�SEASONAL PERFORMANCE OF�INDUCED AND FORCED DRAUGHT COOLING TOWER

Presented By

• 1) Neil Suneria B(34)
• 2) Swapnil Patil B(51)
• 3) Hrishikesh Yadav B(46)
• 4) Niraj Indrekar A(55)

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PROJECT GUIDE :-DR. U. V. ASWALEKAR

CO-GUIDE :-PROF. RAAHUL KRISHNA

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INTRODUCTION

• A cooling tower is a type of heat exchanger used to reduce the temperature of a water stream by extracting heat from water and emitting it to the atmosphere.
• There are different types of cooling tower are available in market but the mechanical cooling towers are used widely.
• Cooling towers are used in different industries like chemical, fabrication , thermal power plant etc.

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Objectives�

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• To Analyse Mechanical Cooling Towers
• To Calculate &Compare Range ,Approach &Tower Effectivness Of Mechanical Cooling Towers

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ABSTRACT

In a cooling tower, water is pumped to the top of the tower & while descending it brakes into minute particles, which comes in contact with the air which cools it. The water is then collected in the tank below on the basis of the draught. The cooling towers we are dealing with are forced & induced type towers.

FORCED DRAUGHT TYPE: The circulation of the air depends upon the fans/blower/pneumatic power supplies located at the bottom of the tower.

INDUCED DRAUGHT TYPE: The prime mover is located at the top from the construction point.

After understanding both the apparatus available in our college we have taken down sample observations twice on both the apparatus and fixed the flaws, cracks, leakages.

As our project deals with the seasonal analysis of both the cooling towers, we have started taking the observations/readings from 1^st of October 2019 {WINTER SEASON}, different parameters required for the calculations are been are recorded for five working days of the week uptill now.

Parameters such as RANGE, APPROACH, EFFICIENCY, ALL TEMPERATURES {BOTH WBT & DBT}, WINDAGE LOSS, EVAPORATIVE LOSS, DRIFT LOSS, etc. are been calculated.

• CLASSIFICATION OF COOLING TOWER

• Atmospheric draught tower
• Natural draught tower
• Spray filled
• Packed
• Force draught tower
• Induced draught tower

• COMPONENTS OF COOLING TOWER

• Frame and casing
• Fill
• Splash fill
• Film fill
• Cold water basin
• Nozzles
• Fan

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• Operating parameters:

• Air flow
• Fan power
• Inlet water flow
• Drift loss
• Purge
• Concentration ratio
• Water loading
• Heat load
• Wet bulb temperature
• Ambient air wet bulb temperature
• Inlet air wet bulb temperature
• Nominal inlet air wet bulb temperature
• Re-cooled water temperature
• Cooling range
• Approach
• effectiveness

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• EXISTING APPARATUS FOR EXPERIMENTATION�

• Forced draught cooling tower

• Induced draught cooling tower

• Technical details

Forced draught cooling tower

Induced draught cooling tower

• Blower :2hp
• Water supply pump :0.5 hp
• Heater :1.5 kW
• Water rotameter:0 to 10 lpm
• Air manometer :0 to 300 mm
• Exhaust fan :250 W
• Water supply tank : 50 liters
• Temperature indicator :0-500°C
• Temperature sensor: cr/al, k type
• Tower packing : ss screen

• Pump: 500 lph
• Heater : 4 kW
• Exhaust Fan :65 W
• Water rotameter:0 to 1000 lph
• Body area:0.5*0.5*0.6 m
• Sump area:0.5*0.5*0.25 m

THERMAL ANALYSIS OF FILLS USING SOLIDWORKS

THERMAL ANALYSIS RESULT

• TEMPERATURE MIN 3.000e+02 K 

MAX 3.133e+02 K

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Observations for forced draught cooling tower:

• Cooling tower size-0.3*0.3 m
• Cross sectional area of the column-0.09m
• Height of the packing-1.2m
• Diameter of the orifice-0.048 m

Observation table:

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Observations for forced draught :

• Where,
• T1=HOT WATER INLET TEMPERATURE
• T2=HOT WATER OUTLET TEMPERATURE
• T3=AIR INLET DRY BULB TEMPERATURE
• T4=AIR INLET WET BULB TEMPERATURE
• T5=AIR OUTLET DRY BULB TEMPERATURE
• T6=AIR OUTLET WET BULB TEMPERATURE
• T7=INTERMEDIATE TEMPERATURE OF AIR IN TO THE TOWER
• T8=INTERMEDIATE TEMPERATURE OF AIR IN TO THE TOWER

