This may seem like a strange question because it involves a non-traditional approach.
What I'm looking for is a standard rackmount cooling/humidity control module. The idea is to build a portable server rack (in a case) that can be deployed to the field but limit the cooling/temperature control requirements to just the case that the server gear is contained in.
I understand that the chiller may warm it's surrounding environment so, as an additional approach, it will be possible to have a separate case for the chiller alone.
Do these exist?
What are they called?
Where can I find one?
There are a couple of manufacturers of shock-mounted rackmount cases with climate control built in. Depending upon the size, weight and heat generation of your equipment, your cooling options are A) Solid State (Pelletier) or B) Compressor based systems. Both systems are typically considered closed-loop.
An often overlooked aspect of climate control is the issue of insulation. Insulating the rackmount case will reduce the effect of solar radiation on the case (thus reducing the workload of the A/C system) but will also mitigate any condensate ("sweating") on the case exterior shell.
As far as humidity control is concerned, my experience has been that the compressor based systems work best at extracting the moisture within the enclosure - there typically is a condensate drain somewhere on the A/C (chiller) system.
If you are looking for something in the 3000 BTU/H to 6000 BTU/H range, I recomend you call Impact Cases (www.impactcases.com) - we manufacture aluminum rackmount cases with both fixed and removable climate control systems.