Thermodynamics

The First Law of Thermodynamics is a statement of the conservation of energy. It states that energy cannot be created or destroyed, only transferred or converted from one form to another:

Where:

• ΔU = change in internal energy (J)
• Q = heat added to the system (J)
• W = work done by the system (J)

The Second Law of Thermodynamics states that the entropy of an isolated system always increases over time. It introduces the concept of entropy as a measure of disorder or randomness:

Where:

• ΔS = change in entropy (J/K)
• Q = heat transfer (J)
• T = absolute temperature (K)

The equality holds for reversible processes, while the inequality applies to irreversible processes.

The Carnot efficiency represents the maximum possible efficiency of a heat engine operating between two temperatures:

Where:

• η = thermal efficiency (dimensionless)
• T₁ = absolute temperature of the hot reservoir (K)
• T₂ = absolute temperature of the cold reservoir (K)

This equation shows that no heat engine can be more efficient than a Carnot engine operating between the same temperature limits.