, especially piston rings and groove, oil ways and filters.

• To form a good between piston rings and cylinder walls.

• To prevent deposition of carbon, soot and lacquer.

• To resists oxidization which causes sludge and lacquers.

FUCTION OF LUBRICATING SYSTEM-

The following are the important function of a lubricating system-

1) Lubrication- The main function of the lubricating system is to keep the moving parts sliding freely past each other and, thus, reduce the engine friction and wear.

2) Cooling- The oil that comes in contact between the two surface also caries the heat and cool then. This cooling action takes place simultaneously with the lubrication.

3) Cleaning- To keep the bearing s and piston rings clean of the products of wear and the products of combustion, especially the carbon, by washing them away and then, not allowing them to agglomerate to from sludge.

4) Sealing- The lubrication oil must from a good seal between piston rings and cylinder walls. The oil should be physically capable of filling the minute leakage paths and surface irregularities of the mechanical sealing elements that is cylinder, pistons and piston rings.

5) Reducing of noise- Lubrication reduces the noise of the engine. These functions are conflicting functions. The oil cools best when it is thin but seals best when it is thick.

TYPES OF LUBRICATION SYSTEM-

1) Charge lubrication system.

2) Wet sump lubrication system.

3) Dry dump lubrication system.

WET SUMP LUBRICATION SYSTEM-

1) SPLASH SYSTEM- Splash system is used on some small four-stroke stationary engine. In this case caps on the big end bearings opf connecting rod are provided with scoops which, when the connecting rod is in the lowest position, just dip into oil through and thus directs the oil through holes in the caps to the big end bearings. Due to splash of oil, it riches the lower portion of the cylinder walls, camshaft and other parts requiring lubrication. Surplus oil eventually flows back to the oil sump. Oil leveling the through by means of a oil pump which takes oil from sump, through a filter.

[pic]

Splash system

Splash system is suitable for low and medium speed engines having moderate bearing loads pressures. For high performance engines, which normally operate at high bearing pressure and rubbing speeds, this system does not serve the purpose.

2) PRESSURE SYSTEM- In this method, oil from oil sump is pumped under

pressure to the various parts requiring lubrication.

[pic]

Pressure system

The oil drawn fro the

sump through filter, and pumped by means of a gear pump. Oil is delivered

by the pressure pump at pressure ranging from 1.5 to 4 kg/cm2 . The oil

under pressure is supplied to main bearings of crankshaft and camshaft.

Holes drilled through the main crankshaft bearing journals communicate oil

to the big end and also small end bearing through hole drilled in connecting

rod.

QUESTIONS FOR VIVA-

1. Discuss the function of lubricant in an engine?

2. What are the desirable properties of lubricant oils?

3. What is the importance of lubrication as far as internal combustion engines are connected?

4. What is the necessity of engine lubrication?

5. What is hydrodynamic lubrication?

6. What is meant by wet sump lubrication?

EXPERIMENT NO-07

OBJECT-

Study of Cooling system of an IC Engine (air cooling and water cooling)

THEORY-

Engine cooling is the process of cooling an engine by using either air or liquid. As engines generate mechanical power they also generate waste heat energy because they are not perfectly efficient, the engine must therefore be cooled to prevent it form cooling in its own heat.

An internal combustion engine produces power by burning fuel within the cylinders; therefore, it is often referred to as a “heat engine.” However, only about 25% of the heat is converted to useful power. Thus, cooling system is provided on a engine for the following reasons:

1. High temperatures reduce strength of piston and cylinder liner.

2. Uneven expansion of piston in the cylinder may result in seizure of the piston.

3. Physical and chemical changes may occur in lubricating oil, which may cause sticking lf piston rings and excessive wear of cylinder.

