Second Law of Thermodynamics
- Identify the direction of a process. (ex: Heat can only transfer from a hot object to a cold object, not the other around)
- Can be used to determine the “Quality” of the energy. (ex: A high-temperature energy source has a higher quality since it is easier to extract energy from it to deliver useable work.)
- Can be used to exclude the possibilities of constructing 100% efficient heat engine and any perpetual-motion machines. (Kevin-Planck statement and Clausius statement)
- Reversible processes and irreversibilities.
- Determine the theoretical limits for the performance of engineering systems. (ex: A Carnot engine is theoretically the most efficient heat engine and its performance can be used to set as a standard for other practical machines)