Study of Steam Condensation on a Single Vertical Tube

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ChE 304

Chemical engineering laboratory - III

Experiment No. 2 Group No. 03 (A2)

Name of the experiment:

Study of steam condensation on a single

vertical tube

Submitted by:

Md. Hasib Al Mahbub

Student Id: 0902045

Level: 3; Term: 2

Section: A2

Date of performance: 11/03/2014

Date of submission: 18/03/2014

Partners’ Student Id. 0902041

0902042

0902043

0902044

Department of Chemical Engineering.

Bangladesh University of engineering and technology, Dhaka.



1

Summary

The objective was to demonstrate the phenomenon of film type condensation on a vertical tube,

to obtain condensation coefficient value with those of the literature values, to determine the

effect of velocity of water on the overall heat transfer coefficient, to observe the variation ofheat load and mass flow with temperature and finally to estimate the heat loss to the

surrounding. To carry out the experiment, water was flown through the inner pipe while the

steam was supplied to the annulus. After the steady state had reached, the temperature was

recorded. The same procedure was done for different flow rates of water at different steam

pressure of 5, 10 and 15 psig. The water flow rate and steam pressure was controlled by valve.

Then by measuring flow rates of water and condensate and by mathematical manipulation the

condensation coefficient was calculated. In this experiment, the condensation coefficient were

found out to be varied from 4713.383 W/m2.oC to 5246.116 W/m2.oC. Graphs of overall heat

transfer coefficient vs. velocity of water, film thickness vs. distance from top, local heat transfer

coefficient vs. distance from top, heat load vs. wall temperature and mass flow rate vs. wall

temperature has been plot. Possible discrepancies are discussed at the end of the report.



2

Experimental Setup

Cold water

inlet

Condensate

produced at

glass tube

Cold water outlet

Glass tubecondensing surface

Saturated

steam

Condensate

Steam trap

Steam trap

Condensate

Saturated

steam

Separated

condensate

Figure 1: Experimental setup for the vertical tube condensation

Gauge

Pressure

Thermometer



3

Observed data

Table 1: Observed data for the condensation on a single vertical tube

SteamPressure

P

(psig)

No of

Obs.

Water

Temperature Water Condensate

Inlet

T1

(°C)

Outlet

T2

(°C)

Volume

V

(L)

Time

(s)

Weight

(kg)

Time

(s)

5

1 29 48 1 54 0.0269 30

2 29 41 1 17 0.045 30

3 29 37 1 10.25 0.0593 30

4 29 35 1 6.35 0.0678 30

10

5 29 84 1 44.06 0.0724 30

6 29 51 1 8.65 0.1109 30

7 29 48 1 7.25 0.1429 30

8 29 45 1 6.31 0.1714 30

15

9 29 91 1 77.1 0.0571 30

10 29 53 1 10.06 0.1382 30

11 29 51 1 9.15 0.144 30

12 29 47 1 6.22 0.155 30



4

Calculated data

Length of vertical tube = 1.6256 m

Table 2: Properties of water at mean temperature

Steam

pressur

e

(psig)

Mean

temperature

of water,

Tm (°C)

Density of

Water

ρ

(kg/m3)

Weight of

Water

(kg)

Mass flow

rate of water,

Mw (kg/sec)

Velocity,

v

(m/s)

5

38.5 970.429 0.970429 0.017970907 0.139518116

35 971.257 0.971257 0.057132765 0.443175191

33 971.726 0.971726 0.094802537 0.735022267

32 971.959 0.971959 0.153064409 1.186453266

10

56.5 963.157 0.963157 0.021860123 0.170993605

40 967.318 0.967318 0.111828671 0.870980144

38.5 967.687 0.967687 0.133474069 1.039169413

37 968.055 0.968055 0.153416006 1.193974365

15

60 959.726 0.959726 0.012447808 0.097716968

41 964.668 0.964668 0.095891451 0.748904398

40 964.919 0.964919 0.105455628 0.8233856

38 965.426 0.965426 0.155213183 1.211250521



5

Table 3: Calculation for condensate flow rate and saturation, wall and film temperature

