Laboratory Manual

Mechanical Engineering Lab - I

Department of Mechanical

Engineering

ME329

2

INDEX

Ex.

No Name of the Experiment

Page

No.

No of

Hours

1 Linear Measurement Using Vernier Height Gauge

& Micrometer 3

2

2 Linear Measurement Using Dial Gauge, Slip and

Calibration of Dial Gauge 7

2

3

To perform the alignment test on the lathe

machine 10

2

4

To understand the theory and principle of Tool

maker‟s microscope for measurement of

dimensional parameters of a work piece.

11

2

5 To find out pitch, pitch circle diameter and thread

angle of the given threaded job 13

2

6 To measure gear parameter by gear tooth Vernier 16 2

7 To use the Dial Indicator as Mechanical

Comparator 18

2

8.a. Measurement of taper angle using sine bar and slip

gauge 20

2

b. Measurement of angle using vernier bevel

protractor

9 To calculate Tonnage capacity of the Air

Conditioning system. 22

2

10 To calculate actual and theoretical coefficient of

performance 24

2

11 To plot the vapor compression refrigeration cycle

on P-H chart 28

2

12 Plot the Psychometric process on Psychometric

chart 30

2

3

Experiment-1

Aim: -

Linear Measurement Using Vernier Height Gauge & Micrometer

Apparatus :-

Vernier Caliper, Vernier Height Gauge, Micrometer, And Measuring Parts

Vernier Height Gauge

This is just as vernier caliper, equipped with special base block and other attachment

which make the instrument suitable for height measurements. Along with the sliding jaw

assembly, arrangement is provided to carry a removable clamp. The upper and lower

surfaces of the measuring jaws are parallel to the base, so that it can be used for

measurements over or under surface. The vernier height gauge is mainly used in the

inspection of parts and work. With a scribing attachment in place of measuring jow, this

can be used to scribe lines at certain distance above the surface. However dial indicator

Can also be attached in the clamp and many useful measurements made as it exactly

gives indication when dial tip just touching surface. For all these measurement, use of

surface plate as datum surface is very essential.

PROCEDURE-

1. Take the material (sample) for which the value must be measured.

2. Check the vernier and main scale must coincide at 0

3. After checking the 0 mark put the sample piece and slowly leaves the measuring jaw

over the piece

4. Tight the screw and measure the main scale also vernier scale reading

5. The line coincide with the main scale that the VSR

6. By adding MSR with VSR*L

DIAGRAM OF VERNIER HEIGHT GAUGE

4

OBSERVATION TABLE FOR VERNIER HEIGHT GAUGE

Sr No MSR VSR LC TSR

1

2

3

4

5

VERNIER INSTRUMENTS:-

The three elements of venire caliper, viz. beam, fixed jaw, and sliding jaw permit

substantial improvements in the commonly used measuring techniques over direct

measurement with line graduated rules. The alignment of the distance boundaries with

the graduations of the rule is ensured by means of the positive contact member

DIAGRAM OF VERNIER CALIPER

OBSERVATION TABLE FOR VERNIER GAUGE

Sr No MSR VSR LC TSR

1

2

3

5

MICROMETER

The end of the screw forms one measuring tip and the other measuring tip is constituted

by a stationary anvil in the base of the frame. The screw is threaded for certain length and

is plan afterwards. The plain portion is called sleeve and its end is the measuring surface.

The spindle is advanced by turning thimble connected to the spindle. The spindle is aside

fit over the barre land barrel is the fixed part attached with frame. The barrel is graduated

in unit of 0.05cm.i.e.20division per cm, which is the lead of the screw for one complete

revolution. The thimble has got 25 divisions around its periphery on circular portion.

Thus it sub-divides each revolution of the screw in 25 equal parts; i.e.each division

corresponds to 0.002cm.

PROCEDURE

1. The whole movable jaw assembly is adjusted so that the two measuring tip just

touch two parts to be measured.

2. Then lock nut is tightened.

3. Final adjustment depending upon the sense of correct feel is made by the

adjusting screw.

4. Measurement the main scale readings i.e. the line coincide with o mark of vernier

scale and noted down the reading.

5. The measuring tip is so designed as to measure inside as well as outside

dimension.

