Irreversibility and Limiting Possibilities of Macrocontrolled Systems I: Thermodynamics

2001 ◽  
Vol 08 (04) ◽  
pp. 315-328 ◽  
Author(s):  
A. M. Tsirlin ◽  
V. Kazakov ◽  
N. A. Kolinko
Keyword(s):  
Equilibrium State ◽  
Second Law Of Thermodynamics ◽  
Perfect Competition ◽  
Second Law ◽  
Extremal Principle ◽  
Maximal Power ◽  
Resource Exchange ◽  
Arbitrary Structure ◽  
Heat Engines ◽  
Maximal Profit

In this paper, two types of systems — thermodynamic and economic — are considered, which include a large number of micro subsystems and are controlled on the macro level (macrocontrolled systems). The analogy between the maximal work problem in thermodynamics and the maximal profit problem in a microeconomic system is investigated. The notion of exergy is generalized for the systems which do not contain reservoirs, and the conditions of maximal power of heat engines are generalized for systems with arbitrary structure. The notion of system profitability and the measure of irreversibility of an microeconomic processes are introduced. The extremal principle which determines an equilibrium state of open microeconomic system, is formulated. The conditions of optimality of resource trading and the expression for profitability of resource exchange are formulated for systems which include market with perfect competition, and for systems which do not include it. Economic analogues of the second law of thermodynamics are formulated using introduced concepts. The first part of the paper is devoted to thermodynamic systems and the second to microeconomic systems.

scholarly journals The maximum efficiency of nano heat engines depends on more than temperature

Quantum ◽  
2019 ◽  
Vol 3 ◽  
pp. 177 ◽  
Author(s):  
Mischa P. Woods ◽  
Nelly Huei Ying Ng ◽  
Stephanie Wehner
Keyword(s):  
Second Law Of Thermodynamics ◽  
Maximum Efficiency ◽  
Second Law ◽  
Single Shot ◽  
Free Energies ◽  
Heat Engines ◽  
A Value ◽  
Quantum Protocols ◽  
Additional Constraints ◽  
Quantum Heat Engines

Sadi Carnot's theorem regarding the maximum efficiency of heat engines is considered to be of fundamental importance in thermodynamics. This theorem famously states that the maximum efficiency depends only on the temperature of the heat baths used by the engine, but not on the specific structure of baths. Here, we show that when the heat baths are finite in size, and when the engine operates in the quantum nanoregime, a revision to this statement is required. We show that one may still achieve the Carnot efficiency, when certain conditions on the bath structure are satisfied; however if that is not the case, then the maximum achievable efficiency can reduce to a value which is strictly less than Carnot. We derive the maximum efficiency for the case when one of the baths is composed of qubits. Furthermore, we show that the maximum efficiency is determined by either the standard second law of thermodynamics, analogously to the macroscopic case, or by the non increase of the max relative entropy, which is a quantity previously associated with the single shot regime in many quantum protocols. This relative entropic quantity emerges as a consequence of additional constraints, called generalized free energies, that govern thermodynamical transitions in the nanoregime. Our findings imply that in order to maximize efficiency, further considerations in choosing bath Hamiltonians should be made, when explicitly constructing quantum heat engines in the future. This understanding of thermodynamics has implications for nanoscale engineering aiming to construct small thermal machines.

Thermodynamic Processes

2019 ◽  
pp. 132-147
Author(s):  
Robert H. Swendsen
Keyword(s):  
Real World ◽  
Heat Engine ◽  
Second Law Of Thermodynamics ◽  
Heat Pumps ◽  
Second Law ◽  
Carnot Cycle ◽  
Heat Engines ◽  
Negative Temperatures ◽  
Special Case ◽  
Thermodynamic Processes

This chapter begins by defining terms critical to understanding thermodynamics: reversible, irreversible, and quasi-static. Because heat engines are central to thermodynamic principles, they are described in detail, along with their operation as refrigerators and heat pumps. Various expressions of efficiency for such engines lead to alternative expressions of the second law of thermodynamics. A Carnot cycle is discussed in detail as an example of an idealized heat engine with optimum efficiency. A special case, called negative temperatures, where temperatures actually exceed infinity, provides further insights. In this chapter we will discuss thermodynamic processes, which concern the consequences of thermodynamics for things that happen in the real world.

Principle of Detailed Balance and the Second Law of Thermodynamics in Chemical Kinetics

2013 ◽  
Vol 135 (4) ◽  
Author(s):  
Mohammad Janbozorgi ◽  
M. Reza H. Sheikhi ◽  
Hameed Metghalchi
Keyword(s):  
Equilibrium State ◽  
Chemical Equilibrium ◽  
Rate Constants ◽  
Detailed Balance ◽  
Second Law Of Thermodynamics ◽  
Second Law ◽  
Elementary Chemical Reaction ◽  
Source Sink ◽  
Elementary Chemical ◽  
Reaction Equilibrium

The principle of detailed balance is shown to be a sufficient condition for the second law of thermodynamics in thermally equilibrated elementary chemical reactions. For an elementary reaction, the principle of detailed balance relates the forward and the reverse rate constants through the reaction equilibrium constant. It is shown that, in addition to the long known thermodynamic inconsistency at chemical equilibrium state, departure from this principle introduces an extra source/sink of entropy in the entropy balance for an elementary chemical reaction. The departure results in the wrong final chemical equilibrium state and, depending on the choice of the reverse rate constants, may lead to negative entropy productions during kinetic transients.

