lab 5 completed
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ABSTRACT
There are seven objectives altogether for the analysis whereby the majority of the experiments
was conducted to study the relationship between pressure, temperature and volume of gas (P,
V and T). This experiment was conducted by using Perfect Gas Expansion Apparatus to
understand the First Law of Thermodynamics, Second Law of Thermodynamics which
consists of Boyles Law, Gay-Lussac Law, Isentropic Expansion Process, Brief
Depressurization and Determination of Ratio of Heat Capacity. Almost the same procedure
used for each experiment. Gay-Lussacs law was proven in experiment 2 and results obtained
in experiment 1 shown that the relationship between pressure, volume and temperature are
parallel to the Boyles law. According to the result, as the pressure increases in the chambers,
the temperature also increases. This confirmed that the experiment is successful because of
following the Gay-Lussac law. Pressure and temperature relationship was observed in
experiment 3. Graph obtained from experiment 5 shows that pressure and temperature
increase proportionally and in experiment 6 and 7, it manages to prove the difference between
theoretical and actual values of gas ratio which has a percentage difference of 2.583% where
it is acceptable.
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INTRODUCTION
Gases, unlike solids and liquids have indefinite shape and indefinite volume. As a result, they
are subject to pressure changes, volume changes and temperature changes. Volume and
temperature are familiar concepts. Pressure is defined as a force per area. When gas molecules
collide with the sides of a container, they are exerting a force over that area of the container.
This gives rise to the pressure inside the container.
The Perfect Gas Law Apparatus is customarily designed and developed to provide a
comprehensive understanding of First Law of Thermodynamics, Second Law of
Thermodynamics and relationship between P, V and T. The Perfect Gas Expansion Apparatus
helps to make a good understanding in energy conservation law and the direction in which the
processes proceed.
The apparatus also equipped with temperature and pressure sensors for both tanks which can
be read on the board. These sensors used to monitor and manipulate the pressure and
temperature. The board displays the temperature and pressure in a digital indicator that dealt
with the PVT laws
The Perfect Gas Expansion Apparatus comes with one pressure vessel and one vacuum
vessel. Both vessels are made of glass tube. The vessels are interconnected with a set of
piping and valves. A large diameter pipe provides gradual or instant change. Air pump is
provided to pressurize or evacuate air inside the vessels with the valves configured
appropriately.
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OBJECTIVE
For this particular experiment, 7 experiment was conducted and the objectives are as follows;
Boyles Law Experiment To determine the relationship between pressure and volume of an ideal gas
To compare the experimental results with theoretical results
Gay-Lussac Law Experiment
To determine the relationship between pressure and temperature of an ideal gas Isentropic Expansion Process
To demonstrate the isentropic expansion process Stepwise Depressurization
To study the response of the pressurized vessel following stepwise depressurization
Brief Depressurization
To study the response of the pressurized vessel following a brief depressurization
Determination of ratio of volume
To determine the ratio of volume and compares it to the theoretical value
Determination of ratio of heat capacity
To determine the ratio of heat capacity
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THEORY
This part will discuss about some of the basic definition on the theorem applied for this
experiments. It will cover two theorem, which is Boyles Law and Gay-Lussac Law.
Boyles Law, according to the (Whitman, 2005), it was developed by an Ireland citizens,
Robert Boyle, in early 1600s. The law stated that the volume of the gas varies inversely with
the absolute pressure, provided the temperature reamins constant. The formula of the Boyles
Law is as folows;
P1V1= P2V2
Where; P1 = Original absolute pressure
P2 = New pressure
V1 = Original volume
V2 = New volume
Figure 1
Figure 1 shows that absolute pressure in a cylinder doubles when the volume is reduced by
half.
Next is the Gay-Lussac Law. This law stated that the relationship between pressure and
temperature, which is pressure is directly proportional with temperature (Myers, 2006). One
of the significance of the law that it provide a method in order to determine the value of
absolute zero. This law is presented by this equation;
1
1=
2
2
Where; P1= original pressure
T1= original temperature
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P2= new pressure
T2= new temperature
Figure 2 Volume VS Temperature
Figure 2 demonstrate by using the Gay-Lussac Law, to determine the absolute zero.
