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Learning Objectives Definition of System Effect How to calculate System Effect System Effect’s effect on power consumption The difference between inlet and outlet System Effect How to avoid System Effect

Fan Efficiency Efficiency, η Results of a fan air performance test are plotted on a curve similar to this. Air Flow, Q

Regulation 3 – 5 % 76 million ton2 of coal Efficiency, η Results of a fan air performance test are plotted on a curve similar to this. Air Flow, Q

What we can do Efficiency, η Results of a fan air performance test are plotted on a curve similar to this. Air Flow, Q

What we can do 25 - 40 % Efficiency, η Results of a fan air performance test are plotted on a curve similar to this. Air Flow, Q

Fan Testing for Air Performance These are pictures of the AMCA Lab. Fans come in to the lab. They’re tested. They get installed. And the performance of the system falls short. What happened?

AMCA Standard 210 Test Fan Auxiliary Fan Nozzles Fan Airflow Piezometer Ring Fan Static Pressure This is a typical fan test setup at AMCA. We measure fan static pressure with a Piezometer ring We measure airflow with nozzles, using Bernoulli’s equation and pressure drop across the nozzles We calculate Fan Total Pressure by adding the Velocity Pressure at the fan outlet to Fan Static Pressure, so fan total pressure is strictly a convention. The auxiliary fan on the right overcomes the pressure loss in the chamber so that we can determine fan performance near free delivery PS = PT – PV PT = PT2 – PT1 PS = PT2 – PT1 – PV PT2 = PS2 + PV2 PS = PS2 + PV2 – PT1 – PV PV = PV2 PS = PS2 + PV2 – PT1 – PV2 PS = PS2 – PT1 PT1 open to atmosphere PS = PS2 PS = PS7

Nozzle Wall These are pictures of the AMCA Lab. Fans come in to the lab. They’re tested. They get installed. And the performance of the system falls short. What happened?

AMCA 210 Test Results 800 2.5 700 2 600 500 1.5 Pressure, P 400 Power, H 1 300 Results of a fan air performance test are plotted on a curve similar to this. 200 0.5 100 2 4 6 8 10 12 Air Flow, Q

AMCA Standards 500-D & -L Piezometer Ring Damper Pressure Drop Nozzles Test Damper Auxiliary Fan Nozzles Damper Airflow Piezometer Ring Damper Pressure Drop This figure illustrates a pressure drop test of an air system component. This figure shows a damper under test, but there are similar tests for louvers, silencers and other components

Fan Operating Point AMCA 500-D Test Results Operating Point 700 600 400 Pressure, P Results of a pressure drop test are plotted on a graph similar to this What this graph actually shows is a system curve for a typical air system where the system resistance follows a parabolic curve For simple systems, resistance is calculated by adding the pressure drops of the system’s components It’s understood that a fan system curve is not strictly parabolic, but it’s shown here as a parabolic curve as this estimation is close enough to reality for this presentation’s purposes. AFTER SECOND CLICK The fan operating point, or the system’s operating point is at the intersection of the system curve and fan curve 300 200 100 2 4 6 8 10 12 Air Flow, Q

Speed Change New Operating Point New speed Operating Point 800 700 600 500 New speed Operating Point 400 Pressure, P 300 A change in speed of the fan will create a new a new fan curve with a new intersecting point somewhere on the system curve 200 100 2 4 6 8 10 12 14 Air Flow, Q

Damper Opening Operating Point New Operating Point New System 700 600 500 Operating Point 400 New Operating Point Pressure, P 300 Changing the system will create a new system curve with a new intersecting point somewhere on the fan curve New System 200 100 2 4 6 8 10 12 Air Flow, Q

System Effect 1ST Definition Installed duct configuration does not match tested duct configuration

Installation Type D —Ducted Inlet / Ducted Outlet Auxiliary Fan Nozzles Fan Airflow Piezometer Ring Fan Static Pressure Test Fan Plenum This is a typical fan test setup at AMCA. What’s important to note here are the ducts on the inlet and outlet. These model a ducted inlet/ducted outlet configuration or Installation Type D. Why is this important? Because if the fan is installed on a plenum without ducts, the fan will not perform as well as when it was tested in the lab. It’s important to match as closely as possible the tested duct configuration to the actual duct configuration where the fan will be installed. (Note to presenter: 2nd click removes chamber, moves fan and ducts to the center) Installed Fan

AMCA Catalog Ratings “Performance certified is for installation type: A: Free inlet, Free outlet” B: Free inlet, Ducted outlet” C: Ducted inlet, Free outlet” D: Ducted inlet, Ducted outlet” These ratings are found in catalogs of certified products. For certified products it is mandatory to include these statements so the use knows how the fan was tested, and whether or not it matches how the fan will be installed.

