UNESCO-NIGERIA TECHNICAL & VOCATIONAL
EDUCATION REVITALISATION PROJECT-PHASE II
NATIONAL DIPLOMA IN
MECHANICAL ENGINEERING TECHNOLOGY
THERMODYNAMICS II
COURSE CODE: MEC213
YEAR II- SEMESTER III
PRACTICAL
Version 1: December 2008
MECHANICAL ENGINEERING TECHNOLOGY
EXPERIMENTS ON THERMODYNAMICS II (MEC 213)
TABLE OF CONTENTS
WEEK 1:
1.0: EXPERIMENT 1
1.1 BRAKE POWER OF AN ENGINE
WEEK 2:
2.0: EXPERIMENT 2
2.1 HEAT CONDUCTION IN A LONG SOLID ROD
WEEK 3:
3.0 EXPERIMENTAL TASK 3
3.1. SOLAR ENERGY
WEEK 4:
4.0 EXPERIMENT 4
4.1 TEMPERATURE OF SATURATED STEAM
WEEK 5:
WEEK 6:
5.0
EXPERIMENT 5
5.1
AIR COMPRESSOR
6.0 EXPERIMENTAL TASK 6
6.1. STEAM TURBINE
WEEK 7:
WEEK 8:
7.0
EXPERIMENT 7
7.1
BOYLE’S LAW
8.0
EXPERIMENT 8
8.1
WEEK 9:
9.0
9.1
CHARLE’S LAW
EXPERIMENT 9
IDEAL GAS LAW
WEEK 10:
WEEK 11:
10.0
EXPERIMENT 10
10.1
PRESSURE LAW
11.0 EXPERIMENT 11
11.1 CALORIFIC VALUE OF A SOLID FUEL
WEEK 12:
12.0 EXPERIMENT 12
12.3 CALORIFIC VALUE OF OIL
WEEK 13:
13.0 EXPERIMENT 13
13.1 CALORIFIC VALUE OF COAL
WEEK 14:
14.0 EXPERIMENT 14
14.1 CALORIFIC VALUE OF LIQUID FUEL
WEEK 15:
15.0 EXPERIMENT 15
15.1 CALORIFIC VALUE OF GAS
EXPERIMENT 1
BRAKE POWER OF AN ENGINE
OBJECTIVE:
To determine the brake power of an engine
APPARATUS
1.
Diesel Engine
2.
Dynamometer
3.
Tachometer
4.
Torque meter gauge
5.
Additional load to meet load requirement
6.
Water supply system
THEORY
The brake power of an engine is the useful power available at the crankshaft of the engine. It is measure
by running the engine against some form of absorption brake, hence its name.
B P= 2πNT
60
Where N = Rev/S
T= Torque
Torque applied to shaft = Force x radius
= F x R(Nm)
PROCEDURE
The test is carried out at full load and different engine speed. Before starting the engine, check the oil
level and top up if necessary. Adjust ignition timing to give maximum torque at lowest speed of which
the engine will run smoothly. Start the engine and allow it to worm up. Load the engine by opening the
water value, thus allowing water into dynamometer at the same time; accelerate the engine to
maximum power. Attach Tachometer to the tail end of the dynameters. Record the reading of the
torque as indicated on the torque meter guage together with the RPM reading on the Tachometer.
Reclude load at interval of 200 or 400 and record the reading at these intervals up to the minimum
engine speeds.
RESULTS:
Tabulate your reading in the table shown and draw the speed characteristics curves.
TEST REV/MIN
NO
N
pb
kw
TORQUE
Nm
CONCLUSION
1.
Why does the brake power decreases very rapidly as the engine approaches its maximum
speed
2.
Determine the point of maximum torque from the curves.
Experiment 2
Heat Conduction in a long solid Rod
Introduction
Perhaps the simplest phenomenon that can be modeled by the heat equation is heat conduction in a
long uniform rod. In most instances heat conduction occurs in three dimensions - a situation that is
complicated to analyze. In the laboratory, we use an apparatus that exhibits one-dimensional heat flow
to demonstrate the basic concepts associated with the heat equation.
Objectives
To solve the heat equation for a general long solid rod and to compare your predictions with the actual
temperature measurements made in the lab, determining the composition of the removable section of
the rod.
Experiment
The heat conduction apparatus consists of a cylindrical metal bar that is insulated. The metal bar is
electrically heated with constant wattage on one end while the other end is exposed to cooling water.
