Standard vs Custom Battery Packs - Decoding the Power Play
Basic civil mechanical Engineering lab manual according to JNTU annathapur syllabus
1. SANTHIRAM ENGINEERING COLLEGE
(Approved by AICTE, New Delhi; Permanent Affiliated to JNTUA, Anantapuramu
An ISO 9001:2008 Certified Institution,2(f) & 12(B) Recognition by UGC Act, 1956
NH-40, Nandyal-518501: Kurnool Dist. A.P.
I-B.Tech II Semester (R-19)
BCME Lab
ACADAMIC YEAR
(2019-2020)
DEPARTMENT OF
Mechanical ENGINEERING
2. List of Experiments in BCME Laboratory
(19A01201P) Basic civil & Mechanical Engineering Lab(EEE)
• Part A
• Laboratory Experiments:
• 1. Bending test on (Steel/Wood) Cantilever beam.
• 2. Bending test on (Steel/Wood) simply supported beam.
• 3. Use of electrical resistance strain gauges.
• 4. Compression test on Bricks
• 5. Water absorption test on Bricks
• 6. Torsion test.
• 7. Tests on closed coiled and open coiled helical springs
Part B
List of Experiments:
• 1. Load test on four stroke Diesel Engine with mechanical loading.
• 2. Load test on four stroke Diesel Engine with DC Generator loading.
• 3. Heat balance test on Four Stroke Diesel Engine.
• 4. Load test on two stroke petrol engine.
• 5. A) Study of Valve & Port diagram.
• B) Study of boilers.
• 6. Performance test on vapour compression refrigeration system.
• 7. Performance test on vapour absorption refrigeration system.
4. Part A
1. Bending test on (Steel/Wood) Cantilever beam.
Aim: To conduct deflection test on the cantilever beam carrying a concentrated load at mid
span.
Apparatus required
1. Deflection beam apparatus
2. Load frame
3. Weights
4. Dial gauge
5. Magnetic dial stand
6. Vernier Caliper
7. Scale / Steel tape
Theory
When the beam is subjected to load, the beam is deflected from its original position.
Due to the load acting on the beam, it will be subjected to bending moment and the beam bend
like arc of circle. All structural and machine elements whether, cantilever, simple supported,
fixed or continuous undergoes deflection when subject to external loads. The deflection of a
member should always be within the specified limits. We can determine the deflection of
beams subject to any type of loading by using standard deflection formulae. The actual
deflection of the member is directly proportional to the load and span cube (for point load
application) and is inversely proportional to flexural rigidity (EI). Actual deflection so
calculated should be less than the permissible deflection.
Deflection apparatus beam set up for Cantilever beam
5. As the loading applied is transverse loading as shown in which is perpendicular to the
plane containing the neutral axis, and hence the member is a beam.
The beam carrying transverse loading
The cross section at XX
Moment of Inertia is calculated about the axis of rotation = I =
6. Procedure
1. Measure the breadth and depth of the given specimen using vernier callipers.
2. Mark the end of the beam.
3. Fix the beam at one end on the test rig support and other end of the beam is free.
4. Set the dial gauge below the free end of the beam and note down the reference point
from the dial gauge.
5. Measure the effective length of the beam from the free end to fixed end by using
scale or steel tape
6. Place the load frame at exact position on the specimen and note down the
corresponding deflection from the corresponding deflection from the dial gauge
7. Similarly note down the deflections by placing different weights on the load frame.
8. Remove the load gradually and record the dial gauge reading while unloading.
7. 1. Least count of Dial gauge= ………
2. Least count of vernier calipers=……..
3. Material of the beam =…………...
4. Length of beam =……………
5. Breadth of beam =……………mm
6. Depth of beam =………………mm
8.
9. Graph
The following graph is drawn by taking load along Y-axis and deflection along X-axis.
Load
Load Vs Deflection
Deflection
Precautions
1) Make sure that the beam and load are placed at proper positions.
2) Measure the dimensions of the beam accurately.
3) Note the readings of the Vernier accurately.
Result
The deflection test on given cantilever beam is conducted.
The Young’s modulus of the given beam from calculation = ……………….… N/mm2.
The Young’s modulus of the given beam from graph = ………………..… N/mm2
Inference
Significance of the test
If the Young’s Modulus of the material of the specimen is equal to the standard value specified
for the material, the deflection is found to be valid.
space for Calculations
Graph paper to be added
10. 2. Bending test on (Steel/Wood) simply supported beam.
Aim
To conduct deflection test on a simply supported beam carrying a point load at a distance ‘a’
from left support.
Apparatus required
1. Deflection beam apparatus
2. Weights
3. Dial gauge
4. Magnetic dial stand
5. Vernier callipers
6. Scale/Steel tape
Theory
When the beam is subjected to load, the beam is deflected from its original position. The
deflection of a member should always be within the specified limits. We can determine the
deflection of beams subject to any type of loading by using standard deflection formulae. The
actual deflection of the member is directly proportional to the load and cube of span (if
subjected to point load) and is inversely proportional to flexural rigidity (EI). Actual deflection
so calculated should be less than the permissible deflection.
Deflection apparatus beam set up
Where,
L-Span of the beam
W-Load applied
a-The distance of the load from left support
As the loading applied is transverse loading as shown in the Fig. 2(a)-2 which is perpendicular
to the plane containing the neutral axis, and hence the member is a beam.
11. Moment of Inertia is calculated about the axis of rotation = I =
Formulae
The general formula for deflection at mid span when load is applied at a distance ‘a’ is given
by
Wa(3L2
4a2)
48EI
If load at ‘a’=L/4 from left support and substituting in above equation,
11WL3 2
Modulus of Elasticity, E
N/mm
768 central
I
(Deflection at the centre of the beam, span L is in ‘mm’ and W in N)
12. 11L3 2
Modulus of Elasticity from graph, E =
slopeX =…… …… …..N/mm
768I
Procedure
1. Note the initial reading of the Vernier Scale.
2. Measure the breadth and depth of the given beam using Vernier Caliper.
3. Adjust cast iron blocks along the bed so that they are symmetrical with respect to the
length of the bed.
4. Place the beam on the knife edges on the blocks so as to project equally beyond each
knife edge. See that the load is applied at the centre of the beam.
5. Set the dial gauge below the center of the beam and note down the reference point from
the dial gauge.
6. Measure the effective length of the beam by using scale or steel tape
7. Place the load frame at exact position on the specimen and note down the corresponding
deflection from the corresponding deflection from the dial gauge
8. Similarly note down the dial gauge readings by placing different weights on the load
frame.
9. Remove the load gradually and record the dial gauge readings while unloading.
Observations & Tables
Calculation of width of the beam
S.No. Main scale Vernier scale Width=M.S.R+L.C.xV.C.
reading (M.S.R.) coincidence
in mm (V.C.) div
1
2
3
Average width in mm=
13.
14. Calculation of depth of the beam
S.No. Main scale Vernier scale Depth=M.S.R+L.C.xV.C.
reading (M.S.R.) coincidence
in mm (V.C.) div
1
2
3
Average depth in mm=
1. Least count of Dial gauge= ………
2. Least count of vernier calipers=……..
3. Material of the beam =…………...
4. Length of beam =…………………mm
5. Breadth of beam =……………mm
6. Depth of beam =………………mm
7. Moment of Inertia of the beam=…………………....mm4
Load Deflection
Young’s
modulus
Sl.
No W
Loading Unloading Avg.
E
(δ1) (δ2) (δ)
Units Kg N mm mm mm m N/mm2
1
2
3
4
5
17. Precautions
1. Make sure that the beam and load are placed at desired positions.
2. Measure the dimensions of the beam carefully.
Graph
The following graph is drawn by taking load along Y-axis and deflection along X-axis.
Load Vs Deflection
Load
Deflection
Result
The deflection test on given simply supported beam is conducted.
The Young’s modulus of the given beam from calculation = …………………… N/mm2.
The Young’s modulus of the given beam from graph = ……………….…….N/mm2
Significance of the test
If the Young’s Modulus of the material of the specimen is equal to the standard value
specified for the material, the deflection found to be correct.
Inference
Space for Calculations
Graph paper to be added
18. 3. Use of electrical resistance strain gauges.
Aim
To learn about the use of the resistance strain gauges and Wheatstone bridges. To learn
to use a static strain indicator
To determine the modulus of elasticity for the given material of the cantilever beam
using electrical resistivity strain gauge
Apparatus
Electrical Resistivity strain gauge set up, Vernier calipers, scale
Introduction
Strain gauges are used as sensors in many systems to measure forces, moments, and the
deformations of structures and materials. The experiment deals with measuring the
strain in the cantilever beam through the use of resistance strain gauges.
