To verify the Boyle's law with the help of general gas laws apparatus (U-tube manometer type).

The main apparatus consists of three U-shaped glass tubes connected at the lower end. The larger tube is called mercury well, in which mercury is filled and compressed down with the help of a wooden piston in the other two tubes, which are of the same diameter. One of the tube is closed from the top end, in which air is trapped as a test gas. The closed tube is called D tube, which is 30 cm long. The third tube is open at the top end and so mercury is always under atmospheric pressure in this tube. The tube assembly is rested on a firm steel base. A scale of 50 cm height is provided which is graduated in mm. The scale secured to steel base with the help of two screws and clamped with the larger tube.

1. The U shaped was filled with mercury, such that the three bulbs were sufficiently filled with mercury.
2. Some gentle strokes were applied to remove air bubbles.
3. The level of mercury in all three tubes was noted.
4. Pressure was increased in the tube A which the help of a plunger and the relative increase in pressure in the tube D and the relative decrease in volume in tube C was noted.
5. The process was repeated for 10 readings.
6. A graph was drawn between P and I/V which gives a straight line.

Boyle’s law states that "Pressure is inversely proportional to volume if the temperature is kept constant."

Mathematically,

P µ 1/V

or

P = constant / V

P * V = constant

In this experiment, the pressure is taken in terms of height of the cylinder.

We know that

If A=1,

P = F

Weight is taken as the force, by which earth is attractive every thing towards its centre so,

W=F

But, W = m * g

So, F = m* g

F = density * g * V

F = density * g * h

So, P = density * g * h

As the density and g are constant,

P = h

The observation and the graphical representation are approximately according to the Boyle’s law. The minute difference is due to the presence of moisture in the air and some personal errors.

Hence Boyle’s law is verified.

In this experiment Boyle’s law was verified which states that pressure is inversely proportionate to volume at constant temperature.

The apparatus used in this experiment consists of three U shaped glass tubes, which are connected at the lower end. Top end of two tubes is open, while the third tube is closed at the top end.

Mercury was filled so that it fills the bulbs of all tubes. The pressure was then increased with the help of a plunger and the difference in volume due to pressure increased was noted.

Graph was plotted between P and I/V which was a straight line and hence the Boyle’s law was verified.

1. Apparatus should be handled with care.
2. There should be no air present in the mercury.
3. There should be no moisture present in the air, which is under observation.
4. Reading should be taken with great care.
5. Mercury level should be noted at the eye level.
6. Plunger should not be pressed very hard.

To verify Charles law with the help of general gas law apparatus.

• Hydrometer jar
• Heating arrangement
• Wire gauze
• Provision of water
• Thermometer of range 0-110ºC

INTRODUCTION

NAME OF PROPOSER: Jacques Charles.

YEAR OF PROPOSAL: 1785

FIELD OF STUDY: This law gave the relation b/w effect of

change in temperature & volume of

a gas at constant pressure.

‘At constant pressure, the volume of a given mass of a gas is directly proportional to the absolute temperature.’

Charles found that all gases expand or contract by same amount, when heated or cooled by same amount of temperature. He calculated that for every degree rise or fall in volume is equal to 1/273 of the volume of a gas at 0ºC.This 1/273 is called fractional change in volume.

According to law,

V µ T

or V=KT (K is constant of proportionality)

or K=V/T ------------------------------- (1)

According to equation no., (1) it can be stated that,

‘At constant pressure, the ratio of volume & absolute temperature is always remain constant.’

Suppose we have a gas in a container having a volume of V1 at T1 temperature. By increasing the temperature from T1 to T2 its volume becomes increases from V1 to V2.

At initial condition

K=V1/T1 ---------------------------- (a)

Similarly, at final condition,

K=V2/T2 ---------------------------- (b)

By comparing equation no. (a) & (b)

V1/T1=V2/T2

Room temperature = 36ºC

Height of Hg column in tube D =6.5cm.

Height of Hg column in tube C =18cm.

Height of Hg in atmosphere B =76cm.

Volume of given gas = V = 30 –D

Pressure of given gas = P = C - D

The graph b/w P & V and T & V is a straight line with same points outside the curve. The deviation may be due to the following reasons:

1. The gas used in practical was not ideal.
2. There was some force of attraction or repulsion.

The values obtained from practical shows that there is a linear relationship b/w pressure and volume AND temperature & volume at constant no. of moles.

