“Entransy,” and Its Lack of Content in Physics

2014 ◽  
Vol 136 (5) ◽  
Author(s):  
Adrian Bejan
Keyword(s):  
Heat Transfer ◽  
Thermal Resistance ◽  
Entropy Generation ◽  
Solid Body ◽  
Thermodynamic Temperature ◽  
Entransy Dissipation ◽  
Minimum Entropy ◽  
Constructal Law ◽  
Minimum Entropy Generation ◽  
False Claim

Here, I show that “entransy” has no meaning in physics, because, at bottom, it rests on the false claim that in order to transfer heat to a solid body of thermodynamic temperature T, the heat transfer must be proportional to T. Entransy “dissipation” is a number proportional to well known measures of irreversibility such as entropy generation and lost exergy (destroyed available work). Furthermore, the “principle of entransy dissipation minimization” adds nothing to existing work based on minimum entropy generation, minimum thermal resistance, and constructal law. The broader trend illustrated by the entransy hoax is that it is becoming easy to take an existing idea, change the keywords, and publish it as new.

Convective Heat Transfer Enhancement in Solar Receivers Using Minimum Entropy Generation Optimization

2011 ◽  
Author(s):  
Qi Li ◽  
Xigang Yuan ◽  
Pierre Neveu ◽  
Gilles Flamant
Keyword(s):  
Heat Transfer ◽  
Convective Heat Transfer ◽  
Heat Transfer Enhancement ◽  
Convective Heat ◽  
Entropy Generation ◽  
Minimum Entropy ◽  
Transfer Enhancement ◽  
Optimal Velocity ◽  
Minimum Entropy Generation ◽  
Convective Heat Transfer Enhancement

Convective heat transfer enhancement can significantly improve the thermal efficiency in the conversion, utilization, recovery and storage of energy (in particular solar thermal). Modifying velocity field is the most direct approach to enhance convective heat transfer. However, in most cases the optimal velocity field is unknown and difficult to find even for an experienced researcher. In this paper, a predictive optimization methodology in convective heat transfer enhancement based on minimum entropy generation (MEG) principle was developed. A set of Euler’s equations were derived by the variation calculus to the Lagrange function established by governing equations, specific constraints and objective functional—total entropy generation rate. The solution of these equations resulted in the optimal velocity fields, leading to the minimum entropy generation. To validate and demonstrate the future application of this methodology to solar absorbers used to convert concentrated solar energy, the steady laminar convection heat transfer process in a two-dimensional channel with fixed heat flux boundaries was optimized for given total viscous dissipations. The numerical simulation results showed that lower value of maximum wall temperature was obtained by MEG optimization, which means cheaper and safer materials. The present work indicated that the new methodology could be a good guide in convective heat transfer enhancement design work, especially in CSP receivers.

Genetic Algorithm-Based Optimal Design of Plate Fins Following Minimum Entropy Generation Considerations

2005 ◽  
Vol 219 (8) ◽  
pp. 757-765 ◽  
Author(s):  
R. K. Jha ◽  
S Chakraborty
Keyword(s):  
Heat Transfer ◽  
Genetic Algorithm ◽  
Optimal Design ◽  
Forced Convection ◽  
Entropy Generation ◽  
Generation Rate ◽  
Entropy Generation Rate ◽  
Minimum Entropy ◽  
Minimum Entropy Generation ◽  
Continuous Plate

This paper deals with estimation of the optimal dimensions of arrays of plate fins cooled by forced convection. The optimization is achieved by minimizing the entropy generation rate using genetic algorithm-based evolutionary computing techniques. Results are presented for staggered plate fins configuration and continuous plate fins configuration. The effects of heat transfer and fluid friction on entropy generation rate are also reported.

