A Compressor draws in ambient air and delivers the air to a combustion chamber. A first part of the air flow is mixed with fuel and burns, transferring heat through metal to the second part of the flow separated from the first part (counter-flows not shown). The second part of the flow then goes to an expander where it does work turning the shaft driving the compressor
The first part of the flow whose oxygen has been depleted by the burning is then taken to a heat exchanger where it gives up heat to ambient air driven by a fan, which can be geared to the shaft. This compressed cooled first part of the air then gives up work to the shaft driving the compressor and is further cooled by its expansion. This first part then emerges through a nozzle and as a cold, -27C, -17F oxygen depleted, 6.7% O2, jet. (Fire requires that the O2 level be more than 8-16%). Condensate can be trapped to achieve a dew point around freezing, which is important for use in continuous volume inerting as for fuel tank ullage.
This device's nitrogen component of the output apparently provides a very important toxicity edge, minutes of warning symptoms before -at worse- unconsciousness, over pure CO2, which at extinguishing-inerting levels -34%- is quickly lethal.
Fire extinguishing is by the cold inert output jet, which can be swept back-and-forth on a hose, disrupting of the flame-fuel relationship, by cooling of the fuel and by inerting preventing renewal of combustion till the fuel has cooled. Enclosed and semi-enclosed space can be totally inerted to extinguish fire. Long term penetrating cooling by inert gas is provided for smoldering fire. The work turbine output can be mixed with fuel to start fire (back-fire) separated in time or space with inert-cold output causing a controlled burn-up particularly for brush and forest fire.
An explosive cartridge jet engine starter can provide quick starting, and if a sodium-azide cartridge (air bag) is used feeding the output expander, an early output of N2 at less than room temperature reduced from the ~300C reaction temperature by the cold expander.