4. Overland cylinder head may lead to pre ignition of the charge, in case of spark ignition engines.

PRIMARY FUNCTIONS OF COOLING SYSTEM-

The cooling system has four primary functions. These functions are as follows:

1. Remove excess heat from the engine.

2. Maintain a constant engine operating temperature.

3. Increase the temperature of a cold engine as quickly as possible.

4. Provide a means for heater operation (warming the passenger compartment).

BASIC PRINCIPLES OF COOLING SYSTEM-

Most internal combustion engines are “air-cooled” or “liquid-cooled”. Each principle has advantage and disadvantage, and particular applications may favor one over the other, For example, most cars and trucks use water-cooled engines, while most small airplane engines are air-cooled.

Most liquid-cooled engines use a mixture of water and other chemicals such as antifreeze and rust inhibitors. Some use no water at all, instead using a liquid with different properties, such as ethylene glycol. Although the term “liquid-cooled” is used here, most air-cooled engines also use some liquid oil cooling, and most liquid-cooled engines subsequently cool the hot liquid with air.

Conductive heat transfer is proportional to the temperature difference b/w materials. If an engines metal is a 300 0c and the air is at 0 0c, then there is a 300 0c temperature difference for cooling. An air-cooled engine uses all of this difference.

In contrast, a liquid-cooled engine might dump heat form the engine to a liquid, heating the liquid to 150 0c which is then cooled with 0 0c air. Thus, in each step, the liquid-cooled engine has half the temperature difference and so may need as much need as much as twice the cooling area.

WORKING OF A COOLING SYSTEM-

[pic]

Diagram of a cooling system: how the plumbing is connected.

Although gasoline engines have improved a lot, they are still not very efficient at turning chemical energy into mechanical power. Most of the energy in the gasoline (perhaps 70%) is converted into heat, and it is the job of the cooling system to take care or that heat. In fact, the cooling systems on a car driving down the freeway dissipate enough heat-to-heat two average-sized houses! The primary job of the cooling system is to deep the engine from overheating by transferring this heat to the air, but the cooling system also has several other important jobs.

The engine in your car runs best at a fairly high temperature. When the engines are cold, components wear out faster, and the engine is less efficient and emits more pollution. So another important hob of the cooling system is to allow the engine to heat to heat up as quickly as possible, and then to keep the engine at a constant temperature.

METHODS OF COOLING SYSTEM-

There are following four methods of engines cooling:

1. Air-cooling.

2. Water-cooling.

3. Liquid cooling.

4. Steam cooling.

5.

AIR COOLING SYSTEM-

Air-cooling is one method of dissipating heat. The value of heat transfer coefficient b\w metal and air is appreciably low. As a result of this cylinder wall temperature of the air-cooled cylinders are considerably higher than those of water-cooled type. In order to lower the cylinder wall temperature the area of the outside surface, which directly dissipates heat to the atmosphere, must be sufficiently high. Providing the fins usually does this.

COOLING FINS-

Cooling fins are either cast integral with the cylinder and cylinder head or may be fixed with the cylinder block separately. The heat dissipating capacity of fins depends upon their cross section and length. At the same time as heat is gradually dissipated from the same surface, the temperature of fin decreases its root to its tip.

Hence the fins surface nearer the tip dissipated heat at lower rate and is lese efficiency. On the other hand as the quantity of heat flowing towards the tip gradually decreases, the thickness of the fin may decrease. The material of the fin is used most effectually if the drop in temperature from the root to the tip is constant per unit length. The rectangular section has least temperature drop whereas the maximum temperature drop is in section least temperature drop whereas as the maximum temperature drop in section a.

[pic]

Fins of different cross-sections.

Fins are used usually given a taper of 3 to 5 degrees in order to give sufficient draft to the tip is made 0.5 to 1.25 mm thick and a clearance of 2.5 to 5 mm is allowed at the root. The fins are made 25 to 50 mm long. Too close spacing of the fins is undesirable as a mutually interface of the boundary layer of adjacent clears restricts the airflow and result is small quantity of heat dissipated.

BAFFLES-

Using baffles, which force the air through the space between the fins, can substantially increase the rate of heat transfer from the cylinder walls. The arrangement at a has the highest-pressure drop it is always desired to have negligible kinetic energy loss between the entrance and the exit.

