I am having trouble with understanding the so called Second Law of thermodynamics.
There are a million different definitions. All of them get to the essence:
"Disorder increases, stuff gets wild and wilder".
Thermodynamics starts out of the curiosity: "Why can my engine not be more efficient?"
- Heat and Work are Internal Energy that's being transferred (from and to the stuff that's being analyzed).
- A heat engine wants to transform heat flow into work flow.
It will work considering that a gas under high pressure and high temperature (state 1)* wants to increase its volume (because it wants to be comfortable in a bigger playground).
- High pressured gas wants to expand [with heat source - stays warm] (positive work flow coming from a loss of its internal energy, but internal energy stays constant while gaining heat flow)
- High pressured gas wants to expand [no heat source - loses internal energy] (generating positive work flow)
Now the gas doesn't want to expand anymore. It's chilling. Balance.
Everything would stop here naturally.
But we want it to work again.
We force compression to take all the stuff back, so everything can restart.
(Question 1) Where does the energy required for the compression come from?
Anyways, the gas compresses, and gets hot because it feels uncomfortable again. But nah, we put something colder around so its increased Internal Energy stays constant (because it will run away as a heat release to the colder place).
And then at a certain point we take away the Cold thing, just so the gas cannot do anything else than keep its increasing internal energy (which comes from uncomfortability).
(Question 2) Why would we divide the compression into two steps? Why can the gas not just be compressed and increase its internal energy so we have more temperature at the (state 1)* to restart all the stuff with more "strength"? What's the point of releasing that internal energy it is gaining from the compression we are forcing?
(Question 3) What's the real beginning of the 2nd law? Where does it come from and how does it apply here, in the engine?