Second‐law analysis: approaches and implications

Rosen, Marc A.

doi:10.1002/(sici)1099-114x(199904)23:5<415::aid-er489>3.3.co;2-z

Cited by 35 publications

(30 citation statements)

References 13 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The exergy is a thermodynamic property that is determined by the system at atmosphere conditions; it is conserved just when the processes between the system and the atmosphere are reversible, and as well is destroyed when the processes are irreversible [11]. Because of the mentioned above the exergy analysis is very useful when the perfection of a real process needs to be studied, that is, to say that the exergy efficiency is more accurate and gives a better idea of the system than the simple energy efficiency.…”

Section: Exergy Analysismentioning

confidence: 99%

“…In the present paper the thermodynamic analysis of the system is developed using the Gibbs free energy minimization method, which has been applied to similar systems by several authors [4,10,11]; as a novel concept this method is used together with the exergy analysis of the whole system represented in Figure 1 to evaluate the efficiency and the irreversibilities losses, giving a measure of the process quality relative to the use of the useful energy.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Thermodynamic Analysis of the Hydrogen Production from Ethanol: First and Second Laws Approaches

Casas-Ledón

Arteaga-Pérez

Morales-Perez

et al. 2012

ISRN Thermodynamics

View full text Add to dashboard Cite

A thermodynamic analysis of hydrogen production from ethanol steam reforming (ESR) is carried out in the present paper. The influence of reactants molar ratio feed into the reforming stage (2.5 < mol Water /mol EtOH < 8), temperature (573 to 1173 K) and pressure (1 < P < 10 atm) over equilibrium compositions is studied. The direct method employed to analyze the system is the minimization of Gibbs free energy (MGFE) in conjunction with Lee-Kesler state equation, using the Kay mixing rules. The temperature and reactants molar ratio showed a positive influence on the hydrogen yield; ethanol conversion is 100% for the whole interval analyzed while the pressure affected greatly the hydrogen production. The carbon deposition exhibits a maximum value at temperatures around 773 K, and three reactions are proposed to describe the solid carbon formation in a wide temperature range based on thermodynamics and experimental predictions. The conditioning stages (mixing, vaporization, and heating) are studied in addition to the reaction to analyze the system quality by means of an exergetic method applying the 2nd law of thermodynamic.

show abstract

Section: Exergy Analysismentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Thermodynamic Analysis of the Hydrogen Production from Ethanol: First and Second Laws Approaches

Casas-Ledón

Arteaga-Pérez

Morales-Perez

et al. 2012

ISRN Thermodynamics

View full text Add to dashboard Cite

show abstract

“…There are two sources of entropy generation in a solar collector for heating air [6][7][8][22][23][24][25]. The first entropy generation is due to loss of energy owing to the friction between the collector surface and the air flowing through it, and the second one is due to the heat transfer or temperature change in the heat carrier fluid (air).…”

Section: Entropy Generation Analysis Of Solar Collectormentioning

confidence: 99%

Entropy generation and thermodynamic analysis of solar air heaters with artificial roughness on absorber plate

Prasad

Sahu

2017

Archives of Thermodynamics

View full text Add to dashboard Cite

This paper presents mathematical modelling and numerical analysis to evaluate entropy generation analysis (EGA) by considering pressure drop and second law efficiency based on thermodynamics for forced convection heat transfer in rectangular duct of a solar air heater with wire as artificial roughness in the form of arc shape geometry on the absorber plate. The investigation includes evaluations of entropy generation, entropy generation number, Bejan number and irreversibilities of roughened as well as smooth absorber plate solar air heaters to compare the relative performances. Furthermore, effects of various roughness parameters and operating parameters on entropy generation have also been investigated. Entropy generation and irreversibilities (exergy destroyed) has its minimum value at relative roughness height of 0.0422 and relative angle of attack of 0.33, which leads to the maximum exergetic efficiency. Entropy generation and exergy based analyses can be adopted for the evaluation of the overall performance of solar air heaters.

show abstract

“…E ,Q represents net i~~~er input flow rate of exergy associated with heat transfer rate Qr across region r on the system boundary at a constant temperature Tr and given by £0 = (1-To 0ITr )Qr (2) W represents net output rate of exergy associated with work and it is equal to shaft work output rate. Exergy consumption or destruction rate is represented by I and given by the Gouy-Stodola relation [6]:…”

Section: Exergy Analysis For a Steady-state Steady-fow Processmentioning

confidence: 99%

“…By preserving exergy through increased efficiency (i.e. degrading as little exergy as necessary for a process), environmental damage is reduced [6]. Therefore, exergy analysis is as important as energy analysis for design, operation and maintenance of different equipment and systems of a power plant.…”

Section: Introductionmentioning

confidence: 99%

Exergy Analysis for Performance Optimization of a Steam Turbine Cycle

Ray¹,

Ganguly

Gupta

2007

2007 IEEE Power Engineering Society Conference and Exposition in Africa - PowerAfrica

View full text Add to dashboard Cite

Exergy analysis of a 500 MWe steam turbine cycle is performed to identify the components that offer significant work potential saving opportunity. Criteria of performance relevant to the individual components are formulated. Exergy flows, exergy consumption due to irreversibilities and rational performance parameters for the turbine cycle and its components are computed by using plant operation data under different conditions. Energy efficiency of the turbine cycle is low due to large energy rejection, but the derived exergy efficiency of the turbine cycle is high due to low exergy rejection from the cycle. Part load operation exhibits lower energy efficiency due to higher energy rejection relative to net output. On the contrary, exergy rejection from the cycle relative to net output does not increase during low load operation. Results show that poor part load exergy efficiency is due to higher exergy destruction relative to net output. Higher pressure feed heaters deal with larger exergy and therefore, need more attention to improve cycle efficiency. Operation and maintenance decisions based on exergy analysis have proved to be more effective in reducing inefficiencies in operating power plant. Exergy-based approach of performance analysis will help practicing power engineers manage energy resources and environment better.

show abstract

Second‐law analysis: approaches and implications

Cited by 35 publications

References 13 publications

Thermodynamic Analysis of the Hydrogen Production from Ethanol: First and Second Laws Approaches

Thermodynamic Analysis of the Hydrogen Production from Ethanol: First and Second Laws Approaches

Entropy generation and thermodynamic analysis of solar air heaters with artificial roughness on absorber plate

Exergy Analysis for Performance Optimization of a Steam Turbine Cycle

Contact Info

Product

Resources

About