The digital Strain Indicator is a field programmable indicator specially designed to be
used with strain gauge based transducers to measure strain. It can take full, half &
quarter bridge of 120 ohms configuration. The resistance strain gauge consists of grid of
fine conducting wire directly bonded to an insulated backing material which is directly
bonded to the machine surface by a thin layer of epoxy resin. The deformation of the
machine surface is transferred to the bonded strain gauge causing its electrical
resistance to change. The strain gauge is found by measuring the change in the
electrical resistance of the strain gauge. The strain gauges are instruments that measure
the stretch/squeeze of the fibres. They are connected to strain gauge boxes through a
data acquisition system that allow us to record the amount of stretching the fibres
undergo when a beam is loaded.
Bridge Configuration
The full, half & quarter bridge configuration can be measured by the strain indicator.
The bridge can be connected to the banana operator provided on the switching unit of
the multi-channel strain indicator. There are four connectors. 1. Red 2. Green 3. Black
& 4. Yellow. Red is input +ve Black is input -ve. Green is output +ve and Yellow is
output -ve.
When the quarter bridge has to be measured, connect the two wires from the strain
gauge to the front side as specified i.e.,. The power supply should be made available
with a proper earthing within two meters of the indicator. Connect the instrument to AC
mains through the
19. connector provided at the rear of the indicator. Strain indicator connection has to be
connected to the switching unit. The calibration is done by setting the gauge factor.
The Quarter bridge strain gauge circuit
Principle of Strain gauge
The normal strain
, where dl = change in the length and L is the original length.
Since
resistance is proportional to , where dR is the change in resistance and R
is
the
electrical =
∝ . The proportionality constant of the strain gauge is
the original
resistance. Thus,
precisely measured by the gauge manufacturer and is supplied as gauge factor (GF). Thus,
= ∗ (1)
20. For a MM Type WA-06-250WT-120 the gauge factor is 2.10 and the resistance is 120
ohms 0.4%.
Mechanics of a Cantilever beam
The experiment deals with the measuring the strain in a cantilever beam through the use
of resistance strain gauges. The strain gauge is parallel to the length of the beam. The
strain measured is the axial strain parallel to the length. A static load will be
incremented at different locations along the beam to produce measurable strains. The
theoretical strain can be found using the theory of simple bending relation
=
where,
‘f’ is the stress produced
‘y’ is the distance of the most distant fibre from the neutral axis
‘M’ is the bending moment
‘I’ is the moment of inertia of the cross section about the axis of rotation
Moment of Inertia is equal to I = bt3/12
where ‘b’ is the width of the section, measured parallel to the axis of the rotation
‘t’ is the thickness
The cantilever plate and the strain gauge
21. The cantilever plate carrying the load
As shown in the Fig.11-2a and Fig.11-2b the load (W) in kg is a gradually applied load
at a distance of L = 150 mm from the strain gauge. The load is applied gradually in
steps of 1kg and the maximum load carrying capacity is equal to 5kg. The bending
moment M = W*150 kg-mm.
The distance from the neutral axis to the most distant fibre, y = t/2
The stress produced at the section where strain gauge is provided can be calculated
using the theory of simple bending. The strain reading is taken from the mirco strain
gauge indicator.
Using Hooke’s law, the ratio of the stress to strain is taken as equal to the modulus of
the elasticity of the material of the cantilever beam.
( )
( ) =
Procedure
1. Switch on the indicator connected to AC Mains.
2. Determine the cross-sectional dimensions (b, t) of
cantilever using Vernier calipers
3. Measure the distance from the point of application of
the load to the section where strain gauge is used as L.
4. Connect the red and white wire to channel 5.
5. Tare the micro strain indicator to zero.
6. Apply the loading in increments of 1 kg each and
note down the corresponding micro strain
7. Calculate the value of stress for each load increment
8. Calculate the modulus of elasticity (E) for each load
increment and average the ‘E’ values
9. Draw the graph with stress v/s strain and determine the
modulus of elasticity
( )
22. Observations
Measure the width (b) of the cantilever beam
S.No. Main Scale Reading VC MSR + VC*LC
The width (b) of the cross section is ___________ mm
Measure the thickness (t) of the cantilever beam
S.No. Main Scale Reading VC MSR + VC*LC
The thickness (t) of the cross section is ____________ mm
The distance from the neutral axis to the most distant fibre y = t/2 = _____________ mm
The Moment of Inertia, I = _________________ mm4
23. Observations for the gradually applied load and the micro strain to calculate the
Modulus of Elasticity of the material (E)
S. No. Load Load Distance Bending Stress (f) Micro Modulus
Applied Applied from the Moment in MPa Strain of the
(W in (W in point of
(M = W*L)
( )
elasticity
kg) N) load to the (E) in
in N-mm
strain MPa
gauge (L)
1
2
3
4
5
Calculations
Precautions
1. The strain gauge is a sensitive instrument and the measurements should be taken
carefully.
2. The wires connecting the strain gauge are delicate and should not be touched.
Result
The electrical resistance using strain gauge test is conducted.
The average value of the modulus of elasticity of the material of the cantilever beam is
_________
The Youngs modulus of elasticity of the material of the cantilever beam from graph is
_________
24. Inference
Significance
1. The modulus of the elasticity can be useful to measure the stresses
produced at any section XX anywhere in the beam as shown in the
Fig. 11-3.
The variation of strain and stress for a cantilever carrying the load
2. To determine the distribution of the stress at any cross section XX
25. 4. Compression test on Bricks
Aim:To determine the compressive strength of a given brick.
Apparatus
Vernier calipers Scale, Compression testing machine.
Theory
Bricks are used in construction of either load bearing walls or in partition walls
of framed structure as shown in the Fig.6-1. In load bearing walls total weight from slab
and upper floor comes directly through brick wall and then it is transferred to the
foundation. In this case the bricks are loaded with compressive nature of force on other
hand in framed structure bricks are used only for construction of partition walls, in
which layer comes directly on the lower layers of wall. However in any case the bricks
in actual practice are to be tested for their compressive strength.
Burnt clay brick
26. Procedure
A. Preparation of test specimen
1) Remove unevenness observed in the bed faces to provide two smooth and
parallel faces by grinding.
2) Immerse in water at room temperature for 24 hours.
3) Remove the specimen and drain out any surplus moisture at room temperature.
4) Fill the frog (if provided) and all voids in the bed face with cement mortar (1 cement,
1 clean course sand of grade 3mm and down).
5) Store under the damp jute bags for 24 hours followed by immersion in clean water for
3 days.
6) Remove, and wipe out any traces of moisture.
B. Test Procedure
1) Measure the length and breadth of the specimen at the center of the brick.
2) Place the specimen with flat faces horizontal, and mortar filled face facing
upwards between two 3-plywood sheets each of 3mm thickness and carefully
centered between plates of the testing machine.
3) Apply load axially at a uniform rate of 14 N/mm2 (140kgf/cm2) per minute till
failure occurs and note the maximum load at failure.
4) The load at failure shall be maximum load at which the specimen fails to
produce any further increase in the indicator reading on the testing machine.
5) Calculate the compressive strength.
6) Repeat the test procedure for minimum of 3 bricks and report the average.
Formula
Compressive Strength = .
27. Tabulation
Area Load
Compressive Average
Identification Height
Strength Compressive
S.N
(N)
A=L X
Mark (H)
(stress) P/A Strength
B (P)
(N/mm2 ) N/mm2
1
2
3
Precautions
1. Measure the dimensions of Brick accurately. .
2. The range of the gauge fitted on the machine should not be more than double
the breaking load of specimen for reliable results.
Result
The average compressive strength of brick sample is found to be…………..
Significance of the test
For load bearing walls, compressive strength of brick is the criterion to decide the
thickness of the wall.
Space for calculation
28. 5. Waterabsorption test on Bricks
Aim: To determine the water absorption capacity of bricks
SAMPLE
Select five brick at random from the lat of brick
EQUIPMENT
1) Drying Oven
2) Immersion Tank etc.
3) Balance (0-10 kg)
PROCEDURE
1) Dry the specimen in a drying oven at a temperature of 1100 C to 1150 C for 24 hrs.
2) Remove the Bricks from the oven and cool them to room temperature and obtain it’s dry
weight M1 (kg).
3) The dried specimen is immersed completely in clean water at a room temperature of 27 ±
20 C for 24 hours.
4) Remove the specimen and wipe out any traces of water with a damp cloth and weighing the
specimen within three minutes after it’s removal from water. Let its weight be M2 (kg).
