This probably relates to your problem. You tell the program to chose the inlet air humrat, but then specify the outlet air humrat.
autosize, !- Design Inlet Air Humidity Ratio {kg-H2O/kg-air}
0.0010, !- Design Outlet Air Humidity Ratio Entering is 0.01178 ,0.0050 does not work
I would run the program for the sizing period and report the outdoor T and W to see how these values change. That warning looks like one that should provide more information. Alternately you could specify both or autosize both.
On 8/3/2011 8:52 AM, Jean marais wrote:
Hi Richard,
I've set the coil and it was working until I upped the entering humidity. I now get:
** Warning ** SizeWaterCoil: Coil="DOAS COOLING COIL", Cooling Coil has leaving humidity ratio > entering humidity ratio.
** ~~~ ** ..will be sized for 50% of entering humidity ratio.
EVENTHOUGH entering air from outside has humidity of 0.01178 and the coil is set to 0.001.
SizingPeriod:DesignDay, Summer Design Day in BBI Terminal, !- Design Day Name
32.0, !- Max Dry-Bulb {C}
10.3, !- Daily Temp Range {C}
0.01178,!21.74, !- Wet-Bulb at Max {C} gH2O/gDryAir
100761.7, !- Barometric Pressure {N/M**2}
0, !- Wind Speed {m/s}
0, !- Wind Direction {Degrees N=0, S=180}
0.98, !- Clearness {0.0 to 1.1}
0, !- Rain {0-no,1-yes}
0, !- Snow on ground {0-no,1-yes}
15, !- Day of Month
7, !- Month
SummerDesignDay, !- Day Type -- used for schedules
1, !- Daylight Savings Time Indicator
HumidityRatio,!WetBulb, !- Type of humidity temperature Indicator
, !- Relative Humidity Day Schedule(not used)
, !- Dry-Bulb Temperature Range Modifier Type (not used)
; !- Dry-Bulb Temperature Range Modifier Schedule (not used)
Coil:Cooling:Water,
DOAS Cooling Coil, !- Name
2, !- Availability Schedule Name
autosize, !- Design Water Flow Rate of Coil {m3/s}
autosize, !- Design Air Volume Flow Rate {m3/s}
6,!autosize, !- Design Inlet Water Temperature {C}
32,!autosize, !- Design Inlet Air Temperature {C}
18,!autosize, !- Design Outlet Air Temperature {C}
autosize, !- Design Inlet Air Humidity Ratio {kg-H2O/kg-air}
!autosize, !- Design Outlet Air Humidity Ratio {kg-H2O/kg-air}
0.0010, !- Design Outlet Air Humidity Ratio Entering is 0.01178 ,0.0050 does not work
DOAS Cooling Coil ChW Inlet, !- Coil Water Inlet Node
DOAS Cooling Coil ChW Outlet, !- Coil Water Outlet Node
DOAS Mixed Air Outlet, !- Air Inlet Node Name
DOAS Cooling Coil Air Outlet, !- Air Outlet Node Name
DetailedAnalysis, !- Type of Analysis
CrossFlow; !- Heat Exchanger Configuration
--- In EnergyPlus_Support@xxxxxxxxxxxxxxx, "Jean marais" <jeannieboef@...> wrote:
>
> I have the following error:
>
> ************* Beginning System Sizing Calculations
> ************* Beginning Plant Sizing Calculations
> ** Warning ** In calculating the design coil UA for Coil:Cooling:Water DOAS COOLING COIL
> ** ~~~ ** the apparatus dew-point is below the coil design inlet water temperature;
> ** ~~~ ** the coil bypass factor is unrealistically large;
> ** ~~~ ** the coil outlet design conditions will be changed to correct the problem.
> ** ~~~ ** The initial design conditions are: Tair,in = 24.4500
> ** ~~~ ** Wair,in = 9.478796E-003
> ** ~~~ ** Twater,in = 6.0000
> ** ~~~ ** Tair,out = 18.0000
> ** ~~~ ** Wair,out = 8.000000E-003
> ** ~~~ ** The revised design conditions are: Tair,out = 14.5987
> ** ~~~ ** Wair,out = 9.371939E-003
>
> All my coil inputs possible are autosized. Zone and System humidity designs are 0.008 (default). My outlet Tair design is 18 deg (as seen in the error msg.)
>
> 1) What is going on here exactly?
> 2) How can I enter other parameters so that the error does not occur and no reheat is nessesary.
>
-- Richard A. Raustad Senior Research Engineer Florida Solar Energy Center University of Central Florida 1679 Clearlake Road Cocoa, FL 32922-5703 Phone: (321) 638-1454 Fax: (321) 638-1439 or 1010 Visit our web site at: http://www.fsec.ucf.edu UCF - From Promise to Prominence: Celebrating 40 Years
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