[TRNSYS-users] Type 666 Chiller Queries

David BRADLEY d.bradley at tess-inc.com
Thu Mar 14 08:00:09 PDT 2013
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Jean,
   The model looks at the full load performance file and determines the 
chiller's nominal capacity (its rated capacity as adjusted by the 
current entering conditions) and its nominal COP (rated COP adjusted by 
the current entering conditions). It then determines how much energy the 
chiller is required to produce and determines PLR = 
qRequired/NominalCapacity. The model then goes looking in the PLR file 
to see what the fraction of full load power is. In a way, the model 
makes use of the kind of data that is available but you are quite right 
in pointing out that the PLR table given by manufacturers isn't entirely 
correct; part load performance isn't as simple as a multiplier on full 
load performance. The only way I have found to get that data from the 
manufacturer is to ask them to generate a whole lot of performance 
points for different entering conditions and for different loading 
conditions, then to assemble a full performance map. Often manufacturers 
are willing to let you have access to their selection software for a 
limited time so that you can generate points yourself.
Best,
  David


On 3/14/2013 00:23, jeannieboef at gmail.com wrote:
> Annoyingly, I also find the PLR data is the hardest to get. I would 
> also assume that Part Load performance is dependent on conditions such 
> as water entering and leaving temps just as the full load table 
> describes. But the PLR table is not built up like that. It is simply a 
> multiplier to the full load table.
>
> How do you go about requesting this data from a manufacturer?
>
> Sent from my iPhone
>
> On 13.03.2013, at 16:19, David BRADLEY <d.bradley at tess-inc.com 
> <mailto:d.bradley at tess-inc.com>> wrote:
>
>> Dear Yeo,
>>   The sample file Samp_C.dat contains full load data for the chiller 
>> and in our experience, at full load, most chiller performance data 
>> looks about the same regardless of the type of compressor. The other 
>> file (Samp_PLR.dat) contains the part load data (the unloading data) 
>> and that does change from one type of compressor to another. 
>> Unfortunately, I do not recall what kind of chiller was used to 
>> develop the sample PLR data. I am fairly certain that it was not a 
>> reciprocating compressor and that it was either a screw or a rotary.
>> Kind regards,
>>  David
>>
>>
>> On 3/12/2013 21:58, #YEO KEAT KEE# wrote:
>>>
>>> Dear All,
>>>
>>> I am just wondering , when Davidmentioned that the normalized 
>>> performance curves of the water cooled chillers look about the same, 
>>> does it refer to a specific type of water cooled chiller, i.e. 
>>> Centrifugals, Screws ordoes it  refer to the normalized performance 
>>> curves of all water cooled chillers ingeneral, regardless of the type.
>>>
>>> I am using TRNSYS 16, and attached isthe performance file that are 
>>> default with the program, does the relationship described in this 
>>> file applies to all types of water cooled chiller ? If not, is it 
>>> possible to find out what kind of chiller does it describe ?
>>>
>>> Best Regards
>>>
>>> Yeo
>>>
>>> *From:*David BRADLEY [mailto:d.bradley at tess-inc.com]
>>> *Sent:* Saturday, 16 February, 2013 1:11 AM
>>> *To:* Jean Marais
>>> *Cc:* #YEO KEAT KEE#; trnsys-users at cae.wisc.edu 
>>> <mailto:trnsys-users at cae.wisc.edu>
>>> *Subject:* Re: [TRNSYS-users] Type 666 Chiller Queries
>>>
>>> Dear Yeo,
>>> Jean's responses are all quite accurate. I wanted to add a little 
>>> bit to the discussion in the hopes that it might make your life a 
>>> little easier. Some years ago, we participated in a research project 
>>> in which we were looking at whether the performance of certain 
>>> pieces of HVAC equipment can effectively be normalized. In other 
>>> words you look at the COP and capacity of a device at a particular 
>>> combination of inlet conditions and then divide the COP and the 
>>> capacity by the rated COP and capacity for the device. Then you plot 
>>> the normalized performance over the entire operation range of the 
>>> equipment and you do the same for the same piece of equipment from 
>>> other manufacturers and of other rated capacities. It turns out that 
>>> some kinds of equipment (particularly single stage heat pumps and 
>>> both air and water cooled chillers) normalize very well meaning that 
>>> their normalized performance curves all look about the same. 
>>> Unloading (part load ratio) curves can look a bit different but they 
>>> begin to look similar again if you first sort them by compressor 
>>> type (screw, rotary, etc.). Other pieces of equipment do not look 
>>> the same at all if you normalize them (absorption chillers are a 
>>> good example).
>>>
>>>   The lesson in all this is that if you have a specific chiller, it 
>>> is best to get the manufacturer's data for that chiller and to 
>>> create a data file from it. If, however, you just need a generic 
>>> chiller, you can use the default performance curves in the 
>>> \Trnsys17\Tess Models\SampleCatalogData\ directory and set the rated 
>>> capacity and COP parameters in the Type; you will be quite close in 
>>> your performance estimates.
>>>
