Mechanical Engineering Laboratory Report

Marcet Boiler

Name (as in SEGi ID): Alwali Muaadh Mohammed Ali Saleh

Student ID: SUKD1700629

Group Code: EME3401

Course Name: Laboratory Investigation1

Submission Date: 22.4.2019

1.0 Abstract:
This experiment was carried out to determine the relationship between the pressure and the
temperature of saturated steam in equilibrium. Besides that, this experiment was also done to
demonstrate the vapor pressure curve. The Marcet Boiler was used for this experiment. When
the pressure increases, the temperature also increases. Therefore, the relationship of pressure
and temperature is directly proportional. The derived formulae and the data were used to
calculate the slope. The dT/dP measured was compared with the data in the steam table.
Theoretically, the values measured should be almost the same with the predicted values.
However, at certain points, the values are not the same. This is caused by the errors made in
the experiment.

2.0 Objective:

- To demonstrate the relationship between the pressure and temperature of

saturated steam in equilibrium with water

- To determine the vapour pressure curve.

3.0 Introduction:

The Marcet Boiler is the unit for the demonstration of the basic principle in Thermodynamics
studies which is the boiling phenomenon. Initially, the discovery of this phenomenon is
founded by Rudolf Clausius, a German physicist that was a thermodynamics power icon.
Marcet boiler is also a device that is used for the understanding of the basic properties of
saturated steam to superheated steam. It consists of cylinders surrounded with isolated
substance in its electrically heated boiler which is used to heat up water and to measure both
the temperature and pressure. Marcet boiler also contains thermometer, barometer and safety
valve. The saturation pressure curve can be determined at the pressure within 10 bar.
Marcet boiler is used to investigate the relationship between the pressure and the temperature
of saturated steam in equilibrium with water at all temperature levels between the atmospheric
dT
pressure and 8 bars. The measured value of the slope of the graph [ ] obtained from the
dP SAT
practical result can be compared with corresponding values calculated from the data in steam
tables.
Clausius-Clapeyron states:
dT Tv
[ ] = fg
dP SAT h fg
¿
Where,
h f +h fg =h g
h fg =h g−h f
¿

v f =specific volume of saturated liquid

v g=specific volume of saturated vapor
h f =enthalpy of saturated liquid
h g=enthalpy of saturated vapor
h fg =latent heat of vaporization

4.0 Apparatus:
i. HE169 Marcet boiler which shown in Figure 1
a- Pressure transducer.
b- Temperature.
c- Pressure.
d- Control panel.
e- Bench.
f- Bourdon tube pressure gauge.
g- Temperature sensor.
h- Pressure relief valve.
i- Water inlet port & valve.
j- Heater.
 a f

b h

g
c i

e
j

Figure 1: HE169 Marcet Boiler

5.0Procedures:

1. Turned on the power supply switch.

2. If the boiler is initially filled with water, We opened the valves at the level side tube to
check the water level. Poured in additional distilled water if necessary. Then, closed the
valves.

3. Sat the temperature controller to 185°C, which is slightly above the expected boiling
point of the water at 10 bar (abs).

4. Opened the valve at feed port and turn on the heater.

WE Always made sure that the valves at the level sight tube are closed before turning on
the heater as the sight tube is not designed to withstand high pressure and temperature.

5. Observed the steam temperature rising as the water boils.

 6. Allowed steam to come out from the valve for about 30 seconds, and then closed the
valve. This step is important to remove air from the boiler as the accuracy of the
experimental results will be significantly affected when air is present.

7. Recorded the steam temperature and pressure when the boiler is heated until the
steam pressure reaches 10 bar (abs).

WE Never opened the valves when the boiler is heated as pressurized steam can cause
severe injury.

8. Then, turned off the heater and the steam temperature and pressure will begin to drop.
Allow boiler cool down to room temperature.

9. Record the steam temperatures at different pressure readings when the boiler is heated
and cooled.
10. Switch off the heater and allow the boiler temperature to drop.

6.0 RESULTS:

Atmospheric pressure : ______100 KP_______ bar

Atmospheric temperature : ________100_____ (0C)