Tabulation
29. CALCULATION
Water absorption capacity of a brick percentage by mass, when immersion in cold water for
24 hours, is calculated by the formula,
RESULTS
The average of result will be reported.
30. 6. Torsion test.
Aim :To find the Modulus of Rigidity of the given test specimen.
Material and Equipment
Torsion testing machine, Standard specimen of mild steel or cast iron, steel rule, and Vernier
calipers (or) Micrometer.
Theory
Torsion test is quite instrumental in determining the value of modulus of Rigidity (ratio of
shear stress to shear strain) of a metallic specimen. The value of modulus of rigidity can be
found out through observations made during the experiment by using the torsion equation.
In the torque equipment (refer figure shown in the next page), one end of the specimen
is held by a fixed support and the other end to a pulley. The pulley provides the necessary
torque to twist the rod by addition of weights (w). The twist meter attached to the rod gives the
angle of twist.
31. Torsion Testing Machine
Procedure
1. Measure the diameter at about three places and find the average value.
2. Select suitable grips to suite the size of the specimen and clamp it in the machine by
adjusting the sliding jaw.
3. Choose the appropriate loading range depending upon specimen.
4. Set maximum load pointer to zero.
5. Continue till failure of the specimen.
6. Calculate the value of modules of rigidity C by using Torsion equation.
7. Plot a torque – Twist graph (T V/s θ).
Observation
Diameter of the Specimen, d = ……………………….mm
Gauge length of the Specimen, l =………… …… …… ...mm
Polar movement of inertia d4
=…… …… …… … …… …..m m
32.
33. Graph Torqu
e
1. Torque vs. Angle of Twist.
Angle of twist
Result
Thus the torsion test on given mild steel specimen is done and the value of modulus of
rigidity is calculated.
Rigidity modulus of the specimen calculated= …………………… N/mm2
Rigidity modulus of the specimen from graph= …………………… N/mm2
Inference
Reference
IS 1717: 2012 Metallic Materials — Wire — Simple Torsion Test
Significance of the test
When a shaft is subjected to torsion, pure shear stresses are developed in the shaft material.
Hence Modulus of rigidity of the material can be determined.
Space for calculations
Graph paper to be added
34. 7. Tests onclosedcoiledand open coiledhelical springs
Aim:To determine the modulus of rigidity of the material of given close coiled helical the spring.
Apparatus:
1. Spring testing machine
2. Screw gauge
3. Vernier caliper
4. Close coil helical spring.
Theory
Spring is an elastic member, which deflects, or distorts under the action of load and
regains its original shape after the load is removed. Springs May be made of carbon steel,
silicon steel, manganese steel or completely alloyed steels. It is essential to know the
rigidity modulus of the springs because it is used as energy absorbing device. The helical
spring are made up of a wire coiled in the form of a helix and is primarily intended to store
strain energy due to axial tensile or compressive load.
Formulae
Where
W – Applied load in Newton’s
δ Deflection of spring in millimeters
C – Rigidity modulus or shear modulus of spring in
N/mm2 D – Mean Diameter of spring in millimeters n –
Number of turns of coil in the spring.
d – Diameter of spring wire in millimeters
35. Closely coiled helical spring
Tabulation
Applied
Deflection of the Spring Stiffness of
Rigidity
Sl in mm the Spring
Load Modulus
No
W(N) loading unloading Avg (δ)
(K=W/δ)
G (N/mm2)
(N/mm)
1
2
3
4
5
36. Procedure
1. By using Vernier caliper measure the diameter of the wire of the spring and also
the diameter of spring coil.
2. Count the number of turns.
3. Insert the spring in the spring testing machine and load the spring by a suitable weight
and note the corresponding axial deflection in compression.
4. Increase the load and take the corresponding axial deflection readings.
5. Plot a graph between load and deflection. The slope of the graph gives the stiffness of
the spring.
Observations
1.
Least count of the screw gauge
=...................
2.
Diameter of the spring wire (d)
=.......................... mm
3. Least count of the Vernier calipers =...................
4.
Outer to Outer Diameter of the spring coil
(D0)=............................. mm
5.
Mean coil diameter (D) =. D0 – 0.5 d – 0.5 d =
..................................... mm
6.
Mean coil radius (R)
=........................................ mm
7.
Number of turns in the coil (n)
=....................
Graph
The following graph is drawn by taking load along Y-axis and deflection along X-
axis. · Load Vs Deflection
Load
Result
Deflection
Rigidity modulus of the spring from calculation= ………………………… N/mm2
Rigidity modulus of the spring from graph = …………………………… N/mm2
37. Inference
Significance of the test
If the value of Rigidity Modulus found using the test is in agreement with the standard
value, then the test conducted is correct. Rigidity modulus is the property of material
representing the torsional characteristics of the spring material.
Space for calculations
Graph paper to be added
39. 1. PERFORMANCE TEST ON A 4 -STROKE DIESEL ENGINES
AIM: To Conduct Performance test on four - stroke water Cooled diesel Engine and to draw the
following graphs:
1. B.P. Vs S.F.C.
2. mech. Vs B.P
3. B.P. Vs bth
4. T.F.C Vs B.P
DESCRIPTION:
The Test Rig consists of Four-Stroke diesel Engine (Water Cooled) to be tested for performance
is coupled to break drum assembly. The arrangement is made for the following measurements of
the set-up.
1) the rate of fuel consumption is measured by using volumetric pipette.
2) air flow is measured by manometer, connected to air box.
3) the different mechanical loading is achieved by loading the engine through rope –
break drum assembly attached to weighing balance.
4) the engine speed is measured by electronic digital meter.
5) temperature at air inlet and engine exhaust gas are measured by electronic
digital temperature indicator with thermocouple.
6) Water flow is measured by water flow meter.
40. SPECIFICATIONS:
* ENGINE TYPE : 4-Stroke, Single Cylinder Diesel Engine
* MAKE : Kirloskar.
* FUEL : DIESEL
* DENSITY OF DIESEL ‘ρ’ : 0.827 gm / ml
* CALORIFIC VALUE OF DIESEL : 40,000kj / kg
* MAXIMUM POWER, ‘P’ : 5 HP.
* RATED SPEED, ‘N’ : 1500 RPM.
* BORE, ‘D’ : 80mm.
* STROKE, ‘L’ : 110mm
* STARTING : By Hand crank
* BRAKE DRUM DIAMETER : 0.3m
* ROPE DIAMETER : 0.015m
41. * EQUIVALENT DIAMETER : 0.315 m
* LOADING : Mechanical loading connected to break drum
* COOLING : Water cooling.
MEASUREMENTS:
* AIR INTAKE : By Volumetric Tank with
Orifice Dia d = 0.02m connected to
Manometer
(Water), Cd = 0.62
* SPEED : By digital RPM indicator.
* FUEL FLOW : By Volumetric Pipette.
OPERATION:
1) Check the diesel in the tank.
2) Allow diesel and start the engine by using Hand crank.
3) Keep the weighing balance to read zero position, initially.
4) Apply the Load to engine by adjusting the weighing balance
5) Allow some time so that the speed stabilizes.
6) Now take down temperature, petrol flow rate and air consumption.
7) Repeat the procedure (4) & (6) for different loads.
8) Tabulate the readings as shown in the enclosed sheet.
9) After the experiment is over, keep the petrol control valve closed.
42. LIST OF FORMULAE
1. BRAKE POWER (BP):
2πNT
BP = --------------------------- KW
60×1000
Where,
N = RPM of Engine
T -Torque = (F × r) N-m
r = radius of brake drum
2. MASS OF FUEL CONSUMED PER MINUTE (mf):
Pipette Reading x ρ x 60
mf = ------------------------------------- Kg / min.
T x 1000
Where
Density of Diesel (ρ) = 0.827g/ml
Conversion from sec to min = 60
Conversion from gm to Kg = 1000
Time taken for fuel flow = T
Pipette reading (Constant) = 10ml
3. TOTAL FUEL CONSUMPTION (TFC):
TFC = mf x 60 in Kg / hr.
Where,
mf = kg/min
60 = Conversion from min to hr.
4. SPECIFIC FUEL CONSUMPTION (SFC):
T.F.C
S.F.C. = -------------- in Kg / KW – hr.
B.P
5.HEAT INPUT ( HI ) :
T.F.C
HI = --------------- x CV in KW
60 x 60
Where,
TFC in Kg /hr.
