Entropy, efficiency, thermodynamics for first-year engineering students

Entropy, energy, and efficiency are concepts with broad applicability. As such, it is reasonable to expect that these concepts would be extremely useful to engineering students from a wide range of backgrounds. However, the classical definition of entropy in terms of heat transfer in a physically reversible operation does not provide intuition about the nature of entropy. Instead of starting with heat, work, and reversible operations, the authors suggest that entropy, conceptualized in terms of unpredictability, can provide an intuitively useful starting point. Starting with entropy, the authors derive the efficiency of an ideal Carnot engine without reference to reversible heat transfer. The authors show how the framework can be applied to understand the efficiency of a hurricane as a heat engine.