Normal refrigeration work by turning a liquid into gas, and gas back into liquid. Doing so heats or cools the medium (one can imagine the molecules inside being

Normal refrigeration work by turning a liquid into gas, and gas back into liquid. Doing so heats or cools the medium (one can imagine the molecules inside being more pressed together when in liquid, thus having more energy in a smaller volume of physical space, which translate as being hotter). When turned into a gas the opposite happens with fewer moving molecules in the volume of space. Going from liquid to solid do not generally causes any changes in volume, but it does releases some energy as part of the conversion process, which if captured could contribute to make both the solid and liquid cooler (less energy among the molecules in the same volume). With the use of a compressor and a vapor chamber in a fridge you can control when and where the liquid turn to a gas or back into a liquid. The hot place will be near a radiator, and the cold place in a vapor chamber next to the cooling area. With this system the salt would be near the radiator turning the solid into a liquid, heating the radiator. Then you would "remove the salt" in what would be similar to a vapor chamber, turning the medium cold. The biggest issue I have with this concept is the efficiency. With a compressor you can make a gas really really hot by turning it into a liquid, and that heat will then have a large gradient difference when run through a radiator (which cools it down using ambient air). I am unsure how one would get a similar effect with solid to liquid.