[labnetwork] Thermal load in cleanrooms ISO 5/6

Mon Mar 16 16:07:25 EDT 2015

I have a different opinion about chillers: A single central unit creates 
a single point of failure for the entire facility, and maintenance 
requires everything to be shut down at once. I would rather have the 
(several small) chillers where I can see them, and I don't trust 
facilities people to do the maintenance properly. Same advice for UPS. 
Out of sight, out of mind. Also, if you have numerous chillers then you 
should keep a spare handy, just as you would for vacuum pumps.

--------------------------------
Michael Rooks
Yale Institute of Nanoscience and Quantum Engineering
nano.yale.edu <http://nano.yale.edu>

On 03/16/2015 12:26 PM, Michael Khbeis wrote:
> Loik
>
> I think that having the electrical load converted to heat load and 
> having the diversity factor is sufficient. You can subtract the heat 
> load dissipated through chilled water but that is presumably also 
> being fed by your primary chiller. I would err on the side of being 
> conservative since cleanrooms always end up being packed to a maximum 
> density of equipment and people during their lifespans - give yourself 
> a 20% margin at the least. I also would not discount the impact of the 
> filter fan unit heat dissipation.  Since you are recycling most of the 
> air several times the joule heating from the FFUs will cause a 
> noticeable temperature rise. Given the class of your Cleanroom the FFU 
> density will not be as high but I would add them into the load calc.
>
> Finally, regarding central chiller vs multiple point of use units - 
> much easier to keep spare parts on hand and do PMs on a central 
> chiller unit as these are usually handled by the building facilities 
> folks. In my opinion, multiple point of use chillers are a maintenance 
> nightmare and you often end up buying something quickly to replace or 
> augment a failing unit. It is nearly impossible to keep multiple point 
> of use units running consistently if you don't have dedicated 
> maintenance staff. The exception to this is if your tools all required 
> different or special temperatures and you end up needing multiple 
> water-to-water heat exchangers then point of use chillers may make sense.
>
> Best,
>
> Dr. Michael Khbeis
> Washington Nanofab Facility
> University of Washington
> Fluke Hall, Box 352143
> (O) 206.543.5101 <tel:206.543.5101>
> (C) 443.254.5192 <tel:443.254.5192>
> khbeis at uw.edu <mailto:khbeis at uw.edu>
>
> On Mar 16, 2015, at 7:36 AM, Loïk GENCE <Loik.gence at cetuc.puc-rio.br 
> <mailto:Loik.gence at cetuc.puc-rio.br>> wrote:
>
>> Hi Everyone,
>>
>> I am working on the design of a small cleanroom facility (70m2) ISO 
>> 5/6. Right now, I am dealing with the problem of thermal load,
>> Which is crucial here in Rio, where the average outside temperature 
>> is of 30 deg C with a relative humidity of  75-80 %.
>>
>> I would like to have your help and/or comments on several points:
>>
>> Most of the manufacturers do not provide a value for the thermal load 
>> (why?). Assuming 2 or max 3 people working simultaneously in the 
>> cleanrooms, and usual cleanroom value: 22 deg C - 55% humidity. The 
>> main issue is: how can I estimate the cooling power required for the 
>> Air Conditioning System (ACS)?
>>
>> I have the list of equipments we'll have and the corresponding 
>> electrical power. I assumed the heat generated by 2 users and added 
>> the total electrical power dissipated as heat inside of the 
>> cleanroom, using a simultaneity factor of 0.75 (all equipments won't 
>> be turned on at the same time) and neglected the heat produced by the 
>> filter fan and lightning.
>> ***
>> **        - Is it reasonable for dimensioning the ACS cooling power ? *
>>
>> Also most of the equipments have a cooling water circuit. But the 
>> cooling power needed is well described in the installation manual 
>> provided with the equipments.
>>
>> *        - Should I subtract from the **ACS cooling power**value, 
>> **the cooling po**wer **from the chillers?*
>>
>>         - *Do you think a central and unique chiller (placed outside 
>> of the building) is preferred to several smaller chillers placed 
>> closer to the equipment?*
>>
>>
>> I thank you very much for your kind help or comments.
>>
>>
>> regards,
>>
>> Loïk.
>>
>> -- 
>> __________________________________________
>> Dr. Loïk Gence
>>
>> PUC-RIO/CETUC-LABSEM
>>
>> End Rua Marques de São Vicente, 225-Gavea
>> CEP:22451-900   Rio de Janeiro, RJ-Brasil
>>
>>        (Telefone)      +55 (021) 3527-2193
>>
>> 	(Mobile)     +55 (021) 99156-5558
>>
>> loik.gence at cetuc.puc-rio.br
>> __________________________________________
>> _______________________________________________
>> labnetwork mailing list
>> labnetwork at mtl.mit.edu <mailto:labnetwork at mtl.mit.edu>
>> https://www-mtl.mit.edu/mailman/listinfo.cgi/labnetwork 
>> <https://urldefense.proofpoint.com/v2/url?u=https-3A__www-2Dmtl.mit.edu_mailman_listinfo.cgi_labnetwork&d=AwMFaQ&c=-dg2m7zWuuDZ0MUcV7Sdqw&r=apnDUg1OD9ejswcjrIvVgS28NpQ7-FGy7Sl7_YPlupc&m=hBL35UTQaOURuTrkXiNi1rZCy7Gy_rS075IrmahPX18&s=ZF7WKY75a9SR06b7Ulb31qeww2Hm1AcHRtLpSb5eXJA&e=>
>
>
> _______________________________________________
> labnetwork mailing list
> labnetwork at mtl.mit.edu
> https://urldefense.proofpoint.com/v2/url?u=https-3A__www-2Dmtl.mit.edu_mailman_listinfo.cgi_labnetwork&d=AwICAg&c=-dg2m7zWuuDZ0MUcV7Sdqw&r=apnDUg1OD9ejswcjrIvVgS28NpQ7-FGy7Sl7_YPlupc&m=hBL35UTQaOURuTrkXiNi1rZCy7Gy_rS075IrmahPX18&s=ZF7WKY75a9SR06b7Ulb31qeww2Hm1AcHRtLpSb5eXJA&e=

-------------- next part --------------
An HTML attachment was scrubbed...
URL: <https://mtl.mit.edu/pipermail/labnetwork/attachments/20150316/5400be6e/attachment.html>