Bài giảng Kỹ thuật lạnh - Chapter 6: Condenser - Nguyễn Duy Tuệ

CHAPTER 6: CONDENSER 12/2015 Chapter 6: Condenser - ThS.Nguyễn Duy Tuệ 1 Lecturer : ThS.Nguyễn Duy Tuệ OBJECTIVES In this chapter st dent can, u : -Understand principle of some kind of condensers -Calculate and chose the condenser met the required capacity 12/2015 2Chapter 6: Condenser - ThS.Nguyễn Duy Tuệ REFERENCES [1] Trane doc ment. u [2]. Kỹ thuật lạnh cơ sở - Nguyễn Đức Lợi 12/2015 3Chapter 6: Condenser - ThS.Nguyễn Duy Tuệ CONTENT AIR COOLED CONDENSER EVAPORATIVE CONDENSER WATER COOLED CONDENSER CONDENSER CALCULATION 12/2015 4Chapter 6: Condenser - ThS.Nguyễn Duy Tuệ AIR COOLED CONDENSER - The condenser is a heat exchanger that rejects heat from the refrigerant to air water or some other, , fluid. - The three common types of condensers are air- cooled, water-cooled, and evaporative. 12/2015 5Chapter 6: Condenser - ThS.Nguyễn Duy Tuệ AIR COOLED CONDENSER - A typical air-cooled condenser uses propeller- type fans to draw outdoor air over a finned tube- heat transfer surface. - The temperature difference between the hot refrigerant vapor and the cooler outdoor air induces heat transfer. The resulting reduction in the heat content of the refrigerant vapor causes it to condense into liquid. Withi th fi l f l th f d t bi- n e na ew eng s o con enser u ng (the subcooler), the liquid refrigerant is further cooled below the temperature at which it was 12/2015 6 condensed. Chapter 6: Condenser - ThS.Nguyễn Duy Tuệ AIR COOLED CONDENSER 12/2015 7Chapter 6: Condenser - ThS.Nguyễn Duy Tuệ AIR COOLED CONDENSER Air cooled condenser without fan 12/2015 8Chapter 6: Condenser - ThS.Nguyễn Duy Tuệ AIR COOLED CONDENSER + Advantage : It requires very little maintenance and does not- require the freeze protection and water treatment that is necessary with a water-cooled condenser. - It is favored in areas that have an inadequate or costly water supply, or where the use of water for air conditioning is restricted. + Disadvantage : High condensing pressure 12/2015 9Chapter 6: Condenser - ThS.Nguyễn Duy Tuệ EVAPORATIVE CONDENSER A modification of the air-cooled condenser is the ti d Withi thi d i thevapora ve con enser. n s ev ce, e refrigerant flows through tubes and air is drawn or blown over the tubes by a fan The difference is that. water is sprayed on the tube surfaces. As the air passes over the coil, it causes a small portion of the water to evaporate. This evaporation process absorbs heat from the coil, causing the refrigerant vapor within the tubes to condense. The remaining water then falls to the sump to be recirculated and used again 12/2015 10 . Chapter 6: Condenser - ThS.Nguyễn Duy Tuệ EVAPORATIVE CONDENSER We can subcool the liquid by using some length of pipe submerged in the water sump or on the path of air flow 12/2015 11Chapter 6: Condenser - ThS.Nguyễn Duy Tuệ EVAPORATIVE CONDENSER + Evaporative condenser without fan : Water poured from the top to the surface of tube; then evaporate by adding heat from condenser. Hot water drop to the sump; and drain out partly; then it is compensated by cool wate 12/2015 12Chapter 6: Condenser - ThS.Nguyễn Duy Tuệ EVAPORATIVE CONDENSER 12/2015 13Chapter 6: Condenser - ThS.Nguyễn Duy Tuệ WATER COOLED CONDENSER - The shell-and-tube is the most common type of water-cooled condenser. With this design, water is pumped through the tubes while the refrigerant vapor fills the shell space surrounding the tubes. - As heat is transferred from the refrigerant to the water the refrigerant vapor condenses on the, tube surfaces. The condensed liquid refrigerant then falls to the bottom of the shell. 