The cooling water is supplied when the tubes from the back of the apparatus and the electric cooler are
attached. The cylinder is fitted with temperature sensors at evenly spaced locations along the rod.
General Apparatus Guidelines
The instrumentation provided permits accurate measurement of temperature and power supply. Fast
response temperature probes, with a resolution of 0.1°C, give direct digital readout. The power control
provides a continuously variable electrical output of 0-30 Watts with direct readout. Figure 1 depicts the
Heat Transfer Module with the necessary equipment (excluding cooler) to perform the experiment
Procedure
CAUTION: The apparatus will get hot during the experiment. Be extra cautious to avoid burns from
hot samples. Also, you will be working with water and electricity in close proximity; make sure that
any water outside of the system is cleaned up.
Setting-up the apparatus
This module consists of five basic elements: a control box, power regulator, selector box, a linear
conduction apparatus with various samples, and a radial conduction apparatus. You will also need to
checkout the Neslab recirculating water chiller that will provide the cooling for the apparatus.
1) Make sure the Control Box (Figure 1A) and the Power Regulator (Figure 1C) are turned OFF.
2) Check that the Control Box is plugged into the Power Regulator.
3) Connect the P-1 Military Plug to the appropriate jack on the LabStation (P1A or P1B)4) Connect the
Heater Power Cable (Figure 1E) from the desired conduction apparatus to the frontControl Box.
Figure 1: Heat Conduction Controls
A: Control Box B: Selector Box
C: Power Regulator D: Heater Knob (CCW is OFF)
E: Heater Power Cable (from either conduction apparatus
5) Use the Linear Apparatus (Figure 2A). Install the desired sample into the middle of the rod. Determine
which thermistors (Figure 2C) should be read by the computer. Connect these thermistor cables (Figure
2D) from the Conduction Apparatus to the connectors on the back of the control box labeled one
through seven. The computer will read these thermistors if desired. It cannot read thermistors 8 and 9.
Figure 2: Heat Conduction Apparatuses
A: Linear Conduction Apparatus B: Radial Conduction Apparatus
C: Thermistors D: Thermistor cables
E: Tubing with quick disconnect fittings
6) Plug the Power Regulator into one of the outlets (either circuit #7 or #8) located next to the computer
hard drives on the LabStation.
7) Plug the water chiller into the other outlet located next to the computer hard drives on the
LabStation. Connect the hoses (Figure 2D) to the water chiller. Place the part of the hose which has
the connections in the bucket to catch any spillage.
8) Begin cooling the water in order to get one end of the rod to a steady state (this takes about 10
minutes). Instructions for the water chiller are indicated on the top of the unit. Set the chiller to 5 10°C (record this value) and let it run for 10-20 minutes until the end temperature of the rod has
stabilized. (If the cooler makes unhappy noises, it may be low on water; seek help.)
IMPORTANT: Do not plug both the Power Regulator and the Water Chiller into the same outlet. Use two
different outlets that run off of separate circuit breakers.
9) Select the mode on the Selector box (Figure 1B) to computer. Remember that the computer can only
read thermistors 1-7 on the control box.
2.2 Running an experiment:
10) Turn the heater knob (Figure 1D) on the control box fully counterclockwise (this is the OFF position).
11) The middle section of the rod is removable so you can change samples. Make sure the connection is
tight.
12) Open the “Heat Conduction Apparatus.vi” within H:\ITLL Documentation\ITLL Modules\Armfield
Heat Conduction\Heat Conduction Apparatus.llb
13) When the VI opens, enter the following information into the “User Inputs” dialogue box:
a. Indicate the temperature units desired
b. Specify the time interval between samples (in minutes)
c. Enter the watts applied for the experiment. This is the same wattage that will be dialed on the
control box when running the experiment. When you run LabView (using the white arrow in the
upper left-hand corner) the program will double-check to see that the watts applied is entered
in the VI by telling you to fill it in before pushing stop. When you press OK, LabView will begin
taking data.
14) Turn ON the Power Regulator and control box.
WARNING: If the heater temperature reaches 100º C the control box will shut down. Monitor your
temperature readings carefully.
15) Turn up the power on the heater to 10W or so and enter this value in the VI.
16) Press OK on the Lab View VI to begin collecting temperature data.
17) Once the temperature has stabilized at the ninth thermostat location (chilling side) you will start the
experiment by plugging in the heater power cord to the control block. Take care to record the
temperatures at each of the points just prior to plugging in the heater cord; this will be the initial
temperature distribution.