The Equivalence of Maximum Power and Minimum Entropy Generation Rate in the Optimization of Power Plants

1996 ◽  
Vol 118 (2) ◽  
pp. 98-101 ◽  
Author(s):  
Adrian Bejan
Keyword(s):  
Heat Transfer ◽  
Power Plant ◽  
Entropy Generation ◽  
Heat Input ◽  
Power Plants ◽  
Generation Rate ◽  
Entropy Generation Rate ◽  
Total Entropy ◽  
Minimum Entropy ◽  
Minimum Entropy Generation

It is shown that to maximize the power output of a power plant is equivalent to minimizing the total entropy generation rate associated with the power plant. This equivalence is illustrated by using two of the oldest and simplest models of power plants with heat transfer irreversibilities. To calculate the total entropy generation rate correctly, one must recognize that the optimization process (e.g., the variability of the heat input) requires “room to move,” i.e., an additional, usually overlooked, contribution to the total entropy generation rate.

An alternative criterion in heat transfer optimization

2010 ◽  
Vol 467 (2128) ◽  
pp. 1012-1028 ◽  
Author(s):  
Qun Chen ◽  
Hongye Zhu ◽  
Ning Pan ◽  
Zeng-Yuan Guo
Keyword(s):  
Heat Transfer ◽  
Thermal Conductivity ◽  
Entropy Generation ◽  
Transfer Process ◽  
Heat Transfer Process ◽  
Optimization Criterion ◽  
Entransy Dissipation ◽  
Minimum Entropy ◽  
Fourier’S Law ◽  
Fourier's Law

Entropy generation is recognized as a common measurement of the irreversibility in diverse processes, and entropy generation minimization has thus been used as the criterion for optimizing various heat transfer cases. To examine the validity of such entropy-based irreversibility measurement and its use as the optimization criterion in heat transfer, both the conserved and non-conservative quantities during a heat transfer process are analysed. A couple of irreversibility measurements, including the newly defined concept entransy , in heat transfer process are discussed according to different objectives. It is demonstrated that although thermal energy is conserved, the accompanied system entransy and entropy in heat transfer process are non-conserved quantities. When the objective of a heat transfer is for heating or cooling, the irreversibility should be measured by the entransy dissipation, whereas for heat-work conversion, the irreversibility should be described by the entropy generation. Next, in Fourier’s Law derivation using the principle of minimum entropy production, the thermal conductivity turns out to be inversely proportional to the square of temperature. Whereas, by using the minimum entransy dissipation principle, Fourier’s Law with a constant thermal conductivity as expected is derived, suggesting that the entransy dissipation is a preferable irreversibility measurement for heat transfer.

Effect of Absorptive Coating of the Hot Fluid Passage of a Heat Exchanger Employing Exergy-Optimized Pin Fins in High Temperature Applications

2009 ◽  
Vol 131 (5) ◽  
Author(s):  
Nwosu P. Nwachukwu ◽  
Samuel O. Onyegegbu
Keyword(s):  
Heat Transfer ◽  
High Temperature ◽  
Simple Relation ◽  
Base Temperature ◽  
Minimum Entropy ◽  
Pin Fin ◽  
Temperature Heat ◽  
Pin Fins ◽  
Minimum Entropy Generation ◽  
Fluid Parameters

An expression for the optimum pin fin dimension is derived on exergy basis for a high temperature exchanger employing pin fins. The present result differs from that obtained by Poulikakos and Bejan (1982, “Fin Geometry for Minimum Entropy Generation in Forced Convection,” ASME J. Heat Transfer, 104, pp. 616–623) for a low temperature heat recovery application. Also, a simple relation is established between the amounts the base temperature of the optimized pin fin is raised for a range of absorptive coating values. Employing this relation, if the absorptivity of the coating, the plate emissivity, the number of protruding fins, and some area and fluid parameters are known, the corresponding value for the base temperature of the fin is immediately obtained. The analysis shows that the thermal performance of the exchanger improves substantially with a high absorptivity coating hence can be seen as a heat transfer enhancement feature of the exchanger operating with radiation dominance.

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