[esp-r] Re: airflow network, problems with component type 20/25

[Jon Hand]

A recent question about air flow components

::I am modelling a passive ventilation system with the air flow facility in
::ESP-r. In my system I have a heat exchanger with the characteristics dP =
::5.6e-3 x m + 4.8e-5 x m^2
::This calls for a quadratic flow component type 20 or 25 to model the heat
::exchanger in my system.
::However using any of the two causes this error message:

::Please check (in the following order) that:
 ::- each node has some flow path to a boundary pressure and
:: - iteration convergence control is not too strict
::Day xx Month xx Hour xx: 100 iterations; flow solution failed

In the simulator you have the option to "turn on trace". This is in
the "Invoke trace facilities" option seen after bps starts.  If you
select the mass flow item it will write out to a file information
at each timestep.  This might help in finding where the
problem is.

There are a number of run-time parameters that
can be set via the "Simulation toggles" menu option
which becomes visible when after you have specified
the period of the simulation.  If it asks you for a
password, it is "101".  In the toggle menu are several
choices for mass flow.  First try increasing the number
of iterations.

And if you are having trouble with flow convergence
shorten your timestep.  You can go down to 1 minute
and this sometimes allows flow networks to converge
better.

::I am using esp-r version 11.2 from learnix.

Suggest that you update your version of ESP-r.  The current
version is 11.4.

Regards, Jon Hand