>>>   One other note; make sure that the rated capacity and COP that you 
>>> enter for parameters are at the same conditions to which the 
>>> external data file is normalized. In other words, if the data file 
>>> is normalized to a 5C oulet chilled water temperature and a 16C 
>>> inlet cooling water temperature then make sure that the capacity and 
>>> COP that you enter as the rated values are at those same conditions.
>>> Best,
>>>  David
>>>
>>> On 2/15/2013 07:10, Jean Marais wrote:
>>>
>>>     Wow. You stated these questions so well that I can only think
>>>     that you did so already knowing the answeres.
>>>     1. You can't. You need a comprehensive data set from your
>>>     chiller supplier, specifying a matrix of COPs at different water
>>>     temperatures on supply and return side as well as condenser
>>>     supply and return side.
>>>     2. This will be clear in the data set. It is very possible.
>>>     3. There is no mathematical thermal corrolation. It is chiller
>>>     dependant. It is a different data set.
>>>     4. Yes. You'll need data at all the points where your chiller
>>>     may operate at. For example if you don't have data for the
>>>     chiller performance at less than 20% of full rated capacity,
>>>     then the simulation will issue a warning when your chiller model
>>>     is required to output results at these conditions (most chillers
>>>     will turn off below 20% demand).
>>>     5. Correct.
>>>     I stand corrected on any points.
>>>
>>>     On 15 February 2013 10:36, #YEO KEAT KEE# <YEOK0031 at e.ntu.edu.sg
>>>     <mailto:YEOK0031 at e.ntu.edu.sg>> wrote:
>>>
>>>     Dear Fellow Trnsys Users
>>>
>>>     I am a new user to Trnsys and is modeling a water cooled chiller
>>>     system using type 666 as the chiller.
>>>
>>>     I understand that if I want to model a specific chiller model in
>>>     the system, I will have to make changes to the chiller
>>>     performance data file and the part load performance data file.
>>>
>>>     In the chiller performance data file, I see that there the
>>>     capacity ratio and the COP ratio being defined as 1 at 7C Outlet
>>>     CHWT 30C INLET CWT.
>>>
>>>     1.If I only have the performance data of the chiller at  6.7C
>>>     Outlet CHWT 29.4C INLET CWT, how can I make use of this data to
>>>     input it into the chiller performance data file?
>>>
>>>     2.Must the capacity ratio and the COP ratio being defined as 1
>>>     at 7C Outlet CHWT 30C INLET CWT, or can it be defined as 1 at
>>>     other  Outlet CHWT and Inlet CWT ?
>>>
>>>     3.How does the part load ratio data of the chiller relate to the
>>>     different Capacity Ratio and COP ratio ?
>>>
>>>     4.In the parameter tab of the type 666 chiller, it is stated
>>>     that "The capacity of the machine at its rated condition
>>>     (typically 30 C (85 F) inlet cooling water temperature and 7 C
>>>     (44 F) chilled water set point temperature)The data file
>>>     associated with this model should be consistent with this rating
>>>     conditions." . Does it mean that I have to include the chiller
>>>     performance at 7C chilled water set point and 30C inlet cooling
>>>     water temperature in the chiller performance data file ?
>>>
>>>     5.In the chiller performance data file, it is observed that the
>>>     chiller capacity ratio can be more than 1.  Does this means that
>>>     the chiller current capacity is higher than the rated capacity?
>>>
>>>     Can anyone kindly advice on the above mentioned queries ?
>>>
>>>      Thank You !
>>>
>>>      Best Regards
>>>
>>>     KK Yeo
>>>
>>>
>>>     _______________________________________________
>>>     TRNSYS-users mailing list
>>>     TRNSYS-users at cae.wisc.edu <mailto:TRNSYS-users at cae.wisc.edu>
>>>     https://mailman.cae.wisc.edu/listinfo/trnsys-users
>>>
>>>
>>>
>>>
>>>     _______________________________________________
>>>
>>>     TRNSYS-users mailing list
>>>
>>>     TRNSYS-users at cae.wisc.edu  <mailto:TRNSYS-users at cae.wisc.edu>
>>>
>>>     https://mailman.cae.wisc.edu/listinfo/trnsys-users
>>>
>>> -- 
>>> ***************************
>>> David BRADLEY
>>> Principal
>>> Thermal Energy Systems Specialists, LLC
>>> 22 North Carroll Street - suite 370
>>> Madison, WI  53703 USA
>>>   
>>> P:+1.608.274.2577
>>> F:+1.608.278.1475
>>> d.bradley at tess-inc.com  <mailto:d.bradley at tess-inc.com>
>>>   
>>> http://www.tess-inc.com
>>> http://www.trnsys.com
>>>
>>>
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>>
>> -- 
>> ***************************
>> David BRADLEY
>> Principal
>> Thermal Energy Systems Specialists, LLC
>> 22 North Carroll Street - suite 370
>> Madison, WI  53703 USA
>>
>> P:+1.608.274.2577
>> F:+1.608.278.1475
>> d.bradley at tess-inc.com  <mailto:d.bradley at tess-inc.com>
>>
>> http://www.tess-inc.com
>> http://www.trnsys.com
>> _______________________________________________
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>
>
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-- 
***************************
David BRADLEY
Principal
Thermal Energy Systems Specialists, LLC
22 North Carroll Street - suite 370
Madison, WI  53703 USA

P:+1.608.274.2577
F:+1.608.278.1475
d.bradley at tess-inc.com

http://www.tess-inc.com
http://www.trnsys.com

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