[pic]

Baffles

B is the normal type of the baffles used petrol engine. The arrangement C for minimizing the kinetic energy loss in showed with a well-rounded entrance to reduce the entrance loss and an exit section that will transfer the velocity head into pressure head and thus decreases the pressure drop. Arrangement D ids adopted or diesel engines.

ADVNTGES-

• Engine weight is less, as there is n radiator, water, water pump etc.

• Engine required less space.

• It is simple in design and manufacturing as it free from water jackets.

• Engine attains operating temperature quickly resulting in less wear of cylinder.

• Due to higher working temperature deposit of carbon is cooperatively less.

• No topping up of water act.

DISADVANTAGES-

• Air-cooled engines produce more sound, as there is no water jacket to damp down sound.

• The volumetric efficiency is less due to higher working temperature of cylinder and head, to cope up with this, big lowers or super charged are used.

• Air-cooling system is not suitable for multi cylinder engines, as the air cannot reach this effectively unless blowers are used.

• Not suitable for multi cylinder engines unless a fan for air circulation is used and the cylinder is arranged in a rear horizontally opposed layout to allowed the air to flow more messily round them.

• If a fns is used, greater mechanical notice is produced.

WATER COOLING-

In this method of cooling engines the cylinder walls and heads are provided with jacked through which the cooling water can circulate. The heat is transferred from cylinder walls to the water by convection and conduction. The liquid becomes heated in its passage through the jackets and is itself cooled by means of an air-cooled radiator system. The heat from water in turn is transferred to air.

The water is usually circulated first through the cylinder jacket than the cylinder head and from there to the exhaust valve cage. Pistons are usually cooled from a separate pipeline. Excessive water circulation resulting in low final temperature is undesirable particular in the case of spatrk ignition engines, as it will cause precipitation of fuel in the pipe line and the disturb the fuel distribution pattern, which will result increase the fuel consumption and less viscosity of lubrication oil which may increase the piston friction. Incase of compressing ignition engines lower jacket temperature results in lower temperatures at the end of compression, which is undesirable from the ignition point of view.

ADVANTAGES-

• For multi cylinder engines, it is more suitable than air-cooling.

• This system is cheap because water is cheap and easily available.

• Engine temperature can be controlled property due to use of thermostat.

• Water jacket reduces the engine noise.

• It is easier to install a ca heater system because heated water from the cooling system is used providing a more efficient heating system.

DISADVANTAGES-

• In water-cooling engine, weight of radiator with water pump, etc, increases dead weight of the vehicle.

• Radiator is usually fitted in from of the vehicle. Due to its presence in from, slope on bonnet cannot be given to avoid wind resistance.

• Water in water-cooled system freezes at zero degree temperature.

• Water boils and evaporates easily at 1000C.

• Water corrodes the metal parts in the system.

QUESTIONS FOR VIVA-

1. What is the necessity for cooling of an engine?

2. How is the seizing of piston caused?

3. Name various method s of cooling?

4. What is the purpose of using fins of an air-cooled engine cylinder?

5. What are the merits and demerits of air-cooled engine?

6. Name the main component of water-cooling system?

7. Where is the inlet for cooling water in the engine?

8. What is the function of a radiator in cooling system?

EXPERIMENT NO-08

OBJECT-

To conduct a performance test on Four-stork Single Cylinder Diesel Engine Test Rig and to draw the heat balance sheet for given load.

DESCRIPTION: -

The Mechanical brake drum is fixed to the engine flywheel and are mounted on a M.S. Channel frame and further mounted on anti-vibromounts. Panel board is used to fix burette with 3-way cock, digital temperature indicator with selector switch, digital RPM indicator and ‘U’ tube manometer.

