PROPERTIES MEASUREMENT/PVT

MUHAMMAD AFIQ NAJWAN BIN JAMILI

CGE536 Thermofluid Laboratory, Oil and Gas Engineering Department,

College of Engineering, Universiti Teknologi MARA, Selangor, Malaysia

Abstract Article info

These investigations sought to ascertain the PVT measurement Article history:
characteristics. The Perfect Gas Expansion apparatus was used
to successfully complete five tests. Using Boyle's Law, the Experiment date: 5 April 2023
volume and pressure of an ideal gas were correlated in the first Submission date: 12 April 2023
experiment. Due to the unstable environment in the pressurised Keywords:
room, the experiment was only conducted in the vacuum
chamber. The outcome demonstrated that pressure and volume Pressure
had an inversely proportionate relationship. A graph of pressure Volume
vs temperature is created using the Gay-Lussac Law in the Ideal gas
second experiment, which is repeated three times to obtain the Temperature
average temperature at the pressurised and unpressurized
chambers and to demonstrate the relationship between pressure
and temperature. Third, do an experiment utilising a pressurised
chamber to ascertain the heat capacity. For this experiment,
pressure and temperature readings were recorded before and
after. The fourth experiment is called Stepwise
Depressurization, and it relates kinetic energy molecules,
pressure, and temperature to how it affects the graph of pressure
against different stages. To establish the time interval for
pressure that opens and closes the valve after a short period of
time, do a brief depressurization experiment.
1.0 INTRODUCTION This experiment illustrates that for
perfect gases, PV=nRT is true. A basic
Students are introduced to the
formula for an ideal gas is PV=nRT, where
foundations of thermodynamics, including
n is the mole of gas that fills the chamber, P
the first law, second law, and the
and T stand for absolute pressure and
relationship between P-V-T, using the
temperature, respectively, R is the gas
Perfect Gas Expansion device. We
constant, with a value of R=8.3145
constantly experience the expansion and
J/mol.K, and R is the gas constant. It is
compression of gas in our surroundings. It
easier to predict the behaviours of gas
is applicable to a number of common
thanks to an approximation obtained from
applications, including those involving heat
simpler gas laws like Boyle's and Gay-
pumps, engines, and refrigerators.
Lussac's Law. Each of these rules describes
A device called Perfect Gas the connection between an ideal gas's
Expansion has two inlets, a pressurized pressure and volume as well as its pressure
chamber, and a vacuum chamber. and temperature.
Temperature and pressure sensors are built
In the first experiment, Boyle's Law
into this gadget to calculate its value. For a
is used. According to Boyle's Law, an ideal
clearer explanation, consider how air
gas's pressure is inversely proportional to
pushed into the pressure chamber will cause
its volume at constant temperature,
the particles to collide, move wildly and
resulting in the equation P1V1 = P2V2.
erratically, and contact the glass wall to
impart momentum. Per unit area of the wall, Meanwhile the second experiment
the gas pressure is equal to the momentum deals with the Gay-Lussac's Law.
that impacted the glass wall. The ideal gas According to Gay-Lussac's Law, a gas's
is an exception since it just collides with the pressure changes proportionally to its
glass wall and doesn't interact with any absolute temperature at a fixed volume,
other particles. A particle will travel until it giving rise to the equation P1/T1 = P2/T2.
collides with a wall, at which point it will The parameters in the equation were
reverse course and collide with another changed so that the data may be visually
wall. Gas expansion is closely connected to represented in order to clearly illustrate
both the law of conservation of energy and these two rules.
the law of conservation of linear
The third experiment aims to
momentum.
demonstrate isentropic gas expansion,
which is a process in which the entropy of container's capacity based on known
the gas is kept constant. An adiabatic properties like pressure and temperature.
isentropic process does not result in a net
1.1 Objectives
mass or heat transfer, which is another
commonly known fact. This approach may Experiment 1:

be used to calculate the specific heat ratio. • To determine the relationship between

In addition, the fourth experiment pressure and volume of an ideal gas.

