Influence of environment and entropy production of a nonequilibrium open system

2008 ◽  
Vol 372 (15) ◽  
pp. 2572-2577 ◽  
Author(s):  
Ming B. Yu
Keyword(s):  
Entropy Production ◽  
Open System

Thermodynamic Analysis of Buoyancy-Induced Flow in Rotating Cavities

2010 ◽  
Vol 132 (3) ◽  
Author(s):  
J. Michael Owen
Keyword(s):  
Entropy Production ◽  
Open System ◽  
Closed System ◽  
Outer Part ◽  
Compressor Rotor ◽  
Circulation Form ◽  
Induced Flow ◽  
Gas Turbine Compressor ◽  
Cooling Air ◽  
Buoyancy Induced Flow

Buoyancy-induced flow occurs in the rotating cavities between the adjacent disks of a gas-turbine compressor rotor. In some cases, the cavity is sealed, creating a closed system; in others, there is an axial throughflow of cooling air at the center of the cavity, creating an open system. For the closed system, Rayleigh–Bénard (RB) flow can occur in which a series of counter-rotating vortices, with cyclonic and anticyclonic circulation, form in the r-ϕ plane of the cavity. For the open system, the RB flow can occur in the outer part of the cavity, and the core of the fluid containing the vortices rotates at a slower speed than the disks: that is, the rotating core “slips” relative to the disks. These flows are examples of self-organizing systems, which are found in the world of far-from-equilibrium thermodynamics and which are associated with the maximum entropy production (MEP) principle. In this paper, these thermodynamic concepts are used to explain the phenomena that were observed in rotating cavities, and expressions for the entropy production were derived for both open and closed systems. For the closed system, MEP corresponds to the maximization of the heat transfer to the cavity; for the open system, it corresponds to the maximization of the sum of the rates of heat and work transfer. Some suggestions, as yet untested, are made to show how the MEP principle could be used to simplify the computation of buoyancy-induced flows.

Stoichiometric network analysis of entropy production in chemical reactions

2018 ◽  
Vol 20 (36) ◽  
pp. 23726-23739 ◽  
Author(s):  
David Hochberg ◽  
Josep M. Ribó
Keyword(s):  
Network Analysis ◽  
Entropy Production ◽  
Chemical Reactions ◽  
Open System ◽  
Reaction Networks ◽  
Stoichiometric Network Analysis

SNA extreme currents allow for the evaluation and understanding of entropy production of NESS in open system reaction networks.

Thermodynamic Analysis of Buoyancy-Induced Flow in Rotating Cavities

2007 ◽  
Author(s):  
J. Michael Owen
Keyword(s):  
Entropy Production ◽  
Open System ◽  
Closed System ◽  
Outer Part ◽  
Compressor Rotor ◽  
Circulation Form ◽  
Induced Flow ◽  
Gas Turbine Compressor ◽  
Cooling Air ◽  
Buoyancy Induced Flow

Buoyancy-induced flow occurs in the rotating cavities between the adjacent discs of a gas-turbine compressor rotor. In some cases, the cavity is sealed, creating a closed system; in others, there is an axial through-flow of cooling air at the centre of the cavity, creating an open system. For the closed system, Rayleigh-Be´nard (R-B) flow can occur in which a series of counter-rotating vortices, with cyclonic and anti-cyclonic circulation, form in the r-φ plane of the cavity. For the open system, R-B flow can occur in the outer part of the cavity, and the core of fluid containing the vortices rotates at a slower speed than the discs: that is, the rotating core ‘slips’ relative to the discs. These flows are examples of self-organizing systems, which are found in the world of far-from-equilibrium thermodynamics and which are associated with the maximum entropy production (MEP) principle. In this paper, these thermodynamic concepts are used to explain the phenomena that have been observed in rotating cavities, and expressions for the entropy production have been derived for both open and closed systems. For the closed system, MEP corresponds to the maximisation of the heat transfer to the cavity; for the open system, it corresponds to the maximisation of the sum of the rates of heat and work transfer. Some suggestions, as yet untested, are made to show how the MEP principle could be used to simplify the computation of buoyancy-induced flows.

Library as a Complex Open System

2012 ◽  
Vol 3 (2) ◽  
pp. 160-161
Author(s):  
JIGAR L DAVE ◽  
Keyword(s):  
Open System

Radiometric dating of hillslope calcrete in the Negev Desert, Israel

2008 ◽  
Vol 104 (11/12) ◽  
Author(s):  
J.C. Vogel ◽  
M.A. Geyh
Keyword(s):  
Open System ◽  
Negev Desert ◽  
Radiometric Dating ◽  
Jordan Valley ◽  
Partial Recrystallization ◽  
Uranium Series ◽  
Uranium Series Dating

The radiometric dating of calcrete is often problematical because impurities and open system conditions affect the apparent ages obtained. By applying both radiocarbon and uranium-series dating to calcrete in colluvium, it is shown that such conditions can be identified. In correlation with the stratigraphy, it is found that partial recrystallization severely decreases the radiocarbon ages of the upslope and shallower samples further down, whereas incorporation of limestone fragments from bedrock significantly increases the apparent ages of some of the uranium-series samples. It is concluded that the hillslope calcrete at the study site near Sede Beker in the Negev Desert, Israel, mainly developed shortly after 40 kyr ago, at a time when the Jordan Valley was being inundated to form the fossil Lake Lisan. Since their formation would have required higher rainfall than today, the results provide further evidence that the whole region was experiencing an increase in precipitation.

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