[BLDG-SIM] Fan-powered VAV systems in doe-2 & EnergyPlus

[Mark Mullins]

Thanks to all who responded to my fan powered VAV question.  

Here's a followup to EnergyPlus Users:  How well does EnergyPlus model Fan powered VAV systems?  The system should be able to model variable air volume in cooling mode, DX cooling, parallel fan-powered boxes that induce air from a plenum, and thermostatically contolled reheat in the VAV box.


(The original question is presented below, and a response follows)
> To PowerDOE/DOE-2 users:
> Has anyone out there successfully modeled a DX fan-powered >VAV system in doe-2.2 or doe-2.1e?  If so, what system did you >use and how did you model the fan box part of it?
>
> The system I have in mind must have the following functionality:
> -VAV
> -DX cooling
> -Evaporative condensing
> -Parallel fan-powered boxes that induce air from a plenum
> -Thermostatically contolled reheat in the VAV box
>
> This is one of the most common types of HVAC systems around, >so I am wondering if someone out there has had any more luck >than me in attempting to conquer the challanges of accurately >modeling its controls & functionality.
>
> Any thoughts?
>
> 

Answer (thanks to Fred Porter of Architectural Energy Corp)
You must decompose the packaged unit into a AHU/CHW/Chiller/Tower system. (No PIU in PVAVS) Set pump heads to near zero. Adjust tower approaches, or adjust virtual chiller EIR to get a reasonable representation of the kW/ton.

You can't use a doe-2 "plenum" as induced-air-zone. Take your pick, either use the core zone, or the perimeter zone itself.

Make sure to coordinate box fan setpoints, and box reheat setpoints as outlined in various 2.1 and 2.2 manuals.


====================================================
--
Fred W. Porter
Senior Engineer
Architectural Energy Corp.
2540 Frontier Ave. Suite 201
Boulder CO 80301
email: fporter at archenergy.com 
phone: 303-444-4149
fax: 303-444-4304


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