[Equest-users] Heat Rejection consumption is so small!!

[Omar Katanani]

Pasha,

 

Thanks for your support!

 

Attached is the Baseline scenario. A colleague of mine once modelled a
big Mall and got the values for Heat Rejection even greater than those
of the Space Cooling! Please find the attached small excel file.

 

As for my school project, the heat rejection is negligible! This is my
concern. Can you please check my tower parameters and the condenser loop
and advise accordingly?

 

Many thanks to all,

Omar

___________________________

Omar Katanani
Sustainable Design Engineer

Email: omar at ecoconsulting.net

 

EcoConsulting (Lebanon)

Nahas Building, 4th floor

4 St-Maron Street / Georges Haddad Avenue

Postal Code: 2028 5806 SAIFI

Beirut, Lebanon

Tel:          +961 (0) 1 971 255
Mobile:    +961 (0) 3 045 045

 

EcoConsulting (UK) Ltd
28 Marshalsea Road
London, SE1 1HF
Tel:  +44 (0) 207 939 0989
Fax:  +44 (0) 207 939 0981

Website: www.ecoconsulting.net <http://www.ecoconsulting.net/> 

 

 

-----Original Message-----
From: Pasha Korber-Gonzalez [mailto:pasha.pkconsulting at gmail.com] 
Sent: 15 July 2010 21:46
To: Omar Katanani
Cc: equest-users at lists.onebuilding.org
Subject: Re: [Equest-users] Heat Rejection consumption is so small!!

 

Hi Omar,

 

here are my thoughts based on your questions and info.

 

First, when I read the condenser/heat rejection baseline requirements
from 90.1-2007 I interpret that it is not indicating two separate
condenser loops, it is stating "individual condenser loop pumps per
chiller", there for you would still have one condenser circulation loop
serving both chillers and one cooling tower.

 

Next, if you have heard from designers with experience in the Lebanon
climate characteristics that your heat rejection energy should be
upwards of 10% then you could/should trust thier given experience.
However; you need to ask them what is this 10% relative too?   Are they
implying that 10% of the whole building end use energy should be around
10% for the Lebanon climate?   (my opinion:  I doubt it.)   Are they
implying that 10% of the Chilled Water System end use energy (i.e.
CHW-chiller, CHW-pumps, CHW-condenser water systems including pumps &
tower, etc?)   (my opinion:  I would guess that this 10% value is
relative to HVAC system(s) end use energy, not whole building end use
energy.  Or is that 10% relative only to the chilled water-side of the
systems (extracted from the total HVAC energy which would include
heating energy.)

 

Last,  if you would like to attach your .pd2 & .inp file myself, or
maybe others might be available to peruse your project file and give you
some indication if your end use heat rejection energy is falling within
a reasonable whole building energy range.

 

p.s.  if you are using a unique (non-eQuest) Lebanon climate weather
file, please attach that too so that I can run your file on my computer.

 

pkg

On Thu, Jul 15, 2010 at 4:54 AM, Omar Katanani <omar at ecoconsulting.net>
wrote:

 

Dear all,

 

What are typical values for heat rejection, if my Space Cooling
constitutes 25% of my school consumption? All I'm getting is 1% or so!

 

I left eQUEST to autosize the capacity of the tower, and I entered many
default values into the inputs of the Open Tower and the Condenser Loop.
I've heard that Heat Rejection in such climates such as Lebanon should
reach at least 10%.

 

One more thing, when modeling the baseline case according to ASHRAE
90.1, I read that I should model a condenser water loop for each
chiller. So if I have 2 chillers, will I need 2 Open Towers?

 

Many thanks,

Omar

___________________________

Omar Katanani
Sustainable Design Engineer

Email: omar at ecoconsulting.net

 

EcoConsulting (Lebanon)

Nahas Building, 4th floor

4 St-Maron Street / Georges Haddad Avenue

Postal Code: 2028 5806 SAIFI

Beirut, Lebanon

Tel:          +961 (0) 1 971 255
Mobile:    +961 (0) 3 045 045

 

EcoConsulting (UK) Ltd
28 Marshalsea Road
London, SE1 1HF
Tel:  +44 (0) 207 939 0989
Fax:  +44 (0) 207 939 0981

Website: www.ecoconsulting.net <http://www.ecoconsulting.net/> 

 

 

 


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