INSTRUMENTATION: -

1. Digital temperature indicator to measure different temperatures sensed by respective thermocouples.

2. Digital RPM indicator to measure the speed of the engine.

3. To measure the quantity of air drawn in to the engine cylinder through a differential manometer.

4. To measure the rate of fuel consumed during running through a manifold burette.

ENGINE SPECIFICATION: -

1. MAKE : KIRLOSKAR

2. BHP : 5

3. SPEED : 1500 RPM

4. NO. OF CYLINDER : ONE

5. COMPRESSION RATIO : 16.5 : 1

6. BORE : 80 mm

7. STROKE : 110 mm

8. ORIFICE DIAMETER : 20 mm

9. TYPE OF IGNITION : COMPRESSION IGNITION

10. METHOD OF LOADING : ROPE BRAKE

11. METHOD OF STARTING : CRANK START

12. METHOD OF COOLING : WATER COOLED

LOADING SYSTEM: -

The engine is fitted with a brake drum and a rope around it with a dead weight platform at one end (bottom end) and a spring balance at the other (top end). The engine can be loaded in terms of ¼, ½, ¾ full load by adding necessary dead weight on to the platform.

FUEL MEASUREMENT: -

The fuel supplied from the main fuel tank through a measuring burette with 3-way manifold system. To measure the fuel consumption of the engine fill the burette by opening the cock marked “tank” in the manifold block by starting a stop clock measure the time taken to consume 25cc of fuel.

Weight of the fuel, wf = 25 * density of fuel * 3600 kg/hr

Time * 1000

AIR FLOW MEASUREMENT: -

An air drum fitted on the panel frame connected with an air hose to the engine facilitate on orifice manifold with orifice and pressure pick-up point at the up and down stream of the orifice. The pressure pick-up points are connected to a ‘U’ tube manometer limbs. The difference in manometer reading is taken at different loads and the air sucked by the engine is calculated by:

Va = Cd * A √ (2*g*hm*ρw/ρa) * 3600 m3/hr

Where, Cd of orifice = 0.62

Diameter of orifice = 20 mm

TEMPERATURE MEASUREMENT: -

A digital temperature indicator with selector switch is provided on the panel to read the temperature in oC directly sensed by thermocouples located at different places on the engine test rig using selector switch.

TC1 : Inlet water temperature to calorimeter and engine jacket

temperature.

TC2 : Outlet water temperature of calorimeter.

TC3 : Exhaust gas temperature inlet to the calorimeter.

TC4 : Exhaust gas temperature outlet of the calorimeter.

TC5 : Engine jacket water temperature.

TC6 : Ambient temperature.

The rotameters are calibrated at a constant head of 5 m (0.5 kg/sq.cm) at an ambient temperature of 27oC.

LOADING SYSTEM: -

The engine test rig is directly coupled with a brake drum and a rope brake around the drum. One end of the rope (top end) is connected to a spring balance and the other end to a weight platform. The load to the engine can be varied by adding slotted weight provided on to the platform. Please see that the weight platform is above the base (hanging) while the engine is loaded, to do so use the hand wheel provided on the loading frame.

PROCEDURE: -

1. Connect water line to the engine jacket inlet and calorimeter inlet to a water source with a constant head of 5m (0.5 kg/sq.cm) through respective rotameters.

2. Open the respective gate valves (control valves) and set any desired flow rate on the rotameter.

3. Connect the panel instrumentation input power line at a 230 V/ 50 Hz single-phase power source.

4. Fill fuel on the fuel tank mounted on the panel frame.

5. Check the lubricating oil in the engine sump with the help of dipstick provided.

6. Open the fuel cock provided under the fuel tank and ensures no air is trapped in the fuel line connecting fuel tank and engine.

7. De-compress the engine by decompression lever provided on the top of the engine head. (Lift the lever for decompression)

8. Crank the engine slowly with the help of handle provided and ascertains proper flow of fuel in to the pump and in turn through the nozzle in to the engine cylinder. Allow the engine to run and stabilize at approximately 1500 rpm.

9. Now load the engine by placing the necessary dead weights on the weight hanger to load the engine in steps of ¼, ½, ¾ and 10% over load. Allow the engine to stabilize on each step load.

10.Record the following parameters indicated on the panel

instruments on each load step.

i) Speeds of the engine from RPM indicator.

ii) Rate of fuel consumption from burette.

iii) Quantity of air sucked in to the engine cylinder from manometer.

iv) Temperatures TC1 to TC6 from the temperature indicator by turning the selector switch to respective position.

v) Quantity of water flowing through engine head and calorimeter from respective rotameters.

vi) Exact load W (in kg) on the engine from the amount of weight added on the pan W1 (in kg) plus weight of pan W2 (in kg) minus spring balance reading W3 (in kg).