 Table 1 Data Collected and Calculated Results

Measured Calculated Slope,

Pressure, P (bar) Temperature
Slope, dT/dP Tvg/hfg
Increase Decrease Average Average
Absolute Gauge Absolute (Kpa)
(C) (C) (C) (K)
1.0 0 100 100.5 99.7 100.1 373.25 - 0.280098704
1.5 0.5 150 111.6 111.4 111.5 384.65 0.2280 0.200342862
2.0 1 200 120.3 120.5 120.4 393.55 0.1780 0.158338808
2.5 1.5 250 127.4 127.9 127.65 400.8 0.1450 0.13206812
3.0 2 300 133.6 134.1 133.85 407 0.1240 0.113967525
3.5 2.5 350 139 139.5 139.25 412.4 0.1080 0.010105093
4.0 3 400 143.8 144.3 144.05 417.2 0.0960 0.090429185
4.5 3.5 450 148.3 148.6 148.45 421.6 0.0880 0.082303765
5.0 4 500 152.3 152.5 152.4 425.55 0.0790 0.075668362
5.5 4.5 550 156.1 156.2 156.15 429.3 0.0750 0.070152854
6.0 5 600 159.4 159.5 159.45 432.6 0.0660 0.065456209
6.5 5.5 650 162.5 162.7 162.6 435.75 0.0630 0.061431197
7.0 6 700 165.5 165.7 165.6 438.75 0.0600 0.057935049
7.5 6.5 750 168.2 168.5 168.35 441.5 0.0550 0.054859016
8.0 7 800 170.9 170.9 170.9 444.05 0.0510 0.052125723
Temperature Avg (K) Pressure (Kpa) dT (K) dP (Kpa) Measured Slope, dT/dP(Kpa)
373.25 100 - - -
384.65 150 11.4 50 0.2280
393.55 200 8.9 50 0.1780
400.8 250 7.25 50 0.1450
407 300 6.2 50 0.1240
412.4 350 5.4 50 0.1080
417.2 400 4.8 50 0.0960
421.6 450 4.4 50 0.0880
425.55 500 3.95 50 0.0790
429.3 550 3.75 50 0.0750
432.6 600 3.3 50 0.0660
435.75 650 3.15 50 0.0630
438.75 700 3 50 0.0600
441.5 750 2.75 50 0.0550
444.05 800 2.55 50 0.0510

Temperature
Pressure (Kpa) Vg hfg Calculated Slope (Tvg/hfg)
(K)
100.0 373.25 1.6941 2257.5 0.280098704
150.0 384.65 1.1594 2226 0.200342862
200.0 393.55 0.88578 2201.6 0.158338808
250.0 400.8 0.71873 2181.2 0.13206812
300.0 407 0.60582 2163.5 0.113967525
350.0 41.4 0.52422 2147.7 0.010105093
400.0 417.2 0.46242 2133.4 0.090429185
450.0 421.6 0.41392 2120.3 0.082303765
500.0 425.55 0.37483 2108 0.075668362
550.0 429.3 0.34261 2096.6 0.070152854
600.0 432.6 0.3156 2085.8 0.065456209
650.0 435.75 0.2926 2075.5 0.061431197
700.0 438.75 0.27278 2065.8 0.057935049
750.0 441.5 0.25552 2056.4 0.054859016
800.0 444.05 0.24035 2047.5 0.052125723
6.1 Graphs:

dT Tv fg
Graph of [ dP ] and versus Pressure (P):
SAT h fg

Figure 2

Figure 3
- Slope of the graph:
T 2−T 1
slope=
P2−P1
Points 2 = (7.5, 441.5)

441.5−393.55
Points 1 = (2.0, 393.55) slope=
7.5−2.0

47.95
slope=
5.5

slope=8.72 ° C /kPa

7.0Discussion:

Marcet boiler was made by Nathan Chamberlain, Boston, USA, in the year1850. He
made this boiler for measuring the vapor pressure of saturated liquid. Later this Marcet
boiler was used to study the evaporation filtration of water.
Pressure and temperature are two fundamental quantities of materials in thermodynamics.
These two factors have relation directly proportional to each other.
When a container contains saturated liquid and is heated to its boiling temperature, the
liquid will be changing its state from liquid to steam. If the steam is not allowed to escape
from the container, its internal pressure will increase. Because, when the liquid becomes
gas by heating, the internal molecular energy will increase and the atoms will be more
excited. All the excited atoms will hit each other and split with more speed or velocities.
As their mass remains constant, so their forces on each other will increases. And
when their forces on them increases, and are not allowed to occupy more area, they exert
pressure on the container, which gradually increases with temperature. Hence it is
calculated and proved from the graph, that temperature is directly proportional to the
pressure.
The error percentage should not cross or exceed 10%, as the experiment was done in
enclosed surface and no volume of experimenting samples are allowed to escape from the
system. That is done in closed system. It is important to remove gas at the beginning to
avoid the flaws of reading due to pressure difference.
Marcet boiler is being used as

8.0Conclusion:
In this experiment, the relationship between pressure and temperature is found to be
directly proportional. When compared to the theoretical slope, the experimental slope
shows a small deviation between them because of certain errors.
Do not considering some negligible faults, this experiment can be considered successful,
to improve the result of the experiment, it should be carried out at room temperature
switching off all the air-conditions, and also by repeating the experiment and taking the
average value. If some insulation were kept on the Marcet boiler to reduce heat loss, the
experiment could be more accurate.

9.0References:
- https://www.coursehero.com/file/18913265/EXPERIMENT-2-MARCET-BOILER/
- http://www.studymode.com/essays/Boiler-Experiment-1059371.html

10.0