UY1: Thermal Bottleneck


If you consider that the first law says you cannot win (or you cannot get a free lunch), the second law says you cannot even break even (you cannot even eat all of your lunch):
– The first law is essentially a statement of conservation of energy and says that you cannot get more energy (work) out of a heat engine than you put in (heat).

– The second law says that you cannot even convert all of that heat into work (although you can convert all mechanical work into heat).

This is the “thermal bottleneck” that severely limits the efficiency of processes which convert stored energy to heat and then convert that heat to work.

Note: This means that 60 to 70% of the input heat will be rejected as wasted heat. No matter what you do, you will be restricted by the efficiency limits set by the Carnot cycle. There is nothing you can do that will raise the efficiency above that efficiency limit, not now, not 1000 years later.

Assuming that the laws of Physics are the same for every part of the Universe, no matter where you go, the thermal efficiency is restricted by the efficiency limit.

Next:

Previous: The Carnot Engine

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