[esp-r] Re: PCM models

Thu Feb 3 08:46:37 GMT 2011

Dear Achim

You have raised a very valid point. In our experiments we tried to reduce the effect of radiation as much as possible as the aim was to derive convective coefficients for the PCM boards. The heated wall was covered with polished aluminium plates with emissivity of about 0.06 to reduce the radiation effect. This was the only heated surface with high temperatures. The temperatures of the other surfaces where considerably lower and did not differ very much. In summary there would have been some radiation effect but we believe that this did not have a significant impact on the results.

It would be interesting if some simulations could be carried out with ESP-r for comparison as we haven't done that yet.

Regards,
Hazim

From: Achim.geissler [mailto:achim.geissler at intergga.ch]
Sent: 03 February 2011 08:07
To: HazimB.Awbi; Achim.geissler
Cc: esp-r at lists.strath.ac.uk; FrancescoFrontini
Subject: AW: RE: [esp-r] Re: PCM models

Dear Hazim

very interesting paper. One question I could not see answered, though: The measurements of heat flux will include a long wave radiative part, won't they? The equations you give (Table 2) are convective, only. As the various surfaces of the test chamber did not seem to have the same temperature, there will have been a long wave exchange component, also. Did you check on its possible magnitude?

Adding an additional approach for "convective heat transfer for PCM" would be straightforward in ESP-r. Do you have a suggestion as to its theoretical/equation-wise description?

Thanks.

Best
Achim

--------- Original-Nachricht --------
Von: "Hazim B. Awbi" <h.b.awbi at reading.ac.uk>
An: "Achim.geissler" <achim.geissler at intergga.ch>
Cc: esp-r at lists.strath.ac.uk, "FrancescoFrontini" <francesco.frontini at polimi.it>
! Betreff: RE: [esp-r] Re: PCM models
Datum: 02/02/11 21:32

Dear Achim and others

We measured heat transfer coefficients for PCM boards on a wall under controlled conditions in an environmental test chamber. This data is available in the 2009 Building & Environment paper "Performance of phase change material boards under natural convection by Liu & Awbi, Vol. 44, pp1788-1793".

Regards,
Hazim

~~~~~~~~~~~~~
Professor Hazim B. Awbi
Director
Technologies for Sustainable Built Environments Centre
JJ Thompson Building
University of Reading
Reading RG6 6AF
UK
Tel: +44 (0) 118 378 6786
Fax: +44 (0) 118 931 4316
http://www.reading.ac.uk/tsbe/

From: esp-r-bounces at lists.strath.ac.uk [mailto:esp-r-bounces at lists.strath.ac.uk] On Behalf Of Achim.geissler
Sent: 02 February 2011 13:38
To: FrancescoFrontini; esp-r at lists.strath.ac.uk
Subject: [esp-r] Re: PCM models

Dear Francesco

the model you are (probably) referring to is part of the development_branch (and has been for some time) and so should be available in the official version. It is type "SPMCMP56" and covers the topics you mention. The model is loosely based on the PhD thesis of Sabine Hoffmann, University of Weimar, September 2006. Tests done with the significantly enhanced model showed quite good results for the PCM material used at that time.

What was / is tricky is finding a good set of coefficients for the functions used for describing melting and solidification behaviour. At the time, this was done via a MathCAD sheet which may still be available.

There are others on the list also involved. Maybe they can/will tune in.

By the way, rumor has it, that ISE did extensive simulations recently with PCMs in curtain walls or better HVAC in curtain walls. It would be intere! sting, which model was used ... ;o)

Best
Achim

--------- Original-Nachricht --------
Von: "Francesco Frontini" <francesco.frontini at polimi.it>
An: "esp-r at lists.strath.ac.uk" <esp-r at lists.strath.ac.uk>
Betreff: [esp-r] PCM models
Datum: 02/02/11 10:20

Dear all,
we are looking for a Phase Change Material PCM model for ESP-r which
include the under cooling effect during the solidification process.
To be a bit more detailed we have to model a PCM from DeltaCool which
has two different curves for the solidification state and for the
melting state. The two capacity peaks differ by 3K.
We heard that there already some new PCM models available (not just
the Heim model) but they are not available yet in the actual release..
Any suggestion? How we can access them?

Best regards

Francesco and Tobias

--
Dr. Francesco Frontini, MEng ! PhD in Buildings Engineering

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