Engines, Refrigerators, and A/Cs

The most interesting thing I read about Atoms and Heat was the actual process that refrigerators and air conditioners use to cool enclosed areas.  Both use mechanical energy to increase the temperature difference between two areas.  In other words they cool an area by heating another.  They do this by reducing the pressure in an enclosure, which, according to the gas law equation, Pressure = constant * Temperature, reduces the temperature.  In doing this, the other side of the machines are heated up.  This is the reason that air conditioners face outward (to increase the outside temperature), and the reason that fridges heat up the surrounding air.  The even more interesting thing, though, is that if you turn the A/C around, you can create a heat pump.  It will reduce the pressure outside, and the reaction will heat up the inside of an enclosure.  All in all, this means that heating a house by burning fuel to create mechanical energy that propels a heat pump is much more efficient than just heating a house by burning fuel.  The main point is that the heat generated by burning also contributes to the heat, so you get a double-win.  I’m definitely going to remember this because I believe it could be a vital part in sustaining an efficient household.

The second interesting thing I learned was about the Volkswagen Beetle.  The original Beetle had a very high mpg rating for the time (30 mpg).  The reason for this was that the engine temperature was very high, creating a great temperature difference used for generating mechanical energy.  This also joined more carbon atoms with oxygen atoms to release carbon dioxide molecules into the atmosphere rather than carbon atoms.  At this time, this was thought to be a great reduction in pollution.  Unfortunately, the hot engine ended up producing great amounts of Nitrous Oxide, a much bigger contributor to Global Warming.  Thus, the idea was shut down by the government and replaced with a conventional water-cooled engine in the next generation.  However, this would be an important concept to remember because it has the potential to create an extremely efficient engine, though the concept has been antiquated with modern alternative power sources.


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