11.To stop the engine after the experiment push/pull the governor

lever towards the engine cranking side.

12.With the above parameters recorded at each step load, the

values are calculated for obtaining the efficiency.

OBSERVATION TABLE-

|Sl.No. |01 |02 |03 |04 |05 |

|Load In K.G. | | | | | |

|TC1 | | | | | |

|TC2 | | | | | |

|TC3 | | | | | |

|TC4 | | | | | |

|TC5 | | | | | |

|TC6 | | | | | |

|Speed | | | | | |

|Spring Load (in k.g.) | | | | | |

|Time taken for Cons- umtion of 10ml fuel | | | | | |

|Manometer Difference | | | | | |

|Rotameter Reading | | | | | |

|in cc/Sec. | | | | | |

|Calorimeter Reading | | | | | |

|In cc/Sec. | | | | | |

CALCULATIONS: -

1. Brake Horse Power (BHP)

BHP = 2*π*N*(W-S)*((D+d)/2)

4500

Where, W = Dead weight in kgf

S = Spring balance reading in kgf

D = Diameter of brake drum in m.

d = Diameter of rope in m.

N = Speed of the engine

2. Weight of fuel consumed (wf) in kg/hr

wf = XCC * Specific gravity of fuel * 60 * 60

T * 1000

Where,XCC = Volume of fuel consumed in T secs.

T = Time in secs.

Density of diesel is 0.838 gm/cc

3. Specific fuel consumption (SFC) in kg/BHP hr.

SFC = wf

BHP

4. Brake thermal efficiency (ηbt)

ηbt = BHP * 4500 * 100 %

427 * CV * wf

Where, CV = Calorific value of fuel (Diesel)

= 11000 Kcal/kg

5. Indicated Horse Power (IHP)

IHP can be calculated by William Line Graph method.

IHP = BHP + FHP

6. Mechanical Efficiency (ηm)

ηm = BHP * 100 %

IHP

7. Actual volume (Va) of air drawn in to the cylinder

Va = Cd * A √ (2*g*hm*ρw/ρa) * 3600 m3/hr

8. Swept volume (VS) of the cylinder

VS = AC * L * (N/2) * 60

Where, AC = Area of the cylinder

L = Stroke length

N = Speed of the engine.

9. Volumetric efficiency (ηv)

ηv = Actual volume * 100 %

Swept volume

CALCULATION BY TABLE: -

|Sl.No. |01 |02 |03 |04 |05 |

|B.H.P. | | | | | |

|Weight of fuel consumed (wf) in kg/hr | | | | | |

|Specific fuel consumption (SFC) ) in kg/BHP | | | | | |

|hr. | | | | | |

|Brake thermal efficiency (ηbt) | | | | | |

|Indicated Horse Power (IHP) | | | | | |

|Mechanical Efficiency (ηm) | | | | | |

|Actual volume (Va) | | | | | |

|Swept volume (VS) | | | | | |

|Volumetric efficiency (ηv) | | | | | |

HEAT BALANCE SHEET BY TABLE: -

1. Heat Input(H) = wf * CV Kcal/hr

2. Heat equivalent to BHP (H1) = BHP * 4500 * 60 Kcal/hr

427

3. Heat carried away by engine jacket cooling water (H2)

H2 = mw * CP * (TC5 – TC1)

Where, mw = mass of water flowing through

engine jacket (kg/hr).

