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Today's Topics:
1. Re: total heating rate and total cooling rate in heat pump
954 (David BRADLEY)
2. Re: (no subject) (haydar =?UTF-8?Q?kepek=C3=A7i?=)
3. Re: (no subject) (mcdowell@tess-inc.com)
4. Re: (no subject) (Jason Glazer)
---------- Forwarded message ----------
From: David BRADLEY <d.bradley@tess-inc.com>
To: "TRNSYS users mailing list at OneBuilding.org" <trnsys-users@lists.onebuilding.org>, trnsys-users <trnsys-users@cae.wisc.edu>
Cc:
Date: Thu, 20 Nov 2014 09:59:49 -0600
Subject: Re: [TRNSYS-users] total heating rate and total cooling rate in heat pump 954
Enyuan,
The total cooling rate is the sensible and latent energy being removed from the air stream by the active section of the heat pump. It is computed as the mass flow rate of air multiplied by the difference between the enthalpy of air leaving the heat pump and the enthalpy of the mixed air (return + ambient) entering the evaporator. The heat pump does not have any kind of economizer controls built into it. The amount of outdoor air being mixed with return air is simply a function of how you have set the outdoor air damper position input. It could be that your heat pump is cooling because there is no ambient air being mixed in and the heat pump is working only with return air. If your concern is that the heat pump would not operate when the ambient temperature is so low (because of freeze up in the condenser) then you have to be careful of your external data file. Performance is interpolated within the range of data given in the file but it is not extrapolated beyond the range. If the heat pump asks for cooling (because of the way you have set the cooling signal input and fan control signal) then the performance (cooling capacity and COP) will be returned for the closest ambient temperature found in the data file.
Regards,
David
On 11/19/2014 14:26, Enyuan Hu wrote:
Dear all,
When I'm using a type 954 air-to-air heat pump to condition a one zone building, I found that even during the winter (ambient temperature is below the cooling threshold), the 'total cooling rate' output from the heat pump is positive instead of being zero as expected. Can anyone help me explain why? Thanks!
best regards,Enyuan Hu
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-- *************************** David BRADLEY Principal Thermal Energy Systems Specialists, LLC 22 North Carroll Street - suite 370 Madison, WI 53703 USA P:+1.608.274.2577 F:+1.608.278.1475 d.bradley@tess-inc.com http://www.tess-inc.com http://www.trnsys.com
---------- Forwarded message ----------
From: "haydar kepekçi" <haydar389@gmail.com>
To: "TRNSYS users mailing list at OneBuilding.org" <trnsys-users@lists.onebuilding.org>
Cc:
Date: Thu, 20 Nov 2014 17:23:16 +0200
Subject: Re: [TRNSYS-users] (no subject)Dont send me e- mail !! I dont want to see ur words about Fucking trnsys !!!
Sent using CloudMagic
On Per, Kas 20, 2014 at 4:32 PM, Ben Heymer <bheymer@gmail.com> wrote:You should look through your "Result" file for the source of the error.
A common cause of errors of this type is convergence. Make sure you
have enough volume in your water loop for at least 1 timestep of water
flow. Sometimes it's also helpful to connect the mass flow output of
the pump right back to the mass flow input.
As a last resort, you can relax the convergence parameters and error
thresholds in the control cards.
Ben Heymer, PE
On Thu, Nov 20, 2014 at 3:52 AM, Michael Stochniol
<stochnio@mail.hs-ulm.de> wrote:
> Hallo everyone,
>
> im trying to create a control function using equations with logic operators for the control of a variable speed pump, in order to adjust the massflow trough the pump. I wrote a control funktion and plotted it without connecting it to the pump and it seemed to work right. But if i am conecting it to the pump my simulation freezes after around 700 timesteps or less. I am trying to create solar domestic hot water system. The question is, is it possible to create this kind of control circuit with equations ? I have similar problems with every control loop i am trying to create this way. The math should work but implemented in TRNSYS (TRNSYS 17) the simulation stick somewhere.
>
> I am no experienced user so maybe someone could give my some advise how to implement this kind of control functions right?
>
> i am very grateful for any help or ideas.
>
> thanks in advance
>
> Michael Stochniol
> _______________________________________________
> TRNSYS-users mailing list
> TRNSYS-users@lists.onebuilding.org
> http://lists.onebuilding.org/listinfo.cgi/trnsys-users-onebuilding.org
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---------- Forwarded message ----------
From: mcdowell@tess-inc.com
To: "TRNSYS users mailing list at OneBuilding.org" <trnsys-users@lists.onebuilding.org>
Cc:
Date: Thu, 20 Nov 2014 11:57:52 -0600
Subject: Re: [TRNSYS-users] (no subject)
Haydar Kepekci -
Please use the links at the bottom of the email to unsubscribe from the TRNSYS mailing list.