CV = Calorific Value of Diesel = 40000 KJ/Kg
43. 6. BRAKE THERMAL EFFICIENCY (Btherm
):
B.P
Btherm
= ------------- x 100
HI
7 INDICATED POWER (IP):
IP = (BP + FP) KW
Where,
FP = (1/3) BP
8. MECHANICAL EFFICIENCY: (m)
BP
m = ---------- x 100%
IP
9 . AIR - FUEL RATIO: (A/F)
m
a
A/F = -------
m
f
Where, m
f
Mass of the fuel intake per minute (kg/min)
ma = Mass of actual mass intake per minute (Kg / min)
kg / min
10. m3/min (Va = Volume of air intake)
.where
Cd = 0.62
(d=0.02m)
mm of water ,
Density of Air = 1.16 Kg/m3
Density of water = 1000 Kg/m3
ma = a Va
44. PRECAUTIONS:
1. Do not run the engine without water supply
2. Do not shut down the engine when maximum load applied to brake drum.
3. After completion of experiments turn off the fuel supply valve.
4. Do not turn off water supply immediately when experiments completes wait for 15 to 30
minutes to maintain the engine temperature cool.
5. Change engine oil when oil turns to black color (approx. once in 6 months).
6. Frequently at least once in three months, grease all visual moving parts.
7. At least every week, operate the unit for five minutes to prevent any clogging of the
moving part.
SAMPLE GRAPHS:
RESULT:
45. • 2. Load test on four stroke Diesel Engine with DC Generator loading.
Exp No: Date
AIM:
To Conduct Performance test on four - stroke water Cooled diesel Engine and to draw the following
graphs:
1. B.P. Vs S.F.C.
2. mech. Vs B.P
3. B.P. Vs bth
4. T.F.C Vs B.P
DESCRIPTION:
The Test Rig consists of Four-Stroke diesel Engine (Water Cooled) to be tested for performance is
coupled to break drum assembly. The arrangement is made for the following measurements of the set-
up.
1) The Rate of Fuel Consumption is measured by using Volumetric Pipette.
2) Air Flow is measured by Manometer, connected to Air Box.
3) The different mechanical loading is achieved by loading the engine through rope –
break drum assembly attached to weighing balance.
4) The engine speed is measured by electronic digital meter.
5) Temperature at air inlet and engine exhaust gas are measured by electronic digital
temperature indicator with thermocouple.
6) Water flow is measured by water flow meter.
46. NOTE: TEMPERATURE POINTS:
T1 = AIR INLET TEMPERATURE
T2 = ENGINE HEAD WATER INLET TEMPERATURE
T3 = ENGINE HEAD WATER OUTLET TEMPERATURE
T4 = EXHAUST GAS OUT LET TEMPERATURE
RESULTANT TABLE:
The whole instrumentation is mounted on a self-contained unit ready for operation.
TOTAL
FUEL
CONSUMP
TION IN
"TFC"
KG/HR
SPECIFIC
FUEL
CONSUMPTI
ON IN "SFC"
KG/KW-hr
HEAT
INPUT
IN KW
BRAKE
THERMA
L
EFFICIEN
CY %η
Bthe
VELOCI
Y OF
AIR
Va IN
m/sec
MASS OF
AIR IN
KG/MIN
AIR
FUEL
RATI
O
FRICTI
ONAL
POWE
R IN
KW
INDICATED
POWER
MECHANIC
AL
EFFICIENCY
%η mech
47. SPECIFICATIONS:
* ENGINE TYPE : 4-Stroke, Single Cylinder Diesel Engine
* MAKE : Kirloskar.
* FUEL : DIESEL
* DENSITY OF DIESEL ‘ρ’ : 0.827 gm / ml
* CALORIFIC VALUE OF DIESEL : 40,000kj / kg
* MAXIMUM POWER, ‘P’ : 5 HP.
* RATED SPEED, ‘N’ : 1500 RPM.
* BORE, ‘D’ : 80mm.
* STROKE, ‘L’ : 110mm
* STARTING : By Hand crank
* BRAKE DRUM DIAMETER : 0.3m
* ROPE DIAMETER : 0.015m
* EQUIVALENT DIAMETER : 0.315 m
* LOADING : Mechanical loading connected to break drum
* COOLING : Water cooling.
MEASUREMENTS:
* AIR INTAKE : By Volumetric Tank with
Orifice Dia d = 0.02m connected to Manometer
(Water), Cd = 0.62
* SPEED : By digital RPM indicator.
* FUEL FLOW : By Volumetric Pipette.
OPERATION:
1) Check the diesel in the tank.
48. 2) Allow diesel and start the engine by using Hand crank.
3) Keep the weighing balance to read zero position, initially.
4) Apply the Load to engine by adjusting the weighing balance
5) Allow some time so that the speed stabilizes.
6) Now take down temperature, petrol flow rate and air consumption.
7) Repeat the procedure (4) & (6) for different loads.
8) Tabulate the readings as shown in the enclosed sheet.
9) After the experiment is over, keep the petrol control valve closed.
LIST OF FORMULAE
1. BRAKE POWER (BP):
2πNT
BP = --------------------------- KW
60×1000
Where,
N = RPM of Engine
T -Torque = (F × r) N-m
r = radius of brake drum
2. MASS OF FUEL CONSUMED PER MINUTE (mf):
Pipette Reading x ρ x 60
mf = ------------------------------------- Kg / min.
T x 1000
Where
Density of Diesel (ρ) = 0.827g/ml
Conversion from sec to min = 60
Conversion from gm to Kg = 1000
Time taken for fuel flow = T
Pipette reading (Constant) = 10ml
3. TOTAL FUEL CONSUMPTION (TFC):
TFC = mf x 60 in Kg / hr.
Where,
49. mf = kg/min
60 = Conversion from min to hr.
4. SPECIFIC FUEL CONSUMPTION (SFC):
T.F.C
S.F.C. = -------------- in Kg / KW – hr.
B.P
5. HEAT INPUT ( HI ) :
T.F.C
HI = --------------- x CV in KW
60 x 60
Where,
TFC in Kg /hr.
CV = Calorific Value of Diesel = 40000 KJ/Kg
6. BRAKE THERMAL EFFICIENCY (Btherm
):
B.P
Btherm
= ------------- x 100
HI
7 INDICATED POWER (IP):
IP = (BP + FP) KW
Where,
FP = (1/3) BP
8. MECHANICAL EFFICIENCY: (m)
BP
m = ---------- x 100%
IP
9 . AIR - FUEL RATIO: (A/F)
m
a
A/F = -------
m
f
Where, m
f
Mass of the fuel intake per minute (kg/min)
ma = Mass of actual mass intake per minute (Kg / min)
50. kg / min
m3/min (Va = Volume of air intake)
.where
Cd = 0.62
(d=0.02m)
mm of water ,
Density of Air = 1.16 Kg/m3
Density of water = 1000 Kg/m3
ma = a Va
51. SREC
II B.Tech II Semester
PRECAUTIONS:
8. Do not run the engine without water supply
9. Do not shut down the engine when maximum load applied to brake drum.
10. After completion of experiments turn off the fuel supply valve.
11. Do not turn off water supply immediately when experiments completes wait for 15 to 30
minutes to maintain the engine temperature cool.
12. Change engine oil when oil turns to black color (approx. once in 6 months).
13. Frequently at least once in three months, grease all visual moving parts.
14. At least every week, operate the unit for five minutes to prevent any clogging of the moving
part.
SAMPLE GRAPHS:
RESULT:
52. SREC
II B.Tech II Semester
Fig: 2-stroke engine with break drum
TABULAR COLUMN:
S.No Speed rpm
Spring balance
(Kg)
Manometer
Reading(hw)
Time for 10 cc of fuel
collected, t ‘sec’
Air Inlet & Oulet
temperatures oc
F1 F2 h1 h2 T1 T2
1.
2.
3.
53. SREC
II B.Tech II Semester
• 3. Heat balance test on Four Stroke Diesel Engine.
AIM:
To conduct performance test on 4-Stroke diesel engine (Single cylinder) and to check the heat
balance of I.C engine.
THEORY:
The thermal energy produced by the engine is not completely utilized for the production of
mechanical power. The thermal energy of IC engines is 33% .Of the available heat energy 1/3 is lost by
the exhaust system and 1/3 is observed and dissipated by cooling system It is the purpose of Heat
balance sheet to know the heat energy distribution i.e. to know the energy usages.
Heat balance sheet of IC engines includes the following heat distribution:
a) Heat energy available from the fuel burnt.
b) Heat energy equivalent to output brake power
c) Heat energy lost to engine cooling water.
d) Heat energy carried away by the exhaust gases
e) Unaccounted heat energy loss.
