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

[Omar Katanani]

James,

 

Thank you for your advice.

 

I did what you told me regarding the LOAD RESET for the condenser water loop. Please find the attached excel file with the results.

 

I am happy that the heat rejection is now a significant number. However:

 

1.	The space cooling for the proposed case is now higher than the baseline case, which is unacceptable due to the better HVAC system
2.	The space cooling for both cases has decreased significantly. Can you please check the numbers and the percentages of the space cooling with respect to the whole building consumption?

 

Unfortunately, I may keep the condenser water loop controls at "Fixed" and "setpoint = 85F", because of the first reason up.

 

Best regards,

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: James Hansen [mailto:JHANSEN at ghtltd.com] 
Sent: 21 July 2010 17:59
To: Omar Katanani; equest-users at lists.onebuilding.org
Subject: RE: [Equest-users] Heat Rejection consumption is so small!!

 

Cooling towers are just fans, so it's no surprise that their percentage relative to the total consumption is small.  Make sure your cell KW or total fan EIR is accurate.

 

And as for your question on reset:  I usually just specify the condenser water loop control strategy to be LOAD RESET, with a minimum reset temperature of 70 degrees.  

 

GHT Limited
James Hansen, PE, LEED AP

Senior Associate

1010 N. Glebe Rd, Suite 200

Arlington, VA  22201-4749

703-338-5754 (Cell)

703-243-1200 (Office)

703-276-1376 (Fax)

 <http://www.ghtltd.com/> www.ghtltd.com

 

 

From: equest-users-bounces at lists.onebuilding.org [mailto:equest-users-bounces at lists.onebuilding.org] On Behalf Of Omar Katanani
Sent: Wednesday, July 21, 2010 9:55 AM
To: Omar Katanani; equest-users at lists.onebuilding.org
Subject: Re: [Equest-users] Heat Rejection consumption is so small!!

 

 

Dear all,

Can anyone please answer my question that I sent last week? Your continuous support is much appreciated!
In addition to that, I have this small question below:

Section G3.1.3.11 of ASHRAE 90.1 - 2007 says:

"Condenser water design supply temperature shall be 85°F or 10°F approaching design wet-bulb temperature, whichever is lower, with a design temperature rise of 10°F. The tower shall be controlled to maintain a 70°F leaving water temperature where weather permits, floating up to leaving water temperature at design conditions."

I was able to put the design set point temperature  and the loop design DT of the Condenser water loop to 85F and 10F respectively.

What about the tower? Where can I input this leaving temperature range from 70F up to the leaving water temperature?


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



-----Original Message-----
From: Omar Katanani
Sent: Thu 7/15/2010 1:54 PM
To: equest-users at lists.onebuilding.org
Subject: Heat Rejection consumption is so small!!



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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