describes stepwise depressurization. The • To compare the experimental results

experiment is carried out to examine how with theoretical results.
the pressurized vessel reacts to stepwise Experiment 2:
depressurization. In general, stepwise
• To determine the relationship between
depressurization refers to releasing the
pressure and temperature of an ideal
pressure of air or gas inside a chamber in a
gas.
number of different steps. An ideal gas is a
fictitious gas whose molecules take up very Experiment 3:
little space and don't interact with other
• To demonstrate the isentropic
gases.
expansion process.
The fifth experiment, on the other
Experiment 4:
hand, studies how the pressurized vessel
reacts to a brief depressurization and deals • To study the response of pressurized
with brief depressurization. Brief vessel following stepwise
depressurization is the reduction of air or depressurization.
gas pressure from a chamber over a brief
Experiment 5:
period of time. Each time a gas particle in
the chamber collides with a wall, • To study the response of the pressurized
vessel following a brief
momentum is added to the particle.
depressurization.
Understanding ideal gases is crucial
since it is a fundamental concept that 1.2 Theory

engineers who work with gases use to This ideal gas molecules have a kinetic-
predict their real behaviour. For instance, molecular theory of gases that assumes that
the ideal gas law is used to forecast a ideal gas molecules are constantly moving,
have an average kinetic energy proportional
to the absolute temperature of ideal gas, A process is defined as isentropic if it
have a negligible volume, intermolecular proceeds from start to finish without
forces, and undergo a perfect elastic changing the system's entropy in either
collision. direction. The fast depressurization of gas
in a chamber is one example of a process
• Boyle’s law Experiment
that is on the verge of being isentropic. The
Low density is taken into consideration system's entropy remains constant. Entropy
while analysing the behaviour of actual gas is a sort of energy similar to heat, work, and
using the parameters of pressure, enthalpy, which is by definition energy lost
temperature, and volume. This equation is throughout a process. An isentropic process
effective when the temperature is is one that is both reversible and adiabatic.
maintained constant during the operation An idealised version of a real process, an
and the pressure rises inversely with the gas isentropic process acts as a limiting case for
volume. Gas systems include randomly a real process. There is no heat energy
moving, loosely packed gas. When the transmission in an adiabatic process.
volume is decreased, the pressure increases
• Stepwise Depressurization
because molecules have less room to travel
and strike the container walls more often. Stepwise depressurization is the process of
slowly or gradually releasing the pressure
• Gay-Lusaac Law Experiment
inside a chamber or tank by letting the gas
According to Gay-Lussac, the pressure a flow out through openings and closures,
gas exerts on a container's sidewalls is which would cause it to expand at each
inversely correlated with the gas's absolute point. This method is used to detect gradual
temperature. This is in accordance with the changes in temperature and pressure, on the
kinetic hypothesis, which claimed that as a other hand, which fall as the gas expands.
gas's temperature rises, its molecules
• Brief Depressurization
become faster and more likely to collide
with container walls. Therefore, if the Brief depressurization takes less time than
volume remains unchanged, boosting the stepwise depressurization but is still
temperature should raise the pressure equivalent. The duration lengthened to a
because it also increases collision few seconds. This is done to make sure that
frequency and energy. the impact on the temperature and pressure
can be seen and compared afterwards. The
• Isentropic Expansion Process
gradient of the graph has to be greater.
2.0 METHODOLOGY 1. The general start-up procedures are
performed and all the valves are
2.1 Material
fully closed.
2. The compressive pump is switched
on in order to allow the pressure
inside the chamber to increase up to
150kPa. The pump is then switched
off and the hose is removed from the
chamber.
3. The pressure reading inside the
2.2 Method chamber is monitored until it
stabilizes.
Procedures
4. The pressure reading for both
General start-up procedures chambers are recorded before
expansion.

1. The equipment is connected to 5. Valve V02 is fully opened to allow

single phase power supply and the the pressurized air flows into the

unit is switched on. atmospheric chamber.

2. All valves are fully opened and the 6. The pressure reading for both

pressure reading on the panel is chambers are recorded after

checked in order to ensure the expansion.

chambers are under atmospheric 7. The experimental procedures are

pressure. then repeated for the following

3. Then, all the valves are closed. conditions which is from

4. The pipe is connected from pressurized chamber to vacuum

compressive port of the pump to chamber.

pressurized chamber or the pipe is 8. The PV value is calculated to prove

connected from the vacuum port of Boyle’s Law.

the pump to vacuum chamber.

