scholarly journals On the Teaching of Performance Evaluation and Assessment of a Combined Cycle Cogeneration System

2009 ◽  
Vol 131 (2) ◽  
Author(s):  
A. Özer Arnas ◽  
Daisie D. Boettner ◽  
Seth A. Norberg ◽  
Gunnar Tamm ◽  
Jason R. Whipple
Keyword(s):  
Performance Evaluation ◽  
Second Law Of Thermodynamics ◽  
Combined Cycle ◽  
Second Law ◽  
First Law Of Thermodynamics ◽  
Systematic Fashion ◽  
Cogeneration System ◽  
The Subject ◽  
Alternative Designs ◽  
Evaluation And Assessment

Performance evaluation and assessment of combined cycle cogeneration systems are not taught well in academia. One reason is these parameters are scattered in the literature with each publication starting and ending at different stages. In many institutions professors do not discuss or even mention these topics, particularly from a second law perspective. When teaching combined cycle cogeneration systems to undergraduates, the professor should introduce pertinent parameters in a systematic fashion and discuss the usefulness and limitations of each parameter. Ultimately for a given situation, the student should be able to determine which parameters form the most appropriate basis for comparison when considering alternative designs. This paper provides two approaches, one based on energy (the first law of thermodynamics) and the other based on exergy (the second law of thermodynamics). These approaches are discussed with emphasis on the “precise” teaching of the subject matter to undergraduates. The intent is to make coverage of the combined cycle cogeneration systems manageable so that professors can appropriately incorporate the topic into the curricula with relative ease.

On the Teaching of Performance Evaluation and Assessment of a Combined Cycle Cogeneration System

2008 ◽  
Author(s):  
A. O¨zer Arnas ◽  
Daisie D. Boettner ◽  
Seth A. Norberg ◽  
Gunnar Tamm ◽  
Jason R. Whipple
Keyword(s):  
Performance Evaluation ◽  
Second Law Of Thermodynamics ◽  
Combined Cycle ◽  
Second Law ◽  
First Law Of Thermodynamics ◽  
Systematic Fashion ◽  
Cogeneration System ◽  
The Subject ◽  
Alternative Designs ◽  
Evaluation And Assessment

Performance evaluation and assessment of combined cycle cogeneration systems are not taught well in academia. One reason is these parameters are scattered in the literature with each publication starting and ending at different stages. In many institutions professors do not discuss or even mention these topics, particularly from a second law perspective. When teaching combined cycle cogeneration systems to undergraduates, the professor should introduce pertinent parameters in a systematic fashion and discuss the usefulness and limitations of each parameter. Ultimately for a given situation, the student should be able to determine which parameters form the most appropriate basis for comparison when considering alternative designs. This paper provides two approaches, one based on energy (the First Law of Thermodynamics) and the other based on exergy (the Second Law of Thermodynamics). These approaches are discussed with emphasis on the “precise” teaching of the subject matter to undergraduates. The intent is to make coverage of the combined cycle cogeneration systems manageable so that professors can appropriately incorporate the topic into the curricula with relative ease.

The wormhole thermodynamics in f (R ) gravity

2019 ◽  
Vol 35 (04) ◽  
pp. 1950360 ◽  
Author(s):  
A. S. Sefiedgar ◽  
M. Mirzazadeh
Keyword(s):  
Continuity Equation ◽  
Energy Momentum Tensor ◽  
Apparent Horizon ◽  
Second Law Of Thermodynamics ◽  
Momentum Tensor ◽  
Second Law ◽  
Standard Entropy ◽  
Field Equations ◽  
First Law Of Thermodynamics ◽  
Generalized Second Law

Thermodynamics of the evolving Lorentzian wormhole at the apparent horizon is investigated in [Formula: see text] gravity. Redefining the energy density and the pressure, the continuity equation is satisfied and the field equations in [Formula: see text] gravity reduce to the ones in general relativity. However, the energy–momentum tensor includes all the corrections from [Formula: see text] gravity. Therefore, one can apply the standard entropy-area relation within [Formula: see text] gravity. It is shown that there may be an equivalency between the field equations and the first law of thermodynamics. It seems that an equilibrium thermodynamics may be held on the apparent horizon. The validity of the generalized second law of thermodynamics (GSL) is also investigated in the wormholes.

scholarly journals A Derivation of the Main Relations of Nonequilibrium Thermodynamics