Stea

m

press

ure

(psig)

Observ

ation

No

Mass flow

rate of

condensat

e, Mc

(kg/sec)

Saturation

temperatur

e of steamTs (°C)

Heat of

vaporizatio

nλ s (J/Kg)

Wall

temperature

,

Tw (°C)

Film

temperatur

e,Tf (°C)

5

10.0008966 108.392

2234.06

73.446 82.1825

20.0015 108.392 71.696 80.87

30.0019766 108.392 70.696 80.12

40.00226 108.392 70.196 79.745

10

60.0024133 115.199

2215.48

85.8495 93.186875

70.0036966 115.199 77.5995 86.999375

80.0047633 115.199 76.8495 86.436875

90.0057133 115.199 76.0995 85.874375

15

110.0019033 120.955

2199.47

90.4775 98.096875

120.0046066 120.955 80.9775 90.971875

130.0048 120.955 80.4775 90.596875

140.0051666 120.955 79.4775 89.846875



6

Table 4: Properties of condensate at film temperature

Stea

m

press

ure

(psig)

Observ

ation

No

Density

(kg/m3)

Viscosity

(kg/m.s)

Thermal

conductivity

(W.m-1.K -1)

Reynolds’

NoPrandtl No.

5

1992.784 0.0003368 0.67145 213.527744 2.04031227

2994.035 0.00034229 0.6706 351.473362 2.07640280

3994.706 0.00034547 0.6701 458.900433 2.09782417

4995.03 0.00034707 0.6699 522.259961 2.10832461

10

6984.965 0.0002961 0.6777 653.693660 1.77638154

7992.22 0.00031795 0.6744 932.495685 1.91755343

8992.784 0.00032005 0.6741 1193.68163 1.93121996

9993.332 0.00032222 0.6737 1422.10753 1.94561190

15

11983.202 0.00028048 0.68 544.262389 1.67702291

12991.833 0.00030365 0.6766 1216.77106 1.82468248

13992.218 0.00030494 0.6764 1262.47332 1.83365236

14992.968 0.00030758 0.676 1347.24853 1.8508035



7

Table 5: Calculated data for heat flow rates and overall heat transfer co-efficient

SteamPress

ure

(psig)

Rate of

heat

taken

by

water,

Qw

(kJ/s)

Rate of

heat

given

up by

steam,

Qc

(KJ/s)

Mean

rate ofheat

flow,

Qm

(KJ/s)

Heat

Loss

(KJ/s)

Perce

nt loss

of

heat,

%

Steam

Side

Heat

transfer

co-

efficient

ho

(W/m2.°

C)

LMTD

∆Tm

(°C)

Overall

heat

transfer

co-

efficient

U

(W/m2.

°C)

5

1.38887 2.003207 1.696038 0.6143363 30.667 4858.601 69.4594 301.17890

2.78899 3.35109 3.070041 0.5620969 16.773 4778.716 73.2282 517.11344

3.08608 4.415991 3.751039 1.3299039 30.115 4734.691 75.3212 614.26303

3.73728 5.04897 4.393128 1.3116937 25.979 4713.383 76.3527 709.69117

10

4.88821 5.346691 5.117455 0.4584732 8.5748 5246.116 54.1193 1166.3301

10.0064 8.189891 9.098193 -1.816605 -22.181 4844.134 74.6595 1503.1065

10.3154 10.55306 10.43426 0.2376063 2.2515 4812.109 76.3051 1686.6617

9.98529 12.65777 11.32153 2.6724801 21.113 4779.972 77.9254 1792.0334

15

3.13783 4.124567 3.662081 1.0484860 25.045 5266.893 55.2780 817.13809

9.35701 10.13222 9.744618 0.7752140 7.6509 4827.728 79.3510 1514.7197

9.43623 10.55745 9.996844 1.1212230 10.620 4807.519 80.4543 1532.6168

11.3644 11.36392 11.36421 -0.000563 -0.0049 4767.676 82.6284 1696.4043



8

Table 6: Calculated data for average thickness of the condensate film & average local

heat transfer co-efficient for z1=0.5m

Steam

Pressure

(psig)

