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Re: [EnergyPlus_Support] Fatal error with sizing of AC coil, what could be the problem?
I ran it again with the Cal. Climate Zone weather file and got this.
** Warning ** Coil:Cooling:DX:SingleSpeed "EL1-SYS1-PSZ-G.E DX
COOLING COIL" - Air volume flow rate per watt of rated total cooling
capacity is out of range at 6.716E-005 m3/s/W.
** ~~~ ** Environment=Climate Zone 15 CA USA CTZRV2
WMO#=747185, at Simulation time=05/08 07:00 - 07:02
** ~~~ ** Expected range for
VolumeFlowPerRatedTotalCapacity=[2.684E-005--6.713E-005]
** ~~~ ** Possible causes include inconsistent air flow rates in
system components,
** ~~~ ** or variable air volume [VAV] system using incorrect
coil type.
** Warning ** Coil:Cooling:DX:SingleSpeed "EL1-SYS1-PSZ-M.E DX
COOLING COIL" - Air volume flow rate per watt of rated total cooling
capacity is out of range at 6.735E-005 m3/s/W.
** Warning ** Coil:Cooling:DX:SingleSpeed "EL1-SYS1-PSZ-T.E DX
COOLING COIL" - Air volume flow rate per watt of rated total cooling
capacity is out of range at 6.715E-005 m3/s/W.
Nothing here about -75C outlet temp so not sure about that one and will
not try to find out what was happening in V7.0
The summary at the bottom of the err file shows the range of the out of
bounds errors.
************* ** Warning ** Coil:Cooling:DX:SingleSpeed
"EL1-SYS1-PSZ-G.E DX COOLING COIL" - Air volume flow rate per watt of
rated total cooling capacity is out of range error continues...
************* ** ~~~ ** This error occurred 358 total times;
************* ** ~~~ ** during Warmup 0 times;
************* ** ~~~ ** during Sizing 0 times.
************* ** ~~~ ** Max=6.917658E-005 Min=6.713307E-005
Since you are not too far over the upper limit you can probably
disregard these as being critical.
You are using AirTerminal:SingleDuct:Uncontrolled objects in the zone so
the flow rate through the supply duct should be constant. If everything
is autosized, the supply flow rate used during the simulation should be
the same as that used for sizing the DX coils.
I do see your sizing objects are a little off in the design supply air
temp for cooling. The zone sizing object determines the air flow rate
and the system sizing object determines the capacity
Sizing:Zone,
EL1-South-PeriQ2, !- Zone or ZoneList Name
14., !- Zone Cooling Design Supply Air
Temperature {C}
Sizing:System,
EL1-Sys1-PSZ-G.C, !- AirLoop Name
12.77779, !- Central Cooling Design Supply Air
Temperature {C}
Not sure how much these inputs will impact the coil sizing. But I think
if you use the same inputs you would be better off.
eio file shows:
Component Sizing Information, Coil:Cooling:DX:SingleSpeed,
EL1-SYS1-PSZ-G.S DX COOLING COIL, Rated Air Flow Rate [m3/s], 1.94398
Component Sizing Information, Coil:Cooling:DX:SingleSpeed,
EL1-SYS1-PSZ-G.S DX COOLING COIL, Rated Total Cooling Capacity (gross)
[W], 32179.75501
which gives 0.0000604 m3/s/W which IS within range so I am a little
stumped as to what would cause this system to exceed the upper flow
ratio limit.
Note that you are only a little above the upper limit so raising the
supply air temperature in the sizing objects may eliminate the warning.
But that won't answer my question and will bother me over the weekend.
On 3/16/2012 1:52 PM, Joe Huang wrote:
> Jim, Yuanlu, and Richard,
>
> Interesting to hear that this is your "favorite" EnergyPlus error. If
> it's a systemic or reoccurring error, that would tell me there's
> something faulty in the EnergyPlus sizing algorithm, or at least for
> certain conditions.
>
> Looking at the comments from Yuanlu and Richard, who reported that the
> file ran fine using either no weather file or for some other location,
> this problem seems related to the weather file used. What I used was
> CZ15RV2 (here attached in Zip form), which is the standard California
> Energy Commission weather file for Climate Zone 15 for the desert areas
> in Southern California. The file is also available from the EnergyPlus
> Weather web site under California.
>
> I appreciate your suggestion about simply shutting off the AC in
> December, but I thought this error was caused in the sizing routine, not
> the simulation. Perhaps someone should explain to me in brief how and
> when EnergyPlus does its sizing calculations. Isn't it done using the
> DDY file?
