Thermodynamic Approach of a Flow with Thermal Non-Equilibrium

Author(s):  
M. Dudeck
2013 ◽  
Vol 13 (5) ◽  
pp. 1330-1356 ◽  
Author(s):  
G. H. Tang ◽  
G. X. Zhai ◽  
W. Q. Tao ◽  
X. J. Gu ◽  
D. R. Emerson

AbstractGases in microfluidic structures or devices are often in a non-equilibrium state. The conventional thermodynamic models for fluids and heat transfer break down and the Navier-Stokes-Fourier equations are no longer accurate or valid. In this paper, the extended thermodynamic approach is employed to study the rarefied gas flow in microstructures, including the heat transfer between a parallel channel andpressure-driven Poiseuille flows through a parallel microchannel andcircular microtube. The gas flow characteristics are studied and it is shown that the heat transfer in the non-equilibrium state no longer obeys the Fourier gradient transport law. In addition, the bimodal distribution of streamwise and spanwise velocity and temperature through a long circular microtube is captured for the first time.


foresight ◽  
2015 ◽  
Vol 17 (1) ◽  
pp. 74-84
Author(s):  
Štefan Volner

Purpose – New non-equilibrium systems theory is a very important theoretical and methodological base of survey and understanding of contemporary economic systems and processes. Equilibrium is considered one of the basic conditions of existence and evolution of natural and social systems, according to scientific literature. Generally speaking, it can be presented as true. But the problem is that classical imagination perceives equilibrium as something real and stable – something more stable than basic condition of evolution of systems. Non-equilibrium state was usually understood as something negative, something destructive and something which has to be eliminated. Non-equilibrium state was understood as an anomaly, as an expression of weakening of system security and as a road to extinction. Thermodynamics comes with an idea that equilibrium is a “short” state of the system, equilibrium is very relative and all systems try to meet it, but they will never reach it. Equilibrium is usually connected with classical science and non-equilibrium state is connected with thermodynamics paradigm, with a new methodology of science. Non-equilibrium state is often seen as a basic condition – as an internal source of system evolution and its activities. Non-equilibrium state is a base of new arrangement of systems. Misunderstanding of contemporary non-equilibrium state theory and new expressions or aspects of dynamic processes can bring about negative impacts on the survey and establishment of new global economic system, e.g. new national and local economic systems. Therefore, the non-equilibrium state theory is a methodological base of new perception and survey of contemporary economic systems. Design/methodology/approach – A study of non-equilibrium thermodynamics. Findings – Irreversibility and non-equilibrium, occurring in each process and evolutionary phase of economic systems, are connected with accidents and openness. Openness of systems enables (and causes) diversification toward wider system or environment and penetration of external elements and processes to internal structure of the system. A system like this is more sensitive to external and internal changes. Considering this, it is very important to be aware of the fact that entropy has different behavior in “closed” systems – different from behavior in open systems. Open economic systems communicate with external environment, interact with external systems and they exchange the energy. They consume energy of external environment and penetrate it. Elements, nodes and joints in open systems can communicate, connect and integrate with elements, nodes and joints from external systems. The growth of entropy is “smoother” and equilibrium of the system, its sub-systems and elements proceeds despite the non-equilibrium state of elements of the own system. They have to communicate and exchange the energy with external environment. This is because of the non-equilibrium state. Originality/value – This is an original thermodynamic approach to the importance of non-equilibrium in the development of economic systems.


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