Second-Law Analysis of Irreversible Losses in Gas Turbines

Jin, Yan; Du, Juan; Li, Zhiyuan; Zhang, Hongwu

doi:10.3390/e19090470

Cited by 14 publications

(10 citation statements)

References 28 publications

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“…For simplicity, the exergy losses in the pipes are assigned to the components between the corresponding interfaces 1 to 4; those in the ambient are assumed to be part of the condenser exergy losses. In Reference [ 14 ], it is shown how this concept can be applied to gas turbine loss considerations.…”

Section: Applying the Energy Devaluation Numbermentioning

confidence: 99%

How to Teach Heat Transfer More Systematically by Involving Entropy

Herwig

2018

Entropy

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Section: Applying the Energy Devaluation Numbermentioning

confidence: 99%

How to Teach Heat Transfer More Systematically by Involving Entropy

Herwig

2018

Entropy

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“…We collected 12 papers in this special issue, covering both engineering applications [8][9][10][11][12] and fundamental studies [13][14][15][16][17][18][19] with respect to CFD of flow and heat transfer problems and interpretation of the CFD results with the SLA.…”

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confidence: 99%

“…Three papers [8][9][10] in this special issue belong to this topic. Jin et al [8] derived the entropy and exergy equations for compressible/incompressible flows in rotating/stationary frames. These equations can not only be applied to assessing gas turbines, but can also be used for analyzing general CFD results.…”

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confidence: 99%

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Second-Law Analysis: A Powerful Tool for Analyzing Computational Fluid Dynamics (CFD) Results

Jin

2017

Entropy

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Second-law analysis (SLA) is an important concept in thermodynamics, which basically assesses energy by its value in terms of its convertibility from one form to another. Highly-valued forms of energy in this context are called exergy, defined as those energies from which the maximum theoretical work is obtainable when the energy is interacting with the environment to equilibrium (see Moran et al. [1], for example).The counterpart of exergy, also called available work, is anergy, so that with this concept energy can generally be regarded as the sum of exergy and anergy. As a consequence of the second law of thermodynamics, exergy can be lost but cannot be created. Therefore, in a reversible process, exergy is preserved, whereas irreversibility (like losses in a flow field) leads to a loss of exergy (in favor of the corresponding increasing anergy).Losses in flow and heat transfer fields can, thus, be determined by their impact on the exergy, i.e., by determining the exergy losses. These losses of exergy are thermodynamically linked to the generation of entropy by the so-called Gouy Stodola theorem. It states that the lost exergy corresponds to the product of entropy generation and the environmental temperature (see, again, Moran et al. [1]).From a thermodynamic point of view, the quality of a flow or heat transfer process can be assessed by the entropy generation rate in this process (see Herwig [2]). However, entropy almost never appears in the textbooks of fluid dynamics and heat transfer (see, e.g., Batchelor, et al. [3] and Incropera, et al. [4]). This concept is widely ignored perhaps because the irreversibility effect is often fundamentally important in these two disciplines.After Bejan [5,6] laid the foundation with respect to analyzing and optimizing thermal systems with the SLA approach, the SLA of flow and heat transfer problems received more and more attention. Applying the SLA in computational fluid dynamics (CFD), Kock and Herwig [7] extended this concept to an in-depth analysis of turbulent flows and identified four different mechanisms of entropy generation: dissipation in a mean and fluctuating velocity field and heat flux in a mean and fluctuating temperature field. They also suggested how to calculate the entropy generation rates with the Reynolds Averaged Navier-Stokes (RANS) results. Herwig [2] stated that, with the help of the SLA, one may answer four important questions regarding a momentum and/or heat transfer process:• Which is the ideal process (no entropy generation)? • Where does entropy generation occur in a non-ideal process? • Why does entropy generation occur at a certain location and with certain strength? • How can entropy generation be reduced overall or locally?The purpose of this special issue is to demonstrate how the CFD results can be better interpreted by the SLA. We collected 12 papers in this special issue, covering both engineering applications [8-12] and

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“…Therefore, from an integrated viewpoint, aircraft engines have been considered and evaluated in scientific research not only with thermodynamic analysis but also with economic analysis. In accordance with the thermodynamic rules, exergy analysis is carried out to put forth the irreversible processes leading to exergy destructions in the system [41][42][43][44][45][46][47]. However, the interpretation of the irreversible processes will be completed by the implementation of the economic analysis.…”

Section: Introductionmentioning

confidence: 99%

Assessing Exergy-Based Economic and Sustainability Analyses of a Military Gas Turbine Engine Fueled with Various Fuels

2020

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This research put forth exergy-based economic and sustainability analyses of a (J85-GE-5H) military turbojet engine (TJE). Firstly, sustainability, conventional exergoeconomic and advanced exergoeconomic cost analyses were executed utilizing kerosene fuel according to real engine working circumstances. The engine was likewise investigated parametrically, considering H2 fuel utilization. The sustainable economic analysis assessment of the TJE was finally actualized by comparing the acquired outcomes for both fuels. The entire engine’s unit exergy cost of product (cPr) with kerosene was determined 76.45 $/GJ for the military (MIL) process mode (PM), whereas it was computed 94.97 $/GJ for the afterburner (AB) PM. Given the use of H2, the cPr increased to 179 and 288 $/GJ for the aforementioned two modes, seriatim. While the sustainability cost index (SCI) values were obtained 52.86 and 78.84 $/GJ for the MIL and AB PM, seriatim, they became 128 and 244 $/GJ when considering H2. Consequently, the higher exergy demolitions occurring in the afterburner exhaust duct (ABED) and combustion chamber (CC) sections led to higher exergy destruction costs in the TJE. However, the engine worked less cost efficient with H2 fuel rather than JP-8 fuel because of the higher cost value of fuel.

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Second-Law Analysis of Irreversible Losses in Gas Turbines

Cited by 14 publications

References 28 publications

How to Teach Heat Transfer More Systematically by Involving Entropy

How to Teach Heat Transfer More Systematically by Involving Entropy

Second-Law Analysis: A Powerful Tool for Analyzing Computational Fluid Dynamics (CFD) Results

Assessing Exergy-Based Economic and Sustainability Analyses of a Military Gas Turbine Engine Fueled with Various Fuels

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