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Energy Efficient Fluid Flow

Energy Efficient Fluid Flow. Fluid Flow System Fundamentals. W motor = W fluid / (Eff motor x Eff drive x Eff pump ). Look For “Inside” Opportunities to Max Savings. Efficiency losses in distribution and primary energy conversion systems multiply “inside” savings Example:

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Energy Efficient Fluid Flow

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  1. Energy Efficient Fluid Flow

  2. Fluid Flow System Fundamentals Wmotor = Wfluid / (Effmotor x Effdrive x Effpump)

  3. Look For “Inside” Opportunities to Max Savings • Efficiency losses in distribution and primary energy conversion systems multiply “inside” savings • Example: • Welec= Wfluid / [Effpumpx Effdrivex Effmotor ] • Welec= 1 kWh/ [.70 x .92 x .90] = 1.7 kWh

  4. Fluid Flow System Fundamentals Wfluid = V DPtotal

  5. Fluid Flow System Fundamentals Wfluid = V DPtotal = V (k V2) = k V3 Wfriction = V DPfriction = k / D5

  6. Pumping System Savings Opportunities • Reduce volume flow rate • Reduce required pump head DPstatic DPvelocity DPelevation DPheadloss • Increase pump, drive, motor efficiency Welec = V DPtotal / [Effpumpx Effdrivex Effmotor ]

  7. Fluid Flow System Saving Opportunities • Reduce Required Pump/Fan DP • Employ Energy Efficient Flow Control • Improve Efficiency of Pumps/Fans

  8. Reduce Pump/Fan DP

  9. Increase Reservoir Level toReduce Elevation Head

  10. Minimize Pipe Friction:Use Bigger Pipes/Ducts • Use large diameter pipes: • DP headloss ~ k / D5 • Doubling pipe diameter reduces friction by 97%

  11. Minimize Pipe FrictionUse Smooth Pipes/Ducts • Use smooth plastic pipes: • fsteel = 0.021 fplastic = 0.018 • Pumping savings from plastic pipe (0.021 – 0.018) / 0.018 = 17%

  12. Use Gradual Elbows

  13. Use Gradual Elbows

  14. Employ Energy Efficient Flow Control

  15. Inefficient Flow Control • By-pass loop • (No savings) • By-pass damper • (No savings) • Outlet valve/damper • (Small savings) • Inlet vanes • (Moderate savings)

  16. Efficient Flow Control • Trim impellor for constant-volume pumps • Slow fan for constant-volume fans • VFD for • variable-volume pumps or fans

  17. Inefficient and Efficient Flow Control

  18. Cooling Towers

  19. Cooling Loop Pumps

  20. Worlds Largest Bypass Pipe

  21. For Constant Speed Pump Applications: Trim Pump Impellor • Look for discharge valve at < 100% open • More energy-efficient to downsize the pump by trimming impellor blades than throttle flow

  22. Trim Impellor and Open Throttling Valve

  23. For Constant Speed Fan Applications: Slow Fan Speed by Changing Pulley Diameter • Look for discharge damper at < 100% open • More energy-efficient to slow fan than throttle flow

  24. For Variable Flow Applications:Install VFD • W2 = W1 (V2/V1)3 • Reducing flow by 50% reduces pumping costs by 87%

  25. Variable Speed Pumping on HVAC Chilled Water Loops Replace 3-way Valve with 2-way valve on AHU

  26. VFDs on Vent Hoods

  27. Need Controls for VFDs on Dust Collection

  28. Use VFDs on Cooling Tower Fans

  29. Pump Long, Pump Slow • Identify intermittent pumping applications • More energy to pump at high flow rate for short period than low flow rate longer • Example: • Current: Two pumps in parallel for four hours • Recommended: One pump for six hours • Estimated Savings: $500 /yr Reason: Wfluid = V DP = k V3

  30. Optimize Efficiency of Pumps/Fans

  31. Correct Fan Inlet/Exit Conditions No Yes

  32. Refurbish Inefficient Pumps Pump not operated at peak efficiency in middle of operating range

  33. Resize Miss-sized Pumps • Pump operating at off-design point M • Eff = 47% • Replace with properly sized pump • Estimated savings: $14,000 /yr

  34. Fluid Flow Summary • Reduce Required Pump/Fan Head • Reduce excess elevation head • Smoother pipes/ducts • Larger diameters • Gradual elbows • Employ Energy Efficient Flow Control • Constant speed pumping: trim impellor blade • Constant speed fans: Slow fan • Variable flow: Install VFDs • Pump slow, pump long • Improve Efficiency Pumps/Fans • Correct fan inlet/exit conditions • Refurbish inefficient pumps • Resize miss-sized pumps/fans

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