Re: [EnergyPlus_Support] timestep

Thanks all, I some has overcome the problem. I increased the condenser loop water volume, which by default was 1lt, now to 100lt, and even with timestep=6 I get realistic solution.Â I think there was a thermal mass issue which was not realistic when 1lt is used for a large plant loop. Thanks for all your suggestions.

TilekÂ

On Thu, 8 Feb 2018 at 7:29 pm, GermÃ¡n Campos ecoeficiente@xxxxxxxxx [EnergyPlus_Support] <EnergyPlus_Support@xxxxxxxxxxxxxxx> wrote:

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One approach I take in this cases is go to the source code and look for the error message. Then I try to go backwards in the code to find out which is the condition that raises this error and sometimes that brings a clue on where the problem may be.
The other alternative, as Jim says is contacting E+ Helpdesk. You may be spending a lot of time trying to figure something that ends up being a bug. Believe me, it happens.

Cheers,

GermÃ¡n
El miÃ©., 7 feb.. 2018 a las 13:16, Jim Dirkes jim@xxxxxxxxxxxxxxxxxxxxxxxxxxx [EnergyPlus_Support] (<EnergyPlus_Support@xxxxxxxxxxxxxxx>) escribiÃ³:
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Tilek,
Two things come to mind:
I think these objects are sensitive to the Input Method and especially the "U-factor time Area Value"; that is worth double-checking to confirm it is correct
It's possible E+ has a bug, so if after checking your inputs you still see a problem, send it to the Help Desk for their review. E+ isn't perfect (yet), though it's become much more robust in recent years. Bugs sometimes become evident when careful modelers like yourself take the time to review results thoughtfully!
On Wed, Feb 7, 2018 at 6:50 AM, Tilek Aberra tilek.aberra@xxxxxxxxx [EnergyPlus_Support] <EnergyPlus_Support@xxxxxxxxxxxxxxx> wrote:
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Hi Jim,

I am using a "dry cooler", and with tighter condenser approach temperature difference the E+ simulation predicts the outgoing water from the fluid cooler is colder than the outdoor ambient - which indicates the simulation has some issues.. I think what is happening is the outdoor temperature is increasing at a higher rate than the plant loop is responding. Also note, I am using the fluid cooler as a condenser water. What I am curious is whether the anomaly is coming from a numerical error or an actual physical limitation of the plant loop. For me partly it appears to be a numerical issue because the hours per year these anomalies occur reduces significantly when I use higher timestep. But if the anomalies are due to physical limitations, then I may explore ways to tackle the extremely hot days, either using a cheaper water spray method, or a more expensive (I suppose so) evaporative cooler as you suggested.

Regards,

Tilek
On Wed, Feb 7, 2018 at 10:30 PM, Jim Dirkes jim@xxxxxxxxxxxxxxxxxxxxxxxxxxx [EnergyPlus_Support] <EnergyPlus_Support@xxxxxxxxxxxxxxx> wrote:
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Â Â If you are using an evaporative fluid cooler, which would be common in a very hot climate, then the water temperature can approach the wetbulb temperature. This is normally substantially cooler in the outdoor air dry bulb temperature.

On Wed, Feb 7, 2018 at 05:59 Tilek Aberra tilek.aberra@xxxxxxxxx [EnergyPlus_Support] <EnergyPlus_Support@xxxxxxxxxxxxxxx> wrote:

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Hi Carlos,
I already noted that. I was looking for some workaround using EMS or similar to overrideÂ the default [which is MAX 60] if anyone has done similar exercise before.

ThanksÂ for the response though.

Tilek

On Wed, Feb 7, 2018 at 9:52 PM, Carlos Krebs clmkrebs@xxxxxxxxx [EnergyPlus_Support] <EnergyPlus_Support@xxxxxxxxxxxxxxx> wrote:

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Dear Tilek,

According to the Input/Output Reference Guide of E+, the number of timesteps (X) per hour will be between thresholds 1 â?¤ X â?¤ 60. You could see this in the IDF Editor with any IDF file opened, in the initial group "Simulation Parameters", in the class list "Timestep". There is a further explanation on screen field for this.

Regards,
Carlos Krebs
+46 769-058-292
MA. Arch. PROGRAU/FAUrb/UFPEL
LEEDÂ® Accredited Professional
Internal Auditor ISO 14.001
Buildingsâ?? Energy Efficiency Consultant

On Feb 7, 2018, at 9:36 AM, tilek.aberra@xxxxxxxxx [EnergyPlus_Support] <EnergyPlus_Support@xxxxxxxxxxxxxxx> wrote:

Hi, Colleagues,

Can anyone suggest a workaround to run E+ with a timestep larger than 60 (the maximum acceptable)?Â Let say 120 (i.e. time integration at 1/2 minutes interval).. I am currently running a simulation that has a "fluid cooler" object and for the very hot days, I get an erroneous water temperature leaving the fluid cooler that isÂ less than the outdoor temperature. The number of such anomalies greatly reduces with higher time resolution (for one case 500hr/yr with timestep=6Â to 0.75hr/yr with timestep=60).. I was trying to get rid of all this erroneous output.

Regards,

TilekÂ

--
Tilek Aberra,
12 Bainton Pl., Doonside,
Sydney, Australia
ph:Â Â +61 (0)2 9534 4731 (home)
Â Â Â Â Â +61 (0)2 8805 0421 (office)
mo:Â +61 (0)4 3959 5937

--
James V Dirkes II,Â CEO / President
The Building Performance Team Inc.
1631 Acacia Dr, Grand Rapids, MI 49504

(alphabet soup of efforts for greater understanding: PE, BEMP, BCxP, LEED AP)

Direct / Mobile: 616.450.8653
jim@xxxxxxxxxxxxxxxxxxxxxxxxxxx

Website l Â LinkedIn

Coffee conversation: The first idea is the worst, but it is the most important because it starts discussion and becomes the building block for other ideas.
--
Tilek Aberra,
12 Bainton Pl., Doonside,
Sydney, Australia
ph:Â Â +61 (0)2 9534 4731 (home)
Â Â Â Â Â +61 (0)2 8805 0421 (office)
mo:Â +61 (0)4 3959 5937
--
James V Dirkes II,Â CEO / President
The Building Performance Team Inc.
1631 Acacia Dr, Grand Rapids, MI 49504
(alphabet soup of efforts for greater understanding: PE, BEMP, BCxP, LEED AP)

Direct / Mobile: 616.450.8653
jim@xxxxxxxxxxxxxxxxxxxxxxxxxxx

Website l Â LinkedIn
Coffee conversation:
The first idea is the worst, but it is the most important because it starts discussion and becomes the building block for other ideas.
--

_______________________________

GermÃ¡n Campos

Aurea Consulting Â
www.ecoeficiente.es
www.designbuilder.es
(+34) 943 104 634

Re: [EnergyPlus_Support] timestep > 60