[Trace-users] Water to Water Heat Pumps (UNCLASSIFIED)

Alex Chapin alexc at 2rw.com
Tue Feb 22 11:59:59 PST 2011


In TRACE:

The help file (press F1 on any screen in TRACE) and User's Manual are pretty helpful with how to model geothermal heat pumps, I would suggest reading through those first. In terms of modeling the appropriate ground loop temperatures and associated WWHP efficiency, there are a couple of ways of doing it (see help file and User's manual for specifics). Just keep in mind that when you create a new WWHP in the Cooling Equipment library and define the Full Load Energy Rate and the Design Entering Condenser Water Temperature, you need to base them on the worst case entering loop temperatures over the year. TRACE assumes you enter the efficiency at the hottest and coldest entering condenser temperatures for Cooling and Heating efficiency respectively and then uses the Power Consumed and Ambient Modification Unloading Curves to adjust the efficiency for air-side load and change in entering loop temperature.

In eQUEST:

I'm a little rusty on eQUEST, but this is how I remember it. You can enter the ground and well properties for your site and system which will be the basis of entering loop temperature for the equipment as a function of the load on the equipment over the year. eQUEST wants the equipment efficiency at ARI conditions and then you enter the unloading curves (see help/Documentation for more info on this). The concept here is similar to TRACE but from what I remember it is more detailed.

Thanks,

Alex Chapin, E.I.T., LEED AP BD+C
Energy Engineer
2rw Consultants
T: 434-296-2116 ext. 305
F: 434-977-1862

P Please consider the environment before printing this e-mail - Thanks!


Message: 1

Date: Tue, 22 Feb 2011 10:37:34 -0600

From: "Eurek, John S NWO" <John.S.Eurek at usace.army.mil<mailto:John.S.Eurek at usace.army.mil>>

To: <trace-users at lists.onebuilding.org<mailto:trace-users at lists.onebuilding.org>>

Subject: [Trace-users] Water to Water Heat Pumps (UNCLASSIFIED)

Message-ID:

      <57E9627AE82514439A8F543A61BFDD6807D574F1 at NWO-ML3OMA.nwo.ds.usace.army.mil<mailto:57E9627AE82514439A8F543A61BFDD6807D574F1 at NWO-ML3OMA.nwo.ds.usace.army.mil>>



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Classification: UNCLASSIFIED

Caveats: NONE



The EER of WWHP can vary from 11.8 to 23.3 depending on the water temperature returning from the well field.  Can Trace model this?



We are designing a lot of geo-thermal heat-pumps. If we can't model the benefit of the well-field accurately, we can't model the energy use.



John Eurek PE, LEED AP

Mechanical Engineer,

US Army Corps of Engineers

Omaha District CENWO-ED-DA

1616 Capitol Avenue

Omaha, NE 68102

Phone: (402) 995-2134

email: john.s.eurek at usace.army.mil<mailto:john.s.eurek at usace.army.mil>





Classification: UNCLASSIFIED

Caveats: NONE







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