6. Calculate MSR, VSR and TSR

DIAGRAM OF MICROMETER:

6

OBSERVATION TABLE FOR VERNIER GAUGE

Sr No MSR VSR LC TSR

1

2

3

RESULT

Linear measurement using vernier caliper, vernier height gauge and micrometer are

successfully completed.

7

Experiment-2

Aim :-

Linear Measurement Using Dial Gauge, Slip and Calibration of Dial Gauge.

Apparatus :-

Dial Gauge, Slip Gauge, Dial Gauge Indicator

Theory :-

The different component of dial gauge indicator is shown in fig. It consist of plunger,

removable contact pt, stem a transparent glass cover, calibrated dial pointer, bezel camp

or bezel locking nut. Revolution counter in order to counter in order to count the no of

revolution of a pointer, dust proof cap etc. It consists of a plunger which slides in

bearing and carries a rack with it. The rack is meshed with pinion (P1) again pinion (P2)

and gear (G2) are on same spindle [because of which magnification is taking place]. The

gear (G1) is meshed with (P1) again pinion (P2) and gear (G2) are on spindle basically

gear (G2) is meshed with pinion (P3) on whose spindle pointer is attached. The pinion

(P3) is meshed with gear (G3) on which a light is here spring is attached in order to guide

the movement of plunger a rack guide is provided and to bring the plunger to its initial

position a light coil spring is attached to plunger. Any linear displacement given causes

rack to move upward during this upward movement as rack is meshed with pinion (P1)

and gear (G1) rotate by some amount but as the no of teeth on gear (G1) is more

compared to that of pinion (P2) which is meshed with it rotate more time. Let us say if

there is 100 teeth on gear G1 and 10 teeth on pinion P2 the 1st stage of magnification is

100/10=10 times again. Therefore overall magnification can be calculated, (G1XG2)/

(P2XP3) EG : (100x100/10x10) = 100 In this way dial indicator works you can take

diff readings by keeping standard and object. Then comparison can be made. The

magnification is about 250-1000.

Dial gauge -

Dial gauges divided in two categories, type1 &type2for general engineering purpose

depending upon the movement of the plunger. These are manufactured in two grades

,grade a and grade b, with total plunger movement or lift of 3,5 and 10mm. Type1 dial

gauge has the plunger movement parallel tip the plane of dial and type 2 has the plunger

8

movement perpendicular to the plane of dial

Indicator gauge-

Dial indicator has been used with several auxiliary devices for a wide variety of length

measurement. Obviously dial indicator can be used for carrying the needed

complimentary function, resulting in a single tool, it is known as indicator gauge. It must

be remembered that indicator gauge are always comparator type measuring instrument

and require the use of a setting gauges for establishing the basic measuring position

Slip gauge-

Slip gauges with three basic forms are commonly found. These are rectangular square

with center hole, and square without center hole. Rectangular forms is the more widely

used because rectangular block are less expensive to manufacture, and adopt themselves

better to application where space is restricted or excess weight is to be provided. For

certain application squarely gauges, through expensive, are preferred. Due to their large

surface area, they wear longer and adhere better to each other when touch to high stack.

PROCEDURE :-

For calibration checking.

1. The slip gauge is used for the purpose of checking the calibration.

2. A known slip gauge is taken and placed on the surface, the indicator gauge which has

3.The least count of instrument is calculated

9

4. The deflection of the pointer is noted and the final reading is obtained

5. For measuring the dimension of a given sample , a known slip gauge is matched with

the given sample ;the comparator is put on the surface without disturbing the reference

setting

6. If the sample is greater than reference one, the pointer shows deflection which is

measured and reading is calculated.

OBSERVATION :

Slip gauge For linear measurement least count = (0.2/200)=0.001 mm/div

For standard dimension For specimen

Main scale reading =MSR = -------

Circular scale reading =CSR= ---------

Total reading (TR) = MSR + ( CSR * LC )

Total Height of specimen = -----------

Calculation of Dial Gauge :-

Slip Gauge Reading Dial Gauge Reading

= 50+ …… = 0.2 + …….

= 51.001 mm = 0.2 + ……

= 51.003 mm = 0.2 + …….

Difference for the both should be equal

Result:-

Thus we have completed the linear measurement using dial gauge and calibration of dial

gauge.

