presentation - ali farhan

الله بسمالرحيم الرحمن

In the name of God the merciful

AL-Mustansiriyah University College of Engineering Mechanical Engineering Department

Study and Evaluation of the Operation Characteristics for the Condensation Load Distribution in Hybrid Systems on the Condenser

Side By

Ali Farhan Muwayez

(B.Sc.2007)

Previous Studies:

Kutscher and Costenaro (2002): Developed a four pre-cooling methods for supplemental evaporative cooling to boost the summer performance of ACC. Spray nozzles, Munters media, Combination of nozzles and Munters, Direct deluge cooling. Wilber and Zammit (2005): Outlines the problems associated with the operation of ACC. They investigated the performance requirements for ITD and back pressure in the range of (14) to (33.3) °C and (2.5) to (7) Hga, respectively. and the ambient temperature of (-17.7) to (43.3) °C.

Gadhamshetty (2006): pre-cool the inflow air to the ACC by using a chilled water storage system on 171 MW plant. This proposed system saves (2.5 %) of the power without using any water.Tarrad (2010): Developed a numerical model for performance prediction of ACC. The improvement in condenser load was (23%) when the air pre-cooling mode applied to decrease the inflow air temperature from (45) to (28)°C.NR EL (2011): Studied the using of air and water hybrid system to assess how they mitigate the net power decrease in hot ambient.

Previous Studies:

Aims of Study:

1 .building an experimental rig to provide a proper operation conditions for the ACC and WCC.

2 .investigating the performance enhancement of ACC with pre-cooling of inflow air at hot ambient conditions (summer in Iraq).

3 .building a computer program (Theoretical Model) for each of the condenser used in the present work.

4 .Providing an assessment for the advantage of using the combined cooling system to improve the ACC performance

and mitigate the water scarcity effect.

Experimental Apparatus:

An experimental facility was constructed to allow two types of condensing system worked together as a test arrangement. Each one represents a separate unit having all of the specifications and instruments that allows condensation data to be collected over a range of operating conditions. The Apparatus elements are:

1 .Steam Generator.

2 .Condensers (Air Cooled Condenser, Water cooled condenser).

3 .Duct system with Heating unit.

4 .Water Feeding tank with water pump, valves and pipes.

5 .Expansion Valve ( Boiler to condenser line ).

6 .Emergency tank ( Cold and Hot water feeding).

7 .Measurement device: temperatures, pressure and water flow rate.

Photographic views of the experimental test facility.

Steam Generator

Cooler

Duct System Water feeding tank with accessories

Measurements

WCC

ACC

Water Loop

Schematic diagram of experimental set-up.

Steam Generator:

Duct System:

Coiled duct heater /2 pass: 10 kW - 220 V

Wings (by pass preventive)

Air inflow section with instruments

ACC

Experimental Results:Air:Without Pre-cooling:

Inlet DbTemp. : (20.7°C – 42°C)Inlet Wb Temp. : (14 °C-23.3°C)Boiler Pressure: (1.2 – 1.8) baraAir flow rate: (1200 – 2400) CFMWith Pre-cooling:

Inlet DbTemp.:(27°C-37°C)Inlet Wb Temp.: (24.5 °C-23°C)

Wb efficiency ≈ 67% Boiler Pressure;(1.2-1.8) baraAir flow rate : (1200- 2400) CFM

Water:Inlet Temperature: (15°C-23°C)Flow rate: (200 – 1000) L/hBoiler Pressure: fixed (1.8 bara)

Hybrid:Air Inlet DbTemp.: (31°C- 42°C)Air Inlet Wb Temp.: (21 °C-24°C)Air flow rate: fixed 1200 CFMWater inlet temperature; 30°C

Water flow rate: (20- 40)% of TFR.*Boiler pressure: fixed (1.8 bara).

Cooling Mode

Db :Dry-bulb

Wb :Wet-bulb

TFR: Total flow rate

Steam Load Variation:

15

17.5

20

22.5

25

27.5

30

32.5

35

37.5

19 22 25 28 31 34 37 40 43 46

Entering Air Dry-Bulb Temperature (°C)

Con

dens

er S

team

Loa

ding

(k

g/hr

)

Air Velocity (6 m/s)


Poly. (Air Velocity (6m/s))


15

17.5

20

22.5

25

27.5

30

32.5

35

37.5

19 22 25 28 31 34 37 40 43 46


Con

dens

er S

team

Loa

ding

(k

g/hr

)





15

17.5

20

22.5

25

27.5

30

32.5

35

37.5

19 22 25 28 31 34 37 40 43 46


Con

dens

er S

team

Loa

ding

(k

g/hr

)

Air velocity (6 m/s)

Air velocity (3 m/s)

Poly. (Air velocity (6m/s))

Poly. (Air velocity (3m/s))

15

17.5

20

22.5

25

27.5

30

32.5

35

19 22 25 28 31 34 37 40 43 46


Con

dens

er S

team

Loa

ding

(k

g/hr

)





