Thermodynamic analysis of combined reforming process using Gibbs energy minimization method: In view of solid carbon formation

2012 ◽  
Vol 21 (6) ◽  
pp. 694-702 ◽  
Author(s):  
Behzad Nematollahi ◽  
Mehran Rezaei ◽  
Ebrahim Nemati Lay ◽  
Majid Khajenoori
Keyword(s):  
Gibbs Energy ◽  
Thermodynamic Analysis ◽  
Energy Minimization ◽  
Solid Carbon ◽  
Carbon Formation ◽  
Minimization Method ◽  
Gibbs Energy Minimization ◽  
Energy Minimization Method

Gibbs Energy Minimization Method for Analysis of Methane Oxidation to Higher Hydrocarbons

2012 ◽  
Author(s):  
Nor Aishah Saidina Amin ◽  
Ee Peng Soon
Keyword(s):  
Gibbs Energy ◽  
Methane Oxidation ◽  
Energy Minimization ◽  
Methane Conversion ◽  
Minimization Method ◽  
Gibbs Energy Minimization ◽  
System Pressure ◽  
Conversion Of Methane ◽  
Higher Hydrocarbons ◽  
Energy Minimization Method

Kaedah peminimuman jumlah tenaga Gibbs sangat berguna untuk menganalisis kemungkinan penukaran metana kepada hidrokarbon dan syngas pada suhu dan tekanan tertentu secara teoritikal. Keputusan numerik menunjukkan penukaran metana meningkat dengan peningkatan kepekatan oksigen dan suhu tindak balas. Bagaimanapun, kehadiran oksigen merencat pembentukan hidrokarbon tinggi yang kebanyakannya mengandungi aromatik, tetapi menggalakkan pembentukan hidrogen. Apabila tekanan sistem bertambah, hasil aromatik, olefin dan hidrogen berkurang, tetapi hasil parafin meningkat. Karbon monoksida menjadi produk mengandungi oksigen yang utama daripada pengoksidaan metana sementara hampir tiada H2O, CH3OH and HCOH yang dikesan walaupun sejumlah kecil karbon dioksida terbentuk pada suhu yang agak rendah dan tekanan tinggi. Kata kunci: Keseimbangan kimia termodinamik, peminimuman jumlah tenaga Gibbs, penukaran metana, hidrokarbon tinggi The total Gibbs energy minimization method is useful to theoretically analyze the feasibility of methane conversion to higher hydrocarbons and syngas at the selected temperature and pressure. Numerical results showed that the conversion of methane increased with oxygen concentration and reaction temperature, but decreased with pressure. Nevertheless, the presence of oxygen suppressed the formation of higher hydrocarbons that mostly consisted of aromatics, but enhanced the formation of hydrogen. As the system pressure increased, the aromatics, olefins and hydrogen yields diminished, but the paraffin yield improved. Carbon monoxide seemed to be the major oxygen-containing equilibrium product from methane oxidation whilst almost no H2O, CH3OH and HCOH were detected although traces amount of carbon dioxide were formed at relatively lower emperature and higher pressure. Key words: Thermodynamic chemical equilibrium, Gibbs energy minimization, methane conversion, higher hydrocarbons

scholarly journals ИСПОЛЬЗОВАНИЕ АЛГОРИТМА ПОСТРОЕНИЯ ДЕФИНИЦИИ В РАМКАХ ТЕРМОДИНАМИЧЕСКОГО ПОДХОДА К ОПИСАНИЮ ХИМИЧЕСКИХ РЕАКЦИЙ

2019 ◽  
Vol 2 (8(38)) ◽  
pp. 3-5
Author(s):  
Бердзенишвили И. Г.
Keyword(s):  
Gibbs Energy ◽  
Energy Minimization ◽  
Chemical Processes ◽  
Thermodynamic Method ◽  
Scientific Concept ◽  
Minimization Method ◽  
Gibbs Energy Minimization ◽  
Isothermal Conditions ◽  
Spontaneous Reaction ◽  
Energy Minimization Method

The article deals with the thermodynamic approach for describing chemical processes and phenomena. It is shown that the Gibbs energy minimization method is successfully used to assess the possibility of a spontaneous reaction in isobaric-isothermal conditions. The author analyzes ways to implement this thermodynamic method for studying chemical processes. In order to disclose the content of a scientific concept “isobaric potential of formation of a substance”, an algorithm for constructing this definition is proposed, which is based on detailing of all its components.