The Test Ring consists of Four-Stroke Diesel Engine, to be tested for performance, is
connected to Rope Brake Drum with Spring Balance (Mechanical Dynamometer) with Exhaust
Gas Calorimeter. The arrangement is made for the following measurements of the Set-up:
1) The Rate of Fuel Consumption is measured by using the pipette reading against the known time.
2) Air Flow is measured by Manometer connected to Air Box.
3) The different mechanical loading is achieved by operating the spring balance of dynamometer in
steps.
4) The different mechanical energy is measured by spring balance and radius of brake drum.
5) The Engine Speed (RPM) is measured by electronic digital RPM Counter.
6) Temperature at different points is measured by electronic digital Temperature Indicator.
7) Water Flow Rate through the engine & calorimeter is measured by Wattmeter.
The whole instrumentation is mounted on a self – contained unit ready for table operation.
PROCEDURE:
54. SREC
II B.Tech II Semester
1. Check the diesel in the diesel tank.
2. Allow diesel, start the engine by using hand cranking.
3. The engine is set to the speed of 1500 RPM.
4. Apply load from the spring balance of dynamometer.
5. Allow some time so that the speed stabilizes.
6. Now take down spring balance readings.
7. Put tank valve in to pipette position and note down the time taken for
particular quantity of fuel consumed by the engine.
8. Note down the temperature readings at different points.
9. Note down the water readings.
10. Repeat the procedure (4) & (7) for different loads.
11. Tabulate the readings as shown in the enclosed list.
12. After the experiment is over, keep the diesel control valve at mains position.
FORMULAS:
Heat energy available from the fuel burnt QS = T.F.C×C.V KJ/min
Heat energy equivalent to output brake power QBP = B.P×60 KJ/min
Heat energy lost to engine cooling water QCW = mw × Cw × (T3-T2) KJ/min
Heat energy carried away by the exhaust gases QEG = mfg × Cfg × (T4-T1) KJ/min
Unaccounted heat energy loss. Qun- counted = QS - { QBP+ QCW+ QEG} KJ/min
Masses mfg=(mf+ma) , mf =mass of fuel , ma =mass of air
Specific heats Cw = 4.187 KJ/kg.k , Cfg=1.005 KJ/kg.k
RESULT:
56. 4. Load test on two stroke petrol engine.
INTRODUCTION
A machine, which uses heat energy obtained from combustion of fuel and
converts it into mechanical energy, is known as a Heat Engine. They are classified
as External and Internal Combustion Engine. In an External Combustion Engine,
combustion takes place outside the cylinder and the heat generated from the
combustion of the fuel is transferred to the working fluid which is then expanded to
develop the power. An Internal Combustion Engine is one where combustion of the
fuel takes place inside the cylinder and converts heat energy into mechanical
energy. IC engines may be classified based on the working cycle, thermodynamic
cycle, speed, fuel, cooling, method of ignition, mounting of engine cylinder and
application.
DESCRIPTION OF THE APPARATUS:
The test rig is built for loading mentioned below:
a. Electrical Dynamometer Loading (AC)
1) The equipment consists of a BAJAJ make 5 port model Petrol Engine (Kick
Start) of 3hp(2.2kW) capacity and is Air cooled The Engine is coupled to a
AC Alternator for Loading purposes. Coupling is done by an extension shaft in
a separate bearing house and is belt driven. The dynamometer is provided with
load controller switches for varying the load.
2) The engine is provided with modified head with cooling arrangement for
different compression ratio and also has an attachment for varying the spark
timing
3) Thermocouples are provided at appropriate positions and are read by digital
temperature indicator with channel selector to select the position.
4) Engine Speed at various condition s is determined by a Digital RPM
Indicator.
5) Load on the engine is measured by means of Electrical Energy meter.
6) A separate air box with orifice assembly is provided for regularizing and
measuring the flow rate of air. The pressure difference at the orifice is measured
by means of a Manometer.
7) A volumetric flask with a fuel distributor is provided for measurement and
directing the fuel to the engine respectively.
57. EXPERIMENTATION:
AIM:
The experiment is conducted to
a. To study and understand the performance characteristics of the engine AND
b. To draw Performance curves and compare with standards.
PROCEDURE:
1. Give the necessary electrical connections to the panel.
2. Check the lubricating oil level in the engine.
3. Check the fuel level in the tank.
4. Release the load if any on the dynamometer.
5. Open the three-way cock so that fuel flows to the engine.
6. Set the accelerator to the minimum condition.
7. Start the engine by cranking.(KICK START)
8. Allow to attain the steady state.
9. Load the engine by switching on the Load controller switches
provided. (Each loading is incremental of 0.5kW)
10. Note the following readings for particular condition,
a. Engine Speed
b. Time taken for cc of petrol consumption
c. Water meter readings.
d. Manometer readings, in cms of water &
e. Temperatures at different locations.
11. Repeat the experiment for different loads and note down the above
readings.
12. After the completion release the load (while doing so release the
accelerator) and then switch of the engine by
pressing the ignition cut – off switch and then turnoff the panel.
OBSERVATIONS:
Sl.
No.
Speed,
rpm
Load
Applied
Manometer
Reading, cm of
water
Time for
10cc of
fuel
collected,
t sec
Time for 5 rev
of Energy
meter,
‘F’ kW h1 h2 hw =
(h1+h2)
59. Where,
D = Bore diameter of the engine = 0.057m
L = Length of the Stroke = 0.057m
N = speed of the engine in rpm.
GR = gear ratio
60. 1st gear = 14.47:1
2nd gear = 10.28:1
3rd gear = 7.31:1
4th gear = 5.36:1
TABULATION:
Sl. Input
Power
Output
Power,
BP
SFC Brake
Thermal
Efficiency
Volumetric
efficiency
1
2
3
4
PRECAUTIONS:
1. Do not run the engine if supply voltage is less than 180V
2. Do not run the engine without the supply of water.
3. Supply water free from dust to prevent blockage in rotameter, engine head and
calorimeter.
4. Note that the range for water supply provided is an approximate standard values,
however the user may select the operating range to his convenience not less than 3 & 2
LPM for engine and calorimeter respectively.
5. Always set the accelerator knob to the minimum condition and start the engine.
6. Switch off the ignition of AUXILLARY while doing in the engine arrangement.
7. Do not forget to give electrical earth and neutral connections correctly.
8. It is recommended to run the engine at 1000rpm otherwise the rotating parts and
bearing of engine may run out.
RESULT: Graphs to be plotted:
1. SFC v/s BP
2. ηbth v/s BP
3. ηvol v/s BP
1.What is the significance of clearance volume?
2.What is a stroke?
3.Difference between SI and CI ?
4.Difference between four stroke and two stroke
5.Why four stroke is mostly preferred ?
6.What is the function of piston rings
7.What are functions of camshaft and crankshaft?
8.What is volumetric efficiency? And it's significance
VIVA QUESTIONS
61. • 5. A) Study of Valve & Port diagram.
AIM:
Determine the actual valve timing for a 4- stroke diesel engine and draw the diagram.
APPARATUS REQUIRED:
1. Four stroke cycle diesel engine
2. Measuring tape
3. Chalk
4. Piece of paper
THEORY:
In a four stroke engine opening and closing of valves and fuel injection do not take place
exactly at the end of dead center positions. The valves open slightly earlier and close after that
respective dead center position. The injection (ignition) also occurs prior to the full compression and
the piston reaches the dead Centre position. All the valves operated at some degree on either side in
terms of crank angles from dead center position.
Inlet valve:
During the suction stroke the inlet valve must be open to admit charge into the cylinder, the
inlet valve opens slightly before the piston starts downward on the suction stroke.
The reason that the inlet valve is open before the start of suction stroke is that the valve is necessary
to permit this valve to be open and close slowly to provide quite operations under high speed
condition.
Inlet Valve Opens (IVO):
It is done at 10 to 250in advance of TDC position.
Inlet Valve Closes (IVC):
It is done at 25 to 500after BDC position
Exhaust Valve
As the piston is forced out on the outstroke by the expanding gases, it has been found
necessary to open the exhaust valve before the piston reaches the end of the stroke. By opening
the exhaust valve before the piston reaches the end of its own power stroke, the gases have an
outlet for expansion and begin to rush out of their own accord. This removes the greater part of
the burnt gases reducing the amount of work to be done by the piston on its return stroke
Exhaust Valve Opens (EVO):
It is done at 30 to 500 in advance of BDC position.
EXHAUST VALVE CLOSES (EVC):
It is done at 10 to 150 after the TDC position.
