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Re: [EnergyPlus_Support] Problems modeling a chiller
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
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> Fax: (321) 638-1439 or 1010
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