System Effect 2nd Definition Even when the tested duct configuration matches the installed duct configuration, improper duct design can introduce adverse flow conditions

Elbow Example One example of a System Effect cause would be elbows installed adjacent to the fan’s inlet and outlet. Even if the friction loss of the elbow was properly accounted for, the proximity of the elbow to the inlet of the fan adversely affects the fan’s performance The uneven velocity profile on the fan’s outlet, or the high velocity jets on the fan’s outlet, cause the actual pressure drop through the elbow to be much greater than that calculated assuming a fully developed flow profile.

AMCA Publication 201—Plenum Example This is an example taken from Publication 201 It shows the difference in required Fan Static Pressure solely due to the change in location of a plenum

Plenum Example REQUIRED Fan PS 922 Pa E-F duct friction at 5000CMH (Q) 747 Pa (duct design) E contraction loss-plenum to duct 50 Pa (part of duct system) E PS energy required to create velocity at E 125 Pa (part of duct system) D PV loss (also PT loss) at D as result of air velocity decrease 0 Pa PS does not change from duct to plenum at D C-D outlet duct on fan as tested 0 Pa -------------------- REQUIRED Fan PS 922 Pa

Plenum Example Plenum This is an example taken from Publication 201 It shows the difference in required Fan Static Pressure solely due to the change in location of a plenum

Plenum Example Note the new location of the plenum, and the new Fan Static Pressure requirement due to System Effect. The next pages show how we arrived at a System Effect Factor of 150 Pa D-E duct friction at 5000CMH (Q) 747 Pa (duct design) D contraction loss-plenum to duct 50 Pa (part of duct system) D PS energy required to create velocity at D 125 Pa (part of duct system) B-C SEF 149 Pa B-C PV loss (also PT loss) at C as result of air velocity decrease 0 Pa PS does not change from duct to plenum at C ------------------ REQUIRED Fan PS 1071 Pa

Plenum Example from AMCA 201 Assuming: Use of the same fan for both systems Can attain both operating points with a change in speed Speed change ratio; (1071/922)0.5 = 1.08 2 PC = NC N ( ) P 1/2 N𝑐 N = PC P ( )

Plenum Example from AMCA 201 HC = NC N ( ) H 3 H, Fan Power 1.083 = 1.25 (Fan Law for Power) The increased in power consumption to overcome System Effect is about 25%

8% Speed Change 25% More H 8% More Q 800 2.5 700 2 600 500 1.5 Pressure, P 400 Power, H 1 300 SECOND CLICK ADDS CURVES FOR SPEED CHANGE THIRD CLICK CALLS OUT 8% MORE AIR FOURTH CLICK CALLS OUT 25% MORE POWER This is illustrated now to demonstrate the penalty in power consumption when fan speed is increased to deliver more airflow 200 8% More Q 0.5 100 2 4 6 8 10 12 14 Air Flow, Q

Inlet System Effect SYSTEM EFFECT ACTUAL FAN CURVE WITH SYSTEM EFFECT CATALOG PERFORMANCE CURVE DESIGN RESISTANCE AIRFLOW DEFICIENCY DESIGN AIRFLOW

Outlet System Effect ACTUAL SYSTEM WITH SYSTEM EFFECT CALCULATED SYSTEM WITH NO ALLOWANCE FOR SYSTEM EFFECT SYSTEM EFFECT LOSS AT DESIGN AIRFLOW CATALOG PERFORMANCE CURVE DESIGN RESISTANCE AIRFLOW DEFICIENCY DESIGN AIRFLOW

Speed Changes Before Increasing Speed Check with the manufacturer for max safe operating speed Determine expected power increase Motor size Electric Service Expect more noise

Rules of Thumb Minimum 2.5 duct diameters on Outlet Minimum 3 to 5 duct diameters on Inlet Avoid inlet swirl

Recommendations Allow enough space in the building design to allow for appropriate fan connections to the system Take into account the fact that the total cost for the building is the original capex cost plus the cost to operate it

Recommendations Use allowances in the design calculations when space or other factors dictate less than optimum arrangement of the fan outlet and inlet connections

Recommendations Include adequate allowance for the effect of all accessories and appurtenances on the performance of the system and the fan Belt drive loss VIVs Belt guards

Questions? Mark Stevens Executive Director AMCA International mstevens@amca.org