20.7°C – 21%

31°C- 27.3%

42°C-23.5%

20.7°C – 19.4%

31°C- 27.8%

42°C-24.3%

20.7°C – 18%

31°C- 27%

42°C-20.3%

20.7°C – 20.9%

31°C- 24%

42°C-16.4%

B.Pr. : 1.8 bara B.Pr. : 1.6 bara

B.Pr. : 1.2 baraB.Pr. : 1.4 bara

Condenser Load Variation:

10

12

14

16

18

20

22

24

19 22 25 28 31 34 37 40 43 46


Con

dens

er L

oad

(kW

)



Poly. (Air Velocity (3m/s))Poly. (Air Velocity (6m/s))

10

12

14

16

18

20

22

24

19 22 25 28 31 34 37 40 43 46


Con

dens

er L

oad

(kW

)




10

12

14

16

18

20

22

24

19 22 25 28 31 34 37 40 43 46


Con

dens

er L

oad

(kW

)




10

12

14

16

18

20

22

19 22 25 28 31 34 37 40 43 46


Con

dens

er L

oad

(kW

)




20.7°C- 21.4%

31°C – 27.2%

42°C – 23.7%

20.7°C- 19.2%

31°C – 27%

42°C – 21%

20.7°C-21.4%

31°C – 24%

42°C – 16.8%

20.7°C- 19.2%

31°C – 27.9%

42°C – 24.6%

B.Pr.: 1.8 bara

B.Pr.: 1.2 baraB.Pr.: 1.4 bara

B.Pr.: 1.6 bara

Steam load variation with entering air temperature:

Experimental results for steam loading variation exhibited a non-linear variation with entering air dry-bulb temperature to the ACC. By using the group average method to fit an approximate straight line described the steam loading variation under recommended air velocity of (3 m/s) as:

naim KT

In the mathematical work that deal with the steam loading variation with air entering dry-bulb temperature. Tarrad (2010) found that the ACC steam loading varies linearly with entering air temperature with constants (K = 759.12 , n = -0.4644 ).

K - range (163.79 – 97.82) , n - range (- 0.5490) to (- 0.4061)

Pre-cooling of Inlet Air:Steam Loading Condenser Load

3) m/s( 6 ) m/s(

10

11

12

13

14

15

16

17

18

22 25 28 31 34 37 40

Air Entering Dry-Bulb Temperature (°C)

Co

nd

ense

r L

oad

(kW

)

Boiler Pr. = 1.8 bara




35.4°C-27°C:

18.7%- 22%

26% - 28.8% 10

12

14

16

18

20

22

22 25 28 31 34 37 40

Air Entering Dry-Bulb Temperature (°C)

Co

nd

en

ser

Lo

ad

(kW

)





35.4°C-27°C:

16.4%- 16.7%

18.2% - 20.9%

15

19

23

27

31

20 23 26 29 32 35 38 41


Co

nd

ense

r S

team

Lo

adin

g (

kg/h

r)

Boiler Pr. =1.8 bara




35.4°C-27°C:

18.4%- 22%

25.8% - 31.3%

15

19

23

27

31

35

20 23 26 29 32 35 38 41


Co

nd

en

ser

Ste

am

Lo

ad

ing

(kg

/hr) Boiler Pr. = 1.8 bara




35.4°C-27°C:

16%- 16.4%

18% - 23.4%

At 27°C:

23.5 - % 20.6%

At 27°C:

19.5 - % 20.6%

Water Cooled Condenser:

Steam Loading Condenser Load

0

2.5

5

7.5

10

12.5

15

17.5

20

22.5

25

27.5

200 400 600 800 1000

Cooling Water Flow Rate (L/hr)

Cond

ense

r Ste

am L

oadi

ng (k

g/hr

)

Inlet Water at 15 °C



0

3

6

9

12

15

18

21

200 400 600 800 1000

Cooling Water Flow Rate (L/hr)

Con

dens

er L

oad

(kW

)

Inlet Water at 15°C



Hybrid (ACC and WCC):200 L/h 400 L/h

0

2.5

5

7.5

10

12.5

15

17.5

20

22.5

25

27.5

Co

nd

en

se

r S

tea

m L

oa

din

g

(kg

/hr)

31 36.5 38.3 42


ACC WCC

0

2.5

5

7.5

10

12.5

15

17.5

20

22.5

25

27.5

Co

nd

en

se

r S

tea

m L

oa

din

g

(kg

/hr)

31 36.5 38.3 42


ACC WCC

0

2.5

5

7.5

10

12.5

15

17.5

Co

nd

ense

r L

oad

(kW

)

31 36.5 38.3 42


ACC WCC

0

2.5

5

7.5

10

12.5

15

17.5

Co

nd

ense

r L

oad

(kW

)