CP = Specific heat of water (Kcal/kg)

4. Heat carried away by exhaust gas (H3)

H3 = (mf + ma) * Cpg * (TC4 – TC3)

Where, mf = mass of fuel (kg/hr)

ma = mass of air (kg/hr)

= Volume of air * density of air

Cpg = Specific heat exhaust gas

(0.24 Kcal/kgoK)

5. Heat carried away by calorimeter water (H4)

H4 = mw * CP * (TC2 – TC1)

Where, mw = mass of water flowing through

Calorimeter water (kg/hr)

CP = Specific heat of water

(Kcal/kgK)

6. Heat Unaccounted (H5)

H5 = H-(H1+H2+H3+H4)

HEAT BALANCE SHEET BY TABLE: -

|Sl.No |Heat Input(H) |(H1) |(H2) |(H3) |(H4) |(H5) |

| |Kcal/hr | | | | | |

|01 | | | | | | |

|02 | | | | | | |

|03 | | | | | | |

************

EXPERIMENT NO-09

OBJECT- To conduct a performance test on Four-stork Four Cylinder petrol Engine Test Rig and to draw the heat balance sheet for given load and performance curve.

DESCRIPTION: -

The Engine and Hydraulic Dynamometer are mounted on a 4” M.S Channel frame and further mounted on anti-vibromounts. Panel board of the engine is used to fix and study the characteristics of solenoid valve, starter, ammeter & temperature indicator. Also panel board is used to fix burette with 3-way cock, digital temperature indicator with selector switch, digital RPM indicator and ‘U’ tube manometer.

INSTRUMENTATION: -

1. Digital temperature indicator to measure different temperatures sensed by respective thermocouples.

2. Digital RPM indicator to measure the speed of the engine.

3. To measure the quantity of air drawn in to the engine cylinder through a differential manometer.

4. To measure the rate of fuel consumed during running through a manifold burette.

ENGINE SPECIFICATION: -

1. MAKE : PAL

2. BHP : 10

3. SPEED : 1500 RPM

4. NO. OF CYLINDER : FOUR

5. COMPRESSION RATIO : 7.8 : 1

6. BORE : 68 mm

7. STROKE : 75 mm

8. ORIFICE DIAMETER : 20 mm

9. TYPE OF IGNITION : SPARK IGNITION

10. METHOD OF LOADING : HYDRAULIC (WATER)

11. METHOD OF STARTING : SELF STARTING

12. METHOD OF COOLING : WATER COOLED

FUEL MEASUREMENT: -

The fuel supplied from the main fuel tank through a measuring burette with 3-way manifold system. To measure the fuel consumption of the engine fill the burette by opening the cock marked “tank” in the manifold block by starting a stop clock measure the time taken to consume 25cc of fuel.

Weight of the fuel, wf = 25 * density of fuel * 3600 kg/hr

Time * 1000

AIR FLOW MEASUREMENT: -

An air drum fitted on the panel frame connected with an air hose to the engine facilitate on orifice manifold with orifice and pressure pick-up point at the up and down stream of the orifice. The pressure pick-up points are connected to a ‘U’ tube manometer limbs. The difference in manometer reading is taken at different loads and the air sucked by the engine is calculated by:

Va = Cd * A √ (2*g*hm*ρw/ρa) * 3600 m3/hr

Where, Cd of orifice = 0.62

Diameter of orifice = 20 mm

TEMPERATURE MEASUREMENT: -

A digital temperature indicator with selector switch is provided on the panel to read the temperature in oC directly sensed by thermocouples located at different places on the engine test rig using selector switch.

TC1 : Inlet water temperature to calorimeter and engine jacket

temperature.

TC2 : Engine jacket water outlet temperature.

TC3 : Exhaust gas temperature outlet of the calorimeter.

TC4 : Exhaust gas temperature inlet of the calorimeter.

TC5 : Outlet water temperature of calorimeter.

TC6 : Ambient temperature.

WATER FLOW MEASUREMENT: -

Two rotameters are provided at the inlet of engine jacket and water calorimeter to measure the quantity of water allowed in to the engine jacket as well as calorimeter. Valves are provided to control the water flow rate and the quantity of water flowing is directly read on the rotameters. The rotameters are calibrated at a constant head pressure of 0.5 kg/cm2 (5m head) at 27oC ambient. Same head should be maintained to achieve accurate results.

