Rowan,
A variable refrigerant system operates much the same way, it
sounds. I recently modeled a VRF by using the same approach as used in the
example file I cited, making the Boiler’s efficiency = 1.0 and the
Chiller’s COP = 1000 (so no compressor heat was added). For
post-processing:
·
I reported Boiler and Chiller energy
·
The loop in that example file operates such that only one of
those is active since the loop always reflects the composite energy of the
entire system
·
Using the VRF manufacturer part load information, I calculated
the electrical energy (in Excel) that would be used to satisfy the Boiler /
Chiller load
Your system may well operate differently, since it sounds as
though you can simultaneously heat and cool. In that case, you’ll
need separate heating and cooling loops, but you may be able to do something
similar…. Good luck!
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 rowan.blakers
Sent: Tuesday, July 06, 2010 11:04 PM
To: EnergyPlus_Support@xxxxxxxxxxxxxxx
Subject: [EnergyPlus_Support] Re: How to model four pipe chiller with
simultaneous heating and cooling
Hello James,
Thanks for taking the time to reply.
The chiller system I am trying to model is a complex beast. Both hot and cold
water loops run through the chiller. There are two evaporators and condensers.
Refrigerant flow can be controlled such that if simultaneous heating and
cooling is required, the heat rejected from the cooling side can be used for
heating, and vice versa. In heating-only or cooling-only it is basically a
reverse-cycle system heating or cooling water.
The idea of taking raw heating/cooling loads and post-processing them sounds
reasonable. I could probably write something in EMS code to do it on the fly.
Perhaps that is the simplest solution.
Regards,
Rowan
--- In EnergyPlus_Support@xxxxxxxxxxxxxxx,
"James V Dirkes II, PE" <jvd2pe@...> wrote:
>
> Dear Rowan,
>
> The example file "5ZoneWaterLoopHeatPump.idf" contains a single
water loop
> which utilizes a chiller for cooling and a boiler for heating. It seems
> that you might:
>
> . Use the example file "as is",
>
> . assign a boiler efficiency of 1.0,
>
> . report all Boiler energy with a Custom Meter and then
>
> . modify the Boiler energy using the Climaventa's heating efficiency
> / COP in a post-process calculation
>
>
>
> p.s., I am not familiar with the chiller type you have mentioned, so I am
> guessing a bit about how it functions.
>
>
>
> The Building Performance Team
> James V. Dirkes II, P.E., LEED AP
> 1631 Acacia Drive NW
> Grand Rapids, MI 49504
> 616 450 8653
>
>
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