[esp-r] Re: Convection coefficients problem

[Michael Lucchi]

Thank you Jon for the precious suggestions.

The facade is connected with a HVAC system and it is a force ventilated
facade. However, I also connected the three zone nodes corresponding to the
ventilated facade with a flow network in order to simulate the behaviour of
the facade when the plant turns off (in this period the mass flow between
the three zones is due to only buoyance effects ). Generally, the
simulation stops after few time-steps.  The only succeded simulation was
set up with both  zones and plants time-steps of 30 minutes, but with wrong
results.
Turning off the Fisher correlation and using default correlation,  the
model runs.

Thank you for eventual helps.


2013/11/12 Jon Hand <jon at esru.strath.ac.uk>

>
> The first thing that caught my attention is [ventilated facade] and
> [forced ventilation].  What
> kind of ventilated facade is this - a rain-screen (in which case there
> would be low velocity
> flow).  Is the facade actually force ventilated or just ventilated by
> differences in temperature
> and thus one might describe it in via a flow network?
>
> mzsad is in the matrix solver.  There are a few folk who might be able to
> address that
> kind of issue.  It might be that the Fisher is causing this or perhaps
> not.  I would first
> explore the use of the [trace] facility in bps - it can write out lots of
> additional information
> about the heat transfer correlations.
>
> I would suggest that you turn off the Fisher in the 3 ventilated facade
> zones and see
> if the model runs.
>
> And also - what is happening at 93 time-steps. (Hour 10 on year day 189)?
>  Does
> the error happen if you run the assessment for a different day?
>
> -Jon
> ________________________________________
> From: esp-r-bounces at lists.strath.ac.uk [esp-r-bounces at lists.strath.ac.uk]
> on behalf of Michael Lucchi [michael.lucchi at gmail.com]
> Sent: 12 November 2013 15:43
> To: esp-r at lists.strath.ac.uk
> Subject: [esp-r]  Convection coefficients problem
>
> Hello ESP-r users,
> I’m trying to model a ventilated façade characterized by a forced
> convection regime using Esp-r (version 12.0 for Windows 7) for my thesis.
> The model is composed by one single room, and the external facades are
> ventilated opaque walls. The ventilated façade is composed by three thermal
> zones, with the aim to obtain the vertical temperature distribution. In
> order to reach reasonable results, I tried to impose the Fisher and
> Pedersen correlation for mechanically driven flows both in the room and in
> the ventilated façades. However, when I run the simulation, a numerical
> error stops any module. The following text is the error displayed by the
> simulator:
> mzsad 1: numerical error after 93 time-steps.
> (Hour 10 on year day 189).
> e(iconst,n)    = -17999998.000000
> a1      = -18000000.0000
> I am still  a novice user of the software and any help is much appreciated.
> Kind regards.
> Michael Lucchi
>
>
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