chilled water storage
chilled water storage
(OP)
I have installed large thermocline type chilled water storage tanks for energy cost reduction. The tanks I installed were several million gallons each and were 30 to 40 feet tall.
I am interested in applying a much smaller storage tank that would provide a short span backup of a critical load. If the chillers serving the load trip, I need to be able to continue serving the load for 10 to 15 minutes while the generators start, automatic transfer switches close, and the chillers come back up to load.
thread403-153938: chilled water storage by Orah back in May 2006 talked about an application just like this but there were no useful responses.
Does anyone know of a firm that makes small chilled water storage system in the 50,000 gallon range? Has anyone ever applied a chilled water storage tank for this purpose?
I am interested in applying a much smaller storage tank that would provide a short span backup of a critical load. If the chillers serving the load trip, I need to be able to continue serving the load for 10 to 15 minutes while the generators start, automatic transfer switches close, and the chillers come back up to load.
thread403-153938: chilled water storage by Orah back in May 2006 talked about an application just like this but there were no useful responses.
Does anyone know of a firm that makes small chilled water storage system in the 50,000 gallon range? Has anyone ever applied a chilled water storage tank for this purpose?





RE: chilled water storage
RE: chilled water storage
A simple tank on the outlet of the chiller will not protect the load during an outage since the warm water pumped into the tank during the chiller outage will still end up going through the cooling coils.
I need a separate thermal storage tank that is normally offline but which can be quickly put into operation if the chiller shuts down. The tank can be recharged after the chiller is back up. I will probably need a small trickle charge to keep the tank cool when it is not being used since it will not be discharged regularly like most thermal storage tanks.
Also, this load is a small part of the load served by a very large chiller plant. If we could justify the economics of a large thermal storage system for the campus that would be great but it is not economical in this case.
RE: chilled water storage
Andy W.
RE: chilled water storage
Also Trane have got a design in there catalog where there is one tank in the supply and return from the chiller. The supply (cold) is connected to the buttom and the return (warm) is connected to the top.
just my one cent contribution.
RE: chilled water storage
The issue is the time it takes for the chillers to come back on line after a trip (order of minutes). In high density datacenters and the like, the heat load can cook the servers in as little as 30 secs. Pumps can respond quickly enough.
The chilled water tank is plumbed in pretty much how you would configure your other TES tanks. This is not the same as a buffer tank mentioned in some of the responses above. The tank could be located in a bypass loop that you can bring in and out to charge during low load times.
A 50,000gal size would probably be a one-off concrete, rather than some arrangement of modular tanks. Ice TES is much more compact.
RE: chilled water storage
Anyway, its easy enough to figure the chilled water demand at peak load over a given time frame - so - what is the given time frame to have adequate chiled water in reserve?
Inquiring minds want to know.....
Andy W.
RE: chilled water storage
Maintaining a fully charged chilled water tank may not be energy efficient if it is not used regularly
RE: chilled water storage
Many fabricators can build a carbon steel tank like that. Use API 650 as a standard. Good painting and vapor-sealed insulation is essential to avoid exterior corrosion.
You might explore a 60 ft hi x 12 ft dia tank which possibly would allow it to be shop fabricated.
A good reference is Erwin G. Hansen, "Hydronic System Design and Operation" McGraw Hill.
RE: chilled water storage
RE: chilled water storage
Just a thought out of the box!
Mark Hutton
RE: chilled water storage
I found one ice storage application for a similar application but that requires an external melt ice system in order to be able to melt fast enough. External melt ice tends to bridge if it is not discharged regularly and could result in channeling during an emergency with most of the ice not melting quickly. Internal melt systems such as the Calmac tanks are not suitable for quick discharge.
I hoped some manufacturer was offering a chilled water storage tank just for this service and already had the kinks worked out. Apparently not.
I will probably do as zerosum suggests and just use a standard tank. If so, I will design my own diffuser for the bottom and top to minimize mixing and get the most out of the tank. It may not be perfect but I bet I can recover 90+% before I lose water temperature. I also like the idea of a 12 foot tank that can be factory fabricated, maybe two tanks 30 foot tall.
Thanks to everyone for the suggestions.
RE: chilled water storage
Give us feedback when you get-r-done.
In a previous life I had seven exotherming batch reactors with 3000T chilled water plus CTW to keep them cool. My interest now is just academic.
Good luck
RE: chilled water storage
Nothing beats a storage tank full of coolimng medium ready to use with a dual set of pumps on emergency circuit (zerosum description).
Adding a DX system as suggested here will require a large emergency generator AND it will not be as reliable as a storage tank.
Two engineers, two opinions. well, if two people got along 98% of the time, one of them is not necessary.
Good luck jds.
RE: chilled water storage