Why Don't I Need a DX Cooling Coil Plant-Side

asked 2018-10-02 12:50:12 -0500

updated 2018-10-03 15:05:03 -0500

I currently have a DX Cooling Coil providing cooling in my supply air, but I haven't got any sort of cooling plant in my model. If the element is truly just a cooling coil, wouldn't that mean that this is just the evaporator? How can cooling possibly be occurring?

What I was hoping was to have the condenser associated with this evaporator reject heat to a cooling tower. Is the element in OpenStudio a complete DX system (evaporator and condenser) with the assumption being that it is air-cooled?

Thanks! image description

edit retag flag offensive close merge delete

Comments

FYI - this image you added of the Refrigeration Condenser Water Cooled item from OpenStudio's HVAC library is meant to be used exclusively for refrigeration systems (walk-in or cases in grocery stores, for example). They can't be used in an air or plant system like you want.

Aaron Boranian ( 2018-10-03 18:13:57 -0500 )edit

@Aaron Boranian Thanks for the heads up...I was a little suspicious of that.

jbatt ( 2018-10-04 05:51:51 -0500 )edit

add a comment

answered 2018-10-03 12:22:45 -0500

David Goldwasser

20295 ●94 ●14 http://www.openstudio.net/

If you want to cool using a plant loop, then choose a CoolingCoil:Water instead of a CoolingCoilDX object. Then create a water loop with an air or water cooled chiller, depending on your use case. Water cooled if you will have a cooing tower.

On the HVAC tab of the OpenStudio application if you click the green plus at the top left you will open a dialog to make various HVAC systems. If you choose "Packaged Rooftop VAV with Reheat" you can inspect the resulting system that has an air loop serving the zones, a chiller water loop, and a condenser water loop.

edit flag offensive delete link

Comments

Thanks, David. That sounds like a reasonable strategy...the only hesitation that I had about doing just that was that in the building I am modeling this is an evaporator coil and I was afraid CoolingCoil:Water would behave as a CHW coil - without any phase change occurring. Is this not something that I need to worry about?

The plant-side that you described is exactly what I'm looking for.

jbatt ( 2018-10-03 12:31:46 -0500 )edit

I believe what the user is asking for is a water-cooled DX cooling coil. So only the condenser water loop would be necessary. Does OS have water-cooled DX coils?

rraustad ( 2018-10-03 12:39:38 -0500 )edit

That's correct. Or some kind of work around using an ordinary cooling coil as David suggested and equating the performance to that of a water-cooled DX coil

jbatt ( 2018-10-03 12:44:11 -0500 )edit

This answer might be useful.

ericringold ( 2018-10-03 13:42:51 -0500 )edit

Ideally, though, it would be a refrigerant (not water) exchanging heat with my air-stream and water loop

jbatt ( 2018-10-03 15:00:52 -0500 )edit

The hope was that I could either connect my DX coil to the object in the above image or that there was an evaporator side that corresponded to this object (I can't seem to find one).

jbatt ( 2018-10-03 15:04:27 -0500 )edit

The DX 'coils' in EnergyPlus model the whole evaporator+condenser assembly. The Coil:Cooling:WaterToAirHeatPump:EquationFit enables modeling equipment that cools air and rejects heat to a water loop using a curve fit model, thus bypassing the need to characterize the refrigerant and individual subcomponents.

ericringold ( 2018-10-03 15:11:38 -0500 )edit

see more comments

Why Don't I Need a DX Cooling Coil Plant-Side

Comments

1 Answer

Comments

Your Answer

Careers

Question Tools

Stats

Why Don't I Need a DX Cooling Coil Plant-Side edit

Comments

1 Answer

Comments

Your Answer

Careers

Question Tools

Stats

Why Don't I Need a DX Cooling Coil Plant-Side