>
> I get back to the reported outlet air temperature of -74 C in the err
> report. This is so out of normal that it makes me question the
> algorithm. I looked at the weather file and the lowest temperatures are
> still above 0C , so what drives EnergyPlus to derive such a
> out-of-bounds result? This reminds me of the problems I had 5 years ago
> when some runs were failing, with zone temperatures exceeding 200 C.
> I attributed those to iterations going haywire, but here I'm wondering
> if it' a problem in the psychrometrics.
>
> I would ask Yuanlu and Richard to try the IDF again with the CZ15RV2
> file, and see if the same error occurs.
>
> Joe
>
> Joe Huang
> White Box Technologies, Inc.
> 346 Rheem Blvd., Suite 108D
> Moraga CA 94556
> yjhuang@xxxxxxxxxxxxxxxxxxxxxxxx
> www.whiteboxtechnologies.com
> (o) (925)388-0265
> (c) (510)928-2683
> "building energy simulations at your fingertips"
>
>
> On 3/16/2012 6:46 AM, Jim Dirkes wrote:
>> Dear Joe,
>>
>> This is my “favorite” EnergyPlus error!
>>
>> Essentially, EnergyPlus is convinced, with good reasons, that DX coils
>> are not rated to operate outside of the range shown in your errors,
>> which corresponds to about 300-450 cfm/ton. (The acceptable range
>> widens for operation).
>>
>> Part of the key here is that we’re talking about the coil rating
>> conditions. For autosizing, E+ assumes the same rating and operating
>> conditions.
>>
>> Richard Raustad of the E+ Help desk is approaching sainthood for his
>> patience in answering many of my questions and bearing with my
>> frustration on this issue, and is probably the “go�to” expert on this
>> topic.
>>
>> I’m trying to think what may cause an autosized file to trip this
>> error and not coming up with too much.
>>
>> ·You are using a reasonable-to-generous delta T of 10.4C / 18.7F,
>> although ASHRAE 90.1 would like you to use 11.1 / 20. Increasing
>> delta T should help.
>>
>> ·The error, however, occurs in December. If your weather file is a
>> northern hemisphere location, there’s no reason a cooling coil should
>> operate. Perhaps you should schedule it off. The schedule for this
>> in a full year simulation is tricky because TMY weather patterns (and
>> winter warm periods) differ, but it may work out for you since the
>> error occurs during warmup�
>>
>> ·There is a simple EMS method for turning off DX coils when the
>> outdoor temp exceeds a specified value; very handy for minimizing
>> warnings about operating your DX coil during cold weather and
>> producing sub-freezing outlet temps.
>>
>> That’s all I can think of for now.
>>
>> *The Building Performance Team
>> **James V. Dirkes II, P.E., BEMP , LEED AP
>> *1631 Acacia Drive NW
>> Grand Rapids, MI 49504
>> 616 450 8653
>>
>> *From:*EnergyPlus_Support@xxxxxxxxxxxxxxx
>> [mailto:EnergyPlus_Support@xxxxxxxxxxxxxxx] *On Behalf Of *Joe Huang
>> *Sent:* Friday, March 16, 2012 4:10 AM
>> *To:* EnergyPlus_Support@xxxxxxxxxxxxxxx
>> *Subject:* [EnergyPlus_Support] Fatal error with sizing of AC coil,
>> what could be the problem?
>>
>> Hello,
>>
>> I have a small project to translate a large number of eQUEST input
>> files to EnergyPlus IDF. I have developed
>> a procedure that seems to work, but in a few cases I have encountered
>> a Fatal error in the HVAC system sizing
>> that persists even when I set the Rated Cooling Capacity, Sensible
>> Heat Ratio, and Air Flow Rate all to "autosize".
>>
>> The *.err file shows the following :
>>
>> ** Severe ** Sizing: Coil:Cooling:DX:SingleSpeed "EL1-SYS1-PSZ-M.S
>> DX COOLING COIL": Rated air volume flow rate per watt of rated total
>> cooling capacity is out of range.
>> ** ~~~ ** Min Rated Vol Flow Per Watt=[4.027E-005], Rated Vol
>> Flow Per Watt=[6.656E-006], Max Rated Vol Flow Per Watt=[6.041E-005].
>> See Input-Output Reference Manual for valid range.
