Analysis of elliptical thermal cloak based on entropy generation and entransy dissipation approach

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.

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Comparative study of the thermal performance of four different parallel flow shell and tube heat exchangers with different performance indicators

Open Physics ◽

10.1515/phys-2020-0202 ◽

2020 ◽

Vol 18 (1) ◽

pp. 1121-1135

Author(s):

Chulin Yu ◽

Haiqing Zhang ◽

Youqiang Wang ◽

Jin Wang ◽

Bingjun Gao ◽

...

Keyword(s):

Nusselt Number ◽

Comparative Study ◽

Friction Factor ◽

Entropy Generation ◽

Performance Indicators ◽

Heat Exchangers ◽

Parallel Flow ◽

Turbulent Regime ◽

Entransy Dissipation ◽

Shell And Tube

Abstract Round rod baffle (RRB), plain plate baffle (PPB), wavy-shaped plate baffle (WSB) and polygonal-shaped plate baffle (PSB) are four commonly used baffles in parallel flow shell and tube heat exchangers (STHXs). Comparative study of these four different baffles are numerically carried out using different performance indicators including Nusselt number, friction factor, performance evaluation criterion, entropy generation ratio, and entransy dissipation ratio for flow in full turbulent regime. Heat transfer mechanism has also been discussed. Correlations for Nusselt number and friction factor are fitted and the cost estimation using Hall’s method is compared. It is found that the Nusselt number of STHX-PPB, STHX-WSB, and STHX-PSB increased by 20.9%, 15.2%, and 23.9% averagely compared with STHX-RRB, respectively. The friction factor can be increased on average by 142.0%, 154.5%, and 242.4%, respectively. However, the overall performance of them is only 90.1%, 84.4%, and 82.3% that of STHX-RRB, respectively. The sequence of entropy generation and entransy dissipation is STHX-RRB > STHX-WSB > STHX-PPB > STHX-PSB. The inlet Re and baffle distance have significant effects on different performance indicators while the baffle width does not. Finally, the results show that the STHX-PSB can reduce the total cost as it has better ability on heat enhancement.

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Optimization of Horizontal Plate Fin Heat Sink in Natural Convection for Electronics Cooling by Simulated Annealing Algorithm

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.1022.91 ◽

2014 ◽

Vol 1022 ◽

pp. 91-95 ◽

Cited By ~ 1

Author(s):

Li Zhou ◽

Yang Liu

Keyword(s):

Simulated Annealing ◽

Heat Source ◽

Entropy Generation ◽

Heat Sink ◽

Dissipation Rate ◽

Geometry Optimization ◽

Horizontal Plate ◽

Entransy Dissipation ◽

Source Temperature ◽

Entransy Dissipation Rate

In this study, the simulated annealing (SA) algorithm was adopted to optimize the geometry of horizontal plate fin heat sink by the extreme entransy dissipation principle. The alculation of the entransy dissipation rate was presented in detail. Using the entransy dissipation rate as the objective condition, the geometry optimization of the fin heat sink was conducted. To verify the results, the heat source temperature and the entropy generation rate were also calculated in the procedure. It is found that the entrasy dissipation rate, entropy generation and heat source temperature have the similar trend. The extreme entransy dissipation principle and minimization of entropy generation play similar roles in the geometry optimization of plate fin heat sink.

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Entropy and Entransy Dissipation Analysis of a Basic Organic Rankine Cycles (ORCs) to Recover Low-Grade Waste Heat Using Mixture Working Fluids

Entropy ◽

10.3390/e20110818 ◽

2018 ◽

Vol 20 (11) ◽

pp. 818 ◽

Cited By ~ 4

Author(s):

Yong-qiang Feng ◽

Qian-hao Luo ◽

Qian Wang ◽

Shuang Wang ◽

Zhi-xia He ◽

...

Keyword(s):

Entropy Generation ◽

Mass Fraction ◽

Waste Heat ◽

Low Grade ◽

Outlet Temperature ◽

Entransy Dissipation ◽

Minimum Entropy ◽

Pinch Point ◽

Working Fluids ◽

Condenser Temperature

Mixture working fluids can reduce effectively energy loss at heat sources and heat sinks, and therefore enhance the organic Rankine cycle (ORC) performance. The entropy and entransy dissipation analyses of a basic ORC system to recover low-grade waste heat using three mixture working fluids (R245fa/R227ea, R245fa/R152a and R245fa/pentane) have been investigated in this study. The basic ORC includes four components: an expander, a condenser, a pump and an evaporator. The heat source temperature is 120 °C while the condenser temperature is 20 °C. The effects of four operating parameters (evaporator outlet temperature, condenser temperature, pinch point temperature difference, degree of superheat), as well as the mass fraction, on entransy dissipation and entropy generation were examined. Results demonstrated that the entransy dissipation is insensitive to the mass fraction of R245fa. The entropy generation distributions at the evaporator for R245/pentane, R245fa/R152a and R245fa/R227ea are in ranges of 66–74%, 68–80% and 66–75%, respectively, with the corresponding entropy generation at the condenser ranges of 13–21%, 4–17% and 11–21%, respectively, while those at the expander for R245/pentane, R245fa/R152a and R245fa/R227ea are approaching 13%, 15% and 14%, respectively. The optimal mass fraction of R245fa for the minimum entropy generation is 0.6 using R245fa/R152a.

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Analyses of entransy dissipation, entropy generation and entransy–dissipation-based thermal resistance on heat exchanger optimization

Applied Thermal Engineering ◽

10.1016/j.applthermaleng.2012.01.017 ◽

2012 ◽

Vol 38 ◽

pp. 31-39 ◽

Cited By ~ 63

Author(s):

Xuetao Cheng ◽

Qinzhao Zhang ◽

Xingang Liang

Keyword(s):

Heat Exchanger ◽

Thermal Resistance ◽

Entropy Generation ◽

Entransy Dissipation

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An alternative criterion in heat transfer optimization

Proceedings of The Royal Society A Mathematical Physical and Engineering Sciences ◽

10.1098/rspa.2010.0293 ◽

2010 ◽

Vol 467 (2128) ◽

pp. 1012-1028 ◽

Cited By ~ 64

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.

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