[Equest-users] Cooling Energy and Exhaust air heat recovery

Mateo Guadalfajara mateo_mw at hotmail.com
Mon May 17 09:30:42 PDT 2010


I have found an explanation:

Look your air system. 

 

      If your cooling system is installed before the heat exchanger you will cool the air and then heat it. So you will need much more energy than without HE. So change the position of the HE in the system. In theory that can be the problem but I don´t have experience with complex energy systems on eQUEST.

 

example summer day 

 

outdoor air ... 30ºC

Cross the cooling system 20ºC   --->delta T=10ºC

cross the HE system 25ºC

 

Without HE

outdoor air ... 30ºC

Cross the cooling system 25ºC   --->delta T=5ºC

 

 

               Mateo de Guadalfajara.

 

 

Mateo de Guadalfajara Pinilla

mateo_mw at hotmail.com

Engineer Energy systems and construction Student

Looking for a job :)

 

 





Date: Mon, 17 May 2010 11:55:04 -0400
From: Glenn.Haynes at kema.com
To: aazhari at jainconsultants.com; equest-users at lists.onebuilding.org
Subject: Re: [Equest-users] Cooling Energy and Exhaust air heat recovery







Your cooling loads are so small, I suspect there is some kind of net effect (sometimes smaller, sometimes greater loads) happening.  For example, if your ERV is sensible only, perhaps the increase in latent loads is more than offsetting your sensible savings.  Can't tell without knowing more about your system and your weather data.  Take a look at your hourly "savings" for clues.
 
Glenn



From: equest-users-bounces at lists.onebuilding.org [mailto:equest-users-bounces at lists.onebuilding.org] On Behalf Of Ahmed Azhari
Sent: Monday, May 17, 2010 11:21 AM
To: equest-users at lists.onebuilding.org
Subject: [Equest-users] Cooling Energy and Exhaust air heat recovery




Hello Users, 
 
I have a packaged (Heating: Gas-Fired, Cooling: DX) air handling unit with VAV boxes in the zones. The cooling coil control for the AHU is Zone reset. I have noticed an odd behavior in the cooling side when I model an exhaust air heat recovery as follow:
 
   
The cooling energy increase from 67.7MBTU to 132MBTU when I include 70% exhaust air heat recovery which doesn’t physically make sense to me.
 
When I change the cooling coil control to Outdoor air reset the results change as follow:
 

 
The above scenario makes sense in a way that both the heating and cooling energy decreased by incorporating exhaust air heat recovery.  
 
I appreciate any explanation on the strange behavior of scenario I
 
Best Regards, 
__________________________________________________________________________
Ahmed Azhari, B.Eng., LEED® AP
Energy Analyst
 
Jain Sustainability Consultants Inc.
 
2260 Argentia Road, 2nd Floor
Mississauga, Ontario L5N 6H7, CANADA
Tel:  (905) 542 7211 Ext 234
Fax: (905) 542 7622
Email: aazhari at jainconsultants.com
Web: www.jainassoc.com
 
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