10

Experiment-3

Aim:

To perform the alignment test on the lathe machine

Apparatus:-

Dial gauge with stand

Figure:-

Procedure:-

1) Clamp the job in universal chuck.

2) Place the dial gauge stand on the compound slide and turn on magnetic lock

3) Adjust the stylus of the dial gauge so that it touches the surface of the

job with pressure.

4) Rotate the chuck by hand.

5) If there is change in the reading of the dial gauge adjust the job to compensate the deflection

6) Rotate the chuck by hand 7) See if there is any deflection does the same as in step number 5

8) Repeat the procedure till there is no deflection in the reading of the dial gauge during complete revolution of the job.

Results:-

Using the above procedure the alignment of the chuck is done.

11

Experiment-4

Aim:

To understand the theory and principle of Tool maker‟s microscope for

measurement of dimensional parameters of a work piece.

Apparatus used:

Tool maker‟s microscope

Theory:

The Tool Maker‟s Microscope (TMM) essentially consists of the cast base, the main

lighting unit, the upright with carrying arm and the sighting microscope.

Tool Maker‟s Microscope

The rigid cast base is resting on three foot screws by means of which the equipment can

be leveled with reference to the built-in spirit level. The base carries the co-ordinate

12

measuring table, consists of two measuring slides: one each for directions X and Y, and a

rotary circular table provided with the glass plate. The slides run on precision balls in

hardened guide ways warranting reliable travel. Two micrometer screws each of them

having measuring range of 0 to 25 mm permit the measuring table to be displaced in the

directions X and Y. The range of movements of the carriage can be widened up to 75 mm

in the X direction and up to 50mm in the Y direction with the use of gauge blocks. The

rotary table has been provided with 360 degrees graduation and with a 60 minute vernier.

The rotary motion is initiated by activation of knurled knob. Slots in the rotary table serve

for fastening different accessories and completing elements. The sighting microscope has

been fastened to column with a carrier arm. The carrier arm can be adjusted in height by

means of a rack. The main lighting unit has been arranged in the rear of the cast base and

equipped with projection lamp where rays are directed via stationary mounted mirror

through table glass plate into the sighting microscope.

Measuring principle:

Tool Maker‟s Microscope is a precision Optical Microscope that consists of single or

multiple objective lenses, which magnifies the object under observation and by the help

of eyepiece lens the object is focused and viewed. A high precision micrometric X-Y

stage and the Z axis travel are used to measure the three dimensions [Length (X), Width

(Y), Depth (Z)]. The angle is measured with the help of a rotating stage and eyepiece

graduation.

Applications:

The tool maker‟s microscope is an essential part of engineering inspection, measurement

and calibration in metrology labs. Hence is used to the following,

Examination of form tools, plate and template gauges, punches and dies, annular

grooved and threaded hobs etc.

Measurement of glass graticules and other surface marked parts.

Elements of external thread forms of screw plug gauges, taps, worms and similar

components.

Shallow bores and recesses.

13

Experiment-5

Aim:

To find out pitch, pitch circle diameter and thread angle of the given threaded job.

Apparatus:

Tool Maker`s Microscope, threading Job

Working Diagram:

Tool maker's microscope:

Tool maker's microscope is versatile instrument that measures by optical means with no

pressure being involved it is thus a very useful instrument for making measurements on

small and delicate parts. The tool maker's microscope is designed for the following

measurements; measurements on parts of complex form for example, the profile of

external thread as well as for the tools, templates and gauges, measuring centre to centre

distance of holes in any plane and other wide variety of linear measurements and accurate

angular measurements.

A tool maker's microscope is as shown in fig. The optical head can be moved up or down

the vertical column and can e clamped at any height by means of clamping screws. The

table which is mounted n the base of the instrument can be moved in two mutually

perpendicular horizontal directions (longitudinal and lateral) by means of accurate

micromeres screws having thimble scale and venires.

A ray of light from light source is reflected by mirror through 90. It is then passes

through a transparent glass plate (on which flat parts may be placed). A shadow image of

the outline or contour of the work piece passes through the objective of the optical head

and is projected by a system of three prisms to ground glass screen. Observations are

made through an eyepiece. Measurements are made by means of cross lines engraved on

14

the ground glass screen. The screen can be rotated trough 360 the angle of rotation is read

through an auxiliary eyepiece.

