[TRNSYS-users] Temperature and %RH setpoint TRNBUILD
David BRADLEY
d.bradley at tess-inc.com
Wed Sep 19 09:26:40 PDT 2012
Gary,
That "addition" and "multiplication" factor are more often used for
changing the units of an input rather than for defining equations like
the ones we are talking about. Set up TRNBuild so that you see something
like this:
Input:
1*CL_SET+0
(you may also need to define a heating set point as well. It would have
the form: 1*HT_SET+0)
Then go back to the TRNSYS Studio (ie save your work in TRNBuild and
exit back to the Studio). Right click on the building (Type56) and
select "update building variable list." Next, define a new equation
(select the menu item Assembly: Insert New Equation...). and define
equations for the heating and cooling set points as we've discussed in
previous emails.
make a connection from the equation to the building and connect the
appropriate equation to the appropriate Type56 input (you should see
HT_SET and CL_SET among the list of Type56 inputs.
A couple notes: you will also have to define the variable "occ" as used
in the equations using either another equation, a forcing function, or
one of the scheduling components in the TESS Applications library.
When you look at your heating and cooling demand that Type56 produces,
be really careful because when you go through a step change in set point
(ie when the building becomes occupied, the cooling system will turn on
and it will have an instantaneous infinite load on it. Type56 is simply
going to report that infinite load and it will be up to your system to
figure out how to deal with it. Normally when running simulations in
this manner (ie in calculating space loads) you get rid of all the
temperature setbacks and setups so as to avoid this problem.
Best,
David
On 9/19/2012 11:01, KUM GARY wrote:
> David,
>
> I have try to define the cooling equation in TRNBUILD but
> unfortunately, i am unable to do so as it only allow me to input a
> constant after the addition(99*(1-occ)) which mean i can only define
> as Tset_cool = 28*occ + constant value. How should i go about to solve
> this?
> Pardon me as i am still new in the software.
>
> Thanks
> Gary
>
>
> On Wed, Sep 19, 2012 at 10:26 PM, David BRADLEY
> <d.bradley at tess-inc.com <mailto:d.bradley at tess-inc.com>> wrote:
>
> Gary,
> The equation that I wrote was for a heating set point
> temperature and you are correct, when the building is unoccupied,
> the temperature would be allowed to fall back to 12C.
>
> The cooling equation might be:
>
> Tset_cool = 28*occ + 99*(1-occ)
>
> In other words, define the cooling set point as an arbitrarily
> high number that the building will never reach. There are of
> course other ways of turning off the cooling but this is effective
> in your situation.
> Best,
> David
>
>
>
> On 9/18/2012 18:57, KUM GARY wrote:
>>
>> David,
>> Thanks for your reply. From your equation, it seem that during
>> period of 0 occupancy, I would get a temperature of 12 degree.
>> But I would like the cooling to be switched off when there is no
>> occupancy. So how should I go about defining the equation?
>>
>> Thanks
>> Gary.
>>
>> On Sep 19, 2012 4:00 AM, "David BRADLEY" <d.bradley at tess-inc.com
>> <mailto:d.bradley at tess-inc.com>> wrote:
>>
>> Gary,
>> Defining your setpoint as a SCHEDULE in TRNBuild simply
>> allows you to set a value that depends upon the time of day.
>> Defining your setpoint using an INPUT allows you a good bit
>> more flexibility. You could define your equation as follows:
>>
>> Tset_heat = 24*occ + 12*(1-occ)
>>
>> occ would have to be defined in another equation or perhaps a
>> Type14 forcing function to have a value of 1 when the
>> building is occupied and a 0 when it is not occupied.
>>
>> Best,
>> David
>>
>>
>>
>> On 9/17/2012 10:29, KUM GARY wrote:
>>> Hi,
>>>
>>> I trying to calculate the cooling demand of my office
>>> building in TRNBUILD and would like the cooling demand to
>>> response according to my occupancy schedule(less cooling at
>>> night and more cooling at day). I try to define the set temp
>>> at the cooling type by i not sure which one should i use
>>> (schedule or input?) And also the equation behind it,
>>> because when i enter like for instance _24degree(set temp)
>>> *occupancy schedule+0_, i would get 0 degree when there is
>>> no occupancy.
>>>
>>> Appreciate your kind assistance on this
>>>
>>> Gary Kum
>>>
>>>
>>> _______________________________________________
>>> TRNSYS-users mailing list
>>> TRNSYS-users at cae.wisc.edu <mailto:TRNSYS-users at cae.wisc.edu>
>>> https://mailman.cae.wisc.edu/listinfo/trnsys-users
>>
>> --
>> ***************************
>> David BRADLEY
>> Principal
>> Thermal Energy Systems Specialists, LLC
>> 22 North Carroll Street - suite 370
>> Madison, WI 53703 USA
>>
>> P:+1.608.274.2577 <tel:%2B1.608.274.2577>
>> F:+1.608.278.1475 <tel:%2B1.608.278.1475>
>> d.bradley at tess-inc.com <mailto:d.bradley at tess-inc.com>
>>
>> http://www.tess-inc.com
>> http://www.trnsys.com
>>
>
> --
> ***************************
> David BRADLEY
> Principal
> Thermal Energy Systems Specialists, LLC
> 22 North Carroll Street - suite 370
> Madison, WI 53703 USA
>
> P:+1.608.274.2577 <tel:%2B1.608.274.2577>
> F:+1.608.278.1475 <tel:%2B1.608.278.1475>
> d.bradley at tess-inc.com <mailto:d.bradley at tess-inc.com>
>
> http://www.tess-inc.com
> http://www.trnsys.com
>
>
--
***************************
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 at tess-inc.com
http://www.tess-inc.com
http://www.trnsys.com
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