[Equest-users] 90.1 App G Fan Power and EER Calculations

[Steve Burley]

Uday,

My understanding is the EER in the table, in this case 11.2 for packaged AC between 65,000 and 135,000 Btu/h, is the overall efficiency of the equipment, i.e. including the fan power. It seems from what you have written below you say it does not; is that correct?

Regards,

Steven Burley

From: Uday Gorre [mailto:u_k_gorre at ateindia.com]
Sent: 29 May 2012 16:41
To: Steve Burley
Subject: RE: [Equest-users] 90.1 App G Fan Power and EER Calculations

Dear Steven Burely

How you calculated the  EIR (0.1779).

As per my calculations

COP= EER/3.412   = 11.2/3.412 = 3.28 ( Generally  EER = (Cooling Load/ Work input)* 3.412    here cooling load is in btu/hr  and work input is compressor and condenser power in W )

Work input =  Cooling load/ COP = 23445.7 (in W)/3.28 =7148 W  (Not included fan power)

Fan Power mentioned below is  2972 W

Gross input power = 2942 + 7148 =10090 W

EIR=1/COP= 1/3.28 = 0.3048   (Cooling equipment)


Regards

Uday...







From: equest-users-bounces at lists.onebuilding.org<mailto:equest-users-bounces at lists.onebuilding.org> [mailto:equest-users-bounces at lists.onebuilding.org] On Behalf Of Steve Burley
Sent: 29 May 2012 5:07 PM
To: equest-users at lists.onebuilding.org<mailto:equest-users at lists.onebuilding.org>
Subject: [Equest-users] 90.1 App G Fan Power and EER Calculations

I'm sure this must have been asked before but I cannot find an answer in the archives - if there is one please point me to it.

I have interpreted the requirements of 90.1, App. G to split the EER of cooling equipment with a supply fan into its components to model the fan energy separately as follows:


1.       Say a space has a cooling load of 80,000Btu/h and the system is packaged single zone, EER - 11.2.

2.       Calculate airflow for 20°F temperature difference - 3708cfm

3.       Calculate fan bhp from Table G3.1.2.9 - 3.49bhp

4.       Calculate fan power as per G3.1.2.9 - 2972W

5.       Calculate gross input power from load and EER - 7143W

6.       Subtract 4 from 5 for compressor/condenser input power - 4171W

7.       Convert to EIR - 0.1779

This appears to make sense from reading App. G but ends up with high fan power consumption and low space cooling loads. Am I wrong here?

Thanks,

Steven Burley


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