Procedure:

The use of - tool maker's microscope for the taking the various measurements is

explained below-

1) To measure the pitch: Rotate micrometer head for X direction to touch the intersection

point of the crosswire to the crest of the thread as seen from the eye piece. Note down

the reading of the micrometer. Again rotate the micrometer head to move the specimen

so that the next successive crest will come in contact with the crosswire intersection

point. Note down the reading. The difference in reading will give the pitch.

2) To measure the depth of the thread: Similarly rotate micrometer head for Y

direction to touch the intersection point of the crosswire (along with the horizontal

dotted line) to the root of the thread, as seen from the eye piece. Note down the reading of

the micrometer. Again rotate the micrometer head to move the specimen so that the

horizontal dotted line touches all the crests. Note down the reading. The difference in

reading will give the depth of the thread.

3) To measure the thread angle: Rotate the crosswire by the silver color knob located

behind the eye piece to match the flank of the thread with the cross wire. Make use of

both the micrometer heads for X and Y direction to move the flank, and note down the

angle by viewing through the lens below the eye piece. Now rotate only the crosswire to

match the opposite flank and note down the angle. The difference will give the thread

angle.

4) Represent all the measured readings of the given specimen (thread gauge) with a neat

diagram.

Different types of gradated and engraved screens and corresponding eye piece are used

for measuring different elements.

15

Results:-

1) Average depth of thread = -------------- mm.

2) Pitch of threads = --------------- mm.

3) Threads angle = --------------- mm.

Precaution:-

1) Obtain clean picture of cross line and the cross thread seen through the eyepiece.

2) For angular measurements lines must remain parallel to flank edge to the tooth.

16

Experiment-6

Aim:

To measure gear parameter by gear tooth Vernier.

Apparatus required:

Gear tooth Vernier, Gear specimen.

Specification:

Gear tooth Vernier: Range = Horizontal =0-40 mm

Vertical = 0-20 mm

L.C = 0.02 mm

Formula:

1. W = NM sin (90/N)

2. d = NM

--------- )/90cos(/21 NN

2

3. m = D

-------------

(N+2)

Where W = Chordal width of tooth in mm

D = Chordal addendum of gear in mm

M = Module of gear in mm

N = NO. Of teeth

D = out side Dia in gear in mm

Procedure:

1. The N, D of the given gear block are measured.

2. The module m‟ it then calculated.

3. Theoretical values of „W‟ and‟d‟ are computed.

4. Theoretical values of „W‟ is set in horizontal Vernier scale of gear tooth

Vernier and corresponding actual „d‟ value scale.

17

5. Theoretical values of „c‟ is set and „W‟ is measured along Horizontal

scale.

6. This procedure is repeated for 5 teeth and value tabulated.

Outside Diameter of Gear

TRIAL

OUT SIDE DIAMETER „D‟ mm

1

2

3

4

5

Measurement of Addendum and Chordal Width

Trial Chordal addendum‟ d‟ mm Chordal width „w‟ mm

Actual . Theoretical Actual Theoretical

1

2

3

4

5

6

7

Result:

Thus the chordal thickness and addendum of gear are measured using gear tooth

Vernier.

The actual values are W =

D =

18

Experiment-7

Aim: To use the Dial Indicator as Mechanical Comparator

Apparatus Required:

Dial indicator, stand, combination of slip gauges and the component to be compared.

Diagram:-

Procedure:-

1) Read the drawing of given component correctly

2) Mount the Dial Indicator on the comparator stand

3) Prepare the correct combination of the slip gauges

19

4) Set zero on the dial indicator with slip gauges at required plunger pressure

5) Clean and dry the component to be checked. 6) Insert the component between contact point of plunger and table of comparator

stand.

7) Note down the reading

Observation:

Basic dimension to be measured = ……………… mm (as per drawing)

Slip gauge set selected = …….. + ……… +……… = …………. mm

Sample No. Observation reading Accept/Rejected

1

2

3

4

5

6

7

Results:

20

Experiment-8

Aim: (a) To measure the taper angle of the given specimen using sine bar

Apparatus Required:

Surface plate, Dial gauge with stand, Sine bar, Slip gauge, Bevel protractor &

specimen.

