Lots of them out there, however they are primary 120v with battery backup, like the BRK6135HD. The units will run for a couple of weeks on just the battery alone.
Couple things to consider, if you are using a fire control system, most of these units will be a 'challenge' to integrate into the system, and even then usually not up to fire code. Up side is they can be tested with any TV IR remote.
You can daisy chain multiple detectors together, the alarm circuit (5vdc/50mA) will trigger all the detectors if one goes off.
Word of caution, on a 90 degree day, the upper reaches of a black tent will easily reach the 135 degree fixed temp of most heat detectors. How would I know this????