Identification of the main components and working of two stroke engine.

We don’t have a proper model of two-stroke spark engine. Few replacements are suggested in the existing two-stroke compression ignition of diesel by which it can be converted into two-stroke spark engine.

1. Fuel injection nozzle is removed and replaced by spark plug.
2. Push rod is removed.
3. Cam and feed back gear are removed.

Practically it is not possible to convert a petrol engine to a diesel one and vice versa.

It is type of engine in which four basic processes: suction, compression, expansion, and exhaust are completed in one revolution or 360 of crank rotation. In this case two processes namely suction and exhaust occur simultaneously with a little time lapse. The time lapse is required for the initial simultaneous openings of exhaust and suction ports during the expansion process.

Thermodynamic cycle of a two stroke spark ignition engine is called OTTO cycle.

It is a process by which the product of combustion is expelled from the cylinder to the atmosphere. It also provides space for the accommodation of new charge. It is a specific property of a two-stroke engine.

The atmospheric air is stored inside the crankcase through atmospheric air suction non-return valve and this storing of air is maximum when the piston reaches the TDC position. In the downward stroke there is pressure building up in the crankcase and this air is allowed through the passage in the cylinder wall and used for scavenging process.

Spark plug : is an external source used for initial ignition.

Head & cylinder

Water jacket : for cooling.

Air deflectors : for scavenging.

Suction & exhaust ports

Carburetor : to regulate air-fuel mixture (1 part fuel, 15-part air).

Piston

Gudgeon : temporary attachment b/w piston and connecting rod.

Connecting rod : changes reciprocating motion to circular motion.

Crank & crank shaft

Crank pin

Crank case : heart shaped and partially filled with lubricating oil. Lubricates all parts of engine.

Power transmission gear : used to store rotational movements of inertia and to compensate energy requirement during the idle stroke.

Flywheel :Suction, compression and exhaust are idle strokes.

The function of a fuel injection system is to meter the fuel accurately and uniformly to the engine cylinders under all operating conditions from idling to full load. The timing of the injection should be accurate enough to give the required cumbustion characteristics.

The cylinder is that part in the engine in which all compressions, expansion, combustion takes place and cylinder head is that cover which covers all the cylinders and also constitutes the cover of the engine, also there is a cylinder block which holds all cylinders and together it with cylinder head makes the body of the engine.

Engine becomes very hot while they are running due to the heat created by combustion. Some form of cooling must therefore be adopted and in most cars water is used. The water enters the cylinder block near the bottom of the cylinder and flows through special passages known as WATER JACKETS cast in the cylinder block and cylinder head. As it absorbs the engine heat its temperature increases and this causes it to flow upward. When it reaches th top of the engine the water is very hot. Now the water itself must be cooled otherwise it would boil. This is done by means of a radiator. The hot water leaves the tope of the engine and filters through the radiator where it is cooled by the passage of air. As it cools it falls to the bottom of the radiator from where it re-enters the engine. A pump, driven by the fan belt, helps to force the water through the system and so improves it cooling efficiency.

Direct injection into the cylinder is attractive from the point of view of efficient fuel distribution, but the injector used would be subject the high pressure and temperature conditions which it would not experience in the manifold. Injection into the manifold allows more time for the fuel and air to mix, giving better combustion, uses simpler injectors and requires easier access to the engine, particularly if it were not originally designed for injection.

Oval grooves are air deflectors inside the cylinder provided to deflect the air that may act like brownian movement of particle of air.

Each cylinder is provided with a piston which fits snugly within the cylinder walls but is able to slide up and down. The movement of a piston up or down a cylinder is known as a stroke. Spring rings are fitted round the pistons. They press outward against the cylinder walls to prevent air escaping downward or too much oil escaping upward between piston and cylinder.

It is used to connect piston and crank it changes the translation of piston in two circular motion.

Oil pin / Gudgeon pin have generally the same purpose. It joins the piston with the connecting rod.

Crank pin is used for joining two webs of the crank shaft. It is also used to join connecting rod and crank.

