Re: [EnergyPlus_Support] DirectIndirectEvapCoolers.idf

Hi James, Lorie,

I am very interested in this paper. Currently, I am working on a data center project in a cold-dry region that combines DX and direct evaporative cooling. Simulation expected great savings, these savings are basically because of humidification energy as the building has to be controlled between 30% and 40% RH.

Regarding Lorie's question,

- I advice you to use RESEARCHSPECIALDIRECTEVAPORATIVE object. It is away easier to define.

- I don't advice you to start with an HVAC system defined in Design Builder. Get only the geometry from Design builder.

- Start with a base system using "UNITARY:COOLING ONLY"

- Add the evaporative cooler between outdoor air mixer and cooling coil.

- Each component have inlet and outlet node, so when you add it make sure that evaporative inlet node is outlet node of outdoor mixer and outlet node is inlet node of DX coil.(track node names allover the file, you may do that easier in the text editing mode instead of IDF editor).

- You also need to add it to the main air loop branch object

- In the evaporative cooler component, select the sensor node in the way you like to control the cooler.

1-If you want it to work on te same time with the DX coil (pre-cooling), then the evaporative outlet node should be the sensor node with a pre cooling set point (you need to define that through a set point manager).

2-If you want it to carry all the load if it can, then set point node should be the Air Loop outlet node (Same node for DX coil and it should have a set point manager as well)

Please feel free to contact me directly if you need more help.

Alaa Kandil

Energy Analysis Specialist

MA, LEED^Â® AP

alaa.kandil@xxxxxxxxxxxx

MechWave Engineering Ltd.

Suite 200, 1518 7^th Street SW

Calgary, Alberta T2R 1A7

Phone: 403-802-1090 Facsimile: 403-244-4440

From: "James V Dirkes II, PE" <jim@xxxxxxxxxxxxxxxxxxxxxxxxxxx>
To: EnergyPlus_Support@xxxxxxxxxxxxxxx
Sent: Wed, October 13, 2010 7:38:03 AM
Subject: RE: [EnergyPlus_Support] DirectIndirectEvapCoolers.idf

Dear Lori,

A couple of thoughts:

Iâ??ve recently completed some models using indirect evap with DX. E+ works OK for some configurations, but not all (at least not without some â??Workaroundsâ??). Generally, itâ??s not a good idea to couple direct evap and DX because of the fact that a direct evap cooler removes no energy from the air (itâ??s adiabatic).

There are a couple of manufacturers who make the indirect + DX type of equipment currently, and they generally use either:

Â· A constant volume supply fan with constant volume exhaust fan. The exhaust fan draws evaporatively cooled air across the DX condenser for additional performance improvement.

Â· An all-variable-volume version of the above.

E+ models the first version fairly straightforwardly. The second version needs some help from you, largely because E+ doesnâ??t know how to make the exhaust fan Variable speed.

I recently completed a paper for the upcoming ASHRAE Winter conference in which I compared performance for traditional DX against a couple versions of indirect evap plus DX in dry climates. I donâ??t think I can share the paper yet, but I can send you an IDF or two to help you. In short, it appears that you canâ??t save much energy by using a cycling (on/off) fan control. For variable speed fans, it appears that you can save substantial energy if your indirect evap effectiveness exceeds 75% or so. For a very high effectiveness indirect evap system, check out www.coolerado.com. (Other such systems may be available, but I donâ??t know about them.)

Please send me a private message and Iâ??ll attach the IDFs.

p.s., If anyone else has interest, Iâ??ll post it to the E+ files on Yahoo.

The Building Performance Team
James V. Dirkes II, P.E., LEED AP
1631 Acacia Drive NW
Grand Rapids, MI 49504
616 450 8653

From: EnergyPlus_Support@xxxxxxxxxxxxxxx [mailto:EnergyPlus_Support@xxxxxxxxxxxxxxx] On Behalf Of jorehome
Sent: Wednesday, October 13, 2010 5:02 AM
To: EnergyPlus_Support@xxxxxxxxxxxxxxx
Subject: [EnergyPlus_Support] DirectIndirectEvapCoolers.idf

I'm looking for help with setting up an evaporative cooler that is used in combination with a DX unit. I'm attempting to use the DirectIndirectEvapCoolers.idf example file to set this up.

Question: How do I combine this example with my model that I assembled with DesignBuilder? I know that I can open both with the EP-Launch software and find the sections that I need to add to my file but how do I get the node naming right? Is there any software available to make this easier?

Thanks in advance.

Lori Jore