Experimental and numerical study on degradation behavior of coke with CO2 or H2O gasification reaction at high temperature

Fuel ◽  
2022 ◽  
Vol 309 ◽  
pp. 122061
Author(s):  
Yuya Ono ◽  
Yuka Fukuda ◽  
Yuya Sumitani ◽  
Yoshiya Matsukawa ◽  
Yasuhiro Saito ◽  
...  
Keyword(s):  
High Temperature ◽  
Numerical Study ◽  
Degradation Behavior ◽  
Gasification Reaction

scholarly journals Numerical Study on Damage Zones Induced by Excavation and Ventilation in a High-Temperature Tunnel at Depth

Energies ◽  
2021 ◽  
Vol 14 (16) ◽  
pp. 4773
Author(s):  
Jianyu Li ◽  
Hong Li ◽  
Zheming Zhu ◽  
Ye Tao ◽  
Chun’an Tang
Keyword(s):  
High Temperature ◽  
Lateral Pressure ◽  
Numerical Study ◽  
Pressure Coefficient ◽  
Fracture Morphology ◽  
In Situ Stress ◽  
Surrounding Rock ◽  
Geothermal System ◽  
Mechanical Coupling ◽  
Lateral Pressure Coefficient

Geothermal power is being regarded as depending on techniques derived from hydrocarbon production in worldwide current strategy. However, it has artificially been developed far less than its natural potentials due to technical restrictions. This paper introduces the Enhanced Geothermal System based on Excavation (EGS-E), which is an innovative scheme of geothermal energy extraction. Then, based on cohesion-weakening-friction-strengthening model (CWFS) and literature investigation of granite test at high temperature, the initiation, propagation of excavation damaged zones (EDZs) under unloading and the EDZs scale in EGS-E closed to hydrostatic pressure state is studied. Finally, we have a discussion about the further evolution of surrounding rock stress and EDZs during ventilation is studied by thermal-mechanical coupling. The results show that the influence of high temperature damage on the mechanical parameters of granite should be considered; Lateral pressure coefficient affects the fracture morphology and scale of tunnel surrounding rock, and EDZs area is larger when the lateral pressure coefficient is 1.0 or 1.2; Ventilation of high temperature and high in-situ stress tunnel have a significant effect on the EDZs scale; Additional tensile stress is generated in the shallow of tunnel surrounding rock, and the compressive stress concentration transfers to the deep. EDZs experiences three expansion stages of slow, rapid and deceleration with cooling time, and the thermal insulation layer prolongs the slow growth stage.

Numerical Study of Bicomponent Droplet Vaporization in a High Pressure Environment

1996 ◽  
Author(s):  
J. Stengele ◽  
H.-J. Bauer ◽  
S. Wittig
Keyword(s):  
High Pressure ◽  
High Temperature ◽  
Gas Phase ◽  
Numerical Study ◽  
Droplet Evaporation ◽  
Single Component ◽  
Vapor Concentration ◽  
Diffusion Limit ◽  
Evaporation Process ◽  
Droplet Vaporization

The understanding of multicomponent droplet evaporation in a high pressure and high temperature gas is of great importance for the design of modern gas turbine combustors, since the different volatilities of the droplet components affect strongly the vapor concentration and, therefore, the ignition and combustion process in the gas phase. Plenty of experimental and numerical research is already done to understand the droplet evaporation process. Until now, most numerical studies were carried out for single component droplets, but there is still lack of knowledge concerning evaporation of multicomponent droplets under supercritical pressures. In the study presented, the Diffusion Limit Model is applied to predict bicomponent droplet vaporization. The calculations are carried out for a stagnant droplet consisting of heptane and dodecane evaporating in a stagnant high pressure and high temperature nitrogen environment. Different temperature and pressure levels are analyzed in order to characterize their influence on the vaporization behavior. The model employed is fully transient in the liquid and the gas phase. It accounts for real gas effects, ambient gas solubility in the liquid phase, high pressure phase equilibrium and variable properties in the droplet and surrounding gas. It is found that for high gas temperatures (T = 2000 K) the evaporation time of the bicomponent droplet decreases with higher pressures, whereas for moderate gas temperatures (T = 800 K) the lifetime of the droplet first increases and then decreases when elevating the pressure. This is comparable to numerical results conducted with single component droplets. Generally, the droplet temperature increases with higher pressures reaching finally the critical mixture temperature of the fuel components. The numerical study shows also that the same tendencies of vapor concentration at the droplet surface and vapor mass flow are observed for different pressures. Additionally, there is almost no influence of the ambient pressure on fuel composition inside the droplet during the evaporation process.

The Degradation Behavior of SiCf/SiO2 Composites in High-Temperature Environment

2017 ◽  
Vol 25 (2) ◽  
pp. 353-364 ◽  
Author(s):  
Xiang Yang ◽  
Feng Cao ◽  
Wang Qing ◽  
Zhi