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*To*: EnergyPlus_Support@xxxxxxxxxxxxxxx*Subject*: Re: [EnergyPlus_Support] VFD for fans*From*: "Richard J. Liesen" <rliesen@xxxxxxxx>*Date*: Wed, 16 Jun 2004 09:56:23 -0500*Delivered-to*: lawrie.com%linda@xxxxxxxxxx*Delivered-to*: mailing list EnergyPlus_Support@xxxxxxxxxxxxxxx*In-reply-to*: <capkec+bqts@eGroups.com>*List-unsubscribe*: <mailto:EnergyPlus_Support-unsubscribe@yahoogroups.com>*Mailing-list*: list EnergyPlus_Support@xxxxxxxxxxxxxxx; contact EnergyPlus_Support-owner@xxxxxxxxxxxxxxx*References*: <capkec+bqts@eGroups.com>*Reply-to*: EnergyPlus_Support@xxxxxxxxxxxxxxx

Hello, The way specific variable speed fan models account for their energy consumption for a given flow rate is by Fan Delta Pressure, efficiency, fan curves, etc. All of these are found in the InputOutput Reference document for the Fan:Simple:Variable Volume object. The input changes that are necessary to model different variable volume fans of the same size and efficiency is with the fan curves which are specified by a curve fit with the 5 coefficients specified as input. I have included Table 18 and the description of the fan coefficient fields from the IO Ref doc. To model your VFD drive you would have to fit that fans curve and enter the 5 coefficient fit in for your fan. What I would do is take the Variable Speed Motor coefficients and plot them with a spreadsheet program. Then compare them to the VFD fan curves that you are trying to model. Then either fit the curve for the VFD drive or adjust the coefficients for the variable speed motor until that curve represents the VFD drive's fan curve. Compare these to the existing variable speed motor fan curve to determine that it represents the fan you are trying to simulate. Then enter the new coefficients for that fan. Thanks Richard Liesen Table 18. Fan Coefficient Values Type of Fan Fan Coeff. 1 Fan Coeff. 2 Fan Coeff. 3 Fan Coeff. 4 Fan Coeff. 5 Inlet Vane Dampers 0.35071223 0.30850535 -0.54137364 0.87198823 0.000 Discharge Dampers 0.37073425 0.97250253 -0.34240761 0.000 0.000 Var. Speed Motor 0.0015302446 0.0052080574 1.1086242 -0.11635563 0.000 Field: FanCoefficient 1 The constant coefficient (C1) in a fourth order polynomial curve giving the fraction of full load power (PLF) as a function of flow fraction (FF). Flow fraction is the air mass flow rate divided by the maximum air mass flow rate. The curve is: PLF = C1 + C2. FF + C3. FF2 + C4. FF3 + C5. FF4 Field: FanCoefficient 2 The linear coefficient (C2) in a fourth order polynomial curve giving the fraction of full load power (PLF) as a function of flow fraction (FF). Flow fraction is the air mass flow rate divided by the maximum air mass flow rate. The curve is: PLF = C1 + C2. FF + C3. FF2 + C4. FF3 + C5. FF4 Field: FanCoefficient 3 The quadratic coefficient (C3) in a fourth order polynomial curve giving the fraction of full load power (PLF) as a function of flow fraction (FF). Flow fraction is the air mass flow rate divided by the maximum air mass flow rate. The curve is: PLF = C1 + C2. FF + C3. FF2 + C4. FF3 + C5. FF4 Field: FanCoefficient 4 The cubic coefficient (C1) in a fourth order polynomial curve giving the fraction of full load power (PLF) as a function of flow fraction (FF). Flow fraction is the air mass flow rate divided by the maximum air mass flow rate. The curve is: PLF = C1 + C2. FF + C3. FF2 + C4. FF3 + C5. FF4 Field: FanCoefficient 5 The coefficient C5 in a fourth order polynomial curve giving the fraction of full load power (PLF) as a function of flow fraction (FF). Flow fraction is the air mass flow rate divided by the maximum air mass flow rate. The curve is: PLF = C1 + C2. FF + C3. FF2 + C4. FF3 + C5. FF4 At 09:11 AM 6/16/2004, you wrote: >I uploaded a idf file to the folder "Files". > >The file name is: Chesapeake_DXVAV_SA55.IDF, it's under my ID: >liao_lucia and posted on 06/06/2004. In which there are 2 fans of >SIMPLE:Variable Volume. > >I talked to the facility guy and found out that they upgraded the >fans with VFDs (variable frequency drive). How can my model reflect >the change ? > >Thanks. > >Lucia > > > > > > >The primary EnergyPlus web site is found at: >http://www.energyplus.gov > >The group web site is: >http://groups.yahoo.com/group/EnergyPlus_Support/ > >Attachments are not allowed -- please post any files to the appropriate >folder in the Files area of the Support Web Site. > >Yahoo! Groups Links > > > > ------------------------ Yahoo! Groups Sponsor --------------------~--> Make a clean sweep of pop-up ads. Yahoo! Companion Toolbar. Now with Pop-Up Blocker. Get it for free! http://us.click.yahoo.com/L5YrjA/eSIIAA/yQLSAA/dkFolB/TM --------------------------------------------------------------------~-> The primary EnergyPlus web site is found at: http://www.energyplus.gov The group web site is: http://groups.yahoo.com/group/EnergyPlus_Support/ Attachments are not allowed -- please post any files to the appropriate folder in the Files area of the Support Web Site. Yahoo! Groups Links <*> To visit your group on the web, go to: http://groups.yahoo.com/group/EnergyPlus_Support/ <*> To unsubscribe from this group, send an email to: EnergyPlus_Support-unsubscribe@xxxxxxxxxxxxxxx <*> Your use of Yahoo! Groups is subject to: http://docs.yahoo.com/info/terms/

**References**:**[EnergyPlus_Support] VFD for fans***From:*liao_lucia

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