Lecture Chapter 10: Refrigeration Accessories - ThS. Nguyễn Duy Tuệ

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Lecture "Chapter 10: Refrigeration Accessories" content presentation: Refrigerant piping, vessels, other equipments. Invite you to reference.

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Nội dung Text: Lecture Chapter 10: Refrigeration Accessories - ThS. Nguyễn Duy Tuệ

CHAPTER 10: REFRIGERATION ACCESSORIES Lecturer: ME.Nguyễn Duy Tuệ 12/2015 Chapter 10: Refrigeration Accessories ThS.Nguyễn Duy Tuệ 1
OBJECTIVES IIn this thi chapter, h t student t d t can : - How to calculatate and know installation criterion it i forf refrigerant fi t piping i i - Understand the function of some vessels and other th accessories i such h as : sight i ht glass, l solenoid l id valve…. 12/2015 Chapter 10: Refrigeration Accessories ThS.Nguyễn Duy Tuệ 2
REFERENCES [1]. [1] R fi Refrigerant t I d ti l Industrial H db k Th Handbook-The McGraw-Hill Companies. [2] Trane, [2]. T D f Danfoss t h i l document technical d t 12/2015 Chapter 10: Refrigeration Accessories ThS.Nguyễn Duy Tuệ 3
CONTENT REFRIGERANT PIPING VESSELS OTHER EQUIPMENTS 12/2015 Chapter 10: Refrigeration Accessories ThS.Nguyễn Duy Tuệ 4
REFRIGERANT PIPING 1. Design principles: - Must M t supply l sufficient ffi i t liquid li id flowrate fl t t to evaporator - Pressure drop must be low - Have enough velocity to draw oil back to compressor g - Don’t let refrigerant come back to compressor p - Piping must be dry and clean 12/2015 Chapter 10: Refrigeration Accessories ThS.Nguyễn Duy Tuệ 5
REFRIGERANT PIPING 12/2015 Chapter 10: Refrigeration Accessories ThS.Nguyễn Duy Tuệ 6
REFRIGERANT PIPING 2. Suction pipe: - Undersizing the suction line reduces compressor capacity by forcing it to operate at a lower suction pressure to maintain the desired evaporator temperature. - Oversizing the suction line increases initial project costs and may result in insufficient refrigerant gas velocity to move oil from the evaporator to the compressor 12/2015 Chapter 10: Refrigeration Accessories ThS.Nguyễn Duy Tuệ 7
REFRIGERANT PIPING Pressure drop arcording to saturate temperature reduction by ASHRAE standard: Refrigerant velocity in suction pipe should be 7~12m/s. Refrigerant velocity should higher 3m/s for horizontal pipe and higher than 7m/s in vertical pipe 12/2015 Chapter 10: Refrigeration Accessories ThS.Nguyễn Duy Tuệ 8
REFRIGERANT PIPING - While operating, the suction line is filled with superheated refrigerant vapor and oil. The oil flows on the bottom of the pipe and is moved along by the refrigerant gas flowing above it. - When the system stops, the refrigerant may condense in the pipe depending on the ambient conditions. This may result in slugging if the liquid refrigerant is drawn into the compressor when the system restarts. 12/2015 Chapter 10: Refrigeration Accessories ThS.Nguyễn Duy Tuệ 9
REFRIGERANT PIPING - To promote good oil return, suction lines should be pitched 1/8 inch per foot (10.4 mm/m) in the direction of refrigerant flow. - Evaporator connections require special care because the evaporator has the potential to contain a large volume of condensed refrigerant during off cycles. - To minimize slugging of condensed refrigerant, the evaporators should be isolated from the suction line with an inverted trap as shown 12/2015 Chapter 10: Refrigeration Accessories ThS.Nguyễn Duy Tuệ 10
REFRIGERANT PIPING The trap should extend above the top of the evaporator before leading to the compressor. - With multiple evaporators, the suction piping should be designed so that the pressure drops are equal and the refrigerant and oil from one coil cannot flow into another coil. - Traps may be used at the bottom of risers to catch condensed refrigerant before it flows to the compressor. Intermediate traps are unnecessary in a properly sized riser as they contribute to pressure drop. 12/2015 Chapter 10: Refrigeration Accessories ThS.Nguyễn Duy Tuệ 11
REFRIGERANT PIPING - Usually with commercially produced air conditioning equipment, the compressors are “prepiped” to a common connection on the side of the unit. - Suction line filter driers are available to help clean the refrigerant before it enters the compressor. Because they represent a significant pressure drop -> be added in some circumstances such as after compressor burnout. 12/2015 Chapter 10: Refrigeration Accessories ThS.Nguyễn Duy Tuệ 12
REFRIGERANT PIPING Observe some diagrams: 12/2015 Chapter 10: Refrigeration Accessories ThS.Nguyễn Duy Tuệ 13
REFRIGERANT PIPING 12/2015 Chapter 10: Refrigeration Accessories ThS.Nguyễn Duy Tuệ 14
REFRIGERANT PIPING + Double suction riser: - In a double suction riser at full capacity, the refrigerant flow passes through both risers with enough velocity to move the oil. - At minimum capacity, oil in the riser flows backward and fills the trap at the bottom. Once the trap is full of oil, refrigerant flow through the large diameter riser is cut off and only refrigerant gas flows through the smaller diameter riser. - The sum of the two risers is sized for full capacity. The smaller diameter riser is sized for minimum capacity. 12/2015 Chapter 10: Refrigeration Accessories ThS.Nguyễn Duy Tuệ 15
REFRIGERANT PIPING 12/2015 Chapter 10: Refrigeration Accessories ThS.Nguyễn Duy Tuệ 16
12/2015 Chapter 10: Refrigeration Accessories ThS.Nguyễn Duy Tuệ 17
REFRIGERANT PIPING 3. Discharge pipe: - Undersizing discharge lines will reduce compressor capacity and increase compressor work. Over sizing discharge lines increases the initial cost of the project and may result in insufficient refrigerant gas velocity to carry oil back to the compressor. - Discharge lines should be sized for no more than 2 to 3°F (1.1 to 1.7°C) pressure loss. The actual pressure drop in PSI will depend upon the refrigerant. 12/2015 Chapter 10: Refrigeration Accessories ThS.Nguyễn Duy Tuệ 18
REFRIGERANT PIPING 12/2015 Chapter 10: Refrigeration Accessories ThS.Nguyễn Duy Tuệ 19
REFRIGERANT PIPING 12/2015 Chapter 10: Refrigeration Accessories ThS.Nguyễn 20 Duy Tuệ