Demystification of the Gouy-Stodola theorem of thermodynamics for closed systems

In the analysis and design of a process from a thermodynamics perspective, the Gouy-Stodola theorem of thermodynamics is very important. It provides a means to improve the efficiency of a process by quantification and minimization of the irreversibilities in the process. According to this theorem, the work lost or the exergy destroyed in a process is directly proportional to the amount of entropy generated in the process. Surprisingly, this theorem has received little attention in the engineering thermodynamics courses taught at the undergraduate level. The textbooks on thermodynamics rarely mention this theorem. The exact mathematical form of this theorem is not clear and the conditions under which this theorem is applicable are also not clearly stated in the existing literature. In this article, a complete analysis of the Gouy-Stodola theorem is presented for closed systems and its limitations are pointed out.