Extrapolation of thermodynamic functions in calculation of phase equilibria by the Gibbs energy minimization method

2013 ◽  
Vol 58 (10) ◽  
pp. 1197-1202 ◽  
Author(s):  
V. A. Bychinskii ◽  
A. A. Tupitsyn ◽  
K. V. Chudnenko ◽  
A. V. Mukhetdinova ◽  
S. V. Fomichev ◽  
...  
Keyword(s):  
Gibbs Energy ◽  
Phase Equilibria ◽  
Thermodynamic Functions ◽  
Energy Minimization ◽  
Minimization Method ◽  
Gibbs Energy Minimization ◽  
Energy Minimization Method

A Gibbs energy minimization method for constrained and partial equilibria

2011 ◽  
Vol 83 (6) ◽  
pp. 1243-1254 ◽  
Author(s):  
Pertti Koukkari ◽  
Risto Pajarre
Keyword(s):  
Gibbs Energy ◽  
Energy Minimization ◽  
Linear Constraints ◽  
Multiphase System ◽  
Energy Calculation ◽  
Minimization Method ◽  
Related Condition ◽  
Gibbs Energy Minimization ◽  
Surface And Interface ◽  
Minimization Procedure

The conventional Gibbs energy minimization methods apply elemental amounts of system components as conservation constraints in the form of a stoichiometric conservation matrix. The linear constraints designate the limitations set on the components described by the system constituents. The equilibrium chemical potentials of the constituents are obtained as a linear combination of the component-specific contributions, which are solved with the Lagrange method of undetermined multipliers. When the Gibbs energy of a multiphase system is also affected by conditions due to immaterial properties, the constraints must be adjusted by the respective entities. The constrained free energy (CFE) minimization method includes such conditions and incorporates every immaterial constraint accompanied with its conjugate potential. The respective work or affinity-related condition is introduced to the Gibbs energy calculation as an additional Lagrange multiplier. Thus, the minimization procedure can include systemic or external potential variables with their conjugate coefficients as well as non-equilibrium affinities. Their implementation extends the scope of Gibbs energy calculations to a number of new fields, including surface and interface systems, multi-phase fiber suspensions with Donnan partitioning, kinetically controlled partial equilibria, and pathway analysis of reaction networks.

Gasification of Municipal Solid Waste: Thermodynamic Equilibrium Analysis Using Gibbs Energy Minimization Method and CFD Simulation of a Downdraft Gasifier

2020 ◽  
Vol 46 (3) ◽  
pp. 274-288 ◽  
Author(s):  
Syed Shabbar Raza ◽  
Sherien Elagroudy ◽  
Isam Janajreh
Keyword(s):  
Gibbs Energy ◽  
Municipal Solid Waste ◽  
Solid Waste ◽  
Thermodynamic Equilibrium ◽  
Equilibrium Model ◽  
Energy Minimization ◽  
Steam Gasification ◽  
Minimization Method ◽  
Thermodynamic Equilibrium Model ◽  
Energy Minimization Method

Millions of tons of municipal solid waste (MSW) are generated annually, posing dramatic threats to our environment. To reduce its environmental impact, MSW can be segregated and thermochemically converted into clean syngas (CO and H2) fuel via gasification process. The feasibility of Gasification of MSW depends on its composition and quantity. In this work, assessment of the gasification metric of MSW is conducted under steam (H2O) as gasification moderator in a pilot scale 20kW gasifier. The characteristic of local MSW are experimentally determined using Flash 2000 organic analyzer (CHNS-O), the thermo-gravimetric analyzer (TGA) and bomb calorimeter following ASTM standards and arriving to molar formula of MSW. A thermodynamic equilibrium model based on Gibbs energy minimization method is used for the steam gasification of MSW to assess the composition of syngas. Using the baseline operating condition from the thermodynamic equilibrium model, a reactive high fidelity numerical model of a downdraft gasifier is developed to gain more fidelity. Result of gasification efficiency of thermodynamic model is 64% while reactive model gives 7% additional efficiency. Nonetheless, the stipulated efficiency and the high-quality syngas produced via the steam gasification of MSW suggest the viability of the process scale up.

Extraction of the Coefficient of Thermal Expansion of Thin Films from Buckled Membranes

1998 ◽  
Vol 546 ◽  
Author(s):  
V. Ziebartl ◽  
O. Paul ◽  
H. Baltes
Keyword(s):  
Thin Films ◽  
Finite Element ◽  
Thermal Expansion ◽  
Silicon Nitride ◽  
Excellent Agreement ◽  
Energy Minimization ◽  
Coefficient Of Thermal Expansion ◽  
Temperature Dependent ◽  
Minimization Method ◽  
Energy Minimization Method

AbstractWe report a new method to measure the temperature-dependent coefficient of thermal expansion α(T) of thin films. The method exploits the temperature dependent buckling of clamped square plates. This buckling was investigated numerically using an energy minimization method and finite element simulations. Both approaches show excellent agreement even far away from simple critical buckling. The numerical results were used to extract Cα(T) = α0+α1(T−T0 ) of PECVD silicon nitride between 20° and 140°C with α0 = (1.803±0.006)×10−6°C−1, α1 = (7.5±0.5)×10−9 °C−2, and T0 = 25°C.

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