Greenheck QEI-L - Drive Comparison and Operating Costs; Belt Drive vs. Direct Drive and Efficiency Savings

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Belt Drive versus Direct Drive
Example of Annual Operating Cost Savings
Forasystemperformancerequirementof25,000cfmat2.5inchesofstaticpressure(wg)thecorresponding
operatingpowerrequirementsare13.97BhpwithaQEI-Isize36and19.8Bhpforasize36tubularcentrifugalfan.
Formulas:
-Kilowatt-Hours=(OperatingPower(Bhp)x0.746xHoursofOperation)/MotorEfficiency
-OperatingCost=Kilowatt-HoursxPowerCostperkWhour
Assumptions:
-Costofelectricityis$0.09perkilowatthour
-3,120annualhoursofoperation(12hoursperday,fivedaysaweek,52weeksayear)
-93.0%motorefficiency(equaltoNEMAPremiumminimumefficiencyfor15and20hp,ODP,1725rpmmotor)
Annual Operating Cost Savings = $4,460 - $3,147 = $1,313
High Efficiencies = Lower Operating Costs
Tubular Centrifugal Fan
kW-Hours=(19.8Bhpx0.746x3120)/0.93=49,554
OperatingCost=49,554x$0.09=$4,460
QEI-I - Mixed Flow Fan
kW-Hours=(13.97Bhpx0.746x3120)/0.93=34,963
OperatingCost=34,963x$0.09=$3,147
Belt Drive Advantages
• Lowersoundlevels
• Motoroutoftheairstreamforeasyaccess
• Motorsizemaybechangedtoaccommodate
possiblefutureaircapacityrequirements
• Finalsystembalancingaccomplishedby
changingdrives
Direct Drive Advantages
• Fewerwearcomponentsandlessmaintenance,no
shaft,bearings,pulleys,orbelts
• Morecompactthanequivalentbeltdrivesize
• Motorinairstreamforincreasedmotorefficiency
andcooling
• Equalloadingbetweenmountingbrackets
• Finalsystembalancingaccomplishedbyadjusting
themotorspeed(ex.variablefrequencydriveuse).