31 36.5 38.3 42


ACC WCC

9.9-% 10.8%-16.4%

5.4-% 15.5-% 17.9%-28.2%

ACC and WCC Percentage Contribution in Total Load:

0

10

20

30

40

50

60

70

80

15.5 16 16.5 17 17.5 18

Total Hybrid System Load (kW)

Pe

rce

nta

ge

Co

ntr

ibu

tio

n (

%)

ACC

WCC

Linear (ACC)

Linear (WCC)

42 °C38.3 °C

36.5 °C

31°C

0

10

20

30

40

50

60

70

80

15.5 16 16.5 17 17.5 18

Total Hybrid System Load (kW)

Perc

en

tag

e C

on

trib

uti

on

(%

)

ACC

WCC

Linear (ACC)

Linear (WCC)

42 °C38.3 °C

36.5 °C

31°C

40

45

50

55

60

65

70

75

80

85

15 20 25 30 35

Condenser Steam Loading (kg/hr)

Ove

rall

Heat

Tra

nsfe

r Coe

ffic

ient

(W

/m2.

°C)

U = 60

U = 77.5

OHTC ( U ): At different operation conditions ( Temperatures, steam loading ).

Water: 200 l/h – 30°C Water: 400 l/h – 30°C

50

55

60

65

70

75

80

85

90

95

100

15 17.5 20 22.5 25 27.5 30 32.5 35 37.5


Ove

rall

Heat

Tra

nsfe

r Coe

ffici

ent

(W/m

2.°C

)

U = 89

U = 64.74

0

100

200

300

400

500

600

700

800

900

1000

5 7.5 10 12.5 15 17.5 20 22.5 25 27.5


Ove

rall

Hea

t Tra

nsfe

r C

oeffi

cien

t (W

/m2

.°C

)

U = 196

U = 835

ACC- (3 m/s) ACC- (6 m/s) WCC

Model Representation:

Air Cooled Condenser

Water Cooled Condenser

OHT (U) Theoretical Samples:

60

62

64

66

68

70

72

74

76

0 0.05 0.1 0.15 0.2 0.25 0.3 0.35

Tube Length (m)

Ove

rall

Hea

t T

ran

sfer

Co

effi

cien

t (W

/m2.

°C)

Row 1

Row 2

60

65

70

75

80

85

90

95

0 0.05 0.1 0.15 0.2 0.25 0.3 0.35

Tube Length (m)

Ove

rall

Hea

t T

ran

sfer

Co

effi

cien

t (W

/m2.

°C)

Row 1

Row 2

0

100

200

300

400

500

600

700

800

900

1000

0 0.05 0.1 0.15 0.2 0.25 0.3 0.35

Tube Length (m)

Ove

rall

He

at

Tra

nsfe

r C

oe

ffic

ien

t (W

/m2.

°C)

WCC

ACC

Comparison of ( Texit and Q):

10

15

20

25

10 15 20 25

Experimental Load (kW)

Th

eore

tica

l L

oad

(kW

)

Thermal Load (kW)

+ 12%

-5%

30

35

40

45

50

55

60

65

70

30 35 40 45 50 55 60 65 70

Experimental Exit Temperature (°C)

Th

eo

reti

cal

Exit

Tem

pera

ture

(°C

)

Air Exit Temperature (°C)

- 5%

5

7

9

11

13

15

17

19

5 7 9 11 13 15 17 19

Experimental Load (kW)

Th

ero

reti

cal

Lo

ad

(kW

)

Thermal Load (kW)

+ 13%

-10%

20

25

30

35

40

45

50

55

60

20 25 30 35 40 45 50 55 60

Experimental Exit Temperature (°C)

Th

eo

reti

cal

Exit

Tem

pera

ture

(°C

)

Water Exit Temperature (°C)

- 5%

+ 5%

Conclusions:

1. The increasing of air flow rate by (50%) increased average steam loading by (17.5%) and corresponding load by (17.6%) with air temperature reduction of (42-20.7 °C).

2. Pre-cooling of air gives an increase in ACC steam loading of (0.58-0.66) kg/hr per each degree reduction of air temperature between (37.5°C) to (27°C).

3. Increasing of air flow rate with pre-cooling increased the average steam loading by (18.2%) and thermal load by (18.46%) with air temperature reduction of (37.5°C) to (27°C).

4. At air flow velocity of (3 m/s) the ACC load increased by (11%) with temperature reduction from (31 to 20.7°C) while the increased in load was (33.6%) with temperature reduction from (42 to 20.7°C) %). Thus, above (30°C) ACC need an assist cooling strategy to reduce the performance deterioration.

5. Increasing of the water flow rate from (200-1000 L/h) increase the steam loading by (54%) and (48%) for inlet temperature variation from (15°C) to (23°C).

6. With hybrid combination steam loading of ACC at (42°C) increased by (14.2%) and thermal load by (22%) with water assist.

Thank You

Ali Farhan Muwayez

presentation - ali farhan

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