62. PROCEDURE:
1. Remove the cylinder head cover and identify the inlet valve, exhaust valve and piston of
particular cylinder.
2. Mark the BDC and TDC position of flywheel
3. This is done by rotating the crank in usual direction of rotation and observe the position of
the fly wheel, when the piston is moving downwards at which the piston begins to move in
opposite direction. i.e. from down to upward direction. Make the mark on the flywheel with
reference to fixed point on the body of the engine. That point is the BDC for that cylinder
.Measure the circumference. That point is TDC and is diametrically opposite to the BDC.
4. Insert the paper in the tappet clearance of both inlet and exhaust valves
5. Slowly rotate the crank until the paper in the tappet clearance of inlet valve is gripped .make
the mark on fly wheel against fixed reference. This position represent the inlet valve open
(IVO). Measure the distance from TDC and tabulate the distance.
6. Rotate the crank further, till the paper is just free to move. Make the marking on the
flywheel against the fixed reference. This position represents the inlet valve close (IVC).
Measure the distance from BDC and tabulate the distance.
7. Rotate the crank further, till the paper in the tappet clearance of exhaust valve is gripped.
Make the marking on the flywheel against fixed reference. This position represents the
exhaust valve open (EVO). Measure the distance from BDC and tabulate.
8. Then convert the measured distances into angle in degrees.
CALCULATION:
Circumferential fly wheel = X cm
... 1 Cm = 360 / X
Required angle (“θ") = _____Cm × (360 / X) in degrees
RESULT:
63. Fig: 2-Stroke Engine with Ports
OBSERVATION AND TABULATION
Circumferential fly wheel = X cm
... 1 Cm = 360 / X
Required angle (“θ") = _____Cm × (360 / X) in degrees
64. Exp No: Date:
1. (b) PORT TIMING DIAGRAM OF AN I.C ENGINE
AIM:
To draw the port timing diagram of given two stroke cycle petrol engine.
APPARATUS REQUIRED:
1. Two stroke petrol engine
2. Measuring tape
3. Chalk
THEORY AND DESCRIPTION:
In the case of two stroke cycle engines the inlet and exhaust valves are not present. Instead,
the slots are cut on the cylinder itself at different elevation and they are called ports. There are three
ports are present in the two stroke cycle engine.
1. Inlet port
2. Transfer port
3. Exhaust port
The Diagram which shows the position of crank with ports are open and close are called as
port timing diagram. The extreme position of the piston at the bottom of the cylinder is called
“Bottom Dead Center” [BDC]. The extreme position of the piston at the top of the cylinder is
called “Top Dead Center” [TDC].In two stroke petrol engine the inlet port open when the piston
moves from BDC to TDC and is closed when the piston moves from TDC to BDC. The transfer
port is opened when the piston is moved from TDC to BDC and the fuel enters into the cylinder
through this transport from the crank case of the engine. The transfer port is closed when piston
moves from BDC to TDC. The transfer port opening and closing are measured with respect to the
BDC. The exhaust port is opened, when the piston moves from TDC to BDC and is closed when
piston moves from BDC to TDC. The exhaust port opening and closing are measured with
respect to the BDC
S.
NO
EVENT
POSITION OF CRANK w.r.t.
TDC OR BDC
DISTANCE IN ‘cm’
ANGLE
DEGREES(“θ")
1 EPO
2 EPC
3 TPO
4 TPC
PROCEDURE:
1. Remove the ports cover and identify the three ports.
2. Mark the TDC and BDC position of the fly wheel. To mark this position follows the same
procedure as followed in valve timing diagram.
3. Rotate the flywheel slowly in usual direction (usually clockwise) and observe the movement
of the piston
4. When the piston moves from BDC to TDC observe when the bottom edge of the piston. Just
uncover the bottom end of the inlet port. This is the inlet port opening (IPO) condition;
make the mark on the flywheel and measure the distance from TDC.
5. When piston moves from TDC to BDC observe when the bottom edge of the piston
completely covers then let port. This is the inlet port closing (IPC) condition. Make the mark
on the flywheel and measure the distance from TDC.
65. 6. When the piston moves from TDC to BDC, observe, when the top edge of the piston just
uncover the exhaust port. This is the exhaust port opening [EPO] condition. Make the mark
on the flywheel and measure the distance from BDC.
7. When the piston moves from BDC to TDC, observe, when the piston completely cover the
exhaust port This is the exhaust port closing condition [EPC]. Make the mark on the
flywheel and measure the distance from BDC.
8. When the piston moves from TDC to BDC observe, when the top edge of the piston just
uncover the transfer port. This is the transfer port opening [TPO] condition. Make the mark
on the flywheel and measure the distance from BDC
9. When the piston moves from BDC to TDC, observe, when the piston completely covers the
transfer port.
10. This is the transfer port closing [TPC] condition. Make the mark on the flywheel and
measure the distance from BDC.
Note:
1. The inlet port opening distance and closing distance from TDC are equal.
2. The exhaust port opening distance and closing distance from BDC are equal.
3. The transfer port opening distance and closing distance from BDC are equal.
RESULT:
Viva Questions:
1. Differentiate valve and port?
2. Define valve timing?.
3. Explain the importance of valve timing?
4. Define mechanism of valve operation?
5. Define the cam mechanism in IC engine?
6. Define crank mechanism?
7. Explain importance of port timing?
66. • B) Study of boilers.
Aim: To study Babcock-Wilcox boiler.
Theory: Evaporating the water at appropriate temperatures and pressures in boilers does
the generation of steam. A boiler is defined as a set of units, combined together consisting
of an apparatus for producing and recovering heat by igniting certain fuel, together with
arrangement for transferring heat so as to make it available to water, which could be heated
and vaporized to steam form. One of the important types of boilers is Babcock-Wilcox
boiler.
Observation: In thermal powerhouses, Babcock Wilcox boilers do generation of steam in
large quantities.
The boiler consists essentially of three parts.
1. A number of inclined water tubes: They extend all over the furnace. Water circulates
through them and is heated.
2. A horizontal stream and water drum: Here steam separate from the water which is
kept circulating through the tubes and drum.
3. Combustion chambers: The whole of space where water tubes are laid is divided into
three separate chambers, connected to each other so that hot gases pass from one to the
other and give out heat in each chamber gradually. Thus the first chamber is the hottest and
the last one is at the lowest temperature. All of these constituents have been shown as in fig.
The Water tubes 76.2 to 109 mm in diameter are connected with each other and
with the drum by vertical passages at each end called
headers. Tubes are inclined in such a way that they slope down towards the back. The rear
header is called the down-take header and the front header is called the uptake header has
been represented in the fig as DC and VH respectively.
Whole of the assembly of tubes is hung along with the drum in a room made of
masonry work, lined with fire bricks. This room is divided into three compartments A, B,
and C as shown in fig, so that first of all, the hot gases rise in A and go down in B, again
rises up in C, and then the led to the chimney through the smoke chamber C. A mud
collector M is attached to the rear and lowest point of the boiler into which the sediment
i.e. suspended impurities of water are collected due to gravity, during its passage through
the down take header.
Below the front uptake header is situated the grate of the furnace, either
automatically or manually fired depending upon the size of the boiler. The direction of hot
gases is maintained upwards by the baffles.
In the steam and water drum the steam is separated from the water and the
remaining water travels to the back end of the drum and descends through the down take
header where it is subjected to the action of fire of which the temperature goes on
increasing towards the uptake header. Then it enters the drum where the separation occurs
and similar process continuous further.
For the purpose of super heating the stream addition sets of tubes of U-shape
fixed horizontally, are fitted in the chamber between the water tubes and the drum. The
steam passes from the steam face of the drum downwards into the super heater entering at
its upper part, and spreads towards the bottom .Finally the steam enters the water box , at
the bottom in a super heated condition from where it is taken out through the outlet pipes.
The boiler is fitted with the usual mountings like main stop valve, safety valve, and
feed valve, and pressure gauge.
Main stop valve is used to regulate flow of steam from the boiler, to steam
pipe or from one steam one steam pipe to other.
The function of safety valve is used to safe guard the boiler from the hazard of
pressures higher than the design value. They automatically discharge steam from the boiler
if inside pressure exceeds design-specified limit.
Feed check valve is used to control the supply of water to the boiler and to
prevent the escaping of water from boiler due to high pressure inside.
67. Pressure gauge is an instrument, which record the inside pressure of the boiler.
When steam is raised from a cold boiler, an arrangement is provided for
flooding the super heater. By this arrangement the super heater is filled with the water up to
the level. Any steam is formed while the super heater is flooded is delivered to the drum
ultimately when it is raised to the working pressure. Now the waterr is drained off from the
super heater through the cock provided for this purpose, and then steam is let in for super
heating purposes.
