Observed Data

8/12/2019 Observed Data

1/19

3

OBSERVED DATA

Shell: Nominal size 6

Schedule no = 40

Tubes:Number of tubes = 19

OD = 0.5 inch

BWG = 16

Length = 96 inch

Pump: Centrifugal pump, 1.5kW; 240V; 50Hz; 2900rpm; Hmax=38m; Qmax=250l/h

Weight of the empty bucket W1= 1.5 kg

Table 01: Observed data for Study of shell and tube heat exchanger

No

of

Obs

Steam

Pressure

(psig)

Flow

meter

reading

(L)

Water

Temperature

(C)

Weight of

condensat

e

+

bucket

(kg)

TimeManometer

Reading

Inlet

(T1)

Outlet

(T2)

Water

(sec)

Condensate

(min)

Left

(inch)

Right

(inch)

1

2.5

10 24.5 32 2.45 11.1 2 33 36

2 10 24.5 31 2.7 8.79 2 32 36.7

3 10 24.5 30.5 3 6.91 2 30.6 37.5

4 10 24.5 29.5 3.2 5.54 2 27.5 38.8

5

5

10 27 34.5 3.1 10.09 2 32.6 36.4

6 10 27 33.5 3.65 8.6 2 31.5 37

7 10 27 32.5 3.75 7 2 30.1 37.5

8 10 27 31 3.9 5.72 2 27.4 38.8


2/19

4

CALCULATED DATA

Table 02: Calculated data for Mean, Saturation, Film and Wall temperature and Heat of

condensation and manometer reading in meter

No

of

Obs

Saturation

Temperature,

Ts (C)

Mean

Temperature,

Tm(C)

Film

Temperature,

Tf(C)

Wall

Temperature,

Tw(C)

Heat of

Condensation

hfg(kJ/kg)

Manometer

Reading

Left

(m)Right

(m)

1 104.44 28.25 75.86875 66.345 2244.6 0.8382 0.9144

2 104.44 27.75 75.68125 66.095 2244.6 0.8128 0.93218

3 104.44 27.5 75.5875 65.97 2244.6 0.77724 0.9525

4 104.44 27 75.4 65.72 2244.6 0.6985 0.98552

5 108.39 30.75 79.275 69.57 2234 0.82804 0.92456

6 108.39 30.25 79.0875 69.32 2234 0.8001 0.9398

7 108.39 29.75 78.9 69.07 2234 0.76454 0.9525

8 108.39 29 78.61875 68.695 2234 0.69596 0.98552


3/19

5

Table 03: Calculated data for properties of water at mean temperature and properties of

condensate at film temperature

No

of

Obs

Properties of water at mean temperatureProperties of condensate at film

temperature

Density

(kg/m3)

Viscosity

(kg/m.s)

Cp

(kJ/kg.C)

Thermal

conductivity

(W/m.C)

Density

(kg/m3)

Viscosity

(kg/m.s)

Thermal

conductivity

(W/m.C)

1 995.96 0.00083865 4.18056775 0.6165596 974.27875 0.00037466 0.6684263

2 996.12 0.00084655 4.18063425 0.6157496 974.39125 0.00037559 0.6682913

3 996.2 0.0008505 4.1806675 0.6153446 974.4475 0.00037606 0.6682238

4 996.36 0.0008584 4.180734 0.6145346 974.56 0.000377 0.6680888

5 995.16 0.00079915 4.18023525 0.6206096 972.235 0.00035763 0.6708788

6 995.32 0.00080705 4.18030175 0.6197996 972.3475 0.00035856 0.6707438

7 995.48 0.00081495 4.18036825 0.6189896 972.46 0.0003595 0.6706088

8 995.72 0.0008268 4.180468 0.6177746 972.62875 0.00036091 0.6704063


4/19

6

Table 04: Calculated data for water and condensate flow rate, Heat rate of water and steam

and mean heat rate

No of

Obs

Water

Flow

Rate, mw

(kg/s)

Condens

ate Flow

rate, mc

(kg/s)

Heat

absorbed

by water

Qw(kW)

Heat

released by

steam, Qc

(kW)

Heat loss

(kW)

Percent

heat loss

Mean Heat

Flow, Qm

(kW)

1 0.89726 0.00791 28.1329612 17.76975 -10.363 -58.31 22.9513556

2 1.13324 0.01 30.7948658 22.446 -8.3488 -37.19 26.6204329

3 1.44167 0.0125 36.1630764 28.0575 -8.1055 -28.88 32.1102882

4 1.79848 0.01416 37.5949109 31.7985 -5.7964 -18.22 34.6967055

5 0.98628 0.0133 30.9217263 29.7866667 -1.1350 -3.81 30.3541965

6 1.15734 0.01791 31.4474379 40.0258333 8.57839 21.43 35.7366356

7 1.42211 0.01875 32.6972877 41.8875 9.19021 21.94 37.2923939

8 1.7407 0.02 29.1089203 44.68 15.57 34.85 36.8944601


5/19

7

Table 05: Calculated data for tube and shell side heat transfer co-efficient

No

of

Obs

Tube side

Reynolds'

No

Tube Side

prandtl no.

