Re: [EnergyPlus_Support] Connectiong two AirLoops to the same zone

On Mon, Aug 15, 2011 at 11:32 AM, Vinay Devanathan <vinay.devanathan@xxxxxxxxx> wrote:

Thanks for your reply.

Yeah, I think 1 can't work as I have more than the number of air handlers that can make the approach possible.

By 2, you are saying I will include the OA/DOAS parameters directly on the air handler in the air loop right?

I was thinking I would use ZoneHVA:OutdoorAirUnit and supply OA to each zone based on the requirement and split the coil capacities and fan power on a weighted average basis.

Do you think this would work and have the same effect. Just that it required more time and work and increases computation time also.

Vinay
On Mon, Aug 15, 2011 at 11:25 AM, Karen Walkerman <kwalkerman@xxxxxxxxx> wrote:
I don't think you can model this system exactly. You are limited because you are only allowed one set of splitters/mixers on an airloop. I can think of 2 configurations that approximate the design:

1. IF the OA ratio is the same for all air handlers AND you have 3 or fewer air handlers (I believe you are limited to 3 outlets for an AirLoop), you can use my approach an make the first branch in the supply side of the airloop contain the DOAS system components (OA Mixer any reheat coils, etc). Then split this air to branches where your air handler equipment is located.

2. If #1 doesn't work for you, you're limited to a separate AirLoop for each air handler. In this case, approximate your DOAS as best you can by splitting between all AirLoops. You might be able to do a better job if you use an EMS system to control the DOAS equipment so that you can control the DOAS attached to each AirLoop in the same manner.

--
Karen
On Mon, Aug 15, 2011 at 11:16 AM, Vinay Devanathan <vinay.devanathan@xxxxxxxxx> wrote:
Karen,

The HVAC system that I am trying to model is configured like this -

Air handlers supplying conditioning air to multiple zones. Fresh OA supply to these air handlers is through a really big DOAS. This DOAS feeds air into the return duct of the air handlers. Do you think this is possible using the splitting airloop approach?

If i am modeling it like in the DDAutosize.idf method, I would have only one airloop with multiple branches for each air handler, but those air handlers are needed to be an airlop by themselves for splitting into multiple terminals. Do you still think it is possible?

Thank you.

Vinay
On Fri, Aug 12, 2011 at 2:57 PM, Vinay Devanathan <vinay.devanathan@xxxxxxxxx> wrote:
In my case, I cannot substitute one of my airloops as a ZoneEquipment unfortunately. They are both air handlers.

The cross mixing idea is great, I never thought about that. But that would make me split all my zones into two which I think is a little difficult as I have a lot of zones. Maybe a good option if I had known this before zoning my building.

The DDAutosize.idf shows how we can split one airloop into multiple braches. On a rough glance, I think this should take care of the situation. Karen, I was just reading the post where you had suggested this approach to someone last month and how it worked for im/her.

Thanks for your valuable suggestions.

Vinay
On Fri, Aug 12, 2011 at 2:49 PM, Karen Walkerman <kwalkerman@xxxxxxxxx> wrote:
If you can't find appropriate zone equipment to substitute for one of your airloops, you can also try to put all of your airloop equipment onto one airloop with two outlets. Airloops are the only type of loop which are allowed to have more than one outlet node. Some example files to look at are the dual duct examples.

--

Karen
On Fri, Aug 12, 2011 at 2:45 PM, Richard Raustad <RRaustad@xxxxxxxxxxxx> wrote:
The solution is to use 1 air loop and 1 zone equipment.

I have also heard that you can trick the simulation by splitting each zone, serving each split zone with a separate air loop, and then using cross-mixing objects with high flow rates to mix the split zones. I have not tried this, but it sounds interesting.

On 8/12/2011 2:39 PM, Vinay Devanathan wrote:

Hello Robin,

Do you have a solution for this issue?

Hope to hear from you.

Vinay

On Fri, May 13, 2011 at 12:00 PM, rgen1202 <robin.genoud@xxxxxxxxx> wrote:

Hello,

I have txo separated AirLoop, one for the mechanichal ventilation, another for the Cooling. My problem is that I want to connect this Loops to one single zone, but there is only one Zone Return Air Node Name. And in fact, if i use this Return Air Node as the Zone Eqipment Outlet Node for both AirLoops, I have a severe error.

I tried using the exhaust node but I can't manage to connect it to the Airloop.

Thanks in advance.

Robin GENOUD
-- 
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