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APPARATUS
1) Pressure Transmitter
2) Pressure Relief Valve
3) Temperature Sensor
4) Big Glass
5) Small Glass
6) Vacuum Pump
7) Electrode
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PROCEDURES
1.1 General Operating Procedures
1.1.1 General Start-up Procedures
1. The equipment was connected to single phase power supply and the unit was
switched on.
2. All valves were fully opened and the pressure reading was checked on the
panel. This is to make sure that the chambers are under atmospheric pressure.
3. Then, all the valves were closed.
4. The pipe was connected from compressive port of the pump to pressurized
chamber or the pipe was connected from vacuum port of the pump to vacuum
chamber.
5. The unit was ready to be used.
1.1.2 General Shut-down Procedures
1. Switch off the pump and remove both pipes from the chambers.
2. Fully open the valves to release the air inside the chambers.
3. Switch off the main switch and power supply.
Experiment 1: Boyles Law Experiment
1) The general start up procedures was performed in section 1.1.1 and all valves are fully
closed.
2) The compressive pump was switched on allowing the pressure inside chamber to increase
up to about 150kPa. Then, the pump was switched off and removed the hose from the
chamber.
3) The pressure reading inside the chamber are monitored until it stabilizes.
4) The pressure reading for both chambers before expansion are recorded.
5) V 02 was fully opened allowing the pressurized air flows into the atmospheric chamber.
6) The pressure reading for both chambers after expansion was then recorded.
7) The experimental procedures was then repeated for the following conditions: from
pressurized chamber to vacuum chamber
8) The PV value was calculated and the Boyles Law is proven.
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Experiment 2: Gay-Lussac Law Experiment
1) The general start up procedures is performed. Make sure all valves are fully closed.
2) The hose is connected from compressive pump to pressurized chamber.
3) The compressive pump is switched on and the temperature is recorded for every
increment of 10kPa in the chamber. The pump is stopped when the pressure PT 1 reaches
about 160kPa.
4) Then, valve V 01 is slightly opened and the pressurized air is allowed to flow out. The
temperature reading is recorded for every decrement of 10kPa.
5) The experiment is stopped when the pressure reaches atmospheric pressure.
6) The experiment is repeated for three times to get the average value.
7) The graph of pressure versus temperature is plotted.
Experiment 3: Isentropic Expansion Process
1) The general start up procedures is performed. Make sure all valves are fully closed.
2) The hose is connected from compressive pump to pressurized chamber.
3) The compressive pump is switched on and the pressure inside chamber is allowed to
increase until about 160kPa. Then, switch off the pump switched off and the hose is
removed from the chamber.
4) The pressure reading inside the chamber is monitored until it is stabilized. The pressure
reading PT 1 and temperature TT 1 is recorded.
5) Then, valve V 01 is opened slightly and the air is allowed to flow out slowly until it
reaches atmospheric pressure.
6) The pressure reading and temperature reading after the expansion process is recorded.
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Experiment 4: Stepwise Depressurization
Experimental procedures:
1) The general start up procedures was performed in section 1.1.1. Ensure that all valves
were fully closed.
2) The hose was connected from compressive pump to pressurized chamber.
3) The compressive pump was connected and the pressure inside chamber was allowed to
increase until about 160kPa. Then, the pump was switched off and the hose was removed
from the chamber.
4) The pressure reading inside the chamber was monitored until it stabilizes. The pressure
reading PT 1 was recorded.
5) Valve V 01 was fully opened and was bring it back to the closed position instantly. The
pressure reading PT 1 was monitored and recorded until it becomes stable.
6) Step 5 was repeated for at least four times.
7) The pressure reading on a graph is displayed and discussed.
Experiment 5: Brief Depressurization
1) The general start up procedures is performed. Make sure all valves are fully closed.
2) The hose is connected from compressive pump to pressurized chamber.
3) The compressive pump is switched on and the pressure inside chamber is allowed to
increase until about 160kPa. Then, switch off the pump switched off and the hose is
removed from the chamber.