18) When you are ready to begin the heating part of the experiment, apply power to the heater using
the heater knob
19) Continue to collect data until you’re sure you have reached steady state or 25 minutes has gone by.
20) When you are finished taking data, hit “STOP” to save the data to a file and stop the VI. The tabdelimited file will record the watts applied, the temperature units, and each data point.
Conclusion:
• While the program is running, it will tell you how many samples it has taken, how long it has been
running, and how long until the next sample.
• The plot shows the various temperatures of each thermistor with a different color in a
temperature versus time format. The graph will remain blank until the second data point is taken
because two data points are needed to create a line.
EXPERIMENTAL TASK 3
SOLAR ENERGY
OBJECTIVE:
To identify the equipments required to harness solar energy.
APPARATUS/MATERIALS:
(1) Photovoltaic cells
Fig 1a) Photovoltaic cells
Fig 1b) Photovoltaic cells
2) Solar collector
Fig 2a) Solar collector
3) Solarimeter
Fig 2b) Solar collector
Fig 3a) Dome shaped Solarimeter
Fig 3b) Tube Solarimeter
PROCEDURE
The students should be informed the functions of each of the equipments mentioned above and
how they are used to harness solar energy for various applications such as heating, cooking,
electricity generation, etc.
For example (1), Photovoltaic energy is the conversion of sunlight into electricity. A
photovoltaic cell, commonly called a solar cell or PV, is the technology used to convert solar
energy directly into electrical power. A photovoltaic cell is a nonmechanical device usually made
from silicon alloys.
(2) Solar collector is a device used for collecting the heat energy from the sun for necessary
utilization.
(3) A solarimeter is a pyranometer, a type of measuring device used to measure combined direct
and diffuse solar radiation. An integrating solarimeter measures energy developed from solar
radiation based on the absorption of heat by a black body
CONCLUSION:
The students have been able to understand how the equipments mentioned above work and
how they are used to achieve the desired applications.
EXPERIMENT 4
TEMPERATURE OF SATURATED STEAM
OBJECT: To study the relationship between the pressure and temperature of saturated steam.
APPARATUS: Pressure vessel (e.g Marcet boiler or Pappin’s apparatus), thermometer, steam
tables.
METHODS
1. Make sure that the boiler contains water.
2. Heat the boiler and allow steam to issue from the cock A until all the air is expelled from
the boiler, then close the cock.
3. Allow the boiler to cool and the pressure to drop to atmospheric (Zero guage pressure).
4. Heat the boiler and note the values of temperature and pressure .
5. Remove the Bunsen,and as the apparatus cools, note the temperature at the same
pressures as before.
6. Calculate the average temperature at each pressure.
7. Plot a graph of absolute pressure against average temperature.
8. on the same axes p[lot a graph of absolute pressure against the temperature given in the
steam tables.
OBSERVATIONS
Barometric Pressure = ………
Guage
Pressure(bar)
Abs.
Pressure(bar)
Tempt. oC
Heating
Tempt. oC
Cooling
Average Temp.
C
o
CONCLUSIONS
1. Does the experimental graph show any simple relationship between temperature and
pressure?
2. How do the two graphs compare? Account for any difference between the graphs
3. Why is it necessary to expel all the air before commencing the experiment?
Experiment 5: on Air Compressor
OBJECTIVES
Measure the performance of an air compressor.
Investigate the effects of compressor pressure and speed on performance.
Observe the differences between one-stage and two-stage compressor operation.
DESCRIPTION
Compressors use mechanical work to take gas at low pressure and raise it to a higher pressure. A
reciprocating compressor consists of a piston and cylinder. The basic arrangement is shown in
figure 1. Other compressor types are centrifugal and axial.
To obtain higher pressures compressors are often arranged in stages, with each stage providing
an increase in pressure. We have two reciprocating compressors. Each compressor has two
identical cylinders operating 180 degrees out of phase. They may be operated individually or in
series (staged).On the intake stroke the piston in figure 1 moves to the right, pressure decreases
until it is less than the inlet manifold pressure and air is drawn in through the intake valve. When
the piston moves to the left the intake valve closes. The volume in the cylinder decreases and the
pressure increases, see figure 2. Once the pressure in the cylinder is greater than the pressure in
the outlet manifold, the outlet valve opens and air flows out.
In figure 2, point 1 is the end of the piston stroke, when the cylinder volume is greatest. Point 2
is when air starts to leave the cylinder. Point 3 is the top of the piston stroke, when the
cylinder volume is smallest. Point 4 is when air starts to enter the cylinder.