2013 ◽  
Vol 2013 ◽  
pp. 1-9 ◽  
Author(s):  
Vladimir N. Pokrovskii
Keyword(s):  
Nonequilibrium Thermodynamics ◽  
Second Law Of Thermodynamics ◽  
Thermodynamic System ◽  
Internal Variables ◽  
Second Law ◽  
Basic Principles ◽  
First Law Of Thermodynamics ◽  
Sum Of Products ◽  
Thermodynamic Forces ◽  
Production Of Entropy

The principles of nonequilibrium thermodynamics are discussed, using the concept of internal variables that describe deviations of a thermodynamic system from the equilibrium state. While considering the first law of thermodynamics, work of internal variables is taken into account. It is shown that the requirement that the thermodynamic system cannot fulfil any work via internal variables is equivalent to the conventional formulation of the second law of thermodynamics. These statements, in line with the axioms introducing internal variables can be considered as basic principles of nonequilibrium thermodynamics. While considering stationary nonequilibrium situations close to equilibrium, it is shown that known linear parities between thermodynamic forces and fluxes and also the production of entropy, as a sum of products of thermodynamic forces and fluxes, are consequences of fundamental principles of thermodynamics.

scholarly journals Thermodynamical Study of FRW Universe in Quasi-Topological Theory

2016 ◽  
Vol 2016 ◽  
pp. 1-10 ◽  
Author(s):  
H. Moradpour ◽  
R. Dehghani
Keyword(s):  
Energy Exchange ◽  
Apparent Horizon ◽  
Second Law Of Thermodynamics ◽  
Second Law ◽  
Frw Universe ◽  
Topological Theory ◽  
First Law Of Thermodynamics ◽  
Horizon Entropy ◽  
Topological Gravity ◽  
Entropy Relation

By applying the unified first law of thermodynamics on the apparent horizon of FRW universe, we get the entropy relation for the apparent horizon in quasi-topological gravity theory. Throughout the paper, the results of considering the Hayward-Kodama and Cai-Kim temperatures are also addressed. Our study shows that whenever there is no energy exchange between the various parts of cosmos, we can get an expression for the apparent horizon entropy in quasi-topological gravity, which is in agreement with other attempts that followed different approaches. The effects of a mutual interaction between the various parts of cosmos on the apparent horizon entropy as well as the validity of second law of thermodynamics in quasi-topological gravity are perused.

scholarly journals Thermodynamics in the Universe Described by the Emergence of Space and the Energy Balance Relation

Entropy ◽  
2019 ◽  
Vol 21 (2) ◽  
pp. 167
Author(s):  
Fei-Quan Tu ◽  
Yi-Xin Chen ◽  
Qi-Hong Huang
Keyword(s):  
Energy Balance ◽  
Present Model ◽  
Thermodynamic Description ◽  
Energy Condition ◽  
Second Law Of Thermodynamics ◽  
Second Law ◽  
First Law Of Thermodynamics ◽  
Generalized Second Law ◽  
Balance Relation ◽  
The Universe

It has previously been shown that it is more common to describe the evolution of the universe based on the emergence of space and the energy balance relation. Here we investigate the thermodynamic properties of the universe described by such a model. We show that the first law of thermodynamics and the generalized second law of thermodynamics (GSLT) are both satisfied and the weak energy condition are also fulfilled for two typical examples. Finally, we examine the physical consistency for the present model. The results show that there exists a good thermodynamic description for such a universe.

Second Law Analysis of Integrated Solar Combined Cycle Power Plants

2015 ◽  
Vol 137 (5) ◽  
Author(s):  
S. Can Gülen
Keyword(s):  
Power Generation ◽  
Power Plants ◽  
Thermal Power ◽  
Second Law Of Thermodynamics ◽  
Combined Cycle ◽  
Solar Thermal ◽  
Second Law ◽  
Seamless Integration ◽  
Gas Combustion ◽  
Use Of Time

Integrated solar combined cycle (ISCC) is an operationally simple, clean electric power generation system that is economically more attractive vis-à-vis stand-alone concentrating solar power (CSP) technology. The ISCC can be designed to achieve two primary goals: (1) replace natural gas combustion with solar thermal power at the same output rating to reduce fuel consumption and stack emissions and/or (2) replace supplementary (duct) firing in the heat recovery steam generator (HRSG) with “solar firing” to boost power generation on hot days. Optimal ISCC design requires a seamless integration of the solar thermal and fossil-thermal technologies to maximize the solar contribution to the overall system performance at the lowest possible size and cost. The current paper uses the exergy concept of the second law of thermodynamics to distill the quite complex optimization problem to its bare essentials. The goal is to provide the practitioners with physics-based, user-friendly guidelines to understand the key drivers and the interaction among them. Ultimately, such understanding is expected to help direct studies involving heavy use of time consuming system models in a focused manner and evaluate the results critically to arrive at feasible ISCC designs.

