History of Refrigerants

The concept of mechanical refrigeration starts back in the 1750s. Researchers knew nothing about cooling except that pressure and gasses somehow played a key roll in absorbing and removing heat. In these early days, everything was tried as a refrigerant: ammonia, alcohol, air, carbon dioxide, and more. It was the days of trial and error to create the robust understanding of physics and chemistry we have today.   Low Temperature Boiling The first experiments in refrigeration used Ether and Alcohol, which are readily evaporated. At sea level, Ether boils at 94F and Alcohol can boil as low as 151F, depending on the exact chemical form. Sea level is important here, as pressure changes the boiling point. Lowering the pressure causes a decrease in the boiling point. These gasses with low boiling points were ideal for early experiments. The first experiments used vacuum chambers and potentially some custom hardware. There isn’t a lot needed to build a basic vacuum chamber. A jar with a good seal, a hose, and a pump can create a vacuum. An observable refrigeration can be done with almost no special equipment at all. At this scale, cooling was possible, but not feasible. Alcohol, Ether, and other chemicals were common and easy to acquire, but no one was going to put a chunk of meat in a vacuum chamber, cover it in alcohol, wait for it to freeze, and try to store it somewhere. There had to […]

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Why is the AC Hissing?

Air conditioners produce liquid water by design and by the simple nature of physics. Sometimes this harmlessly leaks out around the air conditioner, such as with window units, and sometimes it leaks when a drain gets blocked. There is however, a second leak an air conditioner can develop: refrigerant leaks.   The Cooling Compound Air conditioners work by exploiting physics around state-changes. When liquid turns into a gas, it can absorb heat.The effectiveness of the state change varies from compound to compound. For air conditioning, we tend to use things like R134a (freon), R12 (phased out/illegal in much of the world now), and even propane. These are all chemicals which have particular properties ideal for cooling. For example, they won’t turn solid at 0 degrees C like water, so they won’t clog up the air conditioner’s tubing and fittings. These chemicals though have some downsides we can’t really escape. Propane is outright flammable and probably capable of turning your air conditioner into a flaming set piece in the next post-apocalypse movie. R12 destroys the ozone. And R134a is toxic. It causes a wide range of symptoms from headaches to hallucinations and death in the worst case exposures.   The Hissing Leak When the air conditioner is running or has recently been run, the refrigerant will be highly pressurized. In order for us to make it work, we compress it. We’re cramming a lot of material into a small space, which […]

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