It provides torque or rotation. It is a shaft which rotates and correspondingly the pistons move up and down and the whole process of stroke takes place.

It provides power to the feed back gears to run the cams which in turn rotates the fuel injection pump and also water body or impellor.

It transfers the power from main transmission gear to the cam.

It absorbs power pulses from the crank shaft to keep running engine smooth and provides power to the idle strokes (when piston goes down).

The lower part of the cylinder block or the lower part of the engine body inside which the crank shaft is allowed to rotate is known as crank case.

Vertically on the top of the cylinder there is an opening guarded by a non returning valve. Function of this valve is to work one sidedly that is to allow air to enter and then not to leave.

Every engine needs a foundation to be placed on and this foundation is known as the base of the engine.

1. Suction Process:

During the suction process, working substance is allowed to enter inside the cylinder. Piston movement is from TDC to BDC.

2. Compression Process:

Piston movement is from BDC to TDC and both suction and exhaust valve remain closed, volume is reducing as an end effect, there is considerable increase in internal energy and it is maximum at TDC position and the working substance is considered to be in an excited state. Spark is provided from an external source which will initially ignite the working substance, after there will continuous combustion process, resulting in abnormal increase in cylinder pressure.

3. Expansion Process:

When the internal cylinder pressure is high enough to push the piston downward, the expansion process starts and it continues till the pitston reaches BDC position. During this process, power is transferred from cylinder to output shaft. Valves still remain closed and the piston moves from TDC to BDC.

4. Exhaust Process:

Indicates various processes occuring in engine.

External source used for initating ignition.

Fixed part of an engine in which the piston reciprocates.

For inlet and outlet of working substance and exhaust.

� Valves, retaining springs and push rod Push rod is connected with cams. Cam revolves the push rod up and down which as a result opens and closes inlet and outlet valves.

It is a pressure tight cylindrical plunger which is subjected to the expanding gas pressure into a concentrated thrust along the connecting rod.

Piston are thin metallic flexible insertion pieces to be used in piston grooves.

1. � Rings Lubrication Rings: are thicker and have grooves for compensating oil.
2. Compression Rings: are thinner and used in the upper side of the piston. These are always used in the set of two

� Gudgeon pin It acts on a strut and a tie link rod. It connects reciprocating motion into circular motion.

� Cams Time controlling devise of engine.

A system can be any objet, any quantity of matter, any region of space, etc., selected for study and set apart (mentally) from everything else, which then becomes the surroundings.

The imaginary envelope which encloses a system and separates it from the surroundings is called the boundary of the system.

Anything which is not in the boundary of the system is called "Surrounding".

"When a system undergoes a thermodynamic cycle then the net heat supplied to the system from its surrounding plus the net work input to the system from its surrounding must equal zero".

SQ + SW = 0

"It is impossible for a heat engine to produce a net work output in a complete cycle if it exchanges heat only with a single energy reservoir."

OR

"It is impossible to construct a device that operating in a cycle will produce no effect other than the transfer of heat from a cooler to a hotter body."

To study the Ranking Cycle.

Consider a Carnot cycle for steam as shown in fig. (1): at state 3 the steam is wet at T2 but it is difficult to stop condensation at the point 3 and then compress it just to state 4. It is more convenient to allow the condensation process to proceed to completion, as in fig.(2). The working fluid is water at the new state point 3 in fig (2) and this can be conveniently pumped to boiler pressure as shown at state point 4. The pump has much smaller dimensions than it would have if it had to pump a wet vapour, the compression processes carried out more efficiently, and the equipment required is simpler and less expensive. One of the features of the Carnot cycle has thus been departed from by the modification to the condensation process. At state 4 the water is not at the saturation temperature corresponding to the boiler pressure. Thus heat must be supplied to change the state from water at 4 to saturate water at 5; this is a constant pressure process, but is not at constant temperature. Hence the efficiency of this modified cycle is not as high as that of the Carnot cycle. This ideal cycle, which is more suitable as a criterion from actual steam cycles than the Carnot cycle, is called the Rankine Cycle.

The plant required for the Rankine cycle is shown in fig.(3) and the numbers refers to the state points of Fig.(2). The steam at inlet to the turbine may be wet, dry saturated, or superheated, but only the dry saturated condition is shown in fig.(2).