Efficiency of ideal fuel cell and Carnot cycle from a fundamental perspective

2005 ◽  
Vol 219 (4) ◽  
pp. 245-254 ◽  
Author(s):  
H Hassanzadeh ◽  
S H Mansouri
Keyword(s):  
Fuel Cell ◽  
Heat Engine ◽  
Second Law Of Thermodynamics ◽  
Second Law ◽  
Carnot Cycle ◽  
Combustion Engines ◽  
Numerical Examples ◽  
Cell Efficiency ◽  
Electrochemical Systems ◽  
Heat Engines

In this paper, we accept the fact that fuel cell and heat engine efficiencies are both constrained by the second law of thermodynamics and neither one is able to break this law. However, we have shown that this statement does not mean the two systems should have the same maximum thermal efficiency when being fed by the same amounts of chemical reactants. The intrinsic difference between fuel cells (electrochemical systems) and heat engines (combustion engines) efficiencies is a fundamental one with regard to the conversion of chemical energy of reactions into electrical work. The sole reason has been shown to be due to the combustion irreversibility of the latter. This has led to the statement that fuel cell efficiency is not limited by the Carnot cycle. Clarity is achieved by theoretical derivations and several numerical examples.

scholarly journals On Illustrating Carnot’s General Proposition by Means of Reversible Stirling Engines

2020 ◽  
Author(s):  
C Naaktgeboren ◽  
Klunger Arthur Éster Beck ◽  
Jean-Marc Stephane Lafay
Keyword(s):  
Second Law Of Thermodynamics ◽  
Stirling Engine ◽  
Working Fluid ◽  
Second Law ◽  
Working Fluids ◽  
Heat Engines ◽  
General Proposition ◽  
Stirling Engines ◽  
Fluid Properties

Carnot’s general proposition, also referred to as one of Carnot’s principles, states that the work producing potential of heat—harvested by reversible heat engines—is independent on the working fluid and on engine internal details, being only a function of the temperatures of the reservoirs with which the engine exchanges heat. This concept, usually presented to ME students in the context of the second law of thermodynamics, is usually proven by contradiction, using second law concepts and abstractions, without concrete examples, even though Carnot’s proposition mentions concrete things such as working fluids and engine internal details. This work proposes to document the usage of reversible Stirling engine models that take the engine arrangement and fluid properties into account towards illustrating the validity of Carnot’s general proposition.

scholarly journals APPLICATION OF THE POSTULATE OF NONEQUILIBRIUM TO CALCULATE THE NONEQUILIBRIUM OF SYSTEMS OF DISSIMILAR GASES AND LIQUIDS

2020 ◽  
Vol 17 (34) ◽  
pp. 998-1011
Author(s):  
Vladimir V RYNDIN
Keyword(s):  
Equilibrium State ◽  
Quantitative Characteristic ◽  
Second Law Of Thermodynamics ◽  
Irreversible Processes ◽  
Second Law ◽  
Nonequilibrium Systems ◽  
Real Property ◽  
Pure Solvent ◽  
Classical Thermodynamics ◽  
Isothermal Mixing

The postulate of nonequilibrium is at the heart of the second law of thermodynamics. According to this postulate, there is a real property of matter – “nonequilibrium,” which characterizes the uneven distribution of matter and motion in space. All processes (reversible and irreversible) can occur only in nonequilibrium systems. As a quantitative characteristic of the nonequilibrium of the system, the maximum work that can be performed during the transition of the nonequilibrium system to the equilibrium state is considered. The only formulation of the second law is given. When real (irreversible) processes occur, the nonequilibrium of the isolated system decreases, and in reversible processes, the nonequilibrium in the system of locally equilibrium subsystems does not change (the increment of one kind of the nonequilibrium entirely compensated by a decrease in the disequilibrium of some other kind). When the system reaches an equilibrium state, the disequilibrium disappears, and all processes cease. The article provides a calculated confirmation of the theoretical provisions of the concept of nonequilibrium and its mathematical apparatus by examples of determining the loss of the nonequilibrium of system when an isothermal mixing of dissimilar gases, and changes of nonequilibrium of system "pure solvent – solution" in the transition of part of the solvent in the solution. The mixing of the same gases leads to the Gibbs paradox, which is also considered in this paper. The concept of nonequilibrium was developed and the quantitative characteristics (measures) of nonequilibrium of the system were introduced allow to study nonequilibrium systems consisting of locally equilibrium subsystems in the sections of classical thermodynamics as simply as individual equilibrium systems.

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