Specification:

Sine bar : Range:

Formula:

Taper angle „θ‟ = Sin-1 (h/l) in degrees

Where, h = the total height (thickness) of the slip gauges in mm

l = the standard length of the sine bar in mm = 200mm

Procedure:

1. The taper angle of the specimen is first found out approximately with the help of a

bevel protractor.

2. The sine bar is set at this angle on the surface plate with the help of the slip

gauges as shown in the figure.

3. The specimen is placed on the sine bar so that its top taper surface is parallel to

the surface plate.

4. The parallelism is checked and adjusted by increasing or decreasing the height

level of the slip gauges, so that there should be no deflection in the long hand of

the digital gauge when the spindle of the dial gauge is moved over the specimen

surface.

5. The total height (thickness) of the slip gauges is noted down.

6. Trial readings are taken by placing the specimen at different points of the sine bar

surface.

For Small Specimen:

Trial Total height of the slip

gauge Reading (mm)

1

For Large Specimen:

Trial h 1 (mm) h 2 (mm) h 2- h 1

(mm)

1

2

3

21

Result:

The taper angle of the given specimen is

a. Using bevel protractor =_________________________ degrees

b. Using sine bar =_________________________ degrees

………………………………………………………………………………………………

Aim:

(b) To measure the angles of given specimen using bevel protractor.

Apparatus Required:

Surface Plate, Dial Gauge, Slip Gauge, Bevel protractor, specimen

Procedure:

1. Initially bevel protractor is adjusted as per requirements.

2. Specimen is placed between the blades.

3. Reading noted directly from main scale and Vernier scale

4. For measuring, taper angle of sine bar, protractor is fixed to height

gauge.

5. The protractor is corresponding adjusted.

6. Noted reading is tabulated.

Result:

Thus ………… angle of given specimens was determined.

22

Experiment-9

Aim:

The equipment is a Comprehensive test rig and it can be used for a variety of

experiments. Following trials/ experiments can be conducted on this test rig.

1. To calculate Tonnage capacity of the Air Conditioning system.

Procedure:

1) Connect the supply cable to regulated / stabilized power supply.

2) Switch ON the main switch.

3) Put ON the AHU fan.

4) Record the DBT & WBT at the inlet and at the outlet of the duct. (Ensure that the

well of WBT is filled with water.) Use psychrometer.

5) Switch ON the compressor.

6) Allow the system to reach steady state.(RUN FOR 20 MIN.)

7) Record the air temperatures at inlet and outlet (DBT & WBT) Use digital

indicator.

8) Record the Energy-meter reading.

9) Record suction and discharge pressures.

10) Record Rotameter reading, refrigerant temperatures at various locations viz:

before &after compression and before & after expansion.

11) Measure velocity head with the help of manometer at inlet of the ducting.

12) Take the reading 15-20 minutes after starting cooling.

STANDARD VALUES AND FORMULAE

Standard Barometric Pressure = 1.013 bar = 1.013 x 105 N /m2

Density of Water = 1000 kg / m3

Gas Constant for Air = 287 kg / kJ K

Specific Gravity of R-134a at 400 C = 1.2

1 Ton of Refrigeration effect = 3500 Watts = 3.5 kJ / s

Density of Air at 250 C = 1.1 kg/m3

Density of manometric liquid = 810 kg/ m3

CALCULATIONS:

TO DETERMINE

1. TONNAGE CAPACITY OF THE AC PLANT

INLET CONDITIONS :

OUTLET CONDITIONS :

INLET AIR ENTHALPY H1 = (Ref. Phyc. Chart.)

23

OUTLET AIR ENTHALPY H2 =

ENTHALPY DIFFERENCE = H1-H2 = kJ/Kg

HEAD OF LIQUID hw = MM of liquid column

= x 10-3

meters

HEAD OF AIR ha ρw X hw /ρa

where pw = sp. Density of manometer liquid= 0.81 x 10 3

hw = head of liquid

pa = density of air

= 0.81 x 103 x hw / 1.1

= 0.81 x hw mm / 1.1

= mtr

= √2gha

Velocity of air = √ 2 x 9.8 x ha = m/s

Air outlet sectional area = A = 0.051 Sq. Mtr

Volume flow rate of air, Q = V x A cubic mtrs per sec

Mass flow rate of air M = volumen flow rate x Density of air

= Q x 1.1 kg per sec

Refrigeration effect ( Actual) N = Mass flow rate x Enthalpy Difference

= M x (H1 – H2) KJ / sec

TONNAGE CAPACITY TR = N/3.5 TR

RESULTS:

1. THE TONNAGE CAPACITY OF THE PLANT = ----------- TR i.e.-----------KW

24

Experiment-10

Aim:

1. To calculate. a) Actual C. O. P b) Theoretical C. O. P of the cycle.

INTRODUCTION:

The Air Conditioning Trainer works on Vapour compression Refrigeration cycle using

R 134a as a refrigerant.

