[esp-r] Re: Pressure calculation affected by .mfs - .pln mapping

[Geissler Achim]

Dear Dimitrios

sorry, I think I did not quite understand your question first time round.

Based on your clarification below, I am not quite sure I understand your differentiation between "map" and "link" in terms of the setup (however, I am likely out of my depth, here, as I have to date only had one model with linked plant / flow network up and running).

>From your observations I would guess that "mapping" and "linking" is maybe the same (the documentation you cite is quite old, after all). Would you expect the effects you see for your model with (fully) linked plant?

As I cannot really give any more assistance, I took the discussion back to the group. Maybe somebody else out there can help you.

Best
Achim




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Von: Dimitrios Sfakianakis [mailto:dimitrios.sfakianakis at strath.ac.uk]
Gesendet: Montag, 12. Dezember 2011 13:30
An: Geissler Achim
Betreff: RE: [esp-r] Pressure calculation affected by .mfs - .pln mapping

Dear Achim,

Thank you very much for your reply. Although I understand what you wrote, my question still remains. Let me restate it in the following paragraph.

I have a model with a flow network (no plant network for the time being), which when simulated gives me a pressure / time graph for every node.
Once I add a plant network and don't link it to a zone, or map it to the flow network, the pressure / time graph remains as it was before.
Now when I map the plant network to the flow network (and still not link the plant network to a zone) the pressure calculated from the flow solver seems to change.

>From what I have read so far in the literature, by mapping those networks, the only action taken by esp-r is the transfer of mass flow and pressure difference from the flow network to the plant network. Since this is an 'one way' exchange of data (.mfs -> .pln) how can the pressure calculations of .mfs be affected?

Thank you again for your reply and I really appreciate you spending time replying to my e-mail.

Kind regards,

Dimitrios Sfakianakis

From: Geissler Achim [mailto:achim.geissler at fhnw.ch]
Sent: 12 December 2011 11:56
To: Dimitrios Sfakianakis; 'esp-r at lists.strath.ac.uk'
Subject: AW: [esp-r] Pressure calculation affected by .mfs - .pln mapping

Hi Dimitrios

sounds like an interesting model you have. Basically, the mass flow network is a set of equations that must satisfy the mass conservation law. The pressures and mass flows are interdependent and result from taking available flow paths, fixed pressures given at nodes and flow resistances and/or fixed flows (e.g. fans) between flow nodes into account.

So, I would expect changes in pressures if you superpose mass flows on a given network.

Best
Achim


Von: esp-r-bounces at lists.strath.ac.uk<mailto:esp-r-bounces at lists.strath.ac.uk> [mailto:esp-r-bounces at lists.strath.ac.uk]<mailto:[mailto:esp-r-bounces at lists.strath.ac.uk]> Im Auftrag von Dimitrios Sfakianakis
Gesendet: Montag, 12. Dezember 2011 11:13
An: 'esp-r at lists.strath.ac.uk'
Betreff: [esp-r] Pressure calculation affected by .mfs - .pln mapping

Dear list,

I have set up a flow network and a plant network and have mapped two connections of the plant network to the flow network. From what I read in the documentation (Hensen, 1991), by mapping the two networks, the mass flow rate calculated in the .mfs is transferred to the mapped connection in .pln. However I noticed that the pressure of an internal unknown node (linked to a zone in my model) calculated by the .mfs, is affected by this mapping. If the only effect of this mapping is the mass flow rate transfer from .mfr -> .pln how can the pressure calculations in .mfr change? What am I missing?

Kind regards,

-

Dimitrios Sfakianakis

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