And please avoid using offensive language in email messages.
Regards,
Tim
---
Timothy P. McDowell Executive Vice President Thermal Energy System Specialists, LLC 22 N Carroll St, Suite 370 Madison, WI 53703 608-274-2577On 2014-11-20 09:23, haydar kepekçi wrote:
Dont send me e- mail !! I dont want to see ur words about Fucking trnsys !!!
Sent using CloudMagic
On Per, Kas 20, 2014 at 4:32 PM, Ben Heymer <bheymer@gmail.com> wrote:
You should look through your "Result" file for the source of the error.
A common cause of errors of this type is convergence. Make sure you
have enough volume in your water loop for at least 1 timestep of water
flow. Sometimes it's also helpful to connect the mass flow output of
the pump right back to the mass flow input.
As a last resort, you can relax the convergence parameters and error
thresholds in the control cards.
Ben Heymer, PE
On Thu, Nov 20, 2014 at 3:52 AM, Michael Stochniol
<stochnio@mail.hs-ulm.de> wrote:
> Hallo everyone,
>
> im trying to create a control function using equations with logic operators for the control of a variable speed pump, in order to adjust the massflow trough the pump. I wrote a control funktion and plotted it without connecting it to the pump and it seemed to work right. But if i am conecting it to the pump my simulation freezes after around 700 timesteps or less. I am trying to create solar domestic hot water system. The question is, is it possible to create this kind of control circuit with equations ? I have similar problems with every control loop i am trying to create this way. The math should work but implemented in TRNSYS (TRNSYS 17) the simulation stick somewhere.
>
> I am no experienced user so maybe someone could give my some advise how to implement this kind of control functions right?
>
> i am very grateful for any help or ideas.
>
> thanks in advance
>
> Michael Stochniol
> _______________________________________________
> TRNSYS-users mailing list
> TRNSYS-users@lists.onebuilding.org
> http://lists.onebuilding.org/listinfo.cgi/trnsys-users-onebuilding.org
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---------- Forwarded message ----------
From: Jason Glazer <jglazer@gard.com>
To: trnsys-users@lists.onebuilding.org
Cc:
Date: Thu, 20 Nov 2014 11:59:19 -0600
Subject: Re: [TRNSYS-users] (no subject)
As a reminder, to unsubscribe just send a blank email to:
trnsys-users-unsubscribe@onebuilding.org
Jason
On 11/20/2014 9:23 AM, haydar kepekçi wrote:
Dont send me e- mail !! I dont want to see ur words about
trnsys !!!
Sent using CloudMagic
<https://cloudmagic.com/k/d/mailapp?ct=pa&cv=5.1.6.5&pv=4.3>
On Per, Kas 20, 2014 at 4:32 PM, Ben Heymer
<bheymer@gmail.com <mailto:bheymer@gmail.com>> wrote:
You should look through your "Result" file for the
source of the error.
A common cause of errors of this type is convergence.
Make sure you
have enough volume in your water loop for at least 1
timestep of water
flow. Sometimes it's also helpful to connect the mass
flow output of
the pump right back to the mass flow input.
As a last resort, you can relax the convergence
parameters and error
thresholds in the control cards.
Ben Heymer, PE
On Thu, Nov 20, 2014 at 3:52 AM, Michael Stochniol
<stochnio@mail.hs-ulm.de> wrote:
> Hallo everyone,
>
> im trying to create a control function using
equations with logic operators for the control of a
variable speed pump, in order to adjust the massflow
trough the pump. I wrote a control funktion and plotted
it without connecting it to the pump and it seemed to
work right. But if i am conecting it to the pump my
simulation freezes after around 700 timesteps or less. I
am trying to create solar domestic hot water system. The
question is, is it possible to create this kind of
control circuit with equations ? I have similar problems
with every control loop i am trying to create this way.
The math should work but implemented in TRNSYS (TRNSYS
17) the simulation stick somewhere.
>
> I am no experienced user so maybe someone could give
my some advise how to implement this kind of control
functions right?
>
> i am very grateful for any help or ideas.
>
> thanks in advance
>
> Michael Stochniol
> _______________________________________________
> TRNSYS-users mailing list
> TRNSYS-users@lists.onebuilding.org
>
http://lists.onebuilding.org/listinfo.cgi/trnsys-users-onebuilding.org
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--
Jason Glazer, P.E., GARD Analytics, 90.1 ECB chair
Admin for onebuilding.org building performance mailing lists
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