Hey Guys,
I’ve been following your discussion since this is similar to
what I’ve been working on lately, but could the imbalance in your cooling load
be created by occupancy or office equipment?
Michael Grant, MIT
Engineering | Systemair Inc.
(T) 1-506-743-9500
From: EnergyPlus_Support@xxxxxxxxxxxxxxx
[mailto:EnergyPlus_Support@xxxxxxxxxxxxxxx] On Behalf Of yangxiaoshan@xxxxxxxx
Sent: June-17-11 10:29 AM
To: EnergyPlus_Support@xxxxxxxxxxxxxxx
Subject: [EnergyPlus_Support] Re: A question about Latent Cooling Load
in E+
Hey, Richard
Thanks a lot. I am not quite understand your idea. Since The Idea Load Air
System component does not control zone humidity levels (just control zone air
temperature). The zone humidity level varies with the outdoor conditions via
infiltration. For "Idea Load Air System",the constant air temperature
and humidity of the air supplied for cooling the zone are 13 degree Celsius and
9 g/kg. According the ASHRAE sizing method (used by E+), total Cooling is the
rate at which total energy (sensible and latent) is removed from the mixed
outside and return air stream in order to bring the mixed air stream to the
specified temperature and humidity ratio of the supply air stream. For this
case, the only source of latent heat gain is by infiltration, and the
infiltration latent heat gain should be equal to total latent cooling load. But
it isn't......
Xiaoshan
--- In EnergyPlus_Support@xxxxxxxxxxxxxxx,
Richard Raustad <RRaustad@...> wrote:
>
> Are you reporting the zone relative humidity? If the zone moisture level
> is dropping, this would explain the difference. You need to keep the
> zone conditions constant for this to work.
>
> On 6/17/2011 8:56 AM, yangxiaoshan@... wrote:
> >
> > Hi,
> > Thanks for your reply. I had set the infiltration rate to 0 or other
> > values. If ACH is 0, there is no latent cooling load and total
cooling
> > load equals to total sensible cooling load. That makes sense. But
once
> > the ACH is not 0, the infiltration heat gain is always less than
> > latent cooling load. I do not know what else items could be also
> > included in the latent cooling load component.
> >
> > Best,
> > Xiaoshan
> >
> > --- In EnergyPlus_Support@xxxxxxxxxxxxxxx
> > <mailto:EnergyPlus_Support%40yahoogroups.com>, YuanLu Li
<yli006@>
> > wrote:
> > >
> > >
> > > Try changing the infiltration air change per hour to zero and to
2
> > to compare.
> > >
> > > There may be other compoent included in the total cooling load.
> > >
> > > Dr. Li
> > >
> > >
> > >
> > >
> > >
> > >
> > >
> > > To: EnergyPlus_Support@xxxxxxxxxxxxxxx
> > <mailto:EnergyPlus_Support%40yahoogroups.com>
> > > From: yangxiaoshan@
> > > Date: Fri, 17 Jun 2011 06:37:59 +0800
> > > Subject: [EnergyPlus_Support] A question about Latent Cooling
Load in E+
> > >
> > >
> > >
> > >
> > >
> > >
> > >
> > >
> > >
> > > Dear Colleagues,
> > >
> > >
> > > I got a question about latent cooling load in EnergyPlus. The
> > simulation settings are: a single zone with constant cooling setpoint
> > (26â"f through the day), no internal heat gain, 1 air changes
per hour
> > and "Idea Load Air System" automatically used for HVAC
configuration.
> > Theoratically, due to there is no internal heat gain in this case,
the
> > follow correlation should be valid: "Total cooling load - Total
> > sensible cooling load = Latent cooling load = Infiltration latent
heat
> > gain". But the simulation results shown that the infiltration
latent
> > heat gain is always less than the latent cooling load (Total cooling
> > load - Total sensible cooling load), 2% for this case (8-9% less was
> > found in other simulation case). I cannot understand why the
> > infiltration heat gain is not equal to the calculated latent cooling
> > load. Really headache! Look forward to discussing with you, thanks
> > very much.
> > >
> > > Best regards,
> > > Xiaoshan
> > >
> >
> >
>
> --
> Richard A. Raustad
> Senior Research Engineer
> Florida Solar Energy Center
> University of Central Florida
> 1679 Clearlake Road
> Cocoa, FL 32922-5703
> Phone: (321) 638-1454
> Fax: (321) 638-1439 or 1010
> Visit our web site at: http://www.fsec.ucf.edu
>
> UCF - From Promise to Prominence: Celebrating 40 Years
>
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