Eli5: How did people make and keep ice in medieval times, and how do we manufacture ice cubes now ?
In: Technology
They would wait for winter when lakes and rivers froze over. They would then bore a hole, insert saws, and cut out blocks.
The blocks would get stored in insulated shacks, caves, or underground cellars. In between blocks they may use materials like sawdust to insulate the ice and keep the cold in, reducing meltage. Ice would keep like this well into the next winter.
As for modern times, we have refrigerators that take city water and lower its temperature long enough to freeze. Usually the system has some sort of mold so the ice makes cube or chip shapes making it easier to scoop into drinks and bags.
Refrigerators themselves use a compressor to force a coolant around the appliance and it pulls in heat. The heated coolant cycles to an exhaust outside the fridge and is basically dumped into the surrounding area. It extracts the heat from inside and moves it outside.
Bear in mind the coolant doesn’t really get “hot” just warmer than it normally wants to be and then cooled outside. So the process is gradual. Once already cold the temperature is easier to maintain. More cold objects in the fridge or freezer help it resist changes in temperature.
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