[Equest-users] Refrigeration Modeling (2) - Zone Load

Yoni Pollak ypollak at gtp-eng.com
Mon Aug 6 11:34:48 PDT 2012


Chris, thanks for the help!  

 

I agree with what you are saying, the REFG-ZONE-LOAD is the load the space
imparts on the refrigeration case, but that is also the same load the case
imparts on the space, hence the 'free cooling'.

 

Thanks again for confirming the negative number in this keyword!  

 

 

 

Yoni G. Pollak, PE

(T) 770-622-2270

 

From: Chris Jones [mailto:cj at enersave.ca] 
Sent: Monday, August 06, 2012 1:52 PM
To: ypollak at gtp-eng.com; equest-users at lists.onebuilding.org
Cc: equest-users at lists.onebuilding.org; Curt Hepting
Subject: RE: [Equest-users] Refrigeration Modeling (2) - Zone Load

 

I am rethinking my interpretation of the REFG-ZONE-LOAD - I know believe the
manual means "the load on the case work due to heat gain from the adjacent
space" - the larger ( larger in the negative direction ) the zone load, the
move compressor is used.  The reciprocal, heat loss in the space due to the
coolness "spilling out of the cases" is not taken into account by the
program.  Therefore the larger the negative number, the more there is "heat"
in the space and the higher the unmet cooling hours.  Just a guess but if
you fix the REFG-ZONE-LOAD and change the space temperature you achieve the
same effect - lower the space heating temperature set point, the lower the
unmet cooling hours.  If that is the case, then I suspect that the space
somehow sees the zone load as increase in heat in the space?

This would indicate that there are other REFG keywords that might influence
the heat gain to the space due to the compressor working harder when
REFG-ZONE-LOAD is larger.  



At 10:33 AM 06/08/2012, Yoni Pollak wrote:



Chris,
 
You might be right about that heat ending up in the space, but that doesn't
sound right to me.  I was getting an error when REFG-AUK-KW was 0, so I
reset it.  I've actually played around with that number quite a bit since it
seems to have a large impact on the energy consumption.  I'll revisit it
again this morning.  
 
I'm talking aboiut umnet cooling load hours.  The REFG-ZONE-LOAD keyword
seems to be directly related to my space loads but in the opposite way I
thought.  The more REFG-ZONE-LOAD, the more system cooling the space
requires.  
 
 
 
Yoni G. Pollak, PE
(T) 770-622-2270
 
From: Chris Jones [ mailto:cj at enersave.ca <mailto:cj at enersave.ca> ] 
Sent: Saturday, August 04, 2012 12:15 PM
To: ypollak at gtp-eng.com; equest-users at lists.onebuilding.org
Cc: equest-users at lists.onebuilding.org
Subject: Re: [Equest-users] Refrigeration Modeling (2) - Zone Load
 
There are a number of other REFG- keywords that depend on REFG-ZONE-LOAD.
For example:
REFG-AUK-KW - takes three entries (order corresponds to REFG-ZONE-LOAD) of
the fractional rated capacity of lights, fans, anti-sweat heaters - the
default is 40% of the REFG-ZONE-LOAD - I am not entirely sure but I believe
this heat ends up in the space.  

Also, do you mean the unmet load hours are cooling load unmet or heating
load unmet?
 


At 10:21 AM 03/08/2012, Yoni Pollak wrote:

Content-Type: multipart/alternative;
         boundary="----=_NextPart_000_0096_01CD7161.C28847D0"
Content-Language: en-us

Hi All,
 
Has anyone had experience modeling refrigeration cases?  I posted a question
the other day but this one is different.
 
So under Air-Side HVAC Zone Parameters > Refrigeration Tab, Zone Load
(REFG-ZONE-LOAD) I entered the free cooling affect from the refrigeration
cases to the space (as described in the key word help).  But looking at the
SIM file, this parameter is increasing my zone loads rather than decreasing
them, and in fact is causing my space to have more unmet load hours.  Should
I apply a negative number to this parameter, or is this parameter not the
'free cooling' affect.  
 
 
That along with the Walkin Box Load under the Air-Side HVAC System
Parameter.  Not sure how the program is using this value.
 
Thanks!
 
 
 
 
Yoni G. Pollak, P.E.
Mechanical Engineer
 
GTP Consulting Engineers, Inc
4197 Pleasant Hill Rd 
Suite 200
Duluth, GA 30096
(770) 622-2270
ypollak at gtp-eng.com
 
 
 
 
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>>
Christopher Jones, P.Eng.
Suite 1801, 1 Yonge Street
Toronto, ON M5E1W7
Tel. 416-203-7465
Fax. 416-946-1005
email cj at enersave.ca

>>
Christopher Jones, P.Eng.
Suite 1801, 1 Yonge Street
Toronto, ON M5E1W7
Tel. 416-203-7465
Fax. 416-946-1005
email cj at enersave.ca

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