Entransy expression of the second law of thermodynamics and its application to optimization in heat transfer process

Liu, W.; Liu, Z.C.; Jia, Haikun; Fan, Aiwu; Nakayama, A.

doi:10.1016/j.ijheatmasstransfer.2011.02.041

Cited by 109 publications

(34 citation statements)

References 15 publications

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“…(20) indicates that the net power output increases with increasing Q  and T 2 or with decreasing of T 1 . At the same time, the entransy loss rate also increases with increasing Q  and T 2 or with decreasing T 1 .…”

Section: T T T T T T T Tmentioning

confidence: 95%

“…So, the concept of entransy could describe the irreversibility of heat transfer [7,[18][19][20]. Furthermore, Cheng et al [18,21,22] set up the thermal equilibrium criteria based on the concept of entransy, developed a microscopic expression of entransy for a monatomic ideal gas system, related the entransy to the microstate number, indicated the microscopic physical meaning of entransy to some extent, and extended the entransy theory to generalized flows.…”

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confidence: 99%

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Entransy analysis of open thermodynamic systems

2012

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The concept of entransy developed in recent years can describe the heat transport ability. This paper extends this concept to the open thermodynamic system and defines the concept of enthalpy entransy. The entransy balance equation of steady open thermodynamic systems, as well as the concept of entransy loss, is developed. The entransy balance equation is applied to analyzing and discussing the air standard cycle. It is found that the entransy loss rate can describe the change in net power output from the cycle but the entropy generation rate cannot when the heat absorbed by the working medium is from the combustion reaction of the gas fuel. When the working medium is heated by a high temperature stream, both the maximum entransy loss rate and the minimum entropy generation rate correspond to the maximum net power output from the cycle. Hence, the concept of entransy loss is an appropriate figure of merit that describes the cycle performance. As nearly 80% of the total energy consumption is related to heat [1], the optimization design of heat transfer and heatwork conversion has become one of important research topics under the increasing requirements on reducing energy consumption. For instance, the design optimization could improve the performance of heat exchangers and increase heat transfer rate [1]. Optimizing the thermal conductance distribution of the heat exchanger groups could also increase the work output in heat-work conversion [2]. Several theories have been developed for the optimal design of heat transfer and heat-work conversion in recent years [1][2][3][4][5][6][7]. Bejan [4-6] developed the constructal theory and thermodynamic optimizations for heat transfer processes. In heat conduction optimization of the Volume-to-Point problem, Bejan [4] developed the constructal theory, in which the basic, imagined structure of the high conductivity material is given, and the aspect ratio of the structure is optimized through theoretical derivation and numerical simulation to decrease the highest temperature of the heated domain. The sub-structure, third degree structure, etc. are evolved to cover the whole domain. The constructal theory was found to be effective for heat conduction optimization and was extended to heat convection optimizations [8][9][10]. Furthermore, Bejan [4-6] related the optimal heat transfer to the minimum production of entropy generation and extended this idea into other systems. Researchers have done many investigations on heat transfer optimization based on the minimum principle of entropy generation [11,12]. As the objective of this kind of optimization method is to minimize the entropy generation, it is called thermodynamic optimization.However, there are arguments on the constructal theory and thermodynamic optimization in heat transfer [6,[13][14][15][16][17]. Ghodoossi [13,14] applied the constructal theory to analyzing the effect of the complexity levels of the tree network of conducting paths and found that the heat flow performance does not essentially improve if the intern...

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Section: T T T T T T T Tmentioning

confidence: 95%

mentioning

confidence: 99%

Entransy analysis of open thermodynamic systems

2012

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“…Based on this concept, Guo et al (4) and Cheng et al (26) proved that the entransy always decreases during any practical heat transfer process. The decreased entransy was named entransy dissipation, and describes the irreversibility of heat transfer (26,27) . Guo et al (4) derived the minimum entransy dissipation principle for fixed heat flow boundary conditions and the maximum entransy dissipation principle for fixed temperature boundary conditions.…”

Section: Introductionmentioning

confidence: 99%

“…The minimum entransy-dissipation-based thermal resistance principle indicates that smaller thermal resistance leads to better heat transfer performance. These principles of the entransy theory have found applications in optimizing heat conduction (4,(28)(29)(30)(31)(32) , heat convection (4,27,(33)(34)(35) , thermal radiation (36,37) and the design of heat exchangers (12,13,15,38,39) and heat exchangers networks (14,15) , and no paradox similar to the entropy generation paradox is noticed up to now (12,13,15,38) .…”

Section: Introductionmentioning

confidence: 99%

Entransy, Entransy Dissipation and Entransy Loss for Analyses of Heat Transfer and Heat-Work Conversion Processes

Cheng

Liang

2013

JTST

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Entransy is a parameter proposed in recent years to describe the potential of heat in an object. Its balance equation was established based on the energy equation of heat transfer, which contains entransy, entransy flow, entransy dissipation and entransy production due to heat source. It has been proved that the total entransy must be reduced whenever there is heat transfer in an isolated system, leading to entransy dissipation. Entransy dissipation and entransy-based thermal resistance can be used to optimize heat conduction, heat convection, thermal radiation and the design of heat exchangers and heat exchanger networks. On the other hand, the entransy balance equation was also established for heat-work conversion processes. With the equation, entransy loss, which is the difference between the input and output heat entransy flows, was defined and related to thermodynamic processes. For the discussed thermodynamic cycles, it was found that larger entransy loss leads to larger output work.

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“…Based on the concept of entransy dissipation, Guo et al [4] developed the extremum entransy dissipation principle, defined the entransy-dissipation-based thermal resistance, and proposed the minimum thermal resistance principle. It was found that the principles of the entransy theory are appropriate to the optimization of heat conduction [5][6][7][8][9][10][11][12][13], heat convection [14][15][16][17], thermal radiation, design of heat exchangers [21][22][23][24][25][26][27] and phase change heat transfer processes [28]. Eqs.…”

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confidence: 99%

Relationship between microstate number and available entransy

Cheng

Liang

2012

Chin. Sci. Bull.

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Based on the relationship between entransy and microstate number, we discuss the variations of the available transport entransy, the unavailable transport entransy, the available conversion entransy and the unavailable conversion entransy with the microstate number. We focus on physical processes in which heat is used for heating/cooling or doing work. When heat is transported for heating or cooling, the available transport entransy increases if the increase in microstate number is due to the increase in internal energy of the system, and decreases if the increase in microstate number is due to spontaneous heat transfer. When heat is used to do work, both the available conversion entransy and the unavailable conversion entransy increase if the increase in microstate number relates to the growth in internal energy of the system. The available conversion entransy decreases and the unavailable conversion entransy increases if the increase in microstate number results from spontaneous heat transfer. microstate number, entransy, available entransy, unavailable entransy

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Entransy expression of the second law of thermodynamics and its application to optimization in heat transfer process

Cited by 109 publications

References 15 publications

Entransy analysis of open thermodynamic systems

Entransy analysis of open thermodynamic systems

Entransy, Entransy Dissipation and Entransy Loss for Analyses of Heat Transfer and Heat-Work Conversion Processes

Relationship between microstate number and available entransy

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