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Re: [EnergyPlus_Support] ASHRAE Compliant Fans and Pumps





Mr. Dirkes,

That's great.Thank you so much for your assistance.

Regards,
Vinay

On Thu, Jul 8, 2010 at 6:21 AM, James V Dirkes II, PE <jvd2pe@xxxxxxx> wrote:
 

Dear Vinay,

 

While .6 fan efficiency is within normal range, the goal is to define a combination of fan efficiency and pressure rise which results in the acceptable fan power.  You start with known air flow, make a reasonable estimate of fan efficiency and then derive the pressure rise.

 

For a ?Proposed? system, the derivation is not needed; you use the actual fan and motor efficiencies, actual airflow and actual pressure rise.

 

For your information (just in case it?s helpful), the derivation of fan power is shown below in IP units.

 

 

 

 

The Building Performance Team
James V. Dirkes II, P.E., LEED AP
1631 Acacia Drive NW
Grand Rapids, MI 49504
616 450 8653

 

From: EnergyPlus_Support@xxxxxxxxxxxxxxx [mailto:EnergyPlus_Support@xxxxxxxxxxxxxxx] On Behalf Of Vinay Devanathan
Sent: Wednesday, July 07, 2010 9:32 PM


To: EnergyPlus_Support@xxxxxxxxxxxxxxx
Subject: Re: [EnergyPlus_Support] ASHRAE Compliant Fans and Pumps

 

 

Mr. Dirkes,

 

Thanks for your reply. So, is 0.6 Fan Efficiency (including motor efficiency) acceptable? or does it depend on any other variable? I am assuming there are no set specifics for Fan Efficiency value. So, with this procedure, we can calculate Fan Power from Appendix G formula and adjust Pressure difference. Am I right on this?


Thank you.

Regards,

Vinay

 

On Wed, Jul 7, 2010 at 9:25 PM, James V Dirkes II, PE <jvd2pe@xxxxxxx> wrote:

 

Dear Vinay,

 

ASHRAE 90.1-2007 specifies Baseline system fan power in Table G3.1.2.9.  For VAV systems, also use Table G3.1.3.15 for part load performance.  A sample object for the VAV fan is shown below.

 

For all baseline fans, I made a spreadsheet which, based on anticipated motor and fan efficiency, calculates the pressure rise which will result in the correct ASHRAE 90.1 fan power.  Remember that E+, when asking for ?fan efficiency?, really wants (Fan mechanical efficiency x Motor efficiency).  For example, if the fan mechanical efficiency  = .60 and motor efficiency = .90, the E+ ?fan efficiency? = .54.

 

 

Fan:VariableVolume

Name

SFan_MainBldg

Availability Schedule Name

SchCpct_FanOpern

Fan Efficiency (incl. motor)

0.6

Pressure Rise (Pa)

498

Maximum Flow Rate

Autosize

Minimum Flow Rate

0

Motor Efficiency

MT

Motor In Airstream Fraction

1

Fan Coefficient 1

0.0013

Fan Coefficient 2

0.147

Fan Coefficient 3

0.9506

Fan Coefficient 4

-0.0988

Fan Coefficient 5

0

Air Inlet Node Name

NodeOut_ClgCoilAir_MainBldg

Air Outlet Node Name

NodeOut_SFan_MainBldg

End-Use Subcategory

 

 

The Building Performance Team
James V. Dirkes II, P.E., LEED AP
1631 Acacia Drive NW
Grand Rapids, MI 49504
616 450 8653

 

From: EnergyPlus_Support@xxxxxxxxxxxxxxx [mailto:EnergyPlus_Support@xxxxxxxxxxxxxxx] On Behalf Of Vinay Devanathan
Sent: Wednesday, July 07, 2010 5:53 PM

Subject: Re: [EnergyPlus_Support] ASHRAE Compliant Fans and Pumps

 

 

Alan,

In regards to your reply,

Does ASHRAE specify any efficiency value for the fans? If yes, could you please direct me to the same.

Thank you.

Regards,
Vinay

On Tue, Jun 29, 2010 at 11:33 AM, Jackson, Alan <ajackson@xxxxxxxxxxxxxxxxx> wrote:

 

You're going to want to adjust your Static Pressure DeltaP. Once you
have your Watts for the Baseline from auto sizing the flow you can use
DeltaP[Pa] = Power[W]*Eff/Flow[m3/s]

Since ASHRAE is telling you Flow and Power you have to solve for static.

Alan Jackson, LEED AP
KlingStubbins



-----Original Message-----
From: EnergyPlus_Support@xxxxxxxxxxxxxxx
[mailto:EnergyPlus_Support@xxxxxxxxxxxxxxx] On Behalf Of eddiecorwin
Sent: Tuesday, June 29, 2010 11:13 AM
To: EnergyPlus_Support@xxxxxxxxxxxxxxx
Subject: [EnergyPlus_Support] ASHRAE Compliant Fans and Pumps

I am curious as to how people have gone about modeling ASHRAE compliant
pumps and fans.

The pumps seem relatively strait forward, run the model, see what the
flow is, then enter in a wattage that equates to 22W/GPM. The fans,
however, do not have an input for the rated wattage. The only option I
see is to alter the fan's Motor Efficiency until you get close to the
correct W/CFM.

Are these the same methods people have applied in the past, or is there
a better way to the the correct W/GPM and W/CFM?

------------------------------------



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Primary EnergyPlus support is found at:
http://energyplus.helpserve.com or send a message to energyplus-support@xxxxxxxx

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 currently allowed but be mindful that not everyone has a high speed connection.  Limit attachments to small files.

EnergyPlus Documentation is searchable.  Open EPlusMainMenu.pdf under the Documentation link and press the "search" button.




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