What did Carnot and Kelvin know that we don't know?

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A word from the author. I started down this rabbit hole because I was working on a higher efficiency engine. Someone claimed it broke the "Carnot Limit", which it did, and yet the math was right. Having a look around, I saw that Steam driven Electric Generators also break the Carnot Limit, which means there isn't a Carnot Limit. (Or it means every Stem generator manufacturer on the planet is lying. - They are not.)

Reading the Thermodynamic work done in the 1800's is a lesson in humility.

Carnot and Kelvin started from a steam engine, and with experimentation demon started just about everything there is to know about heat engines and heat pumps, even before we had a handle on what energy was or how to quantity it.

Time after time I'd conclude the absolute impossibility of this or that, only to stumble across Kelvin disproving the impossible again and again.

By the way. Efficiency is an important goal of heat engines, and we define that the usual way, the desired result vs the energy added. Efficiency is limited by design, materials and manufacture, never by the Physics of energy transform.

What did Carnot and Kelvin know that we don't know?

In "Reflections"  Carnot and Lord Kelvin conclude some simple fundamentals about heat engines.

  1. All heat engines operate with the same return on consumed heat. (Earliest example of First Law).
  2. It doesn't matter what kind of vapor is used in heat engines or heat pumps. (All Pressure * ΔVolume are equal.)
  3. Maximizing efficiency means not diffusing or exhausting heat. (efficiency is work return on fuel, not  energy in vs energy out.)

When the first water cooled engines were being developed, they were criticized for fundamentally misunderstanding thermodynamics. Cooled heat engines is equal to pouring fuel on the ground. The critics were correct. The early builders of water cooled engines response was, oil is cheap and cooling helps the engine last. The early builders were also correct.

Today oil is not cheap, and we have capability to use much better materials and much better designs, but no one points out what a contradiction water cooled heat engines are, or that they are by far the least efficient heat engine on the planet.

We use Freon on air conditioners, poking a hole in our ozone layer. Equally important, the Freon cycle is a far less efficient heat pump cycle adding needless CO2 to the atmosphere.

  1. Ignoring Carnot and Kelvin has yielded inefficient heat engines.
  2. Ignoring Carnot and Kelvin has yielded inefficient heat pumps (air conditioners, refrigerators).
  3. Ignoring Carnot and Kelvin has yielded pointless air pollution and damage to Ozone layer.

Perpetuating the misinformation perpetuates the damage. The damage could be eliminated with lower cost engines and requiring less costly fuel and by lower cost heat pumps using pollution free air as operating fluid.