Re: [TRNSYS-users] Type204-PCM

[David Bradley <bradley@tess-inc.com>]

Title: Type204-PCM

Bezeid,
  Because there is not a model for a PCM material built in to the Type56 building model, there needs to be some way for a Type that models the PCM to interface with the rest of the building (for example so that the inside surface of the PCM material can be part of the radiative and convective energy balance of the thermal zone). The way that this interaction is often achieved is to define a BOUNDARY wall in TRNBuild/Type56. A BOUNDARY wall is a surface that interacts with the zone on one side and has some known temperature on the other side. When the BOUNDARY wall interfaces with an external Type (such as 204), the temperature required by the BOUNDARY wall is the interface temperature between the back of the BOUNDARY wall and the front of the PCM material. Typically the way that the coupling is achieved is that Type56 calculates the inside surface temperature (TSI) and the amount of energy being transfered through the BOUNDARY wall into the PCM (QCOMI and/or QCOMO). These values are passed to Type204 as inputs; Type204 then computes the reaction of the PCM to those inputs and calculates a new interface temperature, which is passed back to Type56 as the BOUNDARY wall's outside temperature. Iteration continues until energy balances.
Kind regards,
 David



bezeid.deddy@orange-ftgroup.com wrote:

Hello TRNSYS Users,
I am Deddy bezeid and I make a thesis at the bretagne-sud university, I am a new user of TRNSYS and I encounter problems on the TYPE204 - PCM and I already found somebody who put the same questions with which I would like to have answers, here the questionnaires and thank you for your assistance

 I want to use TRNSYS Type 204 for the simulation of PCM layers on a building. Has anyone used this type before? It takes forever to run an one week simulation...However the main problem is i cannot understand the way the model simulates a PCM layer... My questions are about the SUNSPACE example supplied into the files package loaded : There are 2 air zones in the TRNBUILD type 56 model of this example : SunZone and BackZone. SunZone is where "PCM wall" has been installed. So :

- How to make the difference if we want "PCM layer" into all walls surfaces from SunZone, or only into some of them?
 - Why the resistance of the "PCM massless layer" created in TRNBUILD is only 0.1 m².K.h/kJ?
 - Why the "PCM wall" using the "PCM massless layer" into SunZone (boundary wall calling T_PCM input) presents a so small surface of 0.2 m²?

- Why QCOMI is taken from the same "PCM Wall" (14) and not from other walls?
 - Do we have to change values into the 4 text external files supplied (NodeTemp.txt, Tila.txt, Ceff1.txt, ALKU.txt) or do we only have to call their path?

 - Why the PCMeT (average surface temperature of "PCM wall")calculated by type 204 is sent to the boundary "PCM wall" input (T_PCM) into type 56 ?

 type 204 receives QCOMI from 0.2 m² surface (14), and T_AIR from SunZone volume,
then it calculates and sends T_PCM to boundary input for 0.2 m² surface (14)
 => I don't see in which way this sequence allows modelization of PCM introduction into a wall?
I searched all the mailing list but i just found the same questions..and no answers... Please help...Thanks in advance
Deddy bezeid

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