[labnetwork] Local chiller vs. facility chilled water

[Dennis Schweiger]

Here at UofMichigan, we have two distinct process chilled water (PCW) loops
(with redundant pump capacity) that serve various sections of our
cleanroom.  Both of these PCW loops are fabricated from CPVC materials,
polished to ~1Meg-Ohm for resistivity, filled with RO water, and have UV
lamps and filters for "cleaning" them up.  Both of them reject their heat
load into the central campus chiller loop through plate/frame heat
exchangers.  The only time we'll install a local chiller (heat exchanger)
is if we need some special fluid, or much better temperature control (heat
and cool), and even then those local units will be configured to be
water-water so that their heat load goes into our PCW, and not into our
clean air-stream.

You have an interesting dilemma.... What type of capacity do you need, what
quality of water, how long do you expect to be in the same location?  All
of these questions will affect the decision.  I too would lean towards
option #2, with a redundant pump system.  It's the best long term
solution.

Dennis
Schweiger
University of Michigan/LNF
Facilities

734.647.2055 Ofc

On Fri, Aug 31, 2018 at 10:32 AM Kevin McPeak <kmcpeak at lsu.edu> wrote:

> Dear Colleagues,
>
> The central chilled water pump at the facility where the LSU cleanroom is
> housed died earlier this week. Facilities told me that they have no plans
> for replacing the pump. The cost is too high (15K) and most of the beamline
> endstations (our cleanroom lives inside of a synchrotron) have switched to
> local chillers.
>
> So I have two options:
>
> 1). Buy 4 small chillers for an e-beam evaporator, SEM, ICP, sputtering
> system. This number will grow in the future.
>
> 2). Buy one large chiller and connect it to the existing 2" diameter
> cooling pipe network that is plumbed around the cleanroom perimeter.
>
> I lean towards option #2 but it is less flexible than #1 and could put us
> in the same situation we are in now (e.g. most machines down) in the case
> of a failure.
>
> The infastructure of our cleanroom is about 25 years old. So I wanted to
> ask the list members to get a more modern take on chilled water. Do modern
> cleanrooms use central chilled water systems or is the local chiller model
> more popular given the added flexibility and more distributed failure model?
>
> Thanks!
>
> Regards,
> Kevin
>
> --
> Kevin McPeak
> Assistant Professor
> Department of Chemical Engineering
> Louisiana State University
> email: kmcpeak at lsu.edu
> phone: 225-578-0058
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