LOADING SYSTEM: -

The engine test rig is directly coupled to a Hydraulic Dynamometer, which is loaded by water flow in to the dynamometer at 0.5 kg/cm2 constant head pressure. Operating gate valve provided on the inlet line of the dynamometer can vary the load. A breather valve is provided at the bottom of the dynamometer which is to be kept crack opened to a valve to be adjusted depending up on the load conditions.

PROCEDURE: -

1. Connect water line to the engine jacket inlet, Hydraulic Dynamometer and calorimeter inlet to a water source with a constant head of 5m (0.5 kg/cm2) through respective rotameters.

2. Open the respective gate valves (control valves) and set any desired flow rate on the rotameter. Connect the battery terminals to a well-charged 12 V battery.

3. Connect the panel instrumentation input power line at a 230 V/ 50 Hz single-phase power source.

4. Fill fuel (Petrol) on the fuel tank mounted on the panel frame.

5. Check the lubricating oil in the engine sump with the help of dipstick provided.

6. Open the petrol cock provided underneath the petrol tank and ensures that all the knife switches provided for the purpose of Morse test are in engaged position. Also ensure that the accelerator knob is in cut-off position (Idle condition).

7. Insert the ignition key in to the starter switch and turn it clockwise to start the engine. Now the engine is running at idle speed (approx. 800-1000 rpm). Ensure that the oil pressure gauge reads 2 kg/cm2 to 3 kg/cm2.

8. Increase the speed by turning the accelerator knob clockwise until the RPM indicator reads approx. 1500 rpm.

9. Now open the dynamometer inlet gate valve gradually to load the engine through hydraulic dynamometer. The load indicated on a dial type spring balance is in terms of kgf. The dynamometer arm having a length of r = 0.32m gives the torque, T = r*s, where s is the load indicated in the spring balance. Operate the inlet gate valve of the dynamometer and set the load to ¼ of the full load (i.e 3.75kgf + spring balance error if any). Allow the engine to run at the set load with the speed for few minutes.

10. Record the following parameters indicated on the panel instruments on each load step.

a. Speeds of the engine from RPM indicator.

b. Rate of fuel consumption from burette.

c. Load from spring balance.

d. Quantity of air sucked in to the engine cylinder from manometer.

e. Temperatures TC1 to TC6 from the temperature indicator by turning the selector switch to respective position.

f. Quantity of water flowing through engine head and calorimeter from respective rotameters.

10. Repeat the step No. 8 and 9 to load the engine to

¼ load (i.e 3.75 kgf + Spring balance error if any)

½ load (i.e 7.5 kgf + Spring balance error if any)

¾ load (i.e 11.25 kgf + Spring balance error if any)

Full load (i.e 15 kgf + Spring balance error if any)

MORSE TEST: -

To calculate IHP of the engine the engine is loaded by hydraulic dynamometer to full load say 15 kgf on the spring balance. Allow it to run for few minutes. Cut off power to one cylinder by pulling the knife switch provided on the engine panel. Now the engine is running on 3 cylinders only. As a result the speed of the engine decreases, by operating the water inlet gate valve of the the hydraulic dynamometer reduce the load slowly, so the speed of the engine comes back to its rated speed (1500 rpm). Record the spring balance reading. Now without altering the positions of the water inlet to the hydraulic dynamometer the positions of the water inlet to the hydraulic dynamometer and the accelerator knob put back the pulled knife switch to its original position, then the speed increases. Pull out the next knife switch immediately and observe the engine speed. If the speed of the engine does not reach the rated speed, increase or decrease the load as applicable. Record the spring balance reading after attaining the rated speed. Follow the similar procedure for rest of the cylinders.

Calculate the BHP when all four cylinders are working. Similarly calculate the BHP of four cylinders when each of the cylinders is disconnected. This frictional horse calculates power of the engine.