12/2015 14Chapter 6: Condenser - ThS.Nguyễn Duy Tuệ WATER COOLED CONDENSER + Shell-tube water cooled condenser 12/2015 15Chapter 6: Condenser - ThS.Nguyễn Duy Tuệ WATER COOLED CONDENSER - After the warm water leaves the condenser, it must either be disposed of (as in the case of using water from a well) or it must be cooled before it can be reused by the condenser In this example. , the condenser brings in [29°C] water and warms it up to [35°C] Before this water can be used again. , it must be cooled back down to [29°C]. 12/2015 16Chapter 6: Condenser - ThS.Nguyễn Duy Tuệ WATER COOLED CONDENSER 12/2015 17Chapter 6: Condenser - ThS.Nguyễn Duy Tuệ WATER COOLED CONDENSER 12/2015 18Chapter 6: Condenser - ThS.Nguyễn Duy Tuệ WATER COOLED CONDENSER + Vertical shell-tube condenser : 12/2015 19Chapter 6: Condenser - ThS.Nguyễn Duy Tuệ WATER COOLED CONDENSER +Vertical shell-tube condenser: 12/2015 20Chapter 6: Condenser - ThS.Nguyễn Duy Tuệ WATER COOLED CONDENSER + Tube in tube water cooled condenser: compact but it is difficult to clean out scale inside, 12/2015 21Chapter 6: Condenser - ThS.Nguyễn Duy Tuệ WATER COOLED CONDENSER + Plate condenser : - The refrigerant enters at top left of the exchanger as hot gas and starts to condense on the surface of the channels until fully condensed, and is then slightly subcooled. The process is called "free condensation". I h l d d i h li h- n t e enc ose con enser p cture t e g t and dark blue arrows show the location of the brine connections The refrigerant flows counter current in. the opposite channel and is cooled. The light and dark red arrows indicate the locations of the 12/2015 22 refrigerant connections. Chapter 6: Condenser - ThS.Nguyễn Duy Tuệ WATER COOLED CONDENSER . 12/2015 23Chapter 6: Condenser - ThS.Nguyễn Duy Tuệ WATER COOLED CONDENSER + Advantage of PHX: - Compact and high efficiency - Easy to increase capacity by inserting plates into that; and vice versa + Disadvantage : - Not easy to clean out water scale 12/2015 24Chapter 6: Condenser - ThS.Nguyễn Duy Tuệ CONDENSER CALCULATION 1/ Condenser heat transfer area calculation: Energy balance equation: Qk=k.F.∆T , (W) k : Overal heat transfer coefficient, (W/m2.K ) . (We can use the experience of design table ) F : heat transfer area, (m2) T l i diff∆ : ogar t temperature erence + Note : We assume that water in and out are equal with evaporative condenser ∆T=tk-tw 12/2015 25Chapter 6: Condenser - ThS.Nguyễn Duy Tuệ CONDENSER CALCULATION 2/ Experience of heat transfer coefficience table 12/2015 26Chapter 6: Condenser - ThS.Nguyễn Duy Tuệ CONDENSER CALCULATION + Note : For exactly, we have to find out in manufacture catalogue We can follow these ways:. Method 1 : Follow manufacture catalogue-> Real Qk Method 2 : Calculate heat transfere coefficient - > F 12/2015 27Chapter 6: Condenser - ThS.Nguyễn Duy Tuệ CONDENSER CALCULATION Example: Gao Xiang condenser catalogue zjgaoxiang com/en/productsd php?pid=4. . . 63 12/2015 28Chapter 6: Condenser - ThS.Nguyễn Duy Tuệ CONDENSER CALCULATION 12/2015 29Chapter 6: Condenser - ThS.Nguyễn Duy Tuệ CONDENSER CALCULATION 12/2015 30Chapter 6: Condenser - ThS.Nguyễn Duy Tuệ CONDENSER CALCULATION 12/2015 31Chapter 6: Condenser - ThS.Nguyễn Duy Tuệ