----- Reply message ----- From: "James V Dirkes II, PE" <jim@xxxxxxxxxxxxxxxxxxxxxxxxxxx> Date: Thu, Feb 10, 2011 9:21 am Subject: [EnergyPlus_Support] Re: Modeling VRV system To: <EnergyPlus_Support@xxxxxxxxxxxxxxx>
The approach I described is for a LEED project, but has not been submitted yet.
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 9:05 AM To: EnergyPlus_Support@xxxxxxxxxxxxxxx Subject: [EnergyPlus_Support] Re: Modeling VRV system
I really appreciate your help, James. Thank you. Have you ever submitted this type of VRF-approximate model for LEED certification? Has anybody out there submitted any other these "almost-VRF" for LEED?
I would though, if you don't mind and have some free time for it, if you could further describe your method.
Thank you again. Have a great day!
Francisco
--- In EnergyPlus_Support@xxxxxxxxxxxxxxx <mailto:EnergyPlus_Support%40yahoogroups.com> , "James V Dirkes II, PE" <jim@...> wrote: > > 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%40yahoogroups.com> > [mailto:EnergyPlus_Support@xxxxxxxxxxxxxxx <mailto:EnergyPlus_Support%40yahoogroups.com> ] On Behalf Of fm1n0 > Sent: Thursday, February 10, 2011 7:28 AM > To: EnergyPlus_Support@xxxxxxxxxxxxxxx <mailto:EnergyPlus_Support%40yahoogroups.com> > 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 <mailto:EnergyPlus_Support%40yahoogroups.com> > <mailto:EnergyPlus_Support%40yahoogroups.com> , "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 <mailto:EnergyPlus_Support%40yahoogroups.com> > <mailto:EnergyPlus_Support%40yahoogroups.com> > > 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 > > >