Distance

from the

top of the

tube,

z1 (m)

Thickness of

thecondensate

film,

yf

(m)

Average,

yf

(m)

Local heat

transfer co-

efficient,

hlocal

(W/m2.°C)

Average

hlocal

(W/m2.°C)

5

0.5

0.000164469

0.000167264

4082.523709

4009.2080.000167007 4015.399184

0.000168434 3978.406366

0.000169145 3960.5025

10

0.000153738

0.000163468

4408.140683

4134.6050.000165685 4070.367727

0.000166714 4043.458192

0.000167735 4016.455049

15

0.000153652

0.000164157

4425.59854

4131.9760.000166791 4056.582439

0.000167442 4039.601215

0.000168742 4006.122691



9



Steam

Pressure

(psig)

Distance

from the

top of the

tube,

Z2(m)

Thickness of

thecondensate

film,

yf

(m)

Average,

yf

(m)

Local heat

transfer co-

efficient,

hlocal

(W/m2.°C)

Average

hlocal

(W/m2.°C)

5

1.0

0.000195588

0.000198912

3432.979552

3371.3290.000198606 3376.53478

0.000200303 3345.427652

0.000201149 3330.372355

10

0.000182827

0.000194397

3706.789698

3476.7750.000197034 3422.757631

0.000198257 3400.129499

0.000199472 3377.422653

15

0.000182723

0.000195216

3721.469947

3474.5640.000198349 3411.165632

0.000199124 3396.886181

0.000200669 3368.73421



10



Steam

Pressure

(psig)

Distance

from the

top of the

tube,

Z3(m)

Thickness of

the

condensate

film,

yf

(m)

Average,

yf

(m)

Local heat

transfer co-

efficient,

hlocal

(W/m2.°C)

Average

hlocal

(W/m2.°C)

5

1.5

0.000216454

0.000220132

3102.047202

3046.3390.000219794 3051.043592

0.000221672 3022.935129

0.000222608 3009.331133

10

0.000202331

0.000215136

3349.462598

3141.6210.000218054 3092.810653

0.000219408 3072.363828

0.000220752 3051.845876

15

0.000202217

0.000216042

3362.727701

3139.6230.000219509 3082.336099

0.000220366 3069.433159

0.000222077 3043.994982



11

Graphs

1. U as a function of velocity of water at different pressures:

a. For 5 psig steam pressure

Figure 2: Overall Heat Transfer Coefficient vs Velocity of Water for 5 psig steam pressure

280

330

380

430

480

530

580

630

680

0.1 0.3 0.5 0.7 0.9 1.1 1.3

O v e r a l l H e a t T r

a n s f e r C o e f f i c i e n t U ( W / m 2 .

° C

)

Velocity of Water (m/sec)

Overall Heat Transfer Coefficient vs Velocity of Water for 5 psig

steam pressure



12

b. For 10 psig steam pressure


1000

1100

1200

1300

1400

1500

1600

1700

1800

0 0.2 0.4 0.6 0.8 1 1.2 1.4

O v e r a l l H e a t T r a n s f e r C o e f f i c i e n t U ( W / m 2 .

° C )

Velocity of Water (m/sec)


steam pressure



13

c. For 15 psig steam pressure


600

800

1000

1200

1400

1600

1800

0 0.2 0.4 0.6 0.8 1 1.2 1.4

O v e r a l l H e a t T r a n s f e r C o

e f f i c i e n t U ( W / m 2 .

