In sociology, historically, the two most prominent systems approaches have been functionalism, viewing a social system as society as made up of interdependent sections working together to fill the “functions” of society's survival, and general systems theory, a biology-physics type open systems model, developed by Emile Durkheim (1893) and Ludwig Bertalanffy (1950), respectively. 
In thermodynamic terms, a social system is viewed as a set of "socially affined" human molecules (people) delineated by a thermodynamic boundary characterized by an internal energy.  The thermodynamic view of social system is a difficult subject, one that is often skipped over or sometimes slightly addressed by sociologists, some even having objections.
In social thermodynamics, a social system is often viewed a set of human molecules contained in a system, delineated by a social boundary, subjected to daily expansions and contractions in volume according to Boerhaave's law, in the same sense, albeit a reactive one, as water molecules in the boundaried piston-and-cylinder of a heat engine.  In another sense, a social system, thermodynamically, can be considered as a mode of organization of action elements relative to the persistence or ordering processes of change of the interactive patterns of a plurality of actors, which can be divided into exact thermodynamic coordinates driven by thermodynamic forces. 
In the 2001 paper "Social Entropy", Peruvian engineering professor Alfredo Infante argued that social entropy is the quantity that measures the effects of the second law of thermodynamics in human social behavior and that the "state" of a human society as a “system” is described by the degree of dissatisfaction or satisfaction with the social, political, and economic rules. He states that in social systems, the Gibbs free energy is the total energy in the system less the energy that is unavailable and that this difference represents the ‘state’ of the social system. 
|Image: “Man in piston” cartoon drawn by Mark Warmbrunn (1994); re-annotated by Libb Thims (2013) to illustrate the conception of ‘social boundaries’, e.g. Great Wall of China), originally published in Ingo Muller’s 1994 Grundzüge der Thermodynamik : mit historischen Anmerkungen (Essentials of Thermodynamics: with Historical Notes); also shown on cover of Muller’s 2009 Fundamentals of Thermodynamics and Applications; Warmbrunn being a then 14-year old “genius with a pencil and paper”, was a friend of Muller’s son, an art school applicant. |
In 1972, American economist Paul Samuelson, winner the 1970 Nobel Prize in Economics, sole protegé of the American polymath Edwin Wilson, who had himself been the sole protegé of Yale's great physicist Willard Gibbs (the main founder of chemical thermodynamics), commented that: 
“The sign of a half-baked speculator in the social sciences is his search for something in the social system that corresponds to the physicist's notion of entropy.”
Samuelson, however, seemed to have a general disdain and strong objection to any type thermodynamic modeling in either economics or sociology.
In the 1992 book The Meaning of General Theoretical Sociology, for instance, American sociologist Thomas Fararo devotes one page to the subject, where after mentioning Belgian chemist Ilya Prigogine’s “order-from-disorder”, far-from-equilibrium, dissipative structure thermodynamic theory, tells us in defense:
“Of course, the empirical social systems we treat in sociology are not immune to the laws of thermodynamics; each organism, for instance, is in one aspect an open physical system to which a thermodynamic characterization applies.”
In commentary, however, Fararo reasons that although certainly nothing in theoretical sociology is immune from the ultimate constraints of sciences such as thermodynamics, genetics, or mechanics, etc., they are just not as important. Moreover, he adamantly states that sociology should have a different conception of "equilibrium" than that such as used in the various branches of thermodynamics. In conclusion on his thermodynamic digression, Fararo states: 
“The main point is that theoretical sociology should employ an abstract analytical conception of equilibrium in which this concept is in reference to certain states of the social system, not of the biophysical environment … any special emergence of order-from-disorder phenomenon in our field must be accounted for by the mechanism of social interaction, not by a vague appeal to some thermodynamic situation.”
1. Social system (definition) – WordNet® 3.0 by Princeton University.
2. (a) Thims, Libb. (2007). Human Chemistry (Volume One), (preview), (Google books). Morrisville, NC: LuLu.
(b) Thims, Libb. (2007). Human Chemistry (Volume Two), (preview), (Google books). Morrisville, NC: LuLu.
3. Stepanic, Josip, Stefancic, Hrvoje, Zebec, Mislav S., and Perackovic, Kresimir. (2000). “Approach to a Quantitative Description of Social Systems Based on Thermodynamic Formalism.” Entropy, 2(3): pgs 98-105.
4. Infante, Alfredo I. (2001). “Social Entropy: A Paradigmatic Approach of the Second Law of Thermodynamics to an Unusual Domain.”, Nexial Institute.
5. Fararo, Thomas J. (1992). The Meaning of General Theoretical Sociology: Tradition and Formalization, (pg. 86-87). Cambridge University Press.
6. Samuelson, Paul. (1972). The Collected Scientific Papers (pg. 450). Vol. 3, ed. R. Merton. Cambridge, Mass.: MIT Press.
7. Bailey, Kenneth D. (1990). Social Entropy Theory (pg. 13). New York: State University of New York Press.
8. Thims, Libb. (2014-15/16). Chemical Thermodynamics: with Application in the Humanities (pdf). Publisher.