The Trainer is having a hermetically sealed compressor, which sucks cold refrigerant

vapour from the evaporator. The vapour is compressed to higher pressure and

consequently to higher temperature in the compressor. The high pressure and high

temperature refrigerant then enters the condenser, where its latent heat is removed by

rejecting the heat to the air passing over the forced convection condenser. The liquefied

refrigerant passes through drier (where any residual moisture is absorbed) and through

rotameter (where flow is measured) and enters the expansion device. In the expansion

device, the refrigerant is throttled to a lower pressure and as a result, the temperature of

the refrigerant also reduced. This low temperature wet vapour flows through the

evaporator, which is a forced convection air-cooled evaporator. Here, the refrigerant

picks up heat from air passing over it and gains heat; it evaporates and enters the

compressor. This cycle repeats.

In addition to basic system components, many controls such as overload protector, HP/LP

cut-out are provided to safeguard the system against any malfunctioning. To accomplish

psychometric processes, heating elements and humidification arrangement is provided.

To vary the airflow, air dampers are provided.

For measurement of pressures dial type pressure gauges are fitted and to record

temperatures digital temperature scanner is incorporated.

STANDARD VALUES AND FORMULAE

Standard Barometric Pressure = 1.013 bar = 1.013 x 105

N /m2

Density of Water = 1000 kg / m3

Gas Constant for Air = 287 kg / kJ K

Specific Gravity of R-134a at 400

C = 1.2

1 Ton of Refrigeration effect = 3500 Watts = 3.5 kJ / s

Density of Air at 250

C = 1.1 kg/m3

Density of manometric liquid = 810kg/ m3

25

1. CALCULATION OF REFRIGERATION EFFECT

INLET CONDITIONS :

OUTLET CONDITIONS :

INLET AIR ENTHALPY H1 = (Ref. Phyc. Chart.)

OUTLET AIR ENTHALPY H2 =

ENTHALPY DIFFERENCE = H1-H2

kJ/Kg

HEAD OF LIQUID hw

HEAD OF AIR ha

Velocity of air.

=

=

=

=

=

=

=

=

MM of liquid column

X 10 -3

meters

ρw X hw /ρa

where pw = sp. Density of manometer liquid= 0.81 x 10 3

hw = head of liquid

pa = density of air

0.81 x 103 x hw / 1.1

0.81 x hw mm / 1.1

mtr

√2gha

V 2 x 9.8 x ha

m/s

VELOCITY OF AIR= v = M /S

AIR OUTLET SECTINAL AREA = A = 0.051 Sq. mtr

VOLUME FLOW RATE OF AIR, Q = V X A

cubic mtrs per sec

MASS FLOW RATE OF AIR M = VOLUME FLOW RATE X DENSITY OF AIR

= Q X 1.1 kg per sec

REFRIGERATION EFFECT (ACTUAL) = MASS FLOW RATE X ENTHALPY

26

N DIFFERENCE

= M X (H1-H2) KJ / sec

2. ACTUAL C.O.P. OF THE SYSTEM

COMPRESSOR WORK, W = 10x3600

3200xt (where t=time for 10 pulses in

sec.)

=

KW or kJ / s

ACTUAL C.O.P. = N / W

=

3. THEORETICAL C.O.P. OF THE SYSTEM

To evaluate theoretical C.O.P. of the system, carry out following procedure.

1. For any set of readings at a particular time, note suction and discharge

pressures in psig.

2. Divide these pressures by 14.5 to convert them into bar.

3. Add barometric pressure of the present location to obtain absolute pressures in bar.

4. Locate these pressures on “Y” axis of P-H chart. Draw two horizontal lines, one for

low pressure and one for high pressure.

