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Posted by kool on July 16, 2007, 4:00 pm
> wrote:
>
>>
>
>>> Pre-cooling will be a LARGE factor in your design, if you do
>>> it right. Off the top of my head, you should be able to plan on maybe
>>> 10 degree rise during events, which means you can pre-cool to 70,
>>> expect it to rise to 80 during a 4 hour event, which means you can do
>>> the pre-cooling in 4- 8 + unoccupied hours, which means your max size
>>> is much smaller.
>>
>>I had not even considered pre-cooling as an option.That got me thinking
>>about firing up the idle refrigeration plant (195 HP) for a few hours and
>
> You might not even need to add any more cooling, if you do it
> right.
>
>>cool the brine in the 17000sq.ft. floor to just above the dewpoint.That
>>should take the edge off the heatload.I guess the dewpoint would change
>>pretty quick when the 3000 bodys arrive.
>
> You're going to need to go far below dewpoint from the system,
> of course not in terms of the building mass itself, but system output.
>
> Humidity is going to be the largest portion of your total
> load, both from the large OA need, plus persperation from the crowd.
> Anything you can do to lower the humidity, will lower your need for
> making it cooler.
>
> You could look at using the existing plant, with thermal
> banking perhaps, into a purpose-specific dehumidifer, to help pre-dry
> both the space, and the OA intake before it gets into the space.
>
> Also, thermal banking / ice banking could help 'spread out the
> load' as previously.
>
> A space at 80 F, 60 RH is uncomfortable, damp, clammy. At 80
> F 30 RH, it is very comfortable. You want to look very closely at
> the two types of heat you have to deal with ( sensible and latent ),
> and when they occur, in what proportions.
>
> You need to look at the scenario of a rainy evening, when
> you're bringing in all that OA at 90 % RH - you WILL be amazed what
> happens to your loads ! If you just dump that air inside, it will be
> miserable in there, and you'll have mold problems next week. If you
> pre-dry it first ( either mechanically, or using desiccant, etc ) as
> opposed to pre COOLING it, you avoid both problems.
>
> You need to consider things like runaround loops in both the
> air stream and the cooling fluid, with dampers / valves / control
> system / etc that can in effect look at sensible load separately form
> latent load, and tune to each one as needed. IOW, you need to be able
> to control the SHR of the system over a wide range - one simple
> setpoint won't really get it, IMO. You need to be looking at 3 things
> - DB, WB, and ( the combination of them which is ) enthalpy.
>
>
>
>
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>
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The existing airhandlers are rated at approx.10000cfm each x(2) these are
capable of 100% o/a or recirc. and the three exhaust are 3k,3k, and 10k cfm.
We could probably get about 100 tons of cooling with the existing ammonia
plant. If we could tee into the existing brine piping and divert flow to a
closed glycol loop piped to the existing air handlers and add two more, we
could probably get 25 tons froom each one x4.
Humidity is maintained by the dessicant unit but that adds sensible heat to
the space.
Running with higher than normal brine temps will create an overload on the
ammonia plant but the compressors can start up unloaded and gradually load
up as the brine temp. drops.
This is getting interesting as a possibility. Thanks for your helpful input
so far.
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