Result: The Babcock – Wilcox boiler is studied.
68. STUDY OF LANCASHIRE BOILER
AIM: To study Lancashire boiler.
Theory: Evaporating the water at appropriate temperatures and pressures in boilers does
the generation of system. A boiler is defined as a set of units, combined together consisting
of an apparatus for producing and recovering heat by igniting certain fuel, together with
arrangement for transferring heat so as to make it available to water, which could be heated
and vaporized to steam form. One of the important types of boilers is Lancashire boiler.
Observation: Lancashire boiler has two large diameter tubes called flues, through which the
hot gases pass. The water filled in the main shell is heated from within around the flues and
also from bottom and sides of the shell, with the help of other masonry ducts constructed in
the boiler as described below.
The main boiler shell is of about 1.85 to 2.75 m in diameter and about 8 m
long. Two large tubes of 75 to 105 cm diameter pass from end to end through this shell.
These are called flues. Each flue is proved with a fire door and a grate on the front end. The
shell is placed in a placed in a masonry structure which forms the external flues through
which, also, hot gases pass and thus the boiler shell also forms a part of the heating surface.
The whole arrangement of the brickwork and placing of boiler shell and flues is as shown in
fig.
SS is the boiler shell enclosing the main flue tubes. SF are the side flues
running along the length of the shell and BF is the bottom flue. Side and bottom flues are
the ducts, which are provided in masonry itself.
The draught in this boiler is produced by chimney. The hot gases starting from
the grate travel all along the flues tubes; and thus transmits heat through the surface of the
flues. On reaching at the back end of the boiler they go down through a passage, they heat
water through the lower portion of the main water shell. On reaching again at front end they
bifurcate to the side flues and travel in the forward direction till finally they reach in the
smoke chamber from where they pass onto chimney.
During passage through the side flues also they provide heat to the water
through a part of the main shell. Thus it will be seen that sufficient amount of area is
provided as heating surface by the flue tubes and by a large portion of the shell
Operating the dampers L placed at the exit of the flues may regulate the
flow of the gases. Suitable firebricks line the flues. The boiler is equipped with suitable
firebricks line the flues. The boiler is equipped with suitable mountings and accessories.
69. There is a special advantage possessed by such types of boilers. The products of
combustion are carried through the bottom flues only after they have passed through the main flue
tubes, hence the hottest portion does not lie in the bottom of the boiler, where the sediment contained in
water as impurities is likely to fall. Therefore there are less chances of unduly heating the plates at the
bottom due to these sediments.
Result: The Lancashire boiler is studied.
VIVA QUESTIONS
1. Define Boiler
2. Define Steam
3. Classify different types of boilers.
4. Difference between Fire tube and Water tube boiler. ?
5. Define Boiler Horse Power (BHP).?
6. Classify different types of Steams.?
7. What is dryness fraction.
8. What are the accessories of a boiler.?
9. What are the mountings of a boiler.?
10. What is the importance of Mollier Diagram.?
70. 6. Performance test on vapour compression refrigeration system.
Objective: To Study Refrigeration test rig and to study the vapour compression refrigeration cycle.
Aim: To calculate co-efficient of performance with the help of P-h diagram.
Nomenclature:
Nom Column Heading Units Type
Cos Φ Power factor. Given
Cp Specific heat of water kJ/kgoC. Given
(C.O.P.)Rel(b
)
Relative co-efficient of performance for batch operation Calculate
d
(C.O.P.)Rel(c) Relative co-efficient of performance for continuous
operation
Calculate
d
(C.O.P.)Th Theoretical co-efficient of performance. Calculate
d
(C.O.P.)Act(b
)
Actual co-efficient of performance. for batch operation Calculate
d
(C.O.P.)Act(c
)
Actual co-efficient of performance for continuous
Operation
Calculate
d
CWAct Actual compression work kJ/kg Calculate
d
H1 Enthalpy of refrigeration effects at compressor inlet kJ/kg Calculate
d
H2 Enthalpy of compressor work at compressor outle kJ/kg Calculate
d
H3 Enthalpy of sub cooling at the outlet of condenser kJ/kg Calculate
d
H4 Enthalpy of refrigerant inlet of evaporator kJ/kg Calculate
d
I Ammeter reading Amp. Measured
m(b) Mass of water for batch operation kg/sec. Calculate
d
m(c) Mass of water for continuous operation kg/sec. Calculate
d
W Heater Wattage KW Given
P1 Pressure at compressor suction kg/cm2 Measured
P2 Pressure at compressor discharge kg/cm2 Measured
REAct(b) Actual Refrigeration effect for batch operation kJ/sec Calculate
d
REAct(c) Actual Refrigeration effect for continuous operation kJ/sec Calculate
d
T1 Temperature at compressor suction Measured
T2 Temperature at compressor discharge Measured
T3 Temperature at condenser outlet Measured
T4 Temperature at evaporator inlet Measured
T5 Temperature of water inlet for continuous operation Measured
71. T6 Temperature of, water in evaporator for batch
cooling / water outlet for continuous operation
Measured
T6i Temperature of water before cooling in batch operation Measured
T Time sec Measured
V Voltmeter reading Volts Measured
Vwe Volume of water in evaporator for batch cooling Ltrs Measured
Introduction:
Refrigeration may be defined as the process of removing heat from a substance under
controlled conditions. It is used for the manufacture of ice and similar products.
Refrigeration is the branch of science that deals with the process of reducing and maintaining
the temperature of a space or material below the temperature of the surroundings. Heat must
be removed from the body being refrigerated and transferred to another body whose
temperature is below that of the refrigerated body. This is widely used for cooling of storage
chambers in which perishable foods, drinks, and medicines are stored. The refrigeration has
also wide applications in submarine ships, aircrafts.
Theory:
Schematic diagram of Vapour Compression Refrigeration System
Vapour Compression Cycle:
The refrigerant starts at some initial state or condition, passes through a series of processes in
a definite sequence and returns to the initial condition. This series of processes is called a
cycle.
72. The Standard Vapour Compression Cycle (SVCC) consists of the following processes:
Process 1-2: Reversible adiabatic compression from the saturated vapour to a super heated
Condition (electrical) input.
Process 2-3: Reversible heat rejection at constant pressure (de-superheating and condensation
of the refrigeration
Process 3-4: Irreversible constant enthalpy expansion from high pressure saturated liquid to a
low- pressure liquid and small amount of vapour.
Process 4-1: Reversible heat absorption at constant pressure from space to be cooled.
Fig. 1.2 Pressure- Enthalpy Diagram
Standard Vapour Compressor Cycle :
Compressor:
The main function of compressor is to raise the pressure and temperature of the refrigerant by
the compression of the refrigerant vapour and then pump it into the condenser
Condenser:
Condense the vapour refrigerant into the liquid by condenser fan and passes it into the
receiver tank for recirculation.
Capillary Tube:
It expands the liquid refrigerant at high pressure to the liquid refrigerant at low pressure so that
a measured quantity of liquid refrigerant is passed into the evaporator.
Evaporator:
Evaporates the liquid refrigerant by absorbing the heat into vapour refrigerant and sends
back into the compressor.
73. Drier:
A drier is used in between the condenser and expansion device. The main function of the
drier is to absorb the moisture from the liquid refrigerant and filter the dust particles.
Accumulator:
An accumulator is fitted in between the Evaporator and Compressor. It prevents the
liquid refrigerant from entering the compressor.
Co-efficient of Performance:
The coefficient of performance of (C.O.P.) of a refrigerating cycle is defined as the ratio
between net refrigeration (output) and compressor work (input).
Description:
The set up demonstrates the basic principal of a refrigeration cycle. The test rig is
designed for the study of Vapour Compression Refrigeration Cycle. The set up
consist of voltmeter, amperemeter, Energymeter, rotameter, heater. Instrumentation
is done to measure the temperature & pressure wherever necessary
2. Utilities Required:
Electricity Supply: Single Phase, 220 V AC, 50Hz, 5-15Amp. Combined socket with
earth connection.
Water Supply @ 2 LPM at
1 Bar. Floor Drain
required.
