[Equest-users] Geothermal Well Field Modeling

[Umesh Atre]

ClimateMaster has a plug-in for eQUEST that you could look at to
evaluate real vs defaults.
http://www.climatemaster.com/index/equest_download?highlight=eQUEST
 
 
 
 

________________________________

From: equest-users-bounces at lists.onebuilding.org
[mailto:equest-users-bounces at lists.onebuilding.org] On Behalf Of Dan
Russell
Sent: Thursday, April 29, 2010 12:35 PM
To: equest-users at lists.onebuilding.org
Subject: [Equest-users] Geothermal Well Field Modeling



Hi All - I am wondering if anyone has much experience with the
geothermal well field capabilities of eQUEST, in particular with
vertical well fields.  I am concerned about the accuracy of the
calculation methodology for the vertical well fields, primarily due to a
large discrepancy we are getting between the eQUEST results and the
results of a separate geothermal well field software produced by Gaia
Geothermal.  Here are the parameters:

 

Vertical well field

Ground conditions & well field dimensions are identical in both eQUEST
and Gaia simulations.

Equest model has four 4x5 rectangular well fields (80 bore holes total)
with 200 ft bore depth.  Plant report PS-C shows that the fourth well
field has no load, thus using at most 60 of the 200 ft wells. 

Gaia software inputs load data from the DOE2 report SS-I for each zone
along with the matching heat pump size (specific to manufacturer)
selected for the project for the zone.  This software uses its knowledge
of the heat pump performance to generate the required well-field size
and depth.  The result is 120 well fields of 250 ft bore depth or 80
well fields of 350 ft bore depth.  

 

I would expect some discrepancy between different software, but in this
case the eQUEST simulation is using only about 50% of the required
well-field size calculated by the Gaia software.  The Gaia calculation
is coming out much larger than what the owner and design-build
contractor had planned for.

 

How reliable is the eQUEST simulation on vertical well-fields? 

 

I believe the primary difference is that Gaia software uses "real"
manufacturer performance data for heap pump models specified and eQUEST
uses PVVT system with default GSHP performance curves.  Could this
difference really make such huge impact on the results?

 

Thanks in advance for any insight.

 

Dan Russell

 

 

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