Viscosity

of water at

wall

temperature

(kg/m.s)

Tube side

Nusselt NojH value

Tube side

heat

transfer

coefficient,

hi

(W/m2.C)

Shell side

heat transfer

coefficient,

ho

(W/m2.C)

1 7623.25572 5.68644644 0.00042666 67.57398 34.4410319 4433.21835 4730.50156

2 9538.33328 5.74765444 0.00042821 81.1978593 41.2042258 5320.02015 4719.37987

3 12078.0409 5.77831951 0.00042899 98.2895119 49.7692343 6435.61613 4713.85036

4 14928.6017 5.83977219 0.00043054 116.949833 58.9629319 7647.34185 4702.85325

5 8793.78339 5.38282843 0.00040667 74.3788083 38.6104066 4911.70488 4765.7861

6 10218.0062 5.44323121 0.00040822 84.252684 43.5368188 5556.47796 4754.58813

7 12433.8567 5.50379377 0.00040977 99.0236978 50.9387695 6522.09397 4743.47295

8 15001.7891 5.59493858 0.00041209 115.845814 59.194071 7615.08844 4726.953


6/19

8

Table 06: Calculated data for experimental and theoretical overall heat transfer coefficient

No of Obs

Mass velocity

of water

(kg/m2.s)

LMTD (C)

Outside

surface area

of 19 tubes

(m2)

OverallExperimental

heat transfer

coefficient,

UoE

(W/m2.C)

OverallTheoretical

heat transfer

coefficient,

UoT

(W/m2.C)

1 680.277018 76.1284364 1.84847321 163.0978635 1937.165799

2 859.190895 76.6440681 1.84847321 187.8985402 2146.361712

3 1093.03828 76.9009928 1.84847321 225.891088 2368.989501

4 1363.55732 77.41309 1.84847321 242.4714874 2568.412839

5 747.771014 77.5795876 1.84847321 211.6694175 2062.035309

6 877.467745 78.0949212 1.84847321 247.5584263 2204.945136

7 1078.2051 78.6079342 1.84847321 256.6496755 2392.27619

8 1319.79988 79.3732024 1.84847321 251.4630026 2570.629003


7/19

9

Table 07: Calculated data for tube side experimental and theoretical pressure drop

No

of

Obs

Experimental Pressure

Drop from

manometer

reading,

(Pa)

Friction

factor

(sq ft/sq

inch)

Specific

gravity,

s

t(/w)^0.14

Pressure

drop through

tubes Pt

(Pa)

Pressure

drop due to

velocity

head (Pa)

TotalTheoretical

Pressure

drop PT

(Pa)

1 10161.8141 0.0003 0.99596 1.09923283 2362.721233 937.945183 3300.66642

2 15920.1754 0.00027 0.99612 1.100118 3388.780082 1495.46379 4884.24387

3 23372.1724 0.00025 0.9962 1.10055656 5075.783231 2419.70643 7495.48967

4 38276.1663 0.00023 0.99636 1.10142577 7260.296222 3763.82565 11024.1219

5 12871.6312 0.00028 0.99516 1.09919479 2666.729295 1136.0307 3802.75999

6 18629.9925 0.00026 0.99532 1.10012354 3406.298481 1563.52805 4969.82653

7 25065.808 0.00024 0.99548 1.10104053 4742.740664 2359.59079 7102.33145

8 38614.8935 0.00023 0.99572 1.10239447 6800.188707 3532.93806 10333.1268


8/19

10

GRAPHS

1) jH factor vs Reynolds No

a) for 2.5 psig steam pressure:

Figure 02: jH Factor vs Reynolds' No for 2.5 psig Steam Pressure

y = 0.8001x +log0.00395

10

100

1000 10000 100000

jH

Factor

Reynolds' No

jH Factor vs Reynolds' No for 2.5 psig Steam Pressure


9/19

11

b) for 5 psig steam pressure

Figure 03: jH Factor vs Reynolds' No for 5 psig Steam Pressure

y = 0.8001x +log0.00395

10

100

1000 10000 100000

jHF

actor

Reynolds' No

jH Factor vs Reynolds' No for 5 psig Steam Pressure


10/19

12

2) Pressure drop vs velocity of water\

a) For 2.5 psig steam pressure

Figure 04: Pressure Drop vs Velocity of Water for 2.5 psig Steam Pressure

0

5000

10000

15000

20000

25000

30000

35000

40000

0.6 0.7 0.8 0.9 1 1.1 1.2 1.3 1.4

PressureDrop(Pa)

Velocity of Water (m/sec)

Pressure Drop vs Velocity of Water for 2.5 psig Steam

Pressure

Experimental

Theoretical


11/19

13

b) For 5 psig steam pressure:

Figure 05: Pressure Drop vs Velocity of Water for 5 psig Steam Pressure

0

5000

10000

15000

20000

25000

30000

35000

40000

0.7 0.8 0.9 1 1.1 1.2 1.3 1.4

PressureDrop(Pa)

Velocity of Water (m/sec)

Pressure Drop vs Velocity of Water for 5 psig Steam

Pressure

Experimental

Theoretical


12/19

14

SAMPLE CALCULATION

For observation no. 2 (2.5 psig steam pressure):

Water inlet temperature, T1 = 24.5oC

Water outlet temperature, T2 = 31o

C

Water mean temperature, Tm =2

TT21

=

2

315.24 = 27.75oC

Properties of water at mean temperature (27.75oC),

Density, = 996.12 kg/m3

Viscosity, = 0.00084655 kg/m.sec

Thermal conductivity, k = 0.6157496 W/m.oC

Specific Heat, Cp = 4.18063425 kJ/kg. C

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

Saturation temperature at 2.5 psig steam pressure, Ts= 104.44oC

Heat of Condensation at 2.5 psig steam pressure, hfg = 2244.6 kJ/kg

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

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

Weight of bucket and condensate = 2.7 kg

Weight of empty bucket = 1.5 kg

Weight of condensate = (2.7-1.5) kg

= 1.2 kg

Time of condensate taken = 2 minutes

Mass flow rate of condensate, mc=sec602

kg1.2

= 0.01 kg/sec

Heat released by condensation, Qc= mchfg

= (0.012244.6) kW

= 22.446 kW


13/19

15

Volume of water taken = 10L

Time of water taken = 8.79 sec

Mass flow rate of water, mw =

=sec79.8

/12.9961010 333 mkgm

= 1.133242321 kg/sec

Heat absorbed by water, Qw = mwCp(T2-T1)

= 1.1332423214.18063425(31-24.5)

= 30.79486579 kW

Heat loss = (QcQw)

= (22.446 - 30.79486579) kW

= -8.3489 kW

Percent heat loss = %100)(

C

WC

Q

QQ

= -37.195 %

Average heat transfer, Qavg =

2

QQ cw

=2

446.22930.7948657

= 26.6204 kW

Logarithmic Mean Temperature Difference,

LMTD =

2s

1s

2s1s

TT

TTln

)T(T)T(T

=

3144.104

5.2444.104ln

)3144.104()5.2444.104(

= 76.6441 C


14/19

16

For nominal size 6 & schedule 40 steel tube,

Inside diameter (ID) of the tube, Di= 0.37 inch = 0.009398 m

Outside diameter (OD) of tube, Do= 0.5 inch

[From Donald Q. Kern, Process Heat Transfer, McGraw - Hill, International Ed, 1997,

Page-843, Table 10]

Outsied area of 19 tube = nDoL

= 190.596 inch2

= 2865.14 inch2

= 1.84847 m2

Experimental overall heat transfer co-efficient,

UOE =LMTDA

Q

0

avg

=76.64411.84847

100026.6204

= 187.8985 W/m2. C

Flow area of tube, Ai =

=1

1076.019inch2

= 2.0444 inch2

= 0.001318965 m2

Velocity of water =

=996.1250.00131896

11.13324232

= 0.86254 m/sec

Mass velocity of water, =

=50.00131896

11.13324232= 859.191 kg/m2sec


15/19

17

Reynolds number, Re =

vDwi

=0.00084655

12.99686254.00.009398

= 9538.333

Wall temperature Tw =2

)]TT(0.5[Ts 21

= 66.095 oC

Prandtl Number, Pr = 5.74765

Viscosity of water at wall temperature = 0.000428211 kg/m.sec


Using Seider-Tate equation,

Nu=0.027 Re0.8 Pr1/3(/w)0.14

= 0.027(9538.333)0.8 (5.74765)1/3(0.00084655/0.000428211) 0.14

= 81.1978

jH factor calculation,

jH = Nu .Pr-1/3.

