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Re: [EnergyPlus_Support] Problems modeling a chiller
No,. CAPFT describes the full-load capacity as water and air
temperatures vary. The PLR curve takes into account the unloading. So
Pref in your email describes the full-load power. If it is high, then
the CAPFT curve is not accurate.
On 2/10/2012 1:44 PM, Nacho Gomis wrote:
> Hi,
> we have been thinking on the same way.I noticed that the capacity
> power was always so high for the calculation(CAPFTxNominalCapacity)and
> it means for E+ that the electric consumption is not reduced so much.
> This is a way to fix it but I think the problem is the Pref=Qref /
> COPref x CAPFT which is very high,I think the CAPFT curve must be
> reformulated and take into account the PLR.Because I have ran a
> simulation which a chiller with a reference COP of 3 and the maximun
> COP in my simulation was 6.7.
> What do you think about the idea of adding a variable to CAPFT or
> adding a new curve?
> Thanks Richard,
> Ignacio Gomis
>
> On 10 February 2012 18:51, Richard Raustad<RRaustad@xxxxxxxxxxxx> wrote:
>> The EIRFPLR curve is the part-load operating power divided by the
>> available full-load capacity at the specific operating conditions. This
>> means that if the power is 10 kW at a PLR = 0.5, with the CWT = 5 and
>> the OAT = 25, then EIR = 10 kW divided by the full-load available
>> capactiy (PLR=1) at CWT=5 and OAT = 25.
>>
>> On the EIRFPLR tab, change column E to be C2/$B$2, C3/$B$2, C4/$B$2,
>> etc. and then recalculate the coefficients. Tell me how this works. This
>> assumes that the operating conditions are the same for all 4 rows (CWT
>> and CDWT do not change).
>>
>>
>> On 2/10/2012 12:35 PM, Nacho Gomis wrote:
>>> Hi,
>>> finally I recalculated the performance curves and now the model is
>>> working.I had to set the condenser delta temperature to 5K because I
>>> had the leaving water condenser temperature provided by the
>>> manufacturer but I need the entering condenser temperature in order to
>>> model my chiller as Chiller:ElectricEIR.
>>> Now I'm focusing on how E+ control the chiller plant.I found a new
>>> variable for me:
>>> Chiller False Load Heat Trans [J]
>>> I understand it as wasting energy variable in order to met the cooling
>>> capacity supplied by the chiller and the required load supplied by the
>>> chilled water loop.
>>> I have been reading the EngineeringReference.pdf(page 550-55) but I
>>> have no any clear idea how E+ controls the plant.
>>> If I see the performance curves,they show that the chiller works
>>> better with PLR and my simulation shows in the wrong way,when the HVAC
>>> is working for low PLR the COP is very low.
>>> Could someone explain me it better?
>>> Thanks,
>>> Ignacio Gomis
>>> P.S.:I will attack the performance curve spreadsheet,the idf file, its
>>> rvi file and the csv file which is the result of the simulation.
>>>
>>> On 9 February 2012 16:24, Nacho Gomis<nachogo27@xxxxxxxxx> wrote:
>>>> Without looking at your file…
>>>> · Does the pump have sufficient flow to properly transfer the 1MW?
>>>> Well,1MW is the cooling capacity,so the condenser will have a higher
>>>> value but never be 2MW.The pump flow rate is manually sized because
>>>> this data is provided by the chiller manufacturer,the value is
>>>> 0.05743m3/s and it is used in the corresponding field in the
>>>> ElectricChiller:ReformulatedEIR object.(Chiller model:Carrier 30XW
>>>> 1002)
>>>>
>>>> · Is the pump operating? (schedule = 1.0)
>>>> Yes,i have not scheduled the pump.It works fine with the template chiller
>>>> · Is the tower operating?
>>>> Yes,it has cooling capacity because I can see it in the output that
>>>> Richard told me in the message above.
>>>>
>>>> Thanks,
>>>> Ignacio Gomis
>>> ------------------------------------
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>> --
>> 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
>>
>>
>>
>> ------------------------------------
>>
>> Primary EnergyPlus support is found at:
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>>
>> Attachments are currently allowed but be mindful that not everyone has a high speed connection. Limit attachments to small files.
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>> EnergyPlus Documentation is searchable. Open EPlusMainMenu.pdf under the Documentation link and press the "search" button.
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>
> ------------------------------------
>
> Primary EnergyPlus support is found at:
> http://energyplus.helpserve.com or send a message to energyplus-support@xxxxxxxx
>
> The primary EnergyPlus web site is found at:
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> 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.
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>
--
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
------------------------------------
Primary EnergyPlus support is found at:
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Attachments are currently allowed but be mindful that not everyone has a high speed connection. Limit attachments to small files.
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