5. The unit is ready for use. Experiment 2: Gay-Lusaac Law
Experiment

Experiment 1: Boyle’s Experiment 1. The general start-up procedures are

performed and all the valves are
fully closed.
 2. The hose from compressive pump is 4. The pressure reading inside the
connected to pressurized chamber. chamber is monitored until it
3. The compressive pump is switched stabilizes. The pressure reading
on and the temperature for every PT1 and temperature TT1 are
increment of 10kPa in the chamber recorded.
is recorded. The pump is stopped 5. Then, valve V01 is slightly
when the pressure PT1 reaches opened and the air is allowed to
about 160kP. slowly flow out until it reaches
4. Then, valve V01 is slightly opened atmospheric pressure.
and the pressurized air is allowed to 6. The pressure reading and
flow temperature reading are
5. The experiment is stopped when the recorded after the expansion
pressure reaches atmospheric process.
pressure. 7. The isentropic expansion
6. The experiment is repeated for 3 process is discussed.
times to get the average value.
7. The graph of pressure versus Experiment 4: Stepwise Depressurization
temperature is plotted. 1. The general start-up procedures
are performed and all valves are
Experiment 3: Isentropic Expansion fully closed.
Process 2. The hose from compressive
1. The general start-up procedures pump is connected to
are performed and all the valves pressurized chamber.
are fully closed. 3. The compressive pump is
2. The hose from compressive switched on and the pressure
pump is connected to inside the chamber is allowed to
pressurized chamber. increase until about 160kPa.
3. The compressive pump is Then, the pump is switched off
switched on and the pressure and the hose from the chamber
inside the chamber is allowed to is removed.
increase until about 160kPa. 4. The pressure reading inside the
Then, the pump is switched off chamber is monitored until it
and the hose is removed from stabilizes. The pressure reading
the chamber. PT1 is recorded.
 5. Valve V01 is fully opened and
brought it back to the closed General shut down procedures
position instantly. The pressure
1. The pump is switched off and both
reading PT1 is monitored and
pipes from the chambers are
recorded until it becomes stable.
removed.
6. Step 5 is repeated for at least 4
2. The valves are fully opened to
times.
release the air inside the chambers.
7. The pressure reading is
3. The main switch and power supply
displayed on the graph.
are switched off.

Experiment 5: Brief Depressurization

3.0 RESULTS AND DISCUSSION
1. The general start-up procedures are
3.1 Experiment 1: Boyle’s Law Experiment
performed and all the valves are
Pressure reading (kPa)
fully closed.
Before After
2. The hose from compressive pump is
PT1 PT2 PT1 PT2
connected to pressurized chamber.
155.1 106.0 139.0 135.3
3. The compressive pump is switched
Table 1: Experiment 1 data table
on and the pressure inside the
Calculation:
chamber is allowed to increase until
P1V1=P2V2
about 160kPa. Then, the pump is
(155.1 x 0.025) + (106.0 x 0.01237) =
switched off and the hose from the
(139.0 x 0.025) + (135.3 x 0.01237)
chamber is removed.
The different for that condition:
4. The pressure reading inside the
518872 – 5.148661
chamber is monitored until it
= 0.040059
stabilizes. The pressure reading PT1
The calculation based on the data reveals
is recorded.
that the pressure for the gas varies and that
5. Valve V01 is fully opened and
it is inversely related to the volume it fills
brought it back to the closed
in the chamber. It may be computed using
position after few seconds. The
the ideal gas equation PV=nRT. It is thus
pressure reading PT1 is monitored
possible to demonstrate the validity of
and recorded until it becomes
Boyle's Law rule using the formula
stable.
P1V1=P2V2. Calculations also reveal that
6. The pressure reading is displayed on
P1V1 and P2V2 are practically identical.
a graph.
Therefore, the experiment encountered the
same error. We may declare the experiment
to be successful.

3.2 Experiment 2: Gay-Lusaac Law Experiment

Trial 1 Trial 2 Trial 3
Pressur Increment Decrement Increment Decrement Increment Decrement
e (kPa) temperatur temperatur temperatur temperatur temperatur temperatur
e (℃) e (℃) e (℃) e (℃) e (℃) e (℃)
110 25.2 24.2 25.0 24.6 24.4 24.8
120 26.0 24.6 25.6 25.0 25.2 25.2
130 26.8 24.8 26.8 25.4 26.2 25.8
140 27.4 25.0 27.2 26.6 26.8 26.6
150 28.0 25.8 27.6 27.6 27.6 27.4
160 28.2 26.4 28.0 28.0 27.8 28.0
Table 2: Experiment 2 data table

Pressure vs Temperature
180
160
140
Pressure (kPa)

120
100
80
60
40
20
0
24.5 25 25.5 26 26.5 27 27.5 28
Average temperature (℃)

Diagram 1: Pressure vs average temperature graph.

The following experiment examined the connection between pressure and temperature. The
graph displays the variations in pressure and temperature in accordance with Gay-Lussac Law.
Based on Gay-Lussac, it was claimed that the pressure a gas exerts on a container's sidewalls
is proportional to the gas's absolute temperature. Our findings show that the temperature in the
chambers rises as the pressure does. This verified the success of our experiment.