PARAMETERS
The pressure increase created is expressed as the ratio of outlet pressure to inlet pressure, where
both are in units of absolute pressure. This is called the pressure ratio.
Pr =
Po
...............................................................(1)
Pi
OBSERVATIONS
Inlet
Pressure(bar)
Outlet
pressure(bar)
Inlet
Temp.(oC)
Outlet
Temp.(oC)
Volume(m3)
CONCLUSIONS
1. Calculate the isentropic efficiency of air compressor
2. Calculate the pressure ratio
3. Calculate the entropy at different temperatures and pressures
4. Plot graphs of temperature against entropy and pressure against volume
EXPERIMENT 6
STEAM TURBINE
Objectives
Measure the performance of an air turbine.
Investigate the effects of turbine pressure and speed on performance.
Observe the differences between one-stage and two-stage turbine operation.
Description
Turbines use mechanical work to take gas at low pressure and raise it to a higher pressure. A
reciprocating turbine consists of a piston and cylinder. The basic arrangement is shown in figure
1. Other turbine types are centrifugal and axial.
Figure 1.0: Reciprocating Turbine
To obtain higher pressures turbines are often arranged in stages, with each stage providing an
increase in pressure. We have two reciprocating turbines. Each turbine has two identical
cylinders operating 180 degrees out of phase. They may be operated individually or in series
(staged).On the intake stroke the piston in figure 1 moves to the right, pressure decreases until it
is less than the inlet manifold pressure and air is drawn in through the intake valve. When the
piston moves to the left the intake valve closes. The volume in the cylinder decreases and the
pressure increases, see figure 2. Once the pressure in the cylinder is greater than the pressure in
the outlet manifold, the outlet valve opens and air flows out.
In figure 2, point 1 is the end of the piston stroke, when the cylinder volume is greatest. Point 2
is when air starts to leave the cylinder. Point 3 is the top of the piston stroke, when the
cylinder volume is smallest. Point 4 is when air starts to enter the cylinder.
Turbine Volumes and Pressures
Turbine
Parameters
The pressure increase created is expressed as the ratio of outlet pressure to inlet pressure, where
both are in units of absolute pressure. This is called the pressure ratio.
P
Pr = o ...............................................................(1)
Pi
Observations
Inlet
Pressure(bar)
Outlet
pressure(bar)
Inlet
Temp.(oC)
Outlet
Temp.(oC)
Conclusions
1. Calculate the isentropic efficiency of air compressor
2. Calculate the pressure ratio
3. Calculate the entropy at different temperatures and pressures
4. Plot graphs of temperature against entropy and pressure against volume
Experiment 7
Boyle's Law
Aim: To show that Pressure is proportional to the inverse to volume
Method
A gas syringe was attached to a pressure sensor. The pressure sensor was calibrated, assuming the
atmospheric pressure at the time of the experiment was 100kPa. Differing volumes of gas were created
in the gas syringe and they were recorded as were the corresponding values of pressure at that
particular volume. The volume was varied between 20cm3 and 75cm3.
Results
A set of readings was obtained and the results were plotted on two graphs, one showing pressure
against volume and the other showing pressure against the inverse volume.
Conclusion
Volume (m3)
The graph plotted showing pressure against volume does not show any obvious connection, as the
graph takes the shape of an exponential decay
Pressure (bar)
Experiment 8
Charles’Law
Objective
The goal of this project is to measure the relationship between the volume of a gas and its temperature,
when the pressure of the gas is held constant.
Introduction
This is a modern version of a classic experiment by Jacques Charles (who was also interested in flying
balloons). Charles studied the volume of a sample of air—sealed in a glass tube with a U-shaped curve—
as he systematically changed the temperature by immersing the tube in a water bath. The air was
trapped by a column of mercury, added to the open end of the tube. By changing the amount of
mercury in the tube, Charles could maintain a constant pressure on the trapped air as the temperature
was changed. Charles's apparatus was an example of a manometer, a device used to measure pressure.
Materials and Equipment
To do this experiment you will need the following materials and equipment:
i.
35 ml syringe (available, for example, from Science First ("Gas Law Demonstrator Kit", Science
First, Buffalo, NY. http://www.sciencefirst.com/vw_prdct_mdl.asp?prdct_mdl_cd=30170),
ii. a homemade clamp to hold syringe underwater, which can be made with:
o two sturdy chopsticks (or two sturdy wood dowels) longer than the diameter of your
cooking pot,
o two rubber bands,
o a weight (e.g., a can of soup);
iii. small piece of wire,
iv. thermometer (calibrated in °C, range at least 0–100°C),
v. water,
vi. ice,
vii. cooking pot, deeper than syringe is tall,
viii. stove.
