tailieunhanh - THERMO_V3_5

Tham khảo tài liệu 'thermo_v3_5', kỹ thuật - công nghệ, cơ khí - chế tạo máy phục vụ nhu cầu học tập, nghiên cứu và làm việc hiệu quả | Simpo PDFMerae and Split Unregistered Version - http Fluid Flow HEAD LOSS TABLE 1 Typical Values of -D Item L eq D Globe Valve Conventional 400 Y-Pattern 160 Gate Valve Fully Open 10 75 Open 35 50 Open 150 25 Open 900 Standard Tee Flow through Run 10 Flow through Branch 60 90 Standard Elbow 30 45 Standard Elbow 16 Return Bend 50 Example A fully-open gate valve is in a pipe with a diameter of 10 inches. What equivalent length of pipe would cause the same head loss as the gate valve Solution From Table 1 we find that the value of Leq D for a fully-open gate valve is 10. Leq L D D 10 10 inches 100 inches By adding the equivalent lengths of all components to the actual length of pipe in a system we can obtain the Leq value for the entire piping system. Rev. 0 Page 35 HT-03 _ Simpo PDF Merge and Split Unregistered Version - http . HEAD LOSS Fluid Flow Summary The main points of this chapter are summarized below. Head Loss Summary Head loss is the reduction in the total head sum of potential head velocity head and pressure head of a fluid caused by the friction present in the fluid s motion. Frictional loss is that part of the total head loss that occurs as the fluid flows through straight pipes. Minor losses are the head losses that occur due to bends elbows joints valves and other components. Any time the flow experiences a change in direction or a change in cross-sectional area it will experience a head loss. The friction factor for fluid flow can be determined using a Moody Chart if the relative roughness of the pipe and the Reynolds number of the flow can be determined. Darcy s equation can be used to calculate frictional losses. A special form of Darcy s equation can be used to ilh uhtte minor tosses. The length of pipe that would cause the same head loss as a valve or fitting can be determined by multiplying the value of L D for the component found in handbooks or vendor manuals by the diameter of the pipe. HT-03 Page 36 Rev. 0 .