[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]
Re: [EnergyPlus_Support] Re: DX coil psychrometric problems
Sorry, Jim. I have no idea. The guys at the
helpdesk would transition and run the input file for you and be able to
tell, perhaps or be able to lead you?
Or I suppose you could transition and run to see if it has
changed.
Linda
At 11:15 AM 8/14/2018, Jim Dirkes jim@xxxxxxxxxxxxxxxxxxxxxxxxxxx
[EnergyPlus_Support] wrote:
Thanks, Linda.
I'm using the v8.6 included with Designbuilder. Do you think v8.9 has
improved DX coil modeling?
p.s., I'm becoming a champion DX coil bludgeoner, but it's no fun.
Normally I don't have so many problems with Actual coil selections, but I
think these are over-sized.....
On Mon, Aug 13, 2018 at 2:56 PM, Jim Dirkes
<
jim@xxxxxxxxxxxxxxxxxxxxxxxxxxx> wrote:
- Dear Forum,Â
- (excuse cross-posting with UnMetHours)
- Although I have had occasional problems with EnergyPlus giving a
fatal error due to DX cooling coil sizing problems, most have been
associated with autosized coils. I have a project now which uses 11
different rooftop units, all with DX cooling coils. Three of them are
giving me fits (problems). So far, I have:
- disabled the coil below a specified outdoor temp (<= 65F) using an
EMS script
- raised the airflow 20% (for improved flow/watt ratio)
- reduced the coil rated capacity by up to 50% (for improved flow/watt
ratio)
- disabled the coil completely (availability = always OFF)Â
- The only strategy which works is to disable the coil - and that isn't
a very good representation of actual performance :)
- The current problem coil has these characteristics:
- 11,400 cfm VAV fan with minimum flow fraction = 0.7Â
- 385 MBH / 113 kw rated capacityÂ
- single stage coil
- The Fatal error looks like:Â * Severe *Â PsyRhoAirFnPbTdbW:
RhoAir (Density of Air) is calculated <= 0 [-2.69960]. * ~~~ *Â
pb =[98900.00], tdb=[-400.80], w=[9.9866244E-006]. * ~~~ *Â
Routine=Unknown, Environment=STORE 291 - STURGIS (01-01:31-12), at
Simulation time=05/16 01:40 - 01:50Â * Fatal *Program terminates due
to preceding condition.
- Can you suggest ways to correct this? Thanks in advance. The rooftop
unit uses a digital compressor, which unloads very flexibly. Perhaps I
should make the coil multi-stage?
- --
- James V Dirkes II, CEO / President
- The Building Performance Team Inc.
- 1631 Acacia Dr, Grand Rapids, MI 49504
- (alphabet soup of efforts for greater understanding: PE, BEMP, BCxP,
LEED AP)
- Direct / Mobile: 616.450.8653
-
jim@xxxxxxxxxxxxxxxxxxxxxxxxxxx
- Website l Â
LinkedIn
Coffee conversation:
- You are hereby authorized to make two
big mistakes each year, otherwise you will never learn anything.
--
James V Dirkes II, CEO / President
The Building Performance Team Inc.
1631 Acacia Dr, Grand Rapids, MI 49504
(alphabet soup of efforts for greater understanding: PE, BEMP, BCxP, LEED
AP)
Direct / Mobile: 616.450.8653
jim@xxxxxxxxxxxxxxxxxxxxxxxxxxx
Website l Â
LinkedIn
Coffee conversation:
You are hereby authorized to make two big
mistakes each year, otherwise you will never learn anything.
__._,_.___
Posted by: Linda Lawrie <linda@xxxxxxxxxxxxxx>
EnergyPlus support is found at:
http://energyplus.helpserve.com or send a message to energyplus-support@xxxxxxxx
The EnergyPlus web site is found at:
http://www.energyplus.net/
The group web site is:
http://groups..yahoo.com/group/EnergyPlus_Support/
Attachments are currently allowed but be mindful that not everyone has a high speed connection. Limit attachments to small files.
EnergyPlus Documentation is searchable. Open EPlusMainMenu.pdf under the Documentation link and press the "search" button.
![]()
__,_._,___