An assertive statement of the 2nd Law of thermodynamics-updated

Abstract

By and large, common statements of the 2nd Law are about limitations – ideals that cannot be surpassed. Today, at least in many academic circles it is commonly accepted that the concept now called exergy provides a consistent measure for assessing how well a process (consistent, whatever the process might be). In turn, it provides a measure for tracking resource expenditure in equipment and overall plants. That is, exergy provides a rational means for analysis of existing and proposed processes and facilities. 2nd Law statement can be used not only for analysis of processes, but also for modeling processes, as we proposed in a previous paper. In the present paper we go further. Whereas our previous mathematical models (governing equations) for modelling processes through the 2nd Law included energy balances and associated property relations, herein the modeling is achieved without recourse to 1st Law energy balances, using exergy balances instead. There are two keys that allow us to use only the 2nd Law: one is the deduction of exergy without reference to a “dead state” or pre-existing environment. Second is the use of dimensionless property relations for the exergy, again without explicit reference to dead state properties (such as T0 and p0).