5. Locate particular temperatures on these lines and mark 1,2,3,4.

6. Find out enthalpies at salient points by referring to “X‟‟ axis of P-H chart.

H1=

H2=

H3=

27

H4=

7. N= REFRIGERATION EFFECT= H1-H4= KJ/kg

8. W= COMPRESSOR WORK = H2-H1= KJ/Kg

9. THEORETICAL C.O.P. = N / W

= (H1-H4) / (H2-H1)

RESULTS:

1. THE ACTUAL C.O.P. OF THE SYSTEM IS --------------------------

2. THE THEORETICAL C.O.P. OF THE SYSTEM IS -------------------

28

Experiment-11

Aim:

PLOTTING REFRIERATION CYCLE ON P-H CHART

TECHNICAL SPECIFICATIONS OF THE SYSTEM & FUNCTIONS OF COMPONENTS.

NO.

COMPONENT SPECIFICATIONS

1. Compressor Hermetically sealed.

2. Condenser Forced Convection Air cooled

3. Drier / filter Provided

4. Refrigerant flow

measurement

Glass Tube Rotameter

5 Expansion Device Capillary tube.

6. Evaporator Forced convection air cooled

7. Energy meter Provide

8. Condenser Fan Axial flow type

9. Evaporator Fan Axial flow type

11. Heater 1000 Watt Finned type

13. Temperature

Indicator

6 Channel Facility with digital display

14. HP/LP Cut out Provided

15. Pressure Gauges 2 nos

2 ½ “ Dial type

PROCEDURE:

1) Connect the supply cable to regulated / stabilized power supply.

2) Switch ON the main switch.

3) Put ON the AHU fan.

4) Record the DBT & WBT at the inlet and at the outlet of the duct. (Ensure that the

well of WBT is filled with water.) Use psychrometer.

5) Switch ON the compressor.

6) Allow the system to reach steady state.(RUN FOR 20 MIN.)

29

7) Record suction and discharge pressures.

8) For any set of readings at a particular time, note suction and discharge

pressures in psig.

9) Divide these pressures by 14.5 to convert them into bar.

10) Add barometric pressure of the present location to obtain absolute pressures in bar.

11) Locate these pressures on “Y” axis of P-H chart. Draw two horizontal lines, one for

low pressure and one for high pressure.

12) Locate particular temperatures on these lines and mark 1,2,3,4.

30

Experiment-12

Aim:

1) Draw the Psychometric process on Psychometric chart

2) Recording of data from test rig apparatus

PROCEDURE:

TRACE THE DEHUMIDIFICATION PROCESS

Put the AHU on now start dehumidifier/heater on for 5 mins. Record fallowing reading.

Sr. Inlet Outlet

DBT

WBT

LOCATE INLET AND OUTLET CONDITIONS ON PSYCHROMETRIC CHART

AND STUDY THE PROCESS.

TRACE THE HUMIDIFICATION PROCESS

Put the AHU on now start humidifier for 10 mins, don‟t start compressor. Record

fallowing reading

Sr. Inlet Outlet

DBT

WBT

LOCATE INLET AND OUTLET CONDITIONS ON PSYCHROMETRIC CHART

AND STUDY THE PROCESS.

31

AIR CONDITIONING TEST RIG

OBSERVATION TABLE

1. Put on machine & take reading after 10 mins. Date:

SL TIME

HRS

INLET AIR

TEMP. 0

C

OUTLET

AIR TEMP. 0

C

SU

CT

ION

PR

ES

SU

RE

(

LP

)

PS

IG

DIS

CH

AR

GE

PR

ES

SU

RE

(H

P)

PS

IG

R-134a

REFRIGERANT

TEMPERATURES 0 C

EN

ER

GY

ME

TE

R

TIM

E F

OR

10 P

UL

SE

S.

RE

FR

IGE

RA

NT

FL

OW

LP

H

MA

NO

ME

TE

R

RE

AD

ING

mm

of

WG

SE

CT

ION

AL

AR

EA

OF

TH

E D

UC

T

DBT WBT DBT WBT

AF

TE

R

CO

MP

RE

SS

ION

AF

TE

R

CO

ND

EN

SA

TIO

N

AF

TE

R

EX

PA

NS

ION

AF

TE

R

EV

AP

OR

AT

ION

0.051

sq m