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The literature reports the proofs that entropy is an inherent property of any system in any state and governs thermal energy, which depends on temperature and is transferred by heat interactions. A first novelty proposed in the present study is that mechanical energy, determined by pressure and transferred by work interactions, is also characterized by the entropy property. The second novelty is that a generalized definition of entropy relating to temperature, chemical potential and pressure of many-particle systems, is established to calculate the thermal, chemical and mechanical entropy contribution due to heat, mass and work interactions. The expression of generalized entropy is derived from generalized exergy, which in turn depends on temperature, chemical potential and pressure of the system, and by the entropy-exergy relationship constituting the basis of the method adopted to analyze the available energy and its transfer interactions with a reference system which may be external or constitute a subsystem. This method is underpinned by the Second Law statement enunciated in terms of existence and uniqueness of stable equilibrium for each value of energy content of the system. The equality of chemical potential and equality of pressure are assumed, in addition to equality of temperature, to be necessary conditions for stable equilibrium.
Pierfrancesco Palazzo. A Method to Derive the Definition of Generalized Entropy from Generalized Exergy for Any State in Many-Particle Systems. Entropy 2015, 17, 2025 -2038.
AMA StylePierfrancesco Palazzo. A Method to Derive the Definition of Generalized Entropy from Generalized Exergy for Any State in Many-Particle Systems. Entropy. 2015; 17 (4):2025-2038.
Chicago/Turabian StylePierfrancesco Palazzo. 2015. "A Method to Derive the Definition of Generalized Entropy from Generalized Exergy for Any State in Many-Particle Systems." Entropy 17, no. 4: 2025-2038.
Pierfrancesco Palazzo. Thermoeconomics And Exergy Method In Environmental Engineering. Journal of Civil & Environmental Engineering 2013, 3, 1 -2.
AMA StylePierfrancesco Palazzo. Thermoeconomics And Exergy Method In Environmental Engineering. Journal of Civil & Environmental Engineering. 2013; 3 (1):1-2.
Chicago/Turabian StylePierfrancesco Palazzo. 2013. "Thermoeconomics And Exergy Method In Environmental Engineering." Journal of Civil & Environmental Engineering 3, no. 1: 1-2.
The present theoretical study represents a proposal aimed at investigating about the possibility of generalizing the canonical entropy-exergy relationship and the reservoir concept. The method adopted assumes the equality of pressure and chemical potential as necessary conditions of mutual stable equilibrium between a system and a reservoir in addition to the equality of temperature that constitutes the basis for defining entropy as deriving from energy and exergy concepts. An attempt is made to define mechanical and chemical entropy as an additional and additive component of generalized entropy formulated from generalized exergy property. The implications in exergy method and the possible engineering applications of this approach are outlined as future developments among the domains involved.
Pierfrancesco Palazzo. Proposal for Generalized Exergy and Entropy Properties Based on Stable Equilibrium of Composite System-Reservoir. Journal of Modern Physics 2013, 04, 52 -58.
AMA StylePierfrancesco Palazzo. Proposal for Generalized Exergy and Entropy Properties Based on Stable Equilibrium of Composite System-Reservoir. Journal of Modern Physics. 2013; 04 (07):52-58.
Chicago/Turabian StylePierfrancesco Palazzo. 2013. "Proposal for Generalized Exergy and Entropy Properties Based on Stable Equilibrium of Composite System-Reservoir." Journal of Modern Physics 04, no. 07: 52-58.
The mechanical aspect of entropy-exergy relationship, together with the thermal aspect usually considered, leads to a formulation of physical exergy based on both useful work and useful heat that are the outcomes of available energy of a thermodynamic system with respect to a reservoir. This approach suggests that a mechanical entropy contribution can be defined, in addition to the already used thermal entropy contribution, with respect to work interaction due to pressure and volume variations. The mechanical entropy is related to energy transfer by means of work interaction and it is complementary to the thermal entropy that accounts energy transfer by means of heat interaction. Furthermore, the study proposes a definition of exergy based on Carnot cycle that is reconsidered in the case the inverse cycle is adopted and, as a consequence, the concept that work depends on pressure similarly as heat depends on temperature, is pointed out. Then, the logical sequence to get mechanical exergy expression to evaluate useful work withdrawn from available energy is demonstrated. Based on mechanical exergy expression, the mechanical entropy set forth is deduced in a general form valid for any process. Finally, the formulation of physical exergy is proposed that summarizes the contribution of either heat or work interactions and related thermal exergy as well as mechanical exergy that both result as the outcome from the available energy of the composite of the system interacting with a reservoir. This formulation contains an additional term that takes into account the volume and, consequently, the pressure that allow to evaluate exergy with respect to the reservoir characterized by constant pressure other than constant temperature. The basis and related conclusions of this paper are not in contrast with principles and theoretical framework of thermodynamics and highlight a more extended approach to exergy definitions already reported in literature that remain the reference ground of present analysis.
Pierfrancesco Palazzo. Thermal and mechanical aspect of entropy-exergy relationship. International Journal of Energy and Environmental Engineering 2012, 3, 4 .
AMA StylePierfrancesco Palazzo. Thermal and mechanical aspect of entropy-exergy relationship. International Journal of Energy and Environmental Engineering. 2012; 3 (1):4.
Chicago/Turabian StylePierfrancesco Palazzo. 2012. "Thermal and mechanical aspect of entropy-exergy relationship." International Journal of Energy and Environmental Engineering 3, no. 1: 4.