Experimental Procedure
Experimental Apparatus
Diagram showing how to set up syringe. The thin wire between the plunger tip and the inner syringe
wall allows air to escape from in front of the plunger in order to equalize pressure. It is removed
before starting the experiment. Diagram adapted from Gabel, 1996.
1. With the plunger removed from the syringe, seal the tip of the syringe with a tight-fitting cap. If a
suitable cap is not available, you can try epoxy or silicone sealant. Allow the epoxy or silicone
the recommended curing time before proceeding with the experiment. When your sealed
syringe is ready for use, insert the plunger to the 20 ml mark of the syringe along with a thin
wire as shown in the diagram above. The wire will allow air to escape from beneath the
plunger, equalizing the pressure in the syringe with the atmosphere. Use the lower ring of the
plunger as your indicator.
2. Hold the plunger in place and carefully withdraw the wire.
3. Make sure that the plunger can move freely in the syringe, and that the tip of the syringe is wellsealed. Give the plunger a small downward push, and verify that it springs back. If it does not,
you may need to lubricate the side of the plunger with a small amount of silicone lubricant or
you may not have sealed the tip of your syringe properly.
4. When you are satisfied with the results of the previous step, record the initial volume of air in
the syringe and the ambient temperature.
5. You will be immersing the syringe into a water bath, and observing the changes in volume of the
gas as you change the temperature of the water. Since the air in the syringe will make it
buoyant, you need a way to hold the syringe under the water. If you have a ring stand and
clamp, you're all set. Otherwise, you can put together a homemade clamp with materials
you'll probably have around the house. Here's how:
a. Wrap a rubber band around the top of the syringe tube, just below the finger flanges.
b. Insert the chopsticks (as noted in Materials & Equipment, wood dowels can be
substituted for chopsticks) through loops of this rubber band, one on either side of
the syringe. Slide the syringe so that it is about 7–8 cm (3 in) in from the ends of the
chopsticks.
c. Wrap the second rubber band around the short ends of the chopsticks. This will make a
"V" shape, with the syringe held tightly down near the point.
d. This second rubber band can also be used to hold the thermometer upright in the water.
Keep the bulb immersed in the water, but not touching the side or bottom of the pot.
e. Place this assembly on the top of your cooking pot, so that the chopsticks are supported
by the rim of the pot and the syringe sticks down into the pot.
f. To hold the syringe in place when the pot is filled with water, place your weight (e.g., a
can of soup) on top of the wide end of the "V" made by the chopsticks.
g. Make any necessary adjustments to make the syringe and thermometer stable, and
make sure that you can read the scale on the syringe.
Making the Measurements and Presenting Your Results
1. Remove the syringe and thermometer assembly from the pot and set them aside.
2. Place the pot on the stove, but don't turn on the burner yet. Fill the pot with ice cubes and
enough water to immerse the syringe to somewhere between the 30 and 35 ml marks.
3. Replace the syringe and thermometer assembly, and weight it down securely.
4. Allow several minutes temperature in the water bath to stabilize and for the temperature of the
air in the syringe to equilibrate with the water bath. Gentle stirring may help, but be careful
not to break the thermometer or knock your weight off your clamp.
5. Record the temperature of the water bath and the volume of the air in the syringe. You may
want to tap the plunger lightly to make sure it is free to move. (If necessary, carefully (and
briefly) lift the syringe out of the water to read the volume).
6. Turn the burner on (no higher than medium heat) to gradually heat the water. At regular
intervals (e.g., every 10°C), turn the heat off and allow the temperature to stabilize. Again,
record the temperature of the water bath and the volume of air in the syringe.
7. Repeat the previous step up to 80 or 90°C. The pot will be quite full, so it is best to avoid boiling
the water.
8. As with any experiment, it is a good idea to repeat your measurements to be sure that your
results are consistent. We suggest at least three separate trials. (Note that the temperatures
used do not need to be exactly the same from trial to trial!)
9. Make a graph of gas volume vs. temperature for all of your data points. It's a good idea to use a
different symbol for each of your trials (if something was wrong with one particular trial, it
may help you understand what went wrong).
Questions
1. What is the relationship between volume and temperature in your data set?
2. Can you extrapolate from your data to find the temperature that corresponds to a gas volume of
zero? How confident are you with this result, and why?