>> ** Severe ** For object = Coil:Cooling:DX:SingleSpeed, name =
>> "EL1-SYS1-PSZ-M.S DX COOLING COIL"
>> ** ~~~ ** Calculated outlet air relative humidity greater than
>> 1. The combination of
>> ** ~~~ ** rated air volume flow rate, total cooling capacity and
>> sensible heat ratio yields coil exiting
>> ** ~~~ ** air conditions above the saturation curve. Possible
>> fixes are to reduce the rated total cooling
>> ** ~~~ ** capacity, increase the rated air volume flow rate, or
>> reduce the rated sensible heat ratio for this coil.
>> ** ~~~ ** If autosizing, it is recommended that all three of
>> these values be autosized.
>> ** ~~~ ** ...Inputs used for calculating cooling coil bypass
>> factor.
>> ** ~~~ ** ...Inlet Air Temperature = 26.67 C
>> ** ~~~ ** ...Outlet Air Temperature = -74.52 C
>> ** ~~~ ** ...Inlet Air Humidity Ratio = 1.125000E-002 kg/kg
>> ** ~~~ ** ...Outlet Air Humidity Ratio = 1.000000E-005 kg/kg
>> ** ~~~ ** ...Total Cooling Capacity used in calculation =
>> 362778.00 W
>> ** ~~~ ** ...Air Mass Flow Rate used in calculation =
>> 2.783088 kg/s
>> ** ~~~ ** ...Air Volume Flow Rate used in calculation =
>> 2.414784 m3/s
>> ** ~~~ ** ...Air Volume Flow Rate per Watt of Rated Cooling
>> Capacity is also out of bounds at = 6.6563684E-006 m3/s/W
>> ** ~~~ ** During Warmup, Environment=CZ06RV2 COLDEST DAY FROM
>> WEATHER FILE, at Simulation time=12/28 00:00 - 00:15
>> ** Fatal ** Check and revise the input data for this coil before
>> rerunning the simulation.
>>
>> The *.idf file shows the following :
>>
>> Coil:Cooling:DX:SingleSpeed,
>> EL1-Sys1-PSZ-G.S DX Cooling Coil, !- Name
>> S1-Sys1-PSZ-FaQ3, !- Availability Schedule Name
>> autosize, !- Rated Total Cooling Capacity {W}
>> autosize, !- Rated Sensible Heat Ratio
>> 3.172176, !- Rated COP {W/W}
>> autosize, !- Rated Air Flow Rate {m3/s}
>> , !- Rated Evaporator Fan Power Per Volume
>> Flow Rate {W/(m3/s)}
>> EL1-Sys1-PSZ-G.S Mixed Air Outlet, !- Air Inlet Node Name
>> EL1-Sys1-PSZ-G.S Cooling Coil Outlet, !- Air Outlet Node Name
>> Car_48TM012-Cool, !- Total Cooling Capacity Function of
>> Temperature Curve Name
>> SDL-C78, !- Total Cooling Capacity Function of Flow
>> Fraction Curve Name
>> Car_48TM012-EIR-, !- Energy Input Ratio Function of
>> Temperature Curve Name
>> SDL-C93, !- Energy Input Ratio Function of Flow
>> Fraction Curve Name
>> VarSpeedCyclingPLFFPLR; !- Part Load Fraction Correlation Curve Name
>>
>> I'm particularly bothered by the unrealistically low outlet air
>> temperature. Has anyone encountered this problem?
>> Since I've already set everything to autosize, I'm stuck on how else I
>> can fix this problem.
>>
>> Any help or observations would be much appreciated.
>>
>> I've attached the full IDF with this e-mail:
>> OfL-w06-v96-hDXGF-cMsr-mNE-ILtg-FixtPwr-Prim-48in100wT12RefESMg100w-48in55wT8RefEl55w_2.idf
>> . The weather file used is CZ15RV2.epw .
>>
>> Joe
>> Hello,
>>
>> I have a small project to translate a large number of eQUEST input
>> files to EnergyPlus IDF. I have developed
>> a procedure that seems to work, but in a few cases I have encountered
>> a Fatal error in the HVAC system sizing
>> that persists even when I set the Rated Cooling Capacity, Sensible
>> Heat Ratio, and Air Flow Rate all to "autosize".
>>
>> The *.err file shows the following :
>>
>> ** Severe ** Sizing: Coil:Cooling:DX:SingleSpeed "EL1-SYS1-PSZ-M.S
>> DX COOLING COIL": Rated air volume flow rate per watt of rated total
>> cooling capacity is out of range.
>> ** ~~~ ** Min Rated Vol Flow Per Watt=[4.027E-005], Rated Vol
>> Flow Per Watt=[6.656E-006], Max Rated Vol Flow Per Watt=[6.041E-005].
