chnical universityTafila te

Facultry of engineering

Title: lab report of mearcot boiler.

Student name: salam albaradie.

. Date of submission: 1/10/2013

Lecturer name : dr.ali alahmer.

Abstract

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

Introduction

Thermodynamics is a branch of physics, which deals with the energy, and work of a

system. Thermodynamics deals only with the large-scale response of a system that we

can observe and measure in experiments. Small-scale gas interactions are described by

the kinetic theory of gasses, which is a compliment to thermodynamics. The main

objective of this experiment is to determine the relation between vapor and pressure of

saturated steam and also the vapor pressure curve .

Experimental methods and materials

Before starting the experiment the boiler is first filled with enough water before closing

its valves. The temperature is the set to

185.0 °C which is slightly more than the boiling point of water at 10 bar (abs). The valve

at the feed port is opened and the heater is turned on. The temperature of steam is

recorded every time the absolute pressure increases by 0.5 bar. The gauge pressure is

also recorded with the time to reach an increase of 0.5 absolute pressure. The steps are

repeated until the absolute pressure reaches 10 bar. The gauge temperature and time

taken is constantly recorded at an interval of 0.5 absolute pressure. The final reading is

recorded when the gauge pressure reaches 10 bar. During this time the absolute

pressure, temperature and time taken is recorded all this data are then recorded into a

table

The apparatus used in this experiment is known as a marcet boiler. The unit consists of

a stainless steel pressure vessel fitted with high pressure immersion electrical heater.

The unit also comes together with a safety relief valve, temperature and pressure

measuring devices. Water feed port is installed to allow water charging. The unit comes

with comes with temperature and pressure transducers so that students will be able to

read the respective values on the digital indicators easily. The water heater is protected

from burnout by setting the maximum operating temperature with a temperature

controller

Data and Analysis

From the experiment we are able to record the absolute pressure, gauge pressure

temperature. Using this information we would be able to find the slope of dT/dP.

dT: difference of temperature at successive pressure differenced

dP: difference in pressure

Next a (dT/dP) vs p and (TVfg/h) vs P is plotted on the same graph and Temperature

(Kelvin) vs pressure (gauge + atmospheric)

resultsExperimental

Calculated

Slope

(Tvg/hfg)

Measured

Slope

(dT/dP)

Steam

Temp

(k)

Steam

Temp

(c`)

Abs

Pressure

(kpa)

Abs

Pressure

(bar)

Gauge

Pressure

(bar)

s/n

0.279

372.15

99

100

1

0

1

0.152

0.148

379.15

106

200

2

1

2

0.1125

0.1168

394.15

121

300

3

2

3

0.099

0.1035

401.15

128

350

3.5

2.5

4

0.0877

0.092

405.15

132

400

4

3

5

0.0811

411.15

138

450

4.5

3.5

6

atmospheric pressure 100 kpa

Graph of (T) vs (P)

350

360

370

380

390

400

410

420

100 200 300 350 400 450

Tem

p k

Pressure kpa

Column1

0

0.05

0.1

0.15

0.2

0.25

0.3

slo

pe

(Graph of (dT\dP) & (Tvg/hfg

(dT\dP)

(Tvg/hfg)

Sample calculation

Taking the values of fourth row,

hfg Calculation,

For the pressure 350 kpa (from the water-p table)

Vfg Calculation,

T.Vfg Calculation,

,Calculation ).v/hT(

,Calculation) P/d(dT

P vs T graph the romF

of error ercent P

*100%)Slope Measured )/calculated slope-Slope Measured((

*100%=0.0434

Conclusion

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. Sources of errors are measurements or reading accuracy, room

temperature and pressure, the stability of materials and calculations. The

percentage of error ranged from 0.019%-0.0434% which can validate this

experiment