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Re: [EnergyPlus_Support] Problems with coil:water:cooling in a unit ventilator



There are no known issues with unit ventilator, but there are some unverified 
issues with coil:water:cooling.  I have asked someone else to look at this 
further.  If you are in a hurry, you might try using 
COIL:Water:DetailedFlatCooling.

Mike


On 11 Nov 2005, at 17:05, christian1855 wrote:

> Dear all,
> currently I'm modelling a server-room with high electric load (up to 
> 700W/m2). For zone cooling I'm using a UnitVentilator. Actually there 
> are 4 cooling elements in the room. 
> 
> One element is specified as:
>   Air-Temperature-in: 24 °C
>   Air-Temperature-out: 14.2 °C
>   Air-volumn flow rate: 6.11 m3/s
>   Water-Temperature-in: 12 °C
>   Water-Temperature-out:18 °C
>   Water-volumn flow rate: 0.0029 m3/s
>   Total cooling power: 73kW
> 
> The electric load in the zone is about 130kW. The 4 cooling elements 
> have a total cooling power of ~292kW which is more then twice the 
> internal load. So if the unit ventilator works correctly the zone 
> should be exact on the zone setpoint temperature. 
> 
> When I use a coil:water:cooling in the unit ventilator and specify the 
> input values as mentioned above (except the flow-rates have been 
> multiplied with 4) the zone setpoint temperatures cannot be achieved!
> Everything else seems to be OK: no errors, no warnings, correct air 
> flow rate, correct water flow rate, correct water inlet temperature,.
> .. (same result in E+ v1.2.2 and v1.2.3).
> 
> I've now manually calculated the UA value for my cooling element, 
> changed the cooling coil to a coil:water:simplecooling object, used 
> this UA value (93870 W/K for 4 elements) and the model will give the 
> expected result. 
> 
> Are there any know issues using the UnitVentilator with a coil:water:
> cooling?
> 
> Christian
> 
> PS: I will upload the idf file: unitVentilatorCoolingCoilProblem.zip
> 
> 
> 
> 
> 
> 
> The primary EnergyPlus web site is found at:
> http://www.energyplus.gov
> 
> The group web site is:
> http://groups.yahoo.com/group/EnergyPlus_Support/
> 
> Attachments are not allowed -- please post any files to the appropriate folder
> in the Files area of the Support Web Site.
> 
> EnergyPlus Documentation is searchable.  Open EPlusMainMenu.idf and press the
> "search" button.
> 
> Yahoo! Groups Links
> 
> 
> 
> 
> 
> 
> 
> 
> 



========================================================
Michael J. Witte, GARD Analytics, Inc.
EnergyPlus Testing and Support      
EnergyPlus-Support@xxxxxxxx




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