3.3 Experiment 3: Isentropic Expansion Process

Pressure (kPa) Temperature (℃)

Before 160.0 28.6

After 110.2 24.4
Table 3: Experiment 3 data table
𝐾−1
𝑇2 𝑃2( 𝐾
)
=
𝑇1 𝑃1

24.4 110.2 (𝐾−1)

=( ) 𝐾
28.6 160
𝐾−1
0.8531 = 0.6888 ( 𝐾
)

𝑘−1
ln 0.8531 = ln 0.6888( 𝑘
)

𝑘 = 1.46

Isentropic expansion occurs when a system is reversible and adiabatic, which there will be no
heat capacity moved in or out and there will be no energy transformation in determining the
ratio of heat capacity using the expression for the ratio of heat capacity, the result is1.46.
The difference of the ratio of heat capacity with the theoretical value is only 0.04 where the
theoretical value is 1.4. This means the experiment was a success

3.4 Experiment 4: Stepwise Depressurization

Times valve opened Pressure (kPa)

1 144.2
2 134.2
3 127.4
 4 119.6
5 113.6
Table 4: Experiment 4 data table

Pressure vs times valve opened

160 144.2
134.2
140 127.4
119.6
113.6
120
Pressure (kPa)

100
80
60
40
20
0
0 1 2 3 4 5 6
Times valve opened

Diagram 2: Pressure vs times valve opened graph

Stepwise depressurization is a method for implementing an equal time. For an example in the
manufacturing sector in industries, the gradual depressurization strategy in this study produces
a more trustworthy conclusion. When there are less of them because they don't need to collide
more frequently, the molecule in the container is altered. The depressurization demonstrated
that pressure dropped as soon as the valve was opened. The chamber has a low pressure when
the valve is opened more.

3.5 Experiment 5: Brief Depressurization

Valve opened for a few seconds

Before After

Pressure (kPa) 158.4 117.0

Table 5: Experiment 5 data table

 Pressure vs before and after the valve opened for a few
seconds
180 158.4
160
140
117
Pressure (kPa)

120
100
80
60
40
20
0
1 2
1: Before valve opened
2: After valve opened

Diagram 3: Pressure vs before and after the valve opened for a few seconds

A brief depressurization is depicted in the graph that is more linear than stepwise in the results
part of the graph. When the pressure of the gas rises, the expansion happens. As the gas
becomes more and more free to escape, its expansion decreases
4.0 CONCLUSION the instructions or manuals provided. Last
In general, the experiment was successful but not least, always keep an eye on the
since all of the goals were met, despite the sensor while keeping an eye on the board
significant differences in the numbers since the temperature or pressure might
between the theoretical ratio values and the change quickly.
actual numbers. Due to the fact that gases
don't behave exactly in reality, it has been 6.0 REFERENCE
discovered during the investigations that
Admin. (2022, May 18). Gay-Lussac's law
some of the gas laws for the ideal or ideal
- statement, formula, detailed
gas are only limiting rules. Despite this, the
explanation. BYJUS. Retrieved
gas appeared to have followed Boyle's law
April 12, 2023, from
and Gay-Lusaac law in this experiment on
https://byjus.com/chemistry/gay-
the link between pressure, volume, and
lussacs-law/
temperature. The ratio of the gas's volume
reveals and conveys the dynamics of the
Brief depressurization - experiment:
gases' compression and expansion. The heat
EP211 - Chemical Engineering Lab
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https://www.thinkswap.com/my/ucsi
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5.0 RECOMMENDATION
4/brief-depressurization-experiment
The tests must be carried out while adhering
to the P-V-T relationship and measuring the Chemistry. expansion processes of a
ideal gas characteristics. The general start perfect gas - 712 words: Report
up approach needs to be regularly used example. Free Essays. (n.d.).
prior to the experiment in order to reduce Retrieved April 12, 2023, from
side effects that may endanger the outcome. https://ivypanda.com/essays/chemist
To prevent mishaps in the lab, such as ry-expansion-processes-of-a-perfect-
explosions caused by high pressure inside gas/
the chambers, the device must be handled
Encyclopædia Britannica, inc. (n.d.).
cautiously. Each one has to be modified and
Boyle's law. Encyclopædia
attached to the appropriate ports. To
Britannica. Retrieved April 12, 2023,
prevent any errors, the valves had to be
from
carefully monitored and opened in line with
 https://www.britannica.com/science/
Boyles-law

Stepwise depressurization - experiment:

EP211 - Chemical Engineering Lab
4 - UCSI. Thinkswap. (n.d.).
Retrieved April 12, 2023, from
https://www.thinkswap.com/my/ucsi
/ep211-chemical-engineering-lab-
4/stepwise-depressurization-
experiment#:~:text=INTRODUCTI
ON%20Stepwise%20depressurizatio
n%20is%20the,no%20interactions%
20with%20other%20gases.