Entropy generation analysis of fuel lean premixed CO/H2/air flames

Jiang, Donglin; Yang, Wenming; Teng, Jinghua

doi:10.1016/j.ijhydene.2015.02.082

Cited by 66 publications

(9 citation statements)

References 39 publications

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“…Entropy generation in single phase combustion has been also extended to microsystems through analysing combustion of mixtures of H2 and CO [23] and H2 and CH4 [24] in microchannel and micro-planar configurations.…”

Section: Introductionmentioning

confidence: 99%

Gas-phase transport and entropy generation during transient combustion of single biomass particle in varying oxygen and nitrogen atmospheres

Wang

Karimi

Paul

2018

International Journal of Hydrogen Energy

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Transient combustion of a single biomass particle in preheated oxygen and nitrogen atmospheres with varying concentration of oxygen is investigated numerically. The simulations are rigorously validated against the existing experimental data. The unsteady temperature and species concentration fields are calculated in the course of transient burning process and the subsequent diffusion of the combustion products into the surrounding gases. These numerical results are further post processed to reveal the temporal rates of unsteady entropy generation by chemical and transport mechanisms in the gaseous phase of the reactive system. The spatio-temporal evolutions of the temperature, major chemical species including CO, CO2, O2, H2 and H2O, and also the local entropy generations are presented. It is shown that the homogenous combustion of the products of devolatilisation process dominates the temperature and chemical species fields at low concentrations of oxygen. Yet, by oxygen enriching of the atmosphere the post-ignition heterogeneous reactions become increasingly more influential. Analysis of the total entropy generation shows that the chemical entropy is the most significant source of irreversibility and is generated chiefly by the ignition of volatiles. However, thermal entropy continues to be produced well after termination of the particle life time through diffusion of the hot gases. It also indicates that increasing the molar concentration of oxygen above 21% results in considerable increase in the chemical and thermal entropy generation. Nonetheless, further oxygen enrichment has only modest effects upon the thermodynamic irreversibilities of the system.

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Section: Introductionmentioning

confidence: 99%

Gas-phase transport and entropy generation during transient combustion of single biomass particle in varying oxygen and nitrogen atmospheres

Wang

Karimi

Paul

2018

International Journal of Hydrogen Energy

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“…For the numerical simulation, the Ansys Fluent 17 has been used to solve the governing equations. The coupled algorithm is applied for the velocity pressure decoupling of the Navier-Stokes equations (Jiang et al 2015). The standard k- model (Kuo et al (2007)) is used for turbulent flow and the eddy dissipation concept (EDC) model (Akhtar et al (2015)) are applied for the chemical reaction.…”

Section: Numerical Setupmentioning

confidence: 99%

Thermal and Exergy Assessment of a Micro Combustor Fueled by Premixed Hydrogen/Air under Different Sizes: a Numerical Simulation

2020

JAFM

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In this work, a numerical study has been carried out in order to investigate the effects of a micro combustor size on the exergy and energy efficiencies of a premixed hydrogen/air for a micro thermophotovoltaic system. For this purpose, six combustors in different sizes are designed, in which geometry dimensional size gradually reduced. The effects of the combustor size on the entropy, exergy, radiation power, and energy conversion efficiency are investigated. Also, mean and uniform wall temperature are discussed. In order to compare the entropy generation of each micro combustor, a dimensionless entropy generation rate is defined. The hydrogen/air combustion with 9 species and 19 reversible elementary reactions were simulated by using the Eddy Dissipation Concept (EDC) model. Results indicate the micro-combustor geometry size has important effects. A reduction of the combustor geometry size dimensionality causes an increase in average wall temperature and makes it uniform. Moreover, by decreasing micro combustor size, the radiation power efficiency increases from 41.96 to 45.62% and total energy conversion efficiency from 6.46 to 7.02%. The highest exergy efficiency, 38.63%, is achieved in the smallest micro combustor while the minimum exergy efficiency 33.22%, is obtained in the largest micro combustor.

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“…Jiang et al 61 investigated numerically the volumetric entropy generation rate distributions and exergy losses of fuel lean premixed CO/H 2 /air flames in a microscale cylindrical channel at atmospheric pressure. Their numerical simulation predicted the gas properties such as temperature, density, and species concentrations by the detailed gas phase chemistry and transport.…”

Section: Entropy Generation In Microchannels In the Absence Of Nanofluidsmentioning

confidence: 99%

A review of entropy generation in microchannels

Awad

2015

Advances in Mechanical Engineering

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In this study, a critical review of thermodynamic optimum of microchannels based on entropy generation analysis is presented. Using entropy generation analysis as evaluation parameter of microchannels has been reported by many studies in the literature. In these studies, different working fluids such as nanofluids, air, water, engine oil, aniline, ethylene glycol, and non-Newtonian fluids have been used. For the case of nanofluids, ''nanoparticles'' has been used in various kinds such as Al 2 O 3 and Cu, and ''base fluid'' has been used in various kinds such as water and ethylene glycol. Furthermore, studies on thermodynamic optimum of microchannels based on entropy generation analysis are summarized in a table. At the end, recommendations of future work for thermodynamic optimum of microchannels based on entropy generation analysis are given. As a result, this article can not only be used as the starting point for the researcher interested in entropy generation in microchannels, but it also includes recommendations for future studies on entropy generation in microchannels.

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Entropy generation analysis of fuel lean premixed CO/H2/air flames

Cited by 66 publications

References 39 publications

Gas-phase transport and entropy generation during transient combustion of single biomass particle in varying oxygen and nitrogen atmospheres

Gas-phase transport and entropy generation during transient combustion of single biomass particle in varying oxygen and nitrogen atmospheres

Thermal and Exergy Assessment of a Micro Combustor Fueled by Premixed Hydrogen/Air under Different Sizes: a Numerical Simulation

A review of entropy generation in microchannels

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