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Lecture Chapter 9: Cooling tower - ThS. Nguyễn Duy Tuệ

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Lecture "Chapter 9: Cooling tower" content presentation:  Working principle of cooling tower, components of cooling tower, cooling tower choosing, installation. Invite you to reference.

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Nội dung Text: Lecture Chapter 9: Cooling tower - ThS. Nguyễn Duy Tuệ

  1. CHAPTER 9: COOLING TOWER Lecturer: ME. Nguyễn Duy Tuệ 12/2015 Chapter 9: Cooling tower ThS.Nguyễn Duy Tuệ 1
  2. OBJECTIVES In this charpter, student can: Analize operation principle of cooling tower and -Analize other working conditions affects to it’s efficiency o -How to o cchoose oose coocooling g tower o e that a meet ee a demand 12/2015 Chapter 9: Cooling tower ThS.Nguyễn Duy Tuệ 2
  3. REFERENCES [1]. Trane document [1] [2]. Refrigeration and Air-Conditioning - A. R. Trott and T. T Welch 12/2015 Chapter 9: Cooling tower ThS.Nguyễn Duy Tuệ 3
  4. CONTENT WORKING PRINCIPLE OF COOLING TOWER COMPONENTS OF COOLING TOWER COOLING TOWER CHOOSING INSTALLATION 12/2015 Chapter 9: Cooling tower ThS.Nguyễn Duy Tuệ 4
  5. WORKING PRICIPLES OF COOLING TOWER 1. Position of cooling tower : (watch movie ) 12/2015 Chapter 9: Cooling tower ThS.Nguyễn Duy Tuệ 5
  6. WORKING PRICIPLES OF COOLING TOWER 2. Working principles : A cooling tower is a device commonly used to cool condensing water. In this design, warm water is sprayed over the fill inside the cooling tower while a propeller fan draws outdoor air upward through the fill. The movement of air through the spray causes some of the water to evaporate, a process that cools the remaining water. This cooled water then falls to the tower sump to be returned to the condenser. 12/2015 Chapter 9: Cooling tower ThS.Nguyễn Duy Tuệ 6
  7. WORKING PRICIPLES OF COOLING TOWER 12/2015 Chapter 9: Cooling tower ThS.Nguyễn Duy Tuệ 7
  8. WORKING PRICIPLES OF COOLING TOWER 3. The effects of cooling tower performance: - Out door humidity : If the outdoor air is dry, the final water temperature can be considerably lower than the ambient dry-bulb temperature. If the outdoor air is humid, however, the final temperature will be near the ambient dry-bulb temperature. -> The evaporation process uses up water to dissipate heat contributed by the cooling load plus the heat of compression. - Air velocity through the cooling pad - Heat transfer area of cooling pad which contact air and water 12/2015 Chapter 9: Cooling tower ThS.Nguyễn Duy Tuệ 8
  9. WORKING PRICIPLES OF COOLING TOWER + Note : In our country, having hot air and high humidity that affect cooling tower performance. As a result, if installing cooling tower in Ha Noi, we have to choose 1,5 times capacity higher than that is installed in HCM city - Out put water temperature from cooling tower : tout = twet bulb + 3~5K 12/2015 Chapter 9: Cooling tower ThS.Nguyễn Duy Tuệ 9
  10. WORKING PRICIPLES OF COOLING TOWER - In addition, as the water evaporates, the dissolved minerals and water treatment chemicals become concentrated in the sump. To prevent this solution from becoming concentrated and possibly corrosive, water is periodically bled from the sump and an equal amount of fresh water is added. 12/2015 Chapter 9: Cooling tower ThS.Nguyễn Duy Tuệ 10
  11. WORKING PRICIPLES OF COOLING TOWER The concentration of solids in the circulating water will increase until the amount carried away by the bleed water compensates for that not carried away in the water vapour. So, if cm= concentration of solids in make-up water (kg/kg) cb = concentration of solids in bleed-off (kg/kg) we = mass flow of water evaporated (kg/s) wm= mass flow of make-up water (kg/s) 12/2015 Chapter 9: Cooling tower ThS.Nguyễn Duy Tuệ 11
  12. WORKING PRICIPLES OF COOLING TOWER Mass of solids entering = mass of solids leaving The concentration of mains make-up water, cm , is obtained from the water supply authority. The permissible concentration, cb , will be decided by the method of water treatment or the assumed concentration of untreated water which will prevent precipitation. 12/2015 Chapter 9: Cooling tower ThS.Nguyễn Duy Tuệ 12
  13. WORKING PRICIPLES OF COOLING TOWER Example : If water hardness is 560 ppm (parts per million), the water treatment can permit a concentration of solids to 1200 ppm, the cooling capacity is 700 kW and the compressor power 170 kW, how much water should be bled to waste and what is the total make-up required? 12/2015 Chapter 9: Cooling tower ThS.Nguyễn Duy Tuệ 13
  14. WORKING PRICIPLES OF COOLING TOWER + Solution : 12/2015 Chapter 9: Cooling tower ThS.Nguyễn Duy Tuệ 14
  15. WORKING PRICIPLES OF COOLING TOWER + Note : The quantity of water evaporated will take up its latent heat equal to the condenser duty, at the rate of about 2430 kJ/kg evaporated, and will be approximately 12/2015 Chapter 9: Cooling tower ThS.Nguyễn Duy Tuệ 15
  16. COMPONENTS OF COOLING TOWER There are two kinds of cooling tower: 12/2015 Chapter 9: Cooling tower ThS.Nguyễn Duy Tuệ 16
  17. COMPONENTS OF COOLING TOWER + Construction of cooling tower: 12/2015 Chapter 9: Cooling tower ThS.Nguyễn Duy Tuệ 17
  18. COMPONENTS OF COOLING TOWER 12/2015 Chapter 9: Cooling tower ThS.Nguyễn Duy Tuệ 18
  19. COMPONENTS OF COOLING TOWER a. Cooling pad (filling): - This is heat exchanger for water and air 12/2015 Chapter 9: Cooling tower ThS.Nguyễn Duy Tuệ 19
  20. COMPONENTS OF COOLING TOWER b. Fan: Cooling tower use propeller or centrifugal fan made of polymer, plastic; and having suitable flow rate 12/2015 Chapter 9: Cooling tower ThS.Nguyễn Duy Tuệ 20
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