I was in the millitary once many years ago and he is right they used package units set on the ground fully loaded and ready to go as for power they had generators gas diesel etc.. to power them on the hz it was adjustible
easy to pick up an ac in a country with say 50 hz and run it
The military uses ECU'S Environmental Control Units. It's like a mobile RTU that you conect to your tent with flex duct. They heat and cool (electric heat strips and direct expansion). The new ones use r-134a. I have worked on more of these than I care to remember. They are good units and can take a beeting.
The new ones are R 134a 5 ton heat pumps with scroll compressors.
They have their share of problems ,but new versions come out pretty quick with fixes. The FDECU's(field deployable enviromental control unit) are chem/bio capable and are full of electronics. They are better to work on than RTU's there are pins and captive screws that hold things to gether. Also you can stack them and store the ducts inside the power cord comes with a cannon plug and is ready for connection. These units have to stand up to being transported repeatedly because when one breaks we swap it out and fix it back at the shop then put it on the ready line.
There is the CHAMP (chemically hardened air plant)That is about 20 tons and has its own power supply or can run off of generator power.
“Engineers like to solve problems. If there are no problems handily available, they will create their own." Scott Adams
"We can't solve problems by using the same kind of thinking we used when we created them."
The stuff I was supposed to be working on in Iraq are R410a hybrid units built just as rb276 describes them. 20% outside air filtered through NBC (Nuclear, Chemical, Biological) filtration system to keep the air in the tents clean.
The ones I was to be dealing with have all components with roto-lock connections and isolation valves so that components could be replaced without evacuating the units and in some units you could replace parts of one circuit while the system continued to operate on other circuits.
One thing that cracked me up is that R22 systems are not allowed in the Middle East due to environmental restrictions. So, in the middle of a war zone, we cannot take the chance of having R22 escape into the atmosphere because of the "danger" of it.
I was told that the equipment I would be in charge of would have been units that were designed by a multi-brand design team. I assumed that there was some Trane influence since they have roto-lock connections on everything.