Revised interpretation of work potential in thermophysical processes

An alternative development is attempted of the concept of exergy or availab ility by introducing the idea that exergy represents an abstract thermodyna mic metric that, essentially, quantifies the distance from the state of equ ilibrium with respect to a given reference value. Traditional and textbook approaches usually develop exergy as a system's potential to do reversible work. Usually, combining the balance of energy and entropy equations makes it possible to construct a corresponding balance of exergy and to use its d efinition to interpret the resulting terms. In contrast, the essential elem ents presented deal with the mathematical property of concavity of the entr opy as the essence of the second law and how this property translates into a geometric complementarity relation between entropy and exergy. The balanc e of exergy equation is presented as an expression representing the corresp onding convexity of the exergy, again demonstrating a mathematical property intrinsic to the second law.