[BLDG-SIM] Water-to-Water Heat Pump Chillers and GLHE's

[David S Eldridge]

Jeff, the lake/well model is based on ground water circulating through
the chiller heat exchanger.  Therefore the main parameter is the water
temperature.  It sounds like you instead have a ground loop heat
exchanger, where the water is circulated through a closed loop pipe
located in the ground.  I don't believe you are able to use the heat
pump chiller type for that method of heat rejection.
 
One workaround might be that if you know what the water temperatures
will be in the GLHE you could input those monthly temperatures to the
lake/well model and use your model as you currently have it configured.
 
You could make a separate eQuest model using water-to-air heat pumps
(make sure to have the same outside air loads, compressor efficiencies
etc.) using the GLHE heat rejection with the details of your
actual/proposed well field to get some idea what the water temperatures
should be, then plug those temperatures into your WTWHP model using the
lake/well heat rejection.  Also you may want to simulate it with a
high/low range of monthly water temperatures to see how sensitive your
results are to this approximation.
 
You have to judge whether this will provide the accuracy you need for
your project.  Obviously you'll have to make adjustments for the pumping
energy to reflect your intentions.
 
Hope this helps!
 
David
 


________________________________

	From: BLDG-SIM at gard.com [mailto:BLDG-SIM at gard.com] On Behalf Of
Jeff Staller
	Sent: Friday, February 23, 2007 12:57 PM
	To: BLDG-SIM at gard.com
	Subject: [BLDG-SIM] Water-to-Water Heat Pump Chillers and GLHE's
	
	

	 

	In eQuest I am attempting to model a proposed system that
utilizes a 'well-water-to-water heat pump' type chiller that will be
attached to a vertical well ground loop heat exchanger. The chillers are
modular and cycle on and off to meet demand, so they operate at a
constant efficiency.  They will be providing HW and CHW to 2-pipe fan
coil units.  The DOE2.2 documentation indicates this chiller type is
Heat-Pump and that this chiller type can only be attached to lake/well
water loop.  By selecting the lake/well water loop, I am unable to
define the vertical well characteristics, i.e well depth, configuration,
etc.  Does anyone know of a way to attach the Heat-Pump type chiller to
a vertical well system?  If not, is there a method to better describe
the capacity of the lake/well loop?  And finally, does anyone have
experience modeling this system type and can provide any insight?

	 

	Thanks,

	 

	Jeff

	 

	Jeff Staller, CEM

	CTG Energetics

	949-428-6293

	 

	 

	 

	
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