Floor Area Required: 1.5 m x 1m
3. Experimental Procedure:
Starting Procedure (For Batch Operation):
1. For batch operation fill known amount of water in the evaporator tank.
2. Put the temperature sensor T6 in the evaporator tank.
3. Note down the reading of temperature T6i.
4. Switch ON the mains power supply.
5. Switch ON the compressor.
6. Wait for 2-3 minutes to switch ‘ON’ the compressor.
7. Open the valves below the pressure gauges.
8. Switch ON the pump for 30 sec after every 10 minutes.
9. After 10 minutes, note the temperature sensors reading.
10. Note down the voltage and current.
11. Note down the time.
12. Note down the reading of pressure gauges.
74. 13. Note all the reading after every 10 minute till the temperature of water in evaporator
comes constant.
14. Repeat the experiment for different volume of water.
15. Repeat the experiment by switching ‘ON’ the heater (load condition)
Starting Procedure (For Continuous Operation):
1. For continuous operation, open the valve and drain the water.
2. Connect pipe evaporator water outlet to drain.
3. Connect water supply to rotameter.
4. Set a flow rate of water with help of valve.
5. Put the temperature sensor T6 at evaporator water outlet.
6. Switch ON the mains power supply.
7. Switch ON the compressor.
8. Wait for 2-3 minutes to switch ‘ON’ the compressor.
9. Open the valves below the pressure gauges.
10. After 10 minutes, note the temperature sensors reading.
11. Note down the voltage and current.
12. Note down the time.
13. Note down the reading of pressure gauges.
14. Note all the reading after every 10 minute till the temperature of water in
evaporator comes constant.
15. Repeat the experiment for different flow rates of water.
16. Repeat the experiment by switching ‘ON’ the heater (load condition).
Closing Procedure:
1. Switch ‘OFF’ the main supply.
2. Close water supply to rotameter.
3. Open the valve to drain out the water.
Observation & Calculations:
9.1.a Data:
Power factor Cos Φ = 0.7
Density of w = 1000 kg/m3
Specific heat of water Cp = 4.186 kJ/kg oC
Heater Capacity W =..................... KW
75. 9.1.b Observation Table:
T6i = ------------ (oC)
For Batch Operation
Sr.
No
t
min
P1
kg/cm2
P2
kg/cm2
T1
(oC)
T2
(oC)
T3
(oC)
T4
(oC)
T5
(oC)
T6
(oC)
Vwr
(LPH)
V
(Volts)
I
(Amp)
9.1.c OBSERVATION TABLE:
T6i = ------------ (oC)
For continuous operation
Sr.
No
t
min
P1
kg/cm2
P2
kg/cm2
T1
(oC)
T2
(oC)
T3
(oC)
T4
(oC)
T5
(oC)
T6
(oC)
Vwr
(LPH)
V
(Volts)
I
(Amp)
(A) For continuous operation:
76.
77. Precautions & Maintenance Instructions:
1. Never run the apparatus if power supply is less than 180 volts and above 230 volts.
2. Do not start unit, before putting the water in the evaporator.
3. During the observation do note open the evaporator.
Troubleshooting:
If electric panel is not showing the input on the mains light, check the main supply.
Conclusion
78. 7. Performance test on vapour absorption refrigeration system.
Objective: To study Electrolux Refrigeration system.
Aim: To determine COP of Vapour absorption refrigeration system.
1. Nomenclature:
No
m
Column Heading U
n
i
t
s
Type
C
O
P
Co-efficient of Performance Calc
u
l
a
t
e
d
T1 Temperature of generator o
C
Meas
u
r
e
d
T2 Temperature of condenser o
C
Meas
u
r
e
d
T3 Temperature of evaporator o
C
Meas
u
r
e
d
2. Introduction:
Electrolux refrigerator is a absorption type refrigeration system. In absorption refrigeration system
the vapour is drawn from the evaporator by absorption into liquid having high affinity for
refrigerant. The refrigerant is expelled from the solution by application of heat and its
temperature is increased. This refrigerant in the vapour form passes to the condenser
where heat is rejected and the refrigerant gets liquefied. This liquid again flows to the
evaporator at reduced pressure and the cycle is completed.
Absorber:
The main function of Absorber is the absorption of the refrigerant vapour by its weak or poor solution in a
suitable absorbent or adsorbent, forming a strong or rich solution.
Condenser:
Condenses the vapour refrigerant into the liquid by condenser fan and passes it into the receiver tank
for recirculation.
79. Evaporator:
Evaporates the liquid refrigerant by absorbing the heat into vapour refrigerant and sends back to next
run.
3. Theory:
The flow of fluids in the system has been shown in the diagram with different shadings and the index
of these shadings also indicated in diagram. Vertical boiler in which an aqua solution of
ammonia can range itself from distilled water at the bottom of the boiler to strong
ammonia vapour at the surface of liquid.
A water separator which is provided to remove water vapour so that they should not enter the
condenser, get condensed there and pass on to evaporator where chocking might occur due
to its freezing. The water vapour is formed in the boiler as some of the water may
evaporate on application of heat to the boiler. The separator is a jacket with liquid
ammonia at pressure of about 14 bar gauge for which the saturation temperature is about
40 ºCt the dehydrate ammonia gas gets condensed to liquid in the condenser and gravitates
to ‘U’ tube which acts as seal for a gas to enter the evaporator, or any gas passing from
evaporator to condenser.
80. In the evaporator, ammonia liquid comes across an atmosphere of hydrogen at about 12-bar gauge.
The plant is charged to a pressure of about 14 bar. Hence due to Dalton’s law of partial
pressure the pressure of ammonia gas should fall to about 2 bar gauge and the saturation
temperature corresponding to about 2 gauge is about –10 ºC. the temperature surrounding
the evaporator is much higher than this. Thus ammonia evaporates and produces the
refrigerating effect, i.e. absorbs the latent heat of vaporization at 2 bar gauge and about– 10
ºC from the space to be refrigerated.
In order to ensure continuous action, hydrogen gas has to be removed from ammonia vapors. This is
done in the absorber where a descending spray of very dilute ammonia liquid moseys the
ascending mixture of ammonia vapour and hydrogen. Ammonia vapour is readily absorbed
with evaluation of heat so that absorber has to be water jacketed or air cooled, otherwise
evaporation may take place in this unit and the absorption may cease.
Heat exchanger (Condenser): liquid heat exchanger is placed in between absorber and the generator.
This weak liquid gets cooled and strong liquid gets heated, thus is economized and better
thermal efficiency obtained. This heat exchanger is counter flow type. The strong solution
from the absorber is preheated on its way to generator or boiler and the dilute solution on
its way to absorber is cooled. This cooling of weak liquid also helps absorption and
reduces the cooling of absorber by external source.
Working:
1. Strong ammonia solution flows from the absorber vessel to the boiler.
2. When the ammonia solution is heated in the boiler, bubbles of ammonia as raises from the
pump.
3. The ammonia
vapour passes
into the
condenser.
4. Weak
ammonia
solution flows
into the tube.
5. Air
circulatin
g over
the fins
of the
condense
r. Cool
down the
vapour.
Condensi
ng it in
liquid
ammonia
.
6. Liquid
ammonia
flows through
t
h
e
p
i
p
e
t
o
t
h
e
e
v
a
p
o
r
a
t
o
r
.
7. T
h
e
h
y
d
r
o
g
e
n
i
n
t
h
e
e
v
a
p
o
rator lowers the ammonia
vapour pressure and
makes it evaporate.
8. This process extracts
heat from the evaporator,
which in turn extracts
heat from the food
storage space. Thereby
the temperature inside the
refrigeration is lowered.
9. The mixture of hydrogen and
ammonia passes from the
evaporator to the absorber.
10. Weak ammonia solution is fed
from the boiler system.
11. As it turns to the
absorber vessel, it
absorbs the ammonia
from the
ammonia/hydrogen
mixture and gets ready
for another round in the
boiler.
4. Utilities Required:
81. 1. Electrici
ty
Supply: Single Phase, 220 VAC, 50 Hz, 5-15 amp socket with earth connection.
2. Bench Area
Required: 1 m
x 0.5 m.
5. Experimental
Procedure:
1. Ensure that
all ON / OFF
switches given
on the panel
are at OFF
position.
2. S
w
i
t
c
h
O
N
t
h
e
m
a
i
n
S
u
p
p
l
y
.
3. S
w
i
t
ch ON the refrigerator.
4. Record the temperatures
when the steady state is
achieved.
6. Observation & Calculation:
8.1 Observation Table:
S. No. T1 (oC)
7. Precaution & Maintenance Instructions:
Never run the apparatus if power supply is less than 180 volts & above than 230 volts.
Unnecessary handling of equipment should be avoided.
Never open the refrigerator during the experiment.
8. If electric panel is not showing the input on the mains light, check the main supply.
Conclusion