° C )

Velocity of water (m/sec)


steam pressure



14

2. Film Thickness as a function of distance from top at different pressures:


Figure 5: Film Thickness vs Distance from Top for 5 psig steam Pressure



0.00015

0.00016

0.00017

0.00018

0.00019

0.0002

0.00021

0.00022

0.00023

0.4 0.6 0.8 1 1.2 1.4 1.6

F i l m T h i c k n e s s , ( m )

Distance from top (m)

Film Thickness vs Distance from Top for 5 psig steam Pressure

0.00015

0.00016

0.00017

0.00018

0.00019

0.0002

0.00021

0.00022

0.00023

0.4 0.6 0.8 1 1.2 1.4 1.6

F i l m T h i c k n e s

s ( m )

Distance from Top (m)

Film Thickness vs Distance from Top for 10 psig steam

Pressure



15



3. Local heat transfer coefficient as a function of distance from top at different

pressures


Figure 8: Local heat transfer coefficient vs distance from top for 5 psig steam pressure

2500

2700

2900

3100

3300

3500

3700

3900

4100

0.4 0.6 0.8 1 1.2 1.4 1.6

L o c a l h e a t t r a n s f e

r c o e f f i c i e n t

( W / m 2 . 0

C )


Local heat transfer coefficient vs distace from top for 5 psig

steam pressure

0.00015

0.00016

0.00017

0.00018

0.00019

0.0002

0.00021

0.00022

0.00023

0.4 0.6 0.8 1 1.2 1.4 1.6

F i l m T h i c k n e s s ( m )


Film Thickness vs Distance from Top for 15 psig steam Pressure



16





2500

2700

2900

3100

3300

3500

3700

3900

4100

4300

0.4 0.6 0.8 1 1.2 1.4 1.6 L o c a l h e a t t r a n s f e r c o e f f i c i e n t ( W / m 2 . 0 C )



steam pressure

2500

2700

2900

3100

3300

3500

3700

3900

4100

4300

0.4 0.6 0.8 1 1.2 1.4 1.6

L o c a l h e a t t r a n s f e r c o e f f i c i e n t ( W / m 2 . 0

C )



steam pressure



17

4. Heat load of water as a function of wall temperature at different pressure:


Figure 11: Heat load of water vs wall temperature at 5 psig steam pressure



0

0.5

1

1.5

2

2.5

3

3.5

4

70 70.5 71 71.5 72 72.5 73 73.5 74

H e a t

l o a d o f w a t e r , Q w ( k W )

Wall Temperature (oC)

Heat load of water vs wall temperature at 5 psig steam

pressure

4

5

6

7

8

9

10

11

75.4 77.4 79.4 81.4 83.4 85.4

H e a t l o a d o f w a t e r , Q w ( k W )



pressure



18



5. Mass flow rate of water as a function of wall temperature at different pressure


Figure 14: Mass Flow rate of water vs wall temperature at 5 psig steam pressure

3

4

5

6

7

8

9

10

11

12

78 80 82 84 86 88 90

H e a t l o a d o f w a t e r , Q w ( k W )



pressure

0.01

0.03

0.05

0.07

0.09

0.11

0.13

0.15

0.17

70 70.5 71 71.5 72 72.5 73 73.5 74 M a s s F l o w R a t e o f W a

t e r ( k g / s e c )


Mass Flow rate of water vs wall temperature at 5 psig steam

pressure



19





0.02

0.04

0.06

0.08

0.1

0.12

0.14

0.16

75.4 77.4 79.4 81.4 83.4 85.4 M a s s F l o w R a t e o f W a t e r ( k g / s e c )


Mass Flow rate of water vs wall temperature at 10 psig

steam pressure

0.012

0.032

0.052

0.072

0.092

0.112

0.132

0.152

78.8 80.8 82.8 84.8 86.8 88.8 90.8

M a s s F l o w R a t e o f W a t e r ( k g / s e c )


Mass Flow rate of water vs wall temperature at 15 psig steam pressure



20

Sample calculation

For observation no. 5, at 10 psig steam pressure:

Volume of water collected, V= 1.0x10-3 m3

Time, tw= 44.06 sec

Inlet water temperature, T1 =29°C

Outlet water temperature, T2 = 84°C

Weight of condensate collected, Wc = 0.0724 kg

Condensate collection time tc= 30 sec

Mean Temperature, Tm=2

T+T21

=56.5°C

Density at 56.5°C, ρ = 963.157 kg/m3 [From J. P. Holman, Heat Transfer, McGraw - Hill,

10th Ed, 1997, Page-605, Table A-5]

Mass of water=0.9632 kg

Mass flow rate, Mw =wt

water of Mass

= (0.9632/44.06)kg/s

= 0.02186 kg/s

Mass flow rate of condensate, Mc =

ct

Wc

= (0.0724/30) kg/s

= 0.002413 kg/s

*Saturation temperature of steam at 10 psig pressure, Ts = 115.199°C

*Heat of vaporization at 10 psig pressure, λ s = 2215.48 kJ/Kg



21

*At mean temperature heat capacity of water, C p = 4.0657 KJ/Kg°C

*[From J M Smith, H C Van Ness, M M Abbott, Chemical Engineering Thermodynamics,

McGraw - Hill, 7th Ed, 2001, Page-715, Table F1]

Tube wall temperature on steam side, Tw =2

)/T+(T ms

= (115.199+56.5)/2 °C

= 85.8495 °C

Film temperature, Tf = Ts - 0.75×(Ts-Tw)

= 115.199 – 0.75×(115.199-85.8495) °C

= 93.187 °C

Rate of heat taken by water, Qw = Mw×C p×(T2 – T1)

= 0.02186 ×4.0647×(84-29) KJ/s

= 4.888 KJ/s

Rate of heat given up by steam, Qc = Mc × λ s

= 0.002413 ×2215.48 KJ/s

= 5.3466 KJ/s

Mean rate of heat flow, Qm =2

Qc)+(Qw

= (4.888 +5.3466)/2 KJ/s

= 5.1175 KJ/s

Heat loss=(Qc-Qw)=( 5.3466-4.888 ) KJ/s=0.4585 KJ/s

Percent heat loss = 100Qw)-(Qc

Qc%

= [(5.3466-4.888)/5.34664]x100%

= 8.575%



22

Properties of condensate at Tf = 93.187 °C

Density, ρf = 984.965 kg/m3

Viscosity, μf = 0.0002961 kg/m-s

Thermal conductivity, k f = 0.6777 W/m°C

[From J. P. Holman, Heat Transfer, McGraw - Hill, 10th Ed, 1997, Page-605, Table A-5]

Now, Outside diameter of the inner pipe, Do = 0.625 inch=0.0159 m

Inner diameter of the inner pipe, Di =0.5 inch=0.0127m

[From THE COPPER TUBE HANDBOOK, Copper Development Association Inc., Copper

Alliance, Page-21]

Length of the inner pipe, L = 1.6256 m.

Area of condenser, Ac = πDoL

= 0.081073 m2

Reynolds number, Re =f

×Do×

Mc×4

= (4×0.002413)/ (3.1416×0.0159×0.0002961)

= 653.6937

From Nusselt equation, steam side heat transfer co-efficient,

ho = 1.13× f ws

s

2

f

3

f

×)T-(T×L

×g××k

1/4

= 1.13× [(0.67773×984.9652×9.81×2215.48)

/ (1.6256× (115.199-85.8495) × 0.0002961)] 1/4

= 5246.11963 W/m²°C

[From J. P. Holman, Heat Transfer, McGraw - Hill, 10th Ed, 1997, Page-486, Eqn (9.18)]



23

LMTD =)}]T-(T-)T-[ln{(T

)]T-(T-)T-[(T

2s1s

2s1s

= [(115.199-29)-(115.199-84)]/[ln{(115.199-29)- (115.199-84)}]

= 54.1193 °C

Mean Rate of heat flow, Qm =2

)( QcQw

= 5.1175 KJ/s

= 5.1175 J/s

Overall heat transfer co-efficient, U= LMTD Ac

Qm

= 5.1175/ (0.081073 × 54.1193) W/m2. °C

= 1166.330 W/m2. °C

For distance from top of copper tube, z1=0.5m

Thickness of the condensate film, yf = [

g.hg.