4) The pressure reading inside the chamber is monitored until it is stabilized. The pressure
reading PT 1 is recorded.
5) Then, valve V 01 is opened fully and is turned back to close position after few seconds.
The pressure reading PT 1 is monitored and recorded until it becomes stable.
6) The pressure reading on a graph is displayed and discussed.
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Experiment 6: Determination of ratio of volume
1) Perform the general start up procedures in section 5.1. Make sure all valves are fully
closed.
2) Switch on the compressive pump and allow the pressure inside chamber to increase up to
about 150kPa. Then, switch off the pump and remove the hose from the chamber.
3) Monitor the pressure reading inside the chamber until it stabilizes.
4) Record the pressure reading for both chambers before expansion.
5) Open V 02 and allow the pressurized air flows into the atmospheric chamber slowly.
6) Record the pressure reading for both chambers after expansion.
7) The experimental procedures can be repeated for the following conditions: from
pressurized chamber to vacuum chamber
8) Calculate the ratio of volume and compares it with the theoretical value.
Experiment 7: Determination of ratio of heat capacity
1) The general start up procedures was performed in section 1.1.1. All valves were fully
closed.
2) The hose was connected from compressive pump to pressurized chamber.
3) The compressive pump was switched on and the pressure inside chamber was allowed to
increase until about 160kPa. Then, the pump was switched off and the hose wwas
removed from the chamber.
4) The pressure reading inside the chamber have been monitored until it stabilizes. The
pressure reading PT 1 and temperature TT 1 was recorded.
5) Valve V 01 was fully opened and bring it back to the closed position after few seconds.
The pressure reading PT 1 and TT1 was recorded and monitored until it becomes stable.
6) The ratio of heat capacity have been determined and compared with the theoretical value.
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RESULT AND CALCULATION
Experiment 1: Boyles Law Experiment
Condition 1: From pressurised vessel to atmosphere vessel
Before expansion After expansion
PT 1 (kPa abs) 153.6 136.3
PT 2 (kPa abs) 102.4 135.7
Condition 2: From pressurised vessel to vacuum vessel
Before expansion After expansion
PT 1 (kPa abs) 103.8 87.5
PT 2 (kPa abs) 53.3 87.0
Condition 3: From atmospheric vessel to vacuum vessel
Before expansion After expansion
PT 1 (kPa abs) 152.1 120.5
PT 2 (kPa abs) 54.6 119.7
Ideal gas equation, PV=RT. For Boyles law, temperature is constant at room temperature
Hence, R= 8.314 L kPa K-1mol-1, T= 298 @ 25C
i) From pressurized vessel to atmospheric vessel
P1= 153.6Pa, P2= 136.3kPa. Then V1and V2 is calculated
V1= RT/P1
= (8.314 L kPa K-1mol-1) (298.15 K) / (153.6kPa)
=16.14L
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V2 = (8.314 L kPa K-1mol-1) (298.15 K) / (136.3kPa)
=18.19L
According to Boyles law: P1V1=P2V2
P1V1= (153.6kPa) (16.14L) = 2479.10L kPa
P2V2= (136.3kPa) (18.19L) = 2479.30L kPa
ii) From pressurized vessel to vacuum vessel
P1= 103.8kPa, P2= 87.5kPa. Then V1and V2 is calculated
V1= RT/P1
= (8.314 L kPa K-1mol-1) (298.15 K) / (103.8kPa)
=23.88L
V2 = (8.314 L kPa K-1mol-1) (298.15 K) / (87.5kPa)
=28.33L
According to Boyles law: P1V1=P2V2
P1V1= (103.8kPa) (23.88L) = 2478.74L kPa
P2V2= (87.5kPa) (28.33L) = 2478.88 L kPa
iii) From atmospheric vessel to vacuum vessel
P1= 152.1kPa, P2= 120.5kPa. Then V1and V2 is calculated
V1= RT/P1
= (8.314 L kPa K-1mol-1) (298.15 K) / (152.1kPa)
