In a Giffard type steam injector, boiler feed water is added to the boiler by passing steam at around 10 bar/180C through a converging/diverging nozzle, collecting cold water in the vacuum at the vena contracta. The combined steam/water mix is then returned to the boiler at a higher pressure but lower temperature than when the steam left the boiler. The quality of the steam is lower, therefore energy in the form of heat needs to be added to the boiler to restore the status quo.
My question is this: If instead of the boiler, I took a cylinder of refrigerant (vapour pressure of say 10 bar@20C) and the vapour from the top of the cylinder passed through a similar nozzle, with liquid refrigerant from the bottom of the same cylinder being allowed to vaporise at the vena contracta (say 0 bar, -50C) to mix with the high pressure vapour. Would the resulting pressure increase/temperature decrease in the same way as a steam injector?
If so, whilst the resulting vapour/liquid mix which might be at -20C would still need to be restored to its original state by a heat input, this would now be from the addition of heat from ambient air, not by adding fossil fuels
If it does work, would such a closed system produce a 'free' useful temperature drop for refrigeration/air con etc at the point where the liquid vaporises.
I apprciate latent heat of vaporisation plays a part in this process and in water it is high - but then some refrigerants like ammonia are pretty high too.