[Bldg-sim] Gross cooling capacity at ARI conditions

Kingsley, Michael L. MICHAEL.L.KINGSLEY at saic.com
Fri Jan 11 06:52:45 PST 2013


Don't forget to deal with the fan heat as well.

gross cooling capacity - fan heat = net (rated) cooling capacity

 

gross cooling capacity is therefore higher than net capacity, and the
gross EIR will be higher due to both the reduction in electrical  input
(fan input taken out) as well as the higher cooling capacity.

 

Since the fan input energy and heat load are still dealt with, albeit
separately, the net capacity and net EIR are still as expected (rated).

 

I hope this is clear.

 

Best regards,

 

Mike

 

Michael L. Kingsley, PhD, PE, CPMP, LEED AP

Senior Engineer/Project Manager | Energy Efficiency & Demand Response

SAIC Energy, Environment & Infrastructure, LLC

office: 315.434.7205 | mobile: 315.373.4081

www.saic.com/EEandI <http://www.saic.com/EEandI> 

 

 

 

From: bldg-sim-bounces at lists.onebuilding.org
[mailto:bldg-sim-bounces at lists.onebuilding.org] On Behalf Of Nick Caton
Sent: Thursday, January 10, 2013 1:04 PM
To: Rasheed Ahmad; bldg-sim at lists.onebuilding.org
Subject: Re: [Bldg-sim] Gross cooling capacity at ARI conditions

 

I'm not terribly satisfied with the clarity of terminology in the
example provided...

 

The basic concept is "gross (nominal) cooling energy" - "fan energy
input" = "non-fan cooling energy"

 

Put another way, you can ultimately arrive at a cooling EIR (independent
of fan energies) by subtracting the fan kW from the system total kW at
ARI conditions.

 

Trying to present this using capacities instead of kW is only confusing
the point they mean to make, as I understand it.

 

Hope that helps!

 

~Nick

 

 

NICK CATON, P.E.

SENIOR ENGINEER

 

Smith & Boucher Engineers

25501 west valley parkway, suite 200

olathe, ks 66061

direct 913.344.0036

fax 913.345.0617

www.smithboucher.com 

 

From: bldg-sim-bounces at lists.onebuilding.org [
mailto:bldg-sim-bounces at lists.onebuilding.org] On Behalf Of Rasheed
Ahmad
Sent: Thursday, January 10, 2013 6:43 AM
To: bldg-sim at lists.onebuilding.org
Subject: [Bldg-sim] Gross cooling capacity at ARI conditions

 

Hello All,

 

>From the user's guide, the fan power should be removed from the standard
EER
rating of packaged cooling systems. 
 
 
 
A 15-ton packaged rooftop single-zone system having an EER of 8.6 (COP
of
2.5) is
 
specified for a building. The following table gives the design
specifications. How should
 
this be modeled?
 
Equipment parameter                               Value
 
Net Cooling Capacity (Btu/h)                   174,000
 
Total Packaged Unit Input Power (W)        20,128
 
EER                                                         8.64
 
Gross Cooling Cap (ARI conditions)         182,000
 
The supply fan power is the difference between the gross and the net
cooling
capacity.
 
So my Query is that Gross Cooling capacity ( ARI Condition ) is same for
all Packaged system of any tonnage ??? Is it standard one or what ????
........Like i have 1.5 
 
ton of PTAC system, so for 1.5 ton of PTAC system also its gross cooling
capacity is same 182,000????
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