energy efficient fluid flow
DESCRIPTION
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: - PowerPoint PPT PresentationTRANSCRIPT
-
Energy Efficient Fluid Flow
-
Fluid Flow System FundamentalsWmotor = Wfluid / (Effmotor x Effdrive x Effpump)
-
Look For Inside Opportunities to Max SavingsEfficiency 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
-
Fluid Flow System FundamentalsWfluid = V DPtotal
P
V
Pump Curve
System Curve
Wfluid = V P
-
Fluid Flow System FundamentalsWfluid = V DPtotal = V (k V2) = k V3Wfriction = V DPfriction = k / D5
P
V
Pump Curve
System Curve
Wfluid = V P
-
Pumping System Savings OpportunitiesReduce volume flow rateReduce required pump headDPstatic DPvelocity DPelevation DPheadlossIncrease pump, drive, motor efficiencyWelec = V DPtotal / [Effpumpx Effdrivex Effmotor ]
-
Fluid Flow System Saving Opportunities Reduce Required Pump/Fan DPEmploy Energy Efficient Flow Control Improve Efficiency of Pumps/Fans
-
Reduce Pump/Fan DP
-
Increase Reservoir Level toReduce Elevation Head
-
Minimize Pipe Friction:Use Bigger Pipes/Ducts Use large diameter pipes: DP headloss ~ k / D5 Doubling pipe diameter reduces friction by 97%
-
Minimize Pipe FrictionUse Smooth Pipes/DuctsUse smooth plastic pipes: fsteel = 0.021 fplastic = 0.018 Pumping savings from plastic pipe (0.021 0.018) / 0.018 = 17%
-
Use Gradual Elbows
-
Use Gradual Elbows
-
Employ Energy Efficient Flow Control
-
Inefficient Flow ControlBy-pass loop(No savings)By-pass damper (No savings)Outlet valve/damper(Small savings)Inlet vanes(Moderate savings)
-
Efficient Flow ControlTrim impellor for constant-volume pumpsSlow fan for constant-volume fansVFD for variable-volume pumps or fans
-
Inefficient and Efficient Flow Control
Chart2
1.0018640.9951131
0.9739132240.7106170.64
0.8807452320.6506570.36
0.7378879280.6291850.16
0.5608692160.20.04
Outlet Damper
Variable Inlet Vane
Variable Frequency Drive
Volume Flow Rate (%)
Power (%)
Sheet1
FanPower.XLS
For Inlet Vanes
VWVnormWnormWnormVnormVnorm2Vnorm3
4.6001.7001.0001.0001.0001.0001.0001.000
4.3001.4500.9350.8530.8530.9350.8740.817
3.9001.3000.8480.7650.7650.8480.7190.609
3.4501.1500.7500.6760.6760.7500.5630.422
2.3001.1000.5000.6470.6470.5000.2500.125
Wnorm = -0.042487 + 3.6573 * V -6.4957 * V2 + 3.8760 * V3
R2 = 0.997
For Outlet Dampers
VnormWWnormWnormVnormVnorm2Vnorm3
11.6111.0001.0001.0001.000
0.81.580.98136645960.9810.8000.6400.512
0.61.40.86956521740.8700.6000.3600.216
0.41.20.74534161490.7450.4000.1600.064
0.20.90.55900621120.5590.2000.0400.008
for Vnorm >= 0.5: Wnorm = 0.365217 + 0.998965 * V -0.03882 * V^2 +-0.323498 * V^3
r2 = 0.998
for 0>=Vnorm > 0.5: Wnorm = 0.589 + 0.116 * V
For VFD assuming P = k V^2Graph
WnormVnormVnormOutlet DamperVariable Inlet VaneVariable Frequency Drive
1.0001.000100%1.001.001.00
0.6400.80080%0.970.710.64
0.3600.60060%0.880.650.36
0.1600.40040%0.740.630.16
0.0400.20020%0.560.04
Wnorm = Vnorm^2
R2 = 1.0
Sheet1
Outlet Damper
Variable Inlet Vane
Variable Frequency Drive
Volume Flow Rate (%)
Power (%)
800hpfans
W/VIV in blast
%TimeCFMCFM/CFMmaxW/WmaxW
5%20,0000.80.71147323.6635461
75%18,0000.720.670446334.718630316
10%16,0000.640.65443543.5308538384
10%14,0000.560.64943243.2391905936
Average445
w/VFD in blast
%TimeCFMCFM/CFMmaxW/WmaxW
5%20,0000.80.64042621.312
75%18,0000.720.518345258.9408
10%16,0000.640.41027327.27936
10%14,0000.560.31420920.88576
Average328
Sheet3
-
Cooling Towers
-
Cooling Loop Pumps
-
Worlds Largest Bypass Pipe
-
For Constant Speed Pump Applications: Trim Pump ImpellorLook for discharge valve at < 100% open More energy-efficient to downsize the pump by trimming impellor blades than throttle flow
-
Trim Impellor and Open Throttling Valve
-
For Constant Speed Fan Applications: Slow Fan Speed by Changing Pulley DiameterLook for discharge damper at < 100% open More energy-efficient to slow fan than throttle flow
-
For Variable Flow Applications:Install VFD W2 = W1 (V2/V1)3
Reducing flow by 50% reduces pumping costs by 87%
warm water
cool water
cooling tower
city water make-up
7.5 hp pump
25 hp pump
reservoir
process water return
bypass / pressure relief valve
cooling water to process loads
dP
VSD
-
Variable Speed Pumping on HVAC Chilled Water LoopsReplace 3-way Valve with 2-way valve on AHU
-
VFDs on Vent Hoods
-
Need Controls for VFDs on Dust Collection
-
Use VFDs on Cooling Tower Fans
-
Pump Long, Pump SlowIdentify intermittent pumping applicationsMore energy to pump at high flow rate for short period than low flow rate longerExample: Current: Two pumps in parallel for four hoursRecommended: One pump for six hoursEstimated Savings: $500 /yrReason: Wfluid = V DP = k V3
-
Optimize Efficiency of Pumps/Fans
-
Correct Fan Inlet/Exit Conditions No Yes
-
Refurbish Inefficient Pumps Pump not operated at peak efficiency in middle of operating range
-
Resize Miss-sized PumpsPump operating at off-design point MEff = 47%Replace with properly sized pumpEstimated savings: $14,000 /yr
-
Fluid Flow SummaryReduce Required Pump/Fan HeadReduce excess elevation headSmoother pipes/ductsLarger diametersGradual elbowsEmploy Energy Efficient Flow Control Constant speed pumping: trim impellor bladeConstant speed fans: Slow fanVariable flow: Install VFDsPump slow, pump longImprove Efficiency Pumps/FansCorrect fan inlet/exit conditionsRefurbish inefficient pumpsResize miss-sized pumps/fans
************************************