The refrigeration unit, and by extension the freezer, are common household appliances and many would deem them irreplaceable in modern society. You might be surprised, then, that the idea of refrigerator dates back hundreds of years. The fascination with manipulating heat began back in 1755 and found practical application with food preservation in slightly more recent years. How's it work? What have people tried over the years to make it work? Here's the answers to that and more.
Some of the first documented experiments with creating artificial cold were conducted by a Scottish professor by the name of William Cullen in 1755. Previously food was kept chilled by an ice box, using an insulated box with some amount of ice. Cullen experimented with the world's first compressor, which used a vial of diethyl ether in a vacuum. The vacuum caused the ether to boil which in turn absorbed heat from the surrounding air, lowering the overall air temperature. The experiment was more academic than practical but the principles were sound and led to later innovations. American Oliver Evans used the same ether under vacuum principle to create theoretical compressor designs. Many more inventors theorized cold from compression, but in 1856 it was a British journalist that gave life to theory.
In 1856 James Harrison patented a vapor compression system that had the option of using alcohol or ammonia. This resulted in the very first practical refrigerator unit able to create ice. He marketed his machines to brewers and meat packing shops, successfully deploying a number of machines by the early 1860's. More innovations quickly followed, including the first gas absorption system designed by Ferdinand Carré and the domestic refrigeration unit pioneered by Fred W. Wolf. The future had arrived and it was chillier than ever before.
How Refrigeration Compressors Work
The basic idea of any refrigeration compressor
is not so much making things colder, but in moving heat around. This is achieved by using a series of coils, one part of the coils inside the unit and one part on the outside of the unit. The coils inside the unit are called evaporator coils and the coils on the outside are termed condenser coils. Connecting the two sets is the critical expansion device, allowing hot coils to expand and cold coils to contract without causing damage to the coils themselves. A refrigerant vapor is compressed inside the unit and pushed out through the expansion device and into the condenser coils. The refrigerant takes with it heat from inside the unit and takes it outside where it cools against the neutral room temperature air of the kitchen. The vapor then condenses into a high pressure liquid and naturally returns to the coils inside the unit. Heat inside the freezer unit is gathered by the refrigeration compressor before it makes its way tot he compressor where it begins the loop again.
Subscribing to the physical law that energy can either be created or destroyed, heat is moved from inside to be distributed cleverly outside of the unit.
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