Dear Francisco,
I do not think that you can properly simulate VRF with individual zone DX systems.
A VRF system essentially responds to the total system load. If, for example, 5 zones are in heating mode, and 6 are in cooling mode, you might have a cooling load that is a small percentage of the total capacity. This can be true even if the 6 cooling mode zones are operating at 100% of their capacity. In this situation, the true part load of the system may be only 9% (as an example).
I hope that is clear (I don’t have time now for more details)!
For that reason, I think a better approach is:
· WSHP in each zone with COP = 1000 (yes, one thousand so that there is essentially no compressor heat added at the zone level)
· WSHPs served by a chiller (COP= 1000) and boiler (efficiency = 1.0)
· Create a custom meter for the chiller and boiler energy
· Via post-processing (e.g., Excel spreadsheet), calculate the net heating / cooling load and apply a part load factor appropriate for the VRF manufacturer
· Calculate a new total for electric usage based on the new calculated VRF electricity use.
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 fm1n0
Sent: Thursday, February 10, 2011 7:28 AM
To: EnergyPlus_Support@xxxxxxxxxxxxxxx
Subject: [EnergyPlus_Support] Re: Modelling VRV system
Hi.
I'm attempting the approximate-VRF method mentioned below.
COIL:COOL/HEAT:DX:MULTISPEED
1. Should the rated conditions be the same for all speeds?
2. Curves: are they defined by E+ or user-defined?
InputOutput p.1477
"rating point (the air entering the cooling coil at 26.7°C drybulb/19.4°C wetbulb and air entering the outdoor condenser coil at 35°C drybulb/23.9°C wetbulb)"
InputOutput p.1514
"the multispeed coil object is described by specifying the performance at different operating speeds at rated conditions"
thanks
Francisco
--- In EnergyPlus_Support@xxxxxxxxxxxxxxx, "alberto" <ahneto@...> wrote:
>
> Dear Mark,
>
> The four step variation I mentioned is related to the menu COIL:COOLING:DX:MULTISPEED where we can set 04 different speeds where the model of such coil can be simulated. For each speed, you can provide all the parameters that can represent the coil but it is different from a VRF because the system works in a continuous variation of these parameters but I think it is the closest model EnergyPlus have at the moment.
>
> Alberto
>
> ----- Original Message -----
> From: Zoeteman, Mark R.
> To: ahneto@...
> Cc: EnergyPlus_Support@xxxxxxxxxxxxxxx
> Sent: Monday, May 24, 2010 11:40 AM
> Subject: [EnergyPlus_Support] Modelling VRV system
>
>
>
>
>
> Alberto,
>
> Is following page 14 from "Tips and Tricks for Using EnergyPlus" what you are referring to model VRV system? I don't see reference to a four stepped variation you referred to in your response to Felipe Agustin.
>
> Mark Zoeteman, FTC&H
>
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