Modeling Ground water well in EnergyPlus

Hi All,

I need to model a closed loop ground water well. The ground water well feeds water to heat pumps for both hot and chilled water. As this isn’t a traditional ground source heat pump, the heat/cold is coming from the well water rather than the earth, I have been trying to figure out which would be a more appropriate component to model this. My two options at the moment are - “GroundHeatExchanger:Pond” or “WaterHeater:Mixed”?

My question is due to the description of the “GroundHeatExchanger:Pond” component in the I/O reference as a ‘shallow’ pond. This implies that the water temperature around the pipes would vary much more than a well water system and would not provide the correct heat transfer.

The "WaterHeater:Mixed" would allow us to heat the water year round on a schedule to 15°C (or similar) and control the temperatures more.

Does anyone know of any other options or whether there are further considerations to take into account with these two objects?

Thank you in advance,

Raghu

Hi Raghu,

If you have a good idea of what the water temperatures will be year-round, the simplest method is to use a SetpointManager:Scheduled object to control the temperature at the Supply Outlet of your Loop. Then maintain the loop temperature using DistrictHeating and DistrictCooling objects.

If you don't know the actual water temperatures, I would consider using a GroundHeatExchanger:Vertical and oversize it so that heat rejection from the building has little impact on the ground temperatures. There are many factors in implementing this object. Usually building loads are output to separate software (GLD or GLHEPro). This software assists in sizing the borehole design and can provide the g-function pairs required to populate the GroundHeatExchanger:Vertical EnergyPlus object.

For your specific application, I would not use WaterHeater:Mixed. I think this would be too complicated to get it working correctly, and you won't have any more accuracy in your simulation than with my DistrictHeating/Cooling suggestion.

With GroundHeatExchanger:Pond, there are too many unknowns in how the model is implemented for me to suggest trying to push it to operate in a way it was not intended.

Good Luck!

Karen

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kwalkerman

answered 2015-06-30 09:33:49 -0500

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@kwlkerman, Thank you for your answer. The options of the district heating/cooling components and the GroundHeatExchanger:vertical seem very promising. I am presently trying these out and will be able to decide once I have the results. Thanks again for your help!

Thanks, Raghu