[Bldg-sim] Ground-to-air heat exchangers

[Gerald Pde]

What I have previously to model earth-tubes is to
manipulate the weather file that is going in eQUEST.
In my case it was pretty straight forward because the
space being served was internal so there was no heat
transfer from external walls. Hence I was able to use
this method.

1) Modeled the air temperature coming out of an earth
duct in TRNSYS. TRNSYS has ground-air HX types but
also a specific type( Type 260 developed by
Hollmuller) that can model earth ducts. 

2) I then manually modified a tmy2 file for the
location and replaced the dry-bulb, RH and dew-point
with the properties of the air coming out of the tube.

3) Converted the TMY2 files to DOE-2 weather file.

Again, I had to do this because we were evaluating the
total energy savings of an earth duct for
preconditioning. Modifying weather files is definitely
not recommended if the building or space sees outside
conditions.


Hope this helps.
Gerald



--- Michael Tillou <michael.tillou at gmail.com> wrote:

> eQUEST doesn't allow you to directly model earth
> tubes.  Depending on your
> level of eQUEST skill you can make some
> thermodynamic approximations of how
> the earth tubes will effect your annual energy use
> if you first perform some
> external calculations to estimate the performance of
> the tubes based on
> their proposed design (ie: how will the earth tubes
> impact the entering
> outdoor air temperature you see at each air-handling
> system).
>  
> I believe that other simulation programs have the
> capability to directly
> simulate earth tubes which I recommend you
> investigate.
>  
> Mike
>  
>  
> Michael Tillou, PE, LEED
> Tillou Engineering, LLC
> Williamstown, MA 01267
> P: 413-458-9870 C: 413-652-1087
>  
> 
>   _____  
> 
> From: bldg-sim-bounces at lists.onebuilding.org
> [mailto:bldg-sim-bounces at lists.onebuilding.org] On
> Behalf Of Demba Ndiaye
> Sent: Friday, April 04, 2008 9:43 AM
> To: bldg-sim at lists.onebuilding.org
> Subject: Re: [Bldg-sim] Ground-to-air heat
> exchangers
> 
> 
> 
> This system is also known as earth (to) (air) heat
> exchanger, air-to-soil
> heat exchanger, soil-to-air heat exchanger, "puits
> canadien".
> 
>  
> 
> Any advice on how to model this system will be
> highly appreciated.
> 
>  
> 
> ______________
> 
> Demba Ndiaye
> 
>   _____  
> 
> From: bldg-sim-bounces at lists.onebuilding.org
> [mailto:bldg-sim-bounces at lists.onebuilding.org] On
> Behalf Of Demba Ndiaye
> Sent: Thursday, April 03, 2008 10:48 AM
> To: bldg-sim at lists.onebuilding.org
> Subject: [Bldg-sim] Ground-to-air heat exchangers
> 
>  
> 
> Hello, 
> 
>  
> 
> Does anybody have success modeling a ground-to-air
> heat exchanger in eQuest?
> 
>  
> 
> The ground-to-air heat exchanger is a network of
> underground pipes aimed at
> preheating / pre-cooling the outdoor air.
> 
>  
> 
> Any suggestions for modeling this system?
> 
>  
> 
> Thanks.
> 
> ______________
> 
> Demba Ndiaye
> 
>  
> 
> > _______________________________________________
> Bldg-sim mailing list
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