>> See Input-Output Reference Manual for valid range.
>> ** Severe ** For object = Coil:Cooling:DX:SingleSpeed, name =
>> "EL1-SYS1-PSZ-M.S DX COOLING COIL"
>> ** ~~~ ** Calculated outlet air relative humidity greater than
>> 1. The combination of
>> ** ~~~ ** rated air volume flow rate, total cooling capacity and
>> sensible heat ratio yields coil exiting
>> ** ~~~ ** air conditions above the saturation curve. Possible
>> fixes are to reduce the rated total cooling
>> ** ~~~ ** capacity, increase the rated air volume flow rate, or
>> reduce the rated sensible heat ratio for this coil.
>> ** ~~~ ** If autosizing, it is recommended that all three of
>> these values be autosized.
>> ** ~~~ ** ...Inputs used for calculating cooling coil bypass factor.
>> ** ~~~ ** ...Inlet Air Temperature = 26.67 C
>> ** ~~~ ** ...Outlet Air Temperature = -74.52 C
>> ** ~~~ ** ...Inlet Air Humidity Ratio = 1.125000E-002 kg/kg
>> ** ~~~ ** ...Outlet Air Humidity Ratio = 1.000000E-005 kg/kg
>> ** ~~~ ** ...Total Cooling Capacity used in calculation =
>> 362778.00 W
>> ** ~~~ ** ...Air Mass Flow Rate used in calculation =
>> 2.783088 kg/s
>> ** ~~~ ** ...Air Volume Flow Rate used in calculation =
>> 2.414784 m3/s
>> ** ~~~ ** ...Air Volume Flow Rate per Watt of Rated Cooling
>> Capacity is also out of bounds at = 6.6563684E-006 m3/s/W
>> ** ~~~ ** During Warmup, Environment=CZ06RV2 COLDEST DAY FROM
>> WEATHER FILE, at Simulation time=12/28 00:00 - 00:15
>> ** Fatal ** Check and revise the input data for this coil before
>> rerunning the simulation.
>>
>> The *.idf file shows the following :
>>
>> Coil:Cooling:DX:SingleSpeed,
>> EL1-Sys1-PSZ-G.S DX Cooling Coil, !- Name
>> S1-Sys1-PSZ-FaQ3, !- Availability Schedule Name
>> autosize, !- Rated Total Cooling Capacity {W}
>> autosize, !- Rated Sensible Heat Ratio
>> 3.172176, !- Rated COP {W/W}
>> autosize, !- Rated Air Flow Rate {m3/s}
>> , !- Rated Evaporator Fan Power Per Volume
>> Flow Rate {W/(m3/s)}
>> EL1-Sys1-PSZ-G.S Mixed Air Outlet, !- Air Inlet Node Name
>> EL1-Sys1-PSZ-G.S Cooling Coil Outlet, !- Air Outlet Node Name
>> Car_48TM012-Cool, !- Total Cooling Capacity Function of
>> Temperature Curve Name
>> SDL-C78, !- Total Cooling Capacity Function of Flow
>> Fraction Curve Name
>> Car_48TM012-EIR-, !- Energy Input Ratio Function of
>> Temperature Curve Name
>> SDL-C93, !- Energy Input Ratio Function of Flow
>> Fraction Curve Name
>> VarSpeedCyclingPLFFPLR; !- Part Load Fraction Correlation Curve Name
>>
>> I'm particularly bothered by the unrealistically low outlet air
>> temperature. Has anyone encountered this problem?
>> Since I've already set everything to autosize, I'm stuck on how else I
>> can fix this problem.
>>
>> Any help or observations would be much appreciated.
>>
>> I've attached the full IDF with this e-mail:
>> OfL-w06-v96-hDXGF-cMsr-mNE-ILtg-FixtPwr-Prim-48in100wT12RefESMg100w-48in55wT8RefEl55w_2.idf
>> . The weather file used is CZ15RV2.epw .
>>
>> Joe
>>
>> Joe Huang
>> White Box Technologies, Inc.
>> 346 Rheem Blvd., Suite 108D
>> Moraga CA 94556
>> yjhuang@xxxxxxxxxxxxxxxxxxxxxxxx<mailto:yjhuang@xxxxxxxxxxxxxxxxxxxxxxxx>
>> www.whiteboxtechnologies.com<http://www.whiteboxtechnologies.com>
>> (o) (925)388-0265
>> (c) (510)986-2683
>> "building energy simulations at your fingertips"
>>
>>
>
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--
Richard A. Raustad
Senior Research Engineer
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University of Central Florida
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