3. Would your data look different if you used kelvins for the temperature axis instead of degrees
Celsius?
4. Was the assumption of constant pressure valid?
5. What are the possible sources of error in your experiment?
6. What assumption is made about the pressure of the gas in this experiment?
7. What is the relationship between the degrees Celsius and kelvins?
EXPERIMENT 9
IDEAL GAS LAW
INTRODUCTION
The ideal gas law relates the pressure P, volume V , and temperature T of an ideal gas
via
PV = NkT
where k is Boltzmann's constant and N is the number of molecules. The temperature is
measured on the absolute Kelvin scale. In this experiment, we will measure the pressure
vs. temperature, for constant volume.
PROCEDURE
1. Set up the absolute pressure and the temperature sensors in Data Studio. Set the
sampling to \Manual" (click expt, sampling options.)
2. Put ice and cold water in the white plastic percolator. Use just enough ice to have
a little ice left in the water.
3. Mount the chamber on a wooden paint-stirrer with rubber bands. Bind the rubber
cork to the chamber with rubber bands. The chamber is then connected to the
pressure sensor. (It is not necessary to use the cylinder/piston apparatus for this
experiment.)
4. Put the temperature sensor into the percolator. You may want to bind the temperature
sensor to the chamber also. Put the chamber in the percolator and stir gently.
Start the manual data-taking. A click is required for each data point.
5. Once you have a few points in the ice water, turn on the percolator. Stir continually
and take data points.
6. Continue stirring, heating and data-taking. At a temperature of about 70 degrees
Celsius, it is likely that the cork will pop o_. Stop data-taking when this happens.
7. With the data, make a plot of pressure (vertical axis) vs. temperature (horizontal
axis.) You may use either the Data Studio, or put the data into a spreadsheet.
Make the horizontal axis extend far enough to accommodate absolute zero (-273oC).
Make sure the vertical scale extends to zero pressure.
8. Determine the straight line which best fits your data. At what temperature does
the pressure become zero? Compare this with the value of absolute zero.
OBSERVATIONS
Abs. Temp.oC
Pressure (N/m2)
Volume (m3)
CONCLUSIONS
1.Which graph was a straight line through the origin?
2. How are pressure, volume and temperature related?
3. State ideal gas law
EXPERIMENT 10
PRESSURE LAW
To verify the “Pressure Law” and find the Absolute Zero of Temperature
1. PREPARATION:
a) Learn the law.
b) Make sure that you know how to use the kinetic theory to explain why the pressure of a gas increases
with temperature.
2. Using the apparatus shown below, measure the pressure of the air in the
flask for as wide a range of temperatures as possible.
3. To obtain a wide range of temperatures, start by adding ice to the water.
Explain why you should keep the temperature of the water constant for a
few minutes before taking each result.
4. Analysis of the results.
EITHER
Plot a graph of pressure against temperature using a temperature scale
which will allow you to extrapolate below 0°C to find an estimate for the
absolute zero of temperature
OR (better)
Plot a graph of pressure against temperature using the biggest scales
possible. Draw the best fit line and measure its slope.
The equation of the line has the form y = ax + b, and you are trying to find the value of x which makes y =
0.
Using the slope and the co-ordinates of any point on the best fit line,
calculate a value for the constant, b. When b is known, the value of
absolute zero can be found.
EXPERIMENT 11
CALORIFIC VALUE OF A SOLID FUEL.
TITLE: EXPERIMENT TO DETERMINE THE HIGHER CALORIFIC VALUE OF A SOLID FUEL.
DIAGRAM
APPARATUS
IGNITION ROD
SILICA CRUSCIBLE
BATTERY
THERMOMETER
BOMB CONTAINER
BEAKER.
WATER
THEORY
When a given quantity of fuel is burnt, some heat is produced; moreover, some hot flue gases are
also produced. The water which takes up some of the heat evolved is converted into steam. If the
heat taken away by the hot flue gases and the steam is taken into consideration,
then the
amount of heat obtained by complete combustion of 1kg of a fuel, when the products of its
combustion an cooled down to the temperature of supplied air (usually taken as 15oC) is known as
the higher calorific value of fuel.
When the fuels ignite and continues to burn till whole of it is burnt, the heat released during
combustion is absorbed by the surrounding water and the apparatus itself.
