scholarly journals Finding the quantum thermoelectric with maximal efficiency and minimal entropy production at given power output

2015 ◽  
Vol 91 (11) ◽  
Author(s):  
Robert S. Whitney
Keyword(s):  
Entropy Production ◽  
Power Output ◽  
Maximal Efficiency ◽  
Minimal Entropy Production

Ecological Optimization of Generalized Irreversible Chemical Engines

2010 ◽  
Vol 8 (1) ◽  
Author(s):  
Lingen Chen ◽  
Dan Xia ◽  
Fengrui Sun
Keyword(s):  
Mass Transfer ◽  
Entropy Production ◽  
Production Rate ◽  
Power Output ◽  
Optimization Criterion ◽  
Ecological Function ◽  
Maximum Efficiency ◽  
Entropy Production Rate ◽  
Output Entropy ◽  
Ecological Optimization

Optimal ecological performance of generalized irreversible chemical engine cycles with both linear and diffusive mass transfer laws are derived by taking an ecological optimization criterion as the objective, which consists of maximizing a function representing the best compromise between the power output and the entropy production rate of the chemical engines. In this paper, the relations between the ecological function, power output, entropy production rate and the efficiency of a chemical engine cycle with irreversibilities of mass transfer, mass leakage and internal dissipation, in which the mass transfer, are derived. This paper also derives the maximum ecological function and the corresponding power output, entropy production rate and efficiency, the maximum power output and the corresponding ecological function, entropy production rate and efficiency, and the maximum efficiency and the corresponding ecological function, power output and entropy production rate. The results can provide some theoretical guidelines for the design of practical chemical engines.

scholarly journals Spin Isoenergetic Process and the Lindblad Equation

Entropy ◽  
2019 ◽  
Vol 21 (5) ◽  
pp. 503 ◽  
Author(s):  
Congjie Ou ◽  
Yuho Yokoi ◽  
Sumiyoshi Abe
Keyword(s):  
Magnetic Field ◽  
Entropy Production ◽  
Production Rate ◽  
Power Output ◽  
Entropy Production Rate ◽  
Leading Order ◽  
Quantum Thermodynamics ◽  
Lindblad Equation ◽  
Markovian Approximation ◽  
Work Done

A general comment is made on the existence of various baths in quantum thermodynamics, and a brief explanation is presented about the concept of weak invariants. Then, the isoenergetic process is studied for a spin in a magnetic field that slowly varies in time. In the Markovian approximation, the corresponding Lindbladian operators are constructed without recourse to detailed information about the coupling of the subsystem with the environment called the energy bath. The entropy production rate under the resulting Lindblad equation is shown to be positive. The leading-order expressions of the power output and work done along the isoenergetic process are obtained.

scholarly journals Discussion of Some Myths/Features Associated With Gas Turbine Inlet Fogging and Wet Compression

2015 ◽  
Vol 8 (2) ◽  
Author(s):  
Ting Wang ◽  
Jobaidur R. Khan
Keyword(s):  
Entropy Production ◽  
Gas Turbine ◽  
Power Output ◽  
Effective Means ◽  
Weather Conditions ◽  
Total Power ◽  
Water Evaporation ◽  
Water Droplets ◽  
Wet Compression ◽  
Total Power Output

Gas turbine (GT) inlet fogging and overspray (high-fogging) have been considered the most cost-effective means of boosting a GT's total power output, especially under hot or dry weather conditions. The result of employing fogging or overspray is indisputably clear—total power output is increased; however, development of the theory and explanation of the phenomena associated with fogging and overspray are not always consistent and are sometimes misleading and incorrect. This paper focuses on reviewing several interesting features and commonly discussed topics, including (a) entropy production of water evaporation, (b) the effect of centrifugal force on water droplets, and (c) whether water droplets can survive the journey in the compressor and enter the combustor. Furthermore, three turbine myths that fogging/overspray increases the air density in the compressor, reduces the compressor power consumption, and noticeably enhances the GT efficiency are examined and discussed. Some common mistakes in describing the compressor work are identified and corrected. A newly constructed multiphase T–s diagram is used to explain the physics of water droplet evaporation process and corresponding entropy production during wet compression.

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