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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 for f 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 come back to compressor p - Don’t let refrigerant - 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