Sample calculations for forced draught

• Reading no 1
• Cooling tower range :

CT Range (°C) = [HW inlet temp (°C) – CW outlet temp (°C)]

=33-23

=10

• Cooling tower approach (CTA) :

CT Approach (°C) = [CW outlet temp (°C) – Wet bulb temp (°C)]

=24-23

=1

• Effectiveness of cooling tower :

ε = (RANGE)/(RANGE+APPROACH)

=(10)/(10+1)

=0.8182=81.82%

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Calculation for Reading no 1

• MASS FLOW RATE OF WATER

Q=M*C_P*dT

1.5=M*4.187*10

M=0.039m³/hr

• EVAPORATION LOSSES (in m^3/hr)=0.00085*1.8*circulation rate(m³/hr)*(t₁-t₂)

=0.00085*1.8*0.039*10

=0.00055m³/hr

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RESULT TABLE

Forced draught

Forced draught

Week number

Forced draught

Observations for Induced draught cooling tower:

• Fan :65 w
• Body area:0.5*0.5*0.6 m
• Sump area:0.5*0.5*0.25 m
• Observation table:

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OBSERVATIONS FOR INDUCED DRAUGHT

• Where,
• T1=HOT WATER INLET TEMPERATURE
• T2=HOT WATER OUTLET TEMPERATURE
• T3=AIR INLET DRY BULB TEMPERATURE
• T4=AIR OUTLET DRY BULB TEMPERATURE
• T5=AIR INLET WET BULB TEMPERATURE

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Sample calculations for induced draught

• Reading no 1-
• Cooling tower range :

CT Range (°C) = [HW inlet temp (°C) – CW outlet temp (°C)] =

=29-22

=7

• Cooling tower approach (CTA) :

CT Approach (°C) = [CW outlet temp (°C) – Wet bulb temp (°C)]

=22-21

=1

• Effectiveness of cooling tower :

ε = (RANGE)/(RANGE+APPROACH)

=(7)/(7+1)

=0.875=87.5%

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Calculation for Reading no 1

• MASS FLOW RATE OF WATER

Q=M*CP*dT

4.5=M*4.187*7

M=0.153m^3/hr

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• EVAPORATION LOSSES (in m^3/hr)=0.00085*1.8*circulation rate(m^3/hr)*(t1-t2)

=0.00085*1.8*0.153*7

=0.0016m^3/hr

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RESULT TABLE

Induced draught

Induced draught

Induced draught

Induced v/s forced (comparison of range at 5 lpm)

Week number

Temprature (deg c)

conclusions:

• Cooling towers Effectiveness increases as the flow rate increases.
• The Range of both the cooling towers Increases as the flow rate Decreases.
• Approach of both the cooling towers decreases as the flowrate increases.
• In both the cooling towers, the efficiency at the flowrates of 6 lpm is above 80%.

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• Average Effectiveness of the Induced Draught Tower uptill now,
• At 6.66 lpm is 83.42%
• At 5 lpm is 75.84%
• At 3.33 lpm is 69.63%

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• Average Effectiveness of the Forced Draught Tower uptill now,
• At 6 lpm is 84%
• At 5 lpm is 78%
• At 4 lpm is 73.91%

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• REFERENCES:

• M.A. Bernier, Cooling tower performance: theory and experiments. ASHRAE Trans. 100, 114–121 (1994)
• Cooling Tower, Chapter 3.7, Energy Efficiency in Electric Utilities, Bureau of Energy Efficiency (India).
• Cooling Towers: Principles and Practice, 3rd edition, G. B. Hill, E. J. Pring, P. D. Osborn
• https://www.nhb.gov.in/
• https://www.eere.energy.gov.in/
• White, T.L. 1994. Winter cooling tower operation for a central chilled watersystem. ASHRAE Transactions 100(1):811-816.
• W.M. Simpson, T.K. Sherwood, “Performance of small mechanical draft cooling towers”, Am. Soc. Refrig. Eng., 52 (1946) 535–543 and 574–576.
• 23. S.P. Fisenko, A.A. Brin, A.I. Petruchik, “Evaporative cooling of water in a mechanical draft cooling tower”, Int. J. Heat Mass Transf., 47 (2004) 165–177.

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THANK YOU