[TRNSYS-users] Restaurant absorp. cooling Tess example

[Martin Berov]

Hi ,

I did like David proposed, from the one chiller I took information how much
chilled energy can be provided and compared to the cooling load so if it's
bigger than the output is 1 and the second chiller is on if not another
equation switch the  aux.cooler  on. But then in the equation for the main
control signal I tried to put two other conditions i.e for the required hot
and cooling energy but then appeared problem when I run the simulation.
First the hot energy is delivered by aux.heater but when I plot the
required hot energy vs. delivered always the delivered is smaller no matter
how big is the capacity and flow rate of the aux.heater. For the cooling
tower I get bigger values  than the required but that happens starting from
the fourth time step(also tried with Type93) and again the chiller during
the whole simulation is off, can not be started.
The main control signal is made combining three equations(chilled,cooling
and hot energy) i.e. comparing the required and available energy(1 or 0)
and then the three product value 1 if only 3 conditions are 1 otherwise or
0 - that is used as control signal of the working chiller.
Any idea how can I solve the problem with the hot(avalible) and cooling
energy/condition-control signal?

Kind Regards,
Martin


On Fri, Apr 25, 2014 at 4:14 PM, David BRADLEY <d.bradley at tess-inc.com>wrote:

>  Martin,
>   You are correct; Type107 is designed so that it takes the chilled water
> set point as an input and provides the required power as an output. If you
> are working on a simulation where you have a certain amount of power
> available (from a PV or a wind turbine) then what you can do is to
> implement two instances of Type107 in your simulation. One of them would be
> running all the time (i.e. it's control signal input is always set to 1)
> with its cooling water, hot water, and chilled water inputs connected but
> none of its outputs connected. The only output that you would use would be
> the required power. This instance of Type107 would be in your simulation
> only to determine how much power would be required in order to run an
> absorption chiller under current conditions. The required power would feed
> into an equation that would compare the required power to the power that
> you actually have available. If you have more power than you need then the
> equation's value would be 1. If you don't have enough power to run the
> chiller then the equation's value would be 0. The result of the equation
> would be sent as the control signal to a second instance of Type107 that is
> identical to the first except that it is not always on and its outputs (the
> outlet cooling water, chilled water, and hot water outlet conditions) are
> connected.
>   In essence you are using a virtual chiller to determine a control signal
> for the actual chiller.
> Kind regards,
>  David
>
>
>
>
> On 4/25/2014 04:17, Martin Berov wrote:
>
> Thank you, I found the weather block it was in the hidden layer.
> I have one more issue, as I understand the absorption chiller always
> modulate its power so it can reach the chilled water set point temperature?
> - so does it mean that with this type 107 it is not possible to make
> simulations with different chiller powers(rated capacity) and see how they
> affect on the system?
>
>  Kind regards
> Martin
>
>
>
>
> On Fri, Apr 25, 2014 at 2:48 AM, Jeremy Osborne <
> jeremy.osborne at solem-consulting.com> wrote:
>
>>  Hi Martin,
>>
>>
>>
>> The weather data is hidden in a layer. Go to view -> show layers -> and
>> enable weather - data files and you should see TYPE15-2 appear with all the
>> connection.
>>
>>
>>
>> Layers are used to better organise complex models, removing certain
>> clutter.
>>
>>
>>
>> Regards,
>> Jeremy
>>
>>
>>
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>>
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>>
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>>
>> *From:* Martin Berov [mailto:martber88 at gmail.com]
>> *Sent:* Thursday, 24 April 2014 8:02 PM
>> *To:* trnsys-users at cae.wisc.edu
>> *Subject:* [TRNSYS-users] Restaurant absorp. cooling Tess example
>>
>>
>>
>> Hi,
>>
>>
>>
>> I was looking at the example provided  with the Tess library about the
>> Restaurant absorption chilling, so the simulation runs ok, but I can not
>> find the weather block i.e. the collector and building are not connected to
>> it -how is this possible, how does it function, can someone give me
>> explanation?
>>
>>
>>
>> Thank you
>>
>>
>>
>> Best Regards
>>
>> Martin
>>
>
>
>
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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:+1.608.278.1475d.bradley at tess-inc.com
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>
>
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