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=16.30L
V2 = (8.314 L kPa K-1mol-1) (298.15 K) / (120.5kPa)
=20.57L
According to Boyles law: P1V1=P2V2
P1V1= (152.1kPa) (16.30L) = 2479.23L kPa
P2V2= (120.5kPa) (20.57L) = 2478.69 L kPa
Experiment 2: Gay-Lussac Law Experiment
Trial 1 Trial 2 Trial 3
Pressure
(kPa abs)
Temperature (oC)
Pressurise
vessel
Depressurise
vessel
Pressurise
vessel
Depressurise
vessel
Pressurise
vessel
Depressurise
vessel
110 27.3 26.9 26.8 26.9 26.8 27.5
120 27.7 27.2 27.0 27.0 27.0 28.4
130 28.6 27.9 27.7 27.5 27.8 29.5
140 29.5 29.2 28.7 28.5 28.8 30.7
150 30.4 31.0 29.7 29.5 29.8 31.7
160 31.3 31.8 30.7 30.6 30.8 32.2
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Trial 1
increase
decrease
0
20
40
60
80
100
120
140
160
180
27 28 29 30 31 32
Pre
ssu
re
Temperature
Gas expansion
0
20
40
60
80
100
120
140
160
180
26 27 28 29 30 31 32 33
Pre
ssu
re
Temperature
Gas expansion
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Trial 2
Increase
Decrease
0
20
40
60
80
100
120
140
160
180
26 27 28 29 30 31
Pre
ssu
re
Temperature
Gas expansion
0
20
40
60
80
100
120
140
160
180
26 27 28 29 30 31
Pre
ssu
re
Temperature
Gas expansion
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Trial 3
Increase
Decrease
0
20
40
60
80
100
120
140
160
180
26 27 28 29 30 31
Pre
ssu
re
Temperature
Gas expansion
0
20
40
60
80
100
120
140
160
180
27 28 29 30 31 32 33
Pre
ssu
re
Temperature
Gas expansion
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Experiment 3: Isentropic Expansion Process
Before expansion After expansion
PT 1 (kPa abs) 156.0 103.5
PT 2 (kPa abs) 30.1 27.5
Experiment 4: Stepwise Depressurization
Initial PT 1 (kPa abs)
After 1st expansion After 2nd expansion After 3rd expansion After 4th expansion
160 144.7 125.0 116.9 110
144.8 125.1 117.0 110.1
144.9 125.2 117.1 110.2
145.0 125.3 117.2 110.3
145.1 125.4 117.3 110.4
145.2 125.5 117.4 110.5
145.3 125.6 117.5 110.6
145.4 125.6 117.6 110.7
145.5 125.7 117.7 110.8
145.6 125.8 117.8 110.9
145.7 125.9 117.9 111.0
145.8 126.0 118.0 111.1
145.9 126.1 118.1
146.0 126.2 118.2
146.1 126.3 118.3
146.2 126.4
146.3 126.5
146.4
146.5
146.6
146.7
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146.8
146.9
100
110
120
130
140
150
160
RESPONSE OF PRESSURISED VESSEL FOLLOWING STEPWISE DEPRESSURISATION
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Experiment 5: Brief Depressurization
PT 1 (kPa abs)
Initial After brief
expansion
160.3 103.2
103.4
103.5
103.6
103.7
103.8
103.9
104.0
110.4
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Experiment 6: Determination Of Ratio Volume
Condition 1 : From pressurised vessel to atmosphere vessel
PT 1 (kPa abs) PT 2 (kPa abs)
Before expansion 149.5 102.7
After expansion 134.1 133.2
Condition 2 : From pressurised vacuum to vacuum vessel
PT 1 (kPa abs) PT 2 (kPa abs)
Before expansion 106.3 55.2
After expansion 90.3 89.5
Condition 3 : From atmospheric vessel to vacuum vessel
PT 1 (kPa abs) PT 2 (kPa abs)
Before expansion 158.2 53
After expansion 122.8 112.3
0
50
100
150
200
0 2 4 6 8 10
Pre
ssu
re
Expansion
RESPONSE OF PRESSURISED VESSEL FOLLOWING STEPWISE
DEPRESSURISATION
Series1
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i) From pressurized vessel to atmospheric vessel
P1V1 = P2V2
V2
V1 =
P1P2
V2
V1 = 149.5/102.7 = 1.456
ii) From pressurized vessel to vacuum vessel
P1V1 = P2V2
V2
V1 =
P1P2
V2
V1 = 106.3/55.2 = 1.926
iii) From atmospheric vessel to vacuum vessel
P1V1 = P2V2
V2
V1 =
P1P2
V2
V1 = 158.2/53 = 2.985
Theoretical value: V2
V1 = 12.37/ 25.00L = 0.4948
PT1 to PT2 : P1/P2 = 134.1/149.5 = 0.8969