BHP of all cylinders = BHP

BHP of 3 cylinders when 1st cylinder is cutoff = BHP1

BHP of 3 cylinders when 2nd cylinder is cutoff = BHP2

BHP of 3 cylinders when 3rd cylinder is cutoff = BHP3

BHP of 3 cylinders when 4th cylinder is cutoff = BHP4

FHP of 1st cylinder (FHP1) = BHP - BHP1

FHP of 2nd cylinder (FHP2) = BHP – BHP2

FHP of 3rd cylinder (FHP3) = BHP – BHP3

FHP of 4th cylinder (FHP4) = BHP – BHP4

Mean FHP of the engine = FHP1 + FHP2 + FHP3 + FHP4

4

IHP = FHP + BHP

CALCULATIONS: -

1. Brake Horse Power (BHP)

BHP = 2 * π * N * T

4500

Where, T = r * s (r = 0.32m)

s = Spring balance reading in kgf

N = Speed of the engine

2. Weight of fuel consumed (wf) in kg/hr

wf = XCC * Specific gravity of fuel * 60 * 60

T * 1000

Where, XCC = Volume of fuel consumed in T secs.

T = Time in secs.

Density of diesel is 0.838 gm/cc

3. Specific fuel consumption (SFC) in kg/BHP hr.

SFC = wf

BHP

4. Brake thermal efficiency (ηbt)

ηbt = BHP * 4500 * 60 * 100 %

427 * CV * wf

Where, CV = Calorific value of fuel (Petrol)

= 10500 Kcal/kg

5. Indicated Horse Power (IHP)

IHP = Calculated by Morse Test.

6. Mechanical Efficiency (ηm)

ηm = BHP * 100 %

IHP

1. Brake mean effective pressure (Bmep)

Bmep = BHP * 4500

L * A * (N/2)

2. Actual volume (Va) of air drawn in to the cylinder

Va = Cd * A √ (2*g*hm*ρw/ρa) * 3600 m3/hr

Where ρw = density of water = 1000 kg/m3

ρa = density of air = 1.193 kg/m3

3. Swept volume (VS) of the cylinder

VS = AC * L * (N/2) * 60

Where, AC = Area of the cylinder.

L = Stroke length

N = Speed of the engine.

4. Volumetric efficiency (ηv)

ηv = Actual volume * 100 %

Swept volume

CALCULATION BY TABLE: -

|Sl.No. |01 |02 |03 |04 |05 |

|B.H.P. | | | | | |

|Weight of fuel consumed (wf) in kg/hr | | | | | |

|Specific fuel consumption (SFC) ) in kg/BHP | | | | | |

|hr. | | | | | |

|Brake thermal efficiency (ηbt) | | | | | |

|Indicated Horse Power (IHP) | | | | | |

|Mechanical Efficiency (ηm) | | | | | |

|Brake mean effective pressure (Bmep) | | | | | |

|Actual volume (Va) | | | | | |

|Swept volume (VS) | | | | | |

|Volumetric efficiency (ηv) | | | | | |

HEAT BALANCE SHEET: -

1. Heat Input(H) = wf * CV Kcal/hr

2. Heat equivalent to BHP (H1) = BHP * 4500 * 60 Kcal/hr

427

3. Heat carried away by engine jacket cooling water (H2)

H2 = mw * CP * (TC2 – TC1)

Where, mw = mass of water flowing through

engine jacket (kg/hr)

CP = Specific heat of water (Kcal/kg)

4. Heat carried away by exhaust gas (H3)

H3 = (mf + ma) * Cpg * (TC4 – TC5)

Where, mf = mass of fuel (kg/hr)

ma = mass of air (kg/hr)

= Volume of air * density of air

Cpg = Specific heat exhaust gas

(0.24 Kcal/kgK)

5. Heat carried away by calorimeter water (H4)

H4 = mw * CP * (TC3 – TC1)

Where, mw = mass of water flowing through

Calorimeter water (kg/hr)

CP = Specific heat of water (Kcal/kgK)

6. Heat Unaccounted (H5)

H5 = H- (H1+H2+H3+H4)

HEAT BALANCE SHEET BY TABLE: -

|Sl.No |Heat Input (H) |(H1) |(H2) |(H3) |(H4) |(H5) |

| |Kcal/hr | | | | | |

|01 | | | | | | |

|02 | | | | | | |

|03 | | | | | | |

**************

................
................

In order to avoid copyright disputes, this page is only a partial summary.

Google Online Preview   Download