scholarly journals Thermodynamics in f(T) Gravity with Nonminimal Coupling to Matter

2017 ◽  
Vol 2017 ◽  
pp. 1-7
Author(s):  
Tahereh Azizi ◽  
Najibeh Borhani
Keyword(s):  
Apparent Horizon ◽  
Second Law Of Thermodynamics ◽  
Second Law ◽  
Nonminimal Coupling ◽  
Field Equations ◽  
First Law Of Thermodynamics ◽  
Torsion Scalar ◽  
Arbitrary Coupling ◽  
Friedmann Robertson Walker

In the present paper, we study the thermodynamics behavior of the field equations for the generalized f(T) gravity with arbitrary coupling between matter and the torsion scalar. In this regard, we explore the verification of the first law of thermodynamics at the apparent horizon of the Friedmann-Robertson-Walker universe in two different perspectives, namely, the nonequilibrium and equilibrium descriptions of thermodynamics. Furthermore, we investigate the validity of the second law of thermodynamics for both descriptions of this scenario with the assumption that the temperature of matter inside the horizon is similar to that of horizon.

Exergy Analysis of Combined Cycles: Part 1—Air-Cooled Brayton-Cycle Gas Turbines

1987 ◽  
Vol 109 (2) ◽  
pp. 228-236 ◽  
Author(s):  
M. A. El-Masri
Keyword(s):  
Gas Turbines ◽  
Second Law Of Thermodynamics ◽  
Combined Cycle ◽  
Second Law ◽  
Engineering Practice ◽  
Inlet Temperature ◽  
Constant Property ◽  
Loss Analysis ◽  
Turbine Cooling ◽  
Analytical Tools

Quantitative analytical tools based on the second law of thermodynamics provide insight into the complex optimization tradeoffs encountered in the design of a combined cycle. These tools are especially valuable when considering approaches beyond the existing body of experience, whether in cycle configuration or in gas turbine cooling technology. A framework for such analysis was provided by the author [1-3] using simplified, constant-property models. In this paper, this theme is developed to include actual chemical and thermodynamic properties as well as relevant practical design details reflecting current engineering practice. The second-law model is applied to calculate and provide a detailed breakdown of the sources of inefficiency of a combined cycle. Stage-by-stage turbine cooling flow and loss analysis calculations are performed using the GASCAN program and examples of the resulting loss breakdowns presented. It is shown that the dominant interaction governing the variation of cycle efficiency with turbine inlet temperature is that between combustion irreversibility and turbine cooling losses. Compressor and pressure-drop losses are shown to be relatively small. A detailed analysis and loss breakdown of the steam bottoming cycle is presented in Part 2 of this paper.

scholarly journals Exergy Analysis of Combined Cycles: Part 1 — Air-Cooled Brayton-Cycle Gas Turbines

1986 ◽  
Author(s):  
M. A. El-Masri
Keyword(s):  
Gas Turbines ◽  
Second Law Of Thermodynamics ◽  
Combined Cycle ◽  
Second Law ◽  
Engineering Practice ◽  
Inlet Temperature ◽  
Constant Property ◽  
Loss Analysis ◽  
Turbine Cooling ◽  
Analytical Tools

Quantitative analytical tools based upon the second law of thermodynamics provide insight into the complex optimization tradeoffs encountered in the design of a combined cycle. Those tools are especially valuable when considering approaches beyond the existing body of experience, whether in cycle configuration or in gas turbine cooling technology. A framework for such analysis was provided by the author in references [1]-[3] using simplified, constant-property models. In this paper, this theme is developed to include actual chemical and thermodynamic properties as well as relevant practical design details reflecting current engineering practice. The second law model is applied to calculate and provide a detailed breakdown of the sources of inefficiency of a combined cycle. Stage-by-stage turbine cooling flow and loss analysis calculations are performed using the GASCAN program and examples of the resulting loss-breakdowns presented. It is shown that the dominant interaction governing the variation of cycle efficiency with turbine inlet temperature is that between combustion irreversibility and turbine cooling losses. Compressor and pressure-drop losses are shown to be relatively small. A detailed analysis and loss-breakdown of the steam bottoming cycle is presented in Part 2 of this paper.

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