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Experiment 7: Determination Of Heat Capacity
Initial Intermediate Final
PT 1 (kPa abs) 156.7 109.9 111.6
TT 1 (oC) 29.6 28.6 27.7
The expression of heat capacity ratio is
Cv
Rln
T2T1
= 21
2
1=
11
22
8.314 11ln (
300.85
302.75) = ln (
156.7(302.75)
111.6(300.85))
Cv = 456.54 11
Cp = Cv + R
456.54 + 8.314 = 464.854 kPa K1mol1
Ratio:
=
464.854
456.54= 1.0182
Theoretical value of
is
=
ln 156.7ln 109.9
156.7ln 111.6= 1.0452
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DISCUSSION
Regarding to Boyle Rule, the pressure of the gas is inversely proportional to the volume it
occupies and can be calculated by using the ideal gas formula PV = RT. After that by using this
formula, P1V1=P2V2, we can prove Boyles law. From the calculation, we can see that the P1V1 is
nearly equal to the value of P2V2. It means there are same error happened during the experiment.
Hence, we can say that the experiment to prove Boyles law is successful.
In the next experiment, the relationship between pressure and temperature was studied. The
graph shows how the pressure and temperature vary according to Gay-Lussac Law. Based on
Gay-Lussac it stated that the pressure exerted on a containers sides by an ideal is proportional to
the absolute temperature of the gas. According to our result, as the pressure increases in the
chambers, the temperature also increases. This confirmed that our experiment is successful
because of following the Gay- Lussac law (Charles law).
Another two experiments, the volume ratio and the heat capacity ratio were determined. The
percentage in difference of the volume theoretical value with the result acquired is small or
almost zero. For the heat capacity, the difference between the resulted value of heat capacity
ratio and the theoretical value is about 2.583 percent.
CONCLUSION
From the experiment, we can concluded that the experiment was succeed after considering all the
objectives were achieved although deviation between the theoretical values and obtained values.
The result shown over our expectation because we manage to get what we want such as in
experiment one which me manage to prove the Boyles law that is when pressure decrease the
volume will increase and vice versa. We also manage to prove the Gay-Lussac law that is
pressure is proportional to temperature. In conclusion, this experiment is successfully done and
the objective of the experiment is achieved.
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RECOMMENDATION
1) Make sure to be fully equipped with personal protective equipment so that any injuries
can be avoided during the conduction of the experiment.
2) It is best to wait around 3 to 5 minutes for the pressure inside each vessel to be stabilized
before recording the obtained results.
3) The general start up and shut down procedure should be read thoroughly and carefully in
the lab manual before conducting any of the experiments.
REFERENCES
1) Thermo fluid laboratory lab manual
2) Ideal Gas Law. Retrieved May 22, 2014, from
http://hyperphysics.phy-astr.gsu.edu/hbase/kinetic/idegas.html
3) Boyles Law. Retrieved May 22, 2014, from
https://www.boundless.com/chemistry/gases/gas-laws/boyle-s-law-volume-and-pressure/
4) PVT Laboratory Measurements. Retrieved May 22, 2014, from
http://my.safaribooksonline.com/book/petroleum-engineering/9780132485210/reservoir-
fluid-sampling-and-pvt-laboratory-measurements/ch05lev1sec6
5) Cengel, Y.A & Boles, M.A. (2011). Thermodynamics an Engineering Approach
Singapore: McGrawHill.
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APPENDICES
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