Tw).z-(Tsk .4.2

f

1f f

f

] 1/4

= [{4x 0.0002961 x 0.6777 x (115.199-85.8495) x0.5}/ (9.81x 963.1572x2215480)] 1/4

= 0.0001537 m

[From J. P. Holman, Heat Transfer, McGraw - Hill, 10th Ed, 1997, Page-484, eqn (9.6)]

Local heat transfer co-efficient, hlocal = [1

32

)(4 z TwTs

k h g

f

f fg f

] 1/4

= [(9.81x963.1572x2215480x0.67773)/ {4x0.0002961 x (115.199-85.8495) x0.5}] 1/4

= 4408.1407 W/m2. °C




24



g.hg.

Tw).z-(Tsk .4.2

f

2f f

f

] 1/4

= [{4x 0.0002961 x 0.6777 x (115.199-85.8495) x1}/ (9.81x 963.1572x2215480)] 1/4

= 0.001828 m



32

)(4 z TwTs

k h g

f

f fg f

] 1/4

= [(9.81x963.1572x2215480x0.67773)/ {4x0.0002961 x (115.199-85.8495) x1}] 1/4

= 3706.7897 W/m2. °C




g.hg.

Tw).z-(Tsk .4.2

f

3f f

f

] 1/4

= [{4x 0.0002961 x 0.6777 x (115.199-85.8495) x1.5}/ (9.81x 963.1572x2215480)] 1/4

= 0.0002023 m



32

)(4 z TwTs

k h g

f

f fg f

] 1/4

= [(9.81x963.1572x2215480x0.67773)/ {4x0.0002961 x (115.199-85.8495) x1.5}] 1/4

= 3349.4626 W/m2. °C




25

Results and discussions

From the calculated data, the experiment come to end with some findings and observations.

They are cited below:

(a) Overall heat transfer coefficients = 301.1789-1793.033 W/m2.°C

(b) Steam side heat transfer coefficient = 4713.383-5266.893 W/m2.°C.

Moreover, in this experiment we got that the Reynolds no varied from 213.527 to 1422.107.

The prandtl no range was between 1.677 and 2.108.

5 types of graphs for each 3 different steam pressures were plotted. From 1st type of plot, overall

heat transfer coefficient vs velocity of water it was seen that overall heat transfer coefficient

increased with increasing velocity.

From 2nd type of plot, film thickness vs distance from top it was seen that film thickness

increased with distance from the top of the vertical tube and from 3 rd type of plot, local heat

transfer coefficient vs distance from top, local heat transfer coefficient decreased for increasing

distance from top. Because film thickness is higher from top to bottom, and as a result heat

transfer coefficient decreased.

From 4th type of plot, heat load of water vs wall temperature it was seen that heat load decreased

in increasing order of wall temperature for 5 and 15 psig steam pressure and in 15 psig steam

pressure one data showed deviation.

For 5th type of plot, mass flow rate of water vs wall temperature. Mass flow rate of water

decreased with increasing wall temperature.

The provable reasons behind these deviations are discussed below:

One of the elementary need in this experiment was to set the steam pressure at constant. But it

was very difficult to set the steam pressure at constant as the pressure gauge oscillated all over

the experiment.

In the experiment the water flow rate was so not high enough. So it was difficult to take 5

different flow rates. More over the water flow situation was not steady. So the outlet

temperature which was taken might not be the correct one.

Also, there were heat losses due to conduction & radiation to the atmosphere and it affectedheat transfer calculation.



So from the above discussion we can say that our experiment was good enough to study the

vertical tube condensation and we could achieve a good result if a wide range of variation for

the steam and for the water flow were used.

Documents

Study of Steam Condensation on a Single Vertical Tube