Koya University

Faculty of Engineering,

School of chemical& Petroleum Engineering

Chemical Engineering Department

2nd Stage

EXP.NO.4

Aim of the experiment……3

introduction………………….4

theory…………………………...5

procedure………………………6

tools……………………………….7

calculation paper……………8

reading paper ……………… 9

Discussion ………………… 10

references ………………………12

The main aim of this experiment is to obtain a slope of saturated temperature and

pressure of steam, in equilibrium with water, between 0 and 14 bars. These results are

then compared to the theoretical values obtained from published steam tables. A value

for the constants as well as the maximum temperature if heating were continued is

calculated. Moreover, after an expression for the time taken for the temperature to reach

a certain value is derived{1}

Thermodynamics study about the interchange of heat and work

between a system and the surroundings which occurs when the system

undergoes a process. Thermodynamic also concerned about

the changes in the properties of fluid. Most thermodynamics substances

such as gases and vapours are often referred as P-V-T substances .An

ideal gas obeys the equation of state that relates the pressure, specific

volume or density, and absolute temperature with mass of molecule

and the gas constant, R.However, real gas does not absolutely obey the

equation of state. A few modifications on the ideal gas equation of state

allow its application in the properties of real gas. When energy is added

within water, the increasing of activities among the molecules caused

the increase in the number of molecule escape from the surface until

an equilibrium state is reached. The state of equilibrium depends on the

pressure between the water surface and steam. The lower the pressure,

the easier the molecules leaving the water surface and thus less energy

is required to achieve the state of equilibrium (boiling point). The

temperature where equilibrium occurs at a given pressure level is

called saturated temperature. The pressure where equilibrium occurs at

a given temperature is called saturated pressure . Marcet Boiler is used

to investigate the relationship between the pressure and temperature of

saturated steam in equilibrium with water at all temperature

levels between the atmospheric pressure and 10 bars. The measured

value of the slope of the graph (dT/dP)obtained from the experiment

results can be compared to the theoretical value determined through

calculation from the steam table . Clausius-Clapeyron states.{2}

An ideal gas obeys the equation of state that the pressure, specific volume or

density, and absolute temperature with mass of molecule and the gas constant,

R.

PV = mRTM

Where, P = Absolute pressure

V = Volume

n = Amount of substance (moles)

R = Ideal gas constant

T = Absolute temperature (K)

However, real gas does not absolutely obey the equation of state. A few

changes on the ideal gas equation of state allow its application in the properties

of real gas.

When energy increases within water, the increasing of activities among the

molecules enables the increase in the number of molecule escape from the

surface until an equilibrium state is reached. The state of equilibrium depends

on the pressure between the water surface and steam. At lower pressure, the

molecules become easier leaving the water surface while less energy required

in achieving the state of equilibrium (boiling point). The temperature where

equilibrium occurs at a given pressure level is called saturated temperature.

The Marcet Boiler is used to investigate the relationship between the pressure

and temperature of saturated steam in equilibrium with water at all temperature

levels between the atmospheric pressure and 8 bars. The experimental slope

(dT/dP)SAT obtained is compared to the theoretical value determined through

calculation from the steam table.{3}

1/Prepare the benchtop unit as described in section 2.2.

2/Switch on the unit at the master switch.

3/Switch on the heater at the heater switch and heat up the boiler.

4/Log the boiler pressure and temperature values in increments of

approximately 0.5 bar.

5/Enter the measured values in the diagram.

6/Compare your own measurements with the values from the literature.

1 safety valve,

2 boiler with insulating jacket,

3 Bourdon tube pressure gauge,

4 switch cabinet with temperature display,

5 drain valve,

6 heater,

7 overflow,

8 temperature sensor

{4}

NO. Temperature (K)

Pressure (kpa)

Specific volume (Vg) m3 /kg

Latent heat of evaporation

(Hfg ) Kj/kg

1 373 131.3

2 378 151.3

3 383 181.3

4 388 211.3

5 393 251.3

0

50

100

150

200

250

300

370 375 380 385 390 395

Pre

ssu

re(k

pa

)

Temperature(k)

Graph of temperaure & pressure

It is necessary to remove air form the boiler as this could affect the

accuracy of the experimental results. Based on the graphs, the

relationship between pressure and temperature is directly

proportional while there is a small deviation between the

experimental slope and the theoretical slope. The percentage of

error ranged form 0.3%to 44%. Sources of errors are measurements

or reading accuracy, room temperature and pressure, the stability of

materials and calculations. When the liquid absorbed enough heat

energy, it will change to vapour form. As the steam is not

allowed to exit, it will cause an increase in pressure and thus

causing the temperature to increase. Applications of Marcet Boiler

include water boiler, gasified, power plant and cooking utilities. 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. The

percentage of error ranged form 0.3% to 44% which can validate

this experiment.

We use D.W for some reasons ,first one is to prevent the container

in getting corrosion that the impurity makes it ,second one is that

impurity increases the boiling point of the water ,so we will get

error in our calculations .

{5}

.http://www.academia.edu/4916263/Marcet_Boiler_Lab_Report_Shahda_Mazin_Abdulj

abbar_Al-Taie_H00113228_Mechanical_Engineering_-

_2nd_year_Supervised_by_Dr._Mehdi_Nazarinia

http://www.slashdocs.com/pwxyx/marcet-boiler-lab-report.html

http://www.studymode.com/essays/Boiler-Experiment-1059371.html

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y=3436&lang=1&dir=06020400&src=Zeichnung.jpg&color=FF6633&software=0

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