Use ammonia as a refrigerant.
Cold water will absorb a many times its volume of ammonia gas.
Liquid ammonia may be evaporated in an evaporator coil by exposing it to cold water.
This produces cooling.
If the ammonia laden water is then pumped under pressure into a heated vessel, the ammonia will be driven off of the water.
If the gaseous ammonia is then cooled in a condenser coil, it will be condensed back into liquid ammonia.
The liquid ammonia may be returned to the evaporator coil and the water that has been stripped of the ammonia may be returned to absorb more ammonia gas from the evaporator.
There is also a technique that will work without a pump.
AstroAlTM refrigerators and many Recreational Vehicle refrigerators work on this principle,
Electricity, propane gas, or in the case of some very old refrigerators, kerosene is used to produce the heat needed.
