Hi friends,
I am trying to model an Earth Air Tunnel (EAT) system that is being used in
a school for passive precooling.
During summer first the air is pre cooled using the EAT and then evaporative
cooling is done before being circulated into the zone.
During monsoon again precooling is done using EAT and then chillers are
being used for further cooling and dehumidification.
Does anyone have any idea as to how to calculate and incorporate the degree
of precooling that is achieved by the EAT into the eQuest model.
Any help would be greatly appreciated. Thanks
Vishnuraj Nair
Vishnuraj-
This is very difficult and may not lead to the correct results, but one
method would be to manually edit the weather file. You would need to change
the temperatures so that the outdoor air that is pulled into the system
would be at the temperature of the earthduct preconditioned air. However, I
would not recommend doing this without testing to see how it changes the
other aspects of the simulation.
I have seen earthducts modeled correctly in both MATLAB and TRNSYS but I
have not successfully modeled it within eQuest.
--
Steve Mignogna
JRR wrote;
In Energy Plus you could put a purchased air node on the EAT and
then discount it via its separate
meter after the run is done....
A cautionary note here is that changing outside temperature in the
weather file would, among others, change the load seen by the building.
_____________
Demba Ndiaye
You could use OA from system, give the supply air a temperature schedule,
and put the equipment that conditions this air on a separate meter (as there
will be only fan energy required, not heating and cooling).
This, of course, assumes that you know what temperature the air will be
coming in at, but leaves everything else the same.
--
Karen
Thank you all for the help.
One way that we are thinking of to model it is using the indirect and direct
evaporative cooling system both as a separate system.
Indirect system can then be made to the work of Earth Air Tunnel(EAT) of
sensibly precooling.
After this the direct evaporative cooler can further bring down the
temperature as well as humidify the air.
During the monsoon season the fan schedule for the direct cooling system can
be kept off and only indirect system will do the sensible precooling.
However one difficulty here is that we are not able to give the cooling
capacity for the indirect evaporative cooling system.eQuest accepts it only
for DX coils
and cooling coils when chillers are being used.
We are trying to work along these lines and if anyone has any suggestion
please do share.
If we are able to come up with any solution, will certainly let you all
know.
Thanks again for your response.
Vishnuraj Nair