14.0

w

= 41.2042

Tube side heat transfer coefficient

hi = Nu iD

k

= 81.19780.009398

0.6157496

= 5320.0201 W/m2. C


16/19

18

Film temperature, Tf = Ts0.75(Ts-Tw)

= 75.68125 oC

Properties of condensate at film temperature (75.68125oC),

Density, f = 60.859 kg/m3

Viscosity, f = 0.907023 kg/m.sec

Thermal conductivity, kf= 0.386105 W/m.C


Density of steam, v 0

Saturation temperature, Tg=Ts = 104.44 C

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

ho = 0.725

25.0

wgf

3ffgvff

)Tnd(T

kgh)(

= 0.725

25.0

wgof

3ffg

2f

)T(TD

kgh

= 4719.3798 W/m2. C

Theoretical overall heat transfer co-efficient,

UOT =

-1

ii

o

0 hD

D

h

1

= 2146.362 W/m2. C

Pressure Drop Calculation:

For Reynolds no = 9538.333

The value of friction factor, f = 0.00027 sq ft/sq inch

[From Donald Q. Kern, Process Heat Transfer, McGraw - Hill, International Ed, 1997,

Page-836, Figure 26]

Mass velocity of water Gt= 633513.753 lb/hr.ft2

Length of the tube, L = 8 ft

No of tube passes, n = 1


17/19

19

Inner diameter of tube, D = 0.03083333 ft

Specific gravity, s = 0.99612

Pressure drop through tube,

Pt= 0.14w

10

2

)/(sD105.22

nLGtf

= 0.491500997 psi

= 3388.780082 Pa

Velocity of water, v = 2.82985 ft/s

Acceleration of gravity, g = 32.174 ft/s2

Velocity head,'2

2

g

v= 0.1244489 ft

Pressure drop due to velocity head, Pr=

s

n4

'2

2

g

v

144

5.62

= 0.21689868 psi

= 1495.464 Pa

Total pressure drop, PT= Pt+ Pr

= 4884.24387 Pa

Difference in manometer height, h = (0.93218- 0.8128) m Hg

= 0.11848 m Hg

Density of mercury, Hg = 13594 kg/m3

Experimental pressure drop = hHgg

= 0.11848 13594 9.81

= 15920.175 Pa


18/19

20

RESULTS AND DISCUSSIONS

Range of Overall Heat transfer co-efficient:

Experimental Values -------- 163.1 to 256.54 W/m2

. C

Theoretical Values -------- 1937.2 to 2570.6 W/m2. C.

Range of Pressure drop:

Experimental Values -------- 10161.8 to 38614.9 Pa

Theoretical Values -------- 3300.7 to 11024.12 Pa

Some of the heat loss found in this experiment were a negative value. But that was not

expected. The condensate was collected through a steam trap, in which the flow was not

continuous. As a result condensate flow rate was not steady for this experiment, hence

negative heat loss encountered in the experiment. The steam pressure was considered

constant during the experiment but it was not constant. Heat lost during the experiment due to

convection and conduction was not also considered.

Two types of graphs were drawn in the experiment. From the 1sttype of graph, jH factor vs

reynolds no the slope was found 0.8001 both for 2.5 and 5 psig steam pressure, which provesthe validity of Sieder-Tate equation.

From the 2ndtype of graph, pressure drop vs velocity of water the experimental pressure drop

was found somewhat greater than the theoretical pressure drop both for 2.5 and 5 psig steam

pressure. The theoretical values found in this experiment were not absolutely theoretical.

These values are found based on some parameters that are determined experimentally in one

way or another. Hence, they cannot be said to be purely theoretical. However, these

theoretical values can be of great importance when reasonable approximation and comparison

are required in real life consequence. One of the important things in shell and tube exchanger

operation is the pressure limitation that must be abided both in shell and tube sides. Beyond

this pressure limits the system can become unstable and materials of construction is affected

mainly due to corrosion and erosion.

Excess fouling might encounter in tube side which decrease the overall heat transfer co-

efficient.


19/19

21

After two consecutive reading we have to pause our experiment meanwhile heat exchanger

lost its current status & become cool .Thereby temperature exchange not happen linearly

which is great obstacle to perform this experiment.

Documents

Observed Data