[TRNSYS-users] Questions

[Jeff Thornton]

Another option is to impose the building loads on one of the lumped capacitance building models in the TESS Libraries and then connect a thermostat model to the lump.  This thermostat would then turn on and off the heat pump which would feed its energy terms to the lump model as well.  In all these options you need to make sure that heat pump has the capacity to meet the loads or the lump/tank temperature could run away.  In a real system if the loads aren’t met the temperature rises or falls and the load reduces naturally.  By imposing loads from a data file, where it is assumed the loads were always met, you lose that natural interaction and temperatures can continue to spiral away from the setpoint if you’re not careful.

Jeff/TESS


> On Nov 15, 2020, at 11:38 AM, David BRADLEY via TRNSYS-users <trnsys-users at lists.onebuilding.org> wrote:
> 
> 
> The connection between the file containing loads and Type682 is usually done through Type9.
> 
> Your other question is a good bit harder to answer because everything depends on the details of the system that you are trying to model. The fundamental problem is probably that you have hourly loads (energy rate control) while the heat pump model is a temperature level control device that is expecting a thermostat or some other kind of controller to give it an on/off signal. In the real building, the heat pump would turn on and off as needed over the course of the hour to maintain room temperatures. However, the data file contains the total hourly load so you have to recreate, somehow, the part load performance of the heat pump. Here is where things depend on your system:
> 
> One solution is to define a thermal storage tank that circulates liquid through Type682. You can then define an aquastat that senses the tank temperature and turns on and off a heat pump in order to maintain the tank at its desired set point.
> 
> Another solution would be to define a piping loop that has a number of Types 682 along its length as well as some heat pumps to maintain temperature within a defined range.
> 
> Yet another solution is to use the heat pump as a virtual component, giving it the ambient and return conditions and getting back it's COP so that you can estimate its power consumption without modeling its on/off behavior.
> 
> kind regards,
> 
>  David
> 
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> On 11/13/2020 02:53, celia do carmo ferrao Ferrao via TRNSYS-users wrote:
>> Good Morning Users
>> I'm starting models on Trnsys and I'm a little lost.
>> I have data files with, for example, heating and cooling needs, electrical, thermal loads ....
>> The is a file. txt.. I can use Type 682 for Loads, but I don't know what the correct connections are to make:
>> 1 - Connection between the .txt file and for example Loads, Type 682 ...
>> 2 - Connection between Type 682, or another and a heat pump.
>> Thank you!!!
>>  
>> Kind Regards
>> C. Ferrão
>> 
>> -- 
>> Ferrão
>> 
>> 
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> -- 
> ***************************
> David BRADLEY
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> Thermal Energy Systems Specialists, LLC
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> 
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