[Bldg-sim] eQuest Crashing & Modeling Gas-fired Desiccant Systems

[Eric Studer]

Hello!



We are modeling a complex HVAC system with multiple gas-fired desiccant
wheels, fresh air units, and air handling units.  We have had to be rather
creative to shoehorn this system into eQuest, and have basically set up the
fresh air units as VAV systems serving ghost zones and provide 39°F outside
air to the desiccant units. The desiccant units are modeled as VAV systems
serving ghost zones and provide 80°F fresh air to the main AHUs.  The main
AHUs are modeled in the standard way but receive fresh air from the
desiccant system.  The ghost zones have air walls and interior space
temperature setpoints equal to the anticipated discharge temps from the FAUs
and DDs).  Heating and cooling design and control temperatures are offset by
2°F in the ghost spaces.



The model runs and generates an output file, but then the program crashes
immediately afterward.  The following Windows error message is displayed:



The instruction at "0x73dd11c7" referenced memory at "0x00000004".  The
memory could not be "read".



The only other time I have gotten this kind of message was when I put a
period in the file name of the model file (e.g. “90.1 Base Case”), and we
are not making this mistake here.  We can run the model and get results, but
geez is reloading the thing annoying!  Does anybody out there have any
suggestions?  Could the goofiness of modeling three systems in series be the
culprit?



We tried using the system type ‘packaged solid gas desiccant’ (PSGD) but
there does not appear to be a way to have the DD unit get air from the fresh
air unit and there is not a way to put pre-cooling coils on the PSGD system.
Does anyone have any suggestions about how to model this ventilation system:
FAU → DD → AHU?



Eric







Eric Studer, PE, LEED AP
DMI
35 Walnut Street
Wellesley, MA  02481
Ph:   (781) 431-1100 ext 12
Fax:  (781) 431-1109
e-mail:  estuder at dmiinc.com



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