Considering the rise in temperature of water, since the heat liberated is equal to the heat absorbed
(neglecting losses), therefore
Heat liberated by fuel = mf x H.C.V------------------------------------------------(i)
Heat absorbed by water and apparatus=(mw+me) cw (t2-t1)--------------------(ii)
Equating the two equations i.e. equation (i) and equation (ii) than,
mf x H.C.V. = (mw + me) Cw (t2 –t1)
Therefore,
H .C.V =
(m w + ma )C w (t 2 − t1 )
mf
kJ / kg .....................(iii )
where,
mf = mass of fuel sample burnt in kg
H.C.V= Higher calorific value of fuel in kJ/kg
mw= mass of water filled in the calorimeter in kg
me= Water equivalent of apparatus in kg
t1= initial temperature of water and apparatus in oC
t2= Final temperature of water and apparatus in oC
PROCEDURE
Weigh the sample of the fuel (usually 1g or so) and placed it in the crucible.
Admit oxygen through the oxygen valve till the pressure inside the bomb rises to (30KN/m2).
Submerged the bomb completely into a known quantity of water contained in a large copper vessel,
which is placed within a large insulated copper vessel to reduced loss of heat by radiation.
Note the temperature reading when the bomb and its contents reach the steady temperature state.
Ignite the fuel by connecting the battery terminals, while the fuel continues to burn till the whole of it is
burnt.
Note the temperature of the water and the apparatus
Tabulate the reading of the following mass and temperations as follows
Mass of fuel sample burnt in the bomb in kg =mf
Mass of water filled in the calorimeter in kg =mw
Mass equivalent of apparatus in kg =ms
Initial temperature of water and apparatus in oC
Final temperature of water and apparatus in oC
(1) Calculate the higher calorific value of fuel
(2) Comment on the overall result obtained from the experiment
(3) State the sources of error
EXPERIMENT 12
CALORIFIC VALUE OF OIL
Object: To determine the calorific value of Paraffin oil.
Apparatus: Junker’s calorimeter, balance, thermometers, graduated cylinder.
METHOD
1.
2.
3.
4.
5.
6.
7.
8.
9.
Light the oil burner and place it on one side of the balance.
Place the burner in the central combustion cylinder of the calorimeter.
Adjust the water supply.
Wait until the conditions become steady before making any observations (i.e inlet and
outlet water temperatures remain constant).
Place the graduated cylinder under the water outlet and at the same instant note the
reading on the balance.
Note the water inlet and outlet temperatures.
Remove the graduated cylinder and again note the balance reading.
Calculate the weight of fuel burned.
Calculate the calorific value of the oil.
OBSERVATIONS
S/No. Weight of water collected
in graduated cylinder(g)
Weight of
oil
burned(g)
Inlet water Outlet water
temp.= t1oC temp. =t2oC
Heat given up by fuel = Heat gain by water
Therefore,
Heat given up by weight of oil burned= W (t 2 − t1 )
C.V =
W
(t 2 − t1 )
w
CONCLUSION
State the calorific value of the oil in kJ/kg
EXPERIMENT 13
CALORIFIC VALUE OF COAL
OBJECT: To determine the calorific value of a sample of coal.
APPARATUS: Darling calorimeter, thermometers
METHOD
1. Grind the sample of coal to a fine powder, and make a small briquette with a piece of
fuse wire passing through it.
2. Weigh the briquette.
3. Attach the fuse wire to the terminals inside the bell jar, so that the briquette is resting in
the crucible.
4. Fill the glass calorimeter up to the line marked on its side.
5. Connect the oxygen supply to the bell jar, and regulate the supply, so that when the bell
jar is immersed in the water about 4 to 5 bubbles of air per second are expelled from the
bell jar.
6. Take the initial temperature of the water.
7. Switch on the electric current. (The fuse wire becomes red hot and ignites the fuel before
melting.) Switch of f the current.
8. Stir the water as the fuel burns.
9. Note the highest temperature reached during the test.
10. Calculate the calorific value of the coal
11. A the end of the test, weigh the ash and examine it for clinker.
Determining the calorific value of a solid
OBSERVATIONS
S/No. Weight of
fuel burned
(g)
Weight of
water in
calorimeter
(g)
Water
equivalent
of
calorimeter
We (g)
Initial tem. of
water t1oC
Heat given up by fuel = Heat gained by water and calorimeter.
Final temp. of
water t2oC
Weight of
ash (g)
Heat from fuel burned = (W + We )(t 2 − t1 )
 W + We 
C.V = 
(t 2 − t1 )
 w 
% ash =
Weight of ash x100
A
=
x100
Weight of coal sample W
CONCLUSION
State the calorific value of the fuel kJ/kg. Comment on flame during combustion, residue after
combustion, ash.
EXPERIMENT 14
CALORIFIC VALUE OF LIQUID FUEL.
TITLE: EXPERIMENT TO DETERMINE THE HIGHER CALORIFIC VALUE OF A LIQUID FUEL.
DIAGRAM
APPARATUS
IGNITION ROD
SILICA CRUSCIBLE
BATTERY
THERMOMETER
BOMB CONTAINER
BEAKER.
WATER
THEORY
When a given quantity of fuel is burnt, some heat is produced; moreover, some hot flue gases are
also produced. The water which takes up some of the heat evolved is converted into steam. If the
heat taken away by the hot flue gases and the steam is taken into consideration,
then the
amount of heat obtained by complete combustion of 1kg of a fuel, when the products of its
combustion an cooled down to the temperature of supplied air (usually taken as 15oC) is known as
the higher calorific value of fuel.
When the fuels ignite and continues to burn till whole of it is burnt, the heat released during
combustion is absorbed by the surrounding water and the apparatus itself.
Considering the rise in temperature of water, since the heat liberated is equal to the heat absorbed
(neglecting losses), therefore
Heat liberated by fuel = mf x H.C.V------------------------------------------------(i)
Heat absorbed by water and apparatus=(mw+me) cw (t2-t1)--------------------(ii)
Equating the two equations i.e. equation (i) and equation (ii) than,
mf x H.C.V. = (mw + me) Cw (t2 –t1)
Therefore,
H .C.V =
(m w + ma )C w (t 2 − t1 )
mf
kJ / kg .....................(iii )
where,
mf = mass of fuel sample burnt in kg
H.C.V= Higher calorific value of fuel in kJ/kg
mw= mass of water filled in the calorimeter in kg
me= Water equivalent of apparatus in kg
t1= initial temperature of water and apparatus in oC
t2= Final temperature of water and apparatus in oC
PROCEDURE
Weigh the sample of the fuel (usually 1g or so) and placed it in the crucible.
Admit oxygen through the oxygen valve till the pressure inside the bomb rises to (30KN/m2).
Submerged the bomb completely into a known quantity of water contained in a large copper vessel,
which is placed within a large insulated copper vessel to reduced loss of heat by radiation.
Note the temperature reading when the bomb and its contents reach the steady temperature state.
Ignite the fuel by connecting the battery terminals, while the fuel continues to burn till the whole of it is
burnt.
Note the temperature of the water and the apparatus
Tabulate the reading of the following mass and temperations as follows
Mass of fuel sample burnt in the bomb in kg =mf
Mass of water filled in the calorimeter in kg =mw
Mass equivalent of apparatus in kg =ms
Initial temperature of water and apparatus in oC
Final temperature of water and apparatus in oC
(4) Calculate the higher calorific value of fuel
(5) Comment on the overall result obtained from the experiment
(6) State the sources of error
EXPERIMENT 15
CALORIFIC VALUE OF GAS
OBJECT: To determine the calorific value of the gas.
Apparatus: Boy’s gas calorimeter, gas meter, pressure regulator, constant head water supply.
METHOD
1. Light the gas burner and regulate the gas supply.
2. Regulate the water supply through the calorimeter.
3. Wait until the conditions become steady before any observations are made (i.e inlet and
outlet water temperatures remain constant). This usually requires about 40 minutes. If any
adjustments are necessary, the conditions must be allowed to become steady again before
carrying out the test.
4. Place the water receptacle under the water outlet and note the weight of water collected
during the combustion.
5. Note the barometer reading and the gas temperature and pressure.
6. Calculate the absolute pressure of the gas (i.e barometer reading + manometer reading).
7. Calculate the calorific value of the gas
OBSERVATIONS
S/No.
Weight
Inlet
of water temp.
collected of
water
t1oC
Outlet
temp
of
water
t2oC
Volume
of gas
burned
( V1)
Barometer Manometer Absolute Temperature
reading
reading ( h pressure of gas =
(mm of
mm of Hg) of gas = T1oC abs.
Hg)
(B + h)
mm of
Hg
CALCULATIONS
Let
P1V1 P2V2
=
T1
T2
V2 =
P1V1T2
P2T1
Heat given up by gas = Heat gained by the water
Heat given up by V2 = W x (t2- t1)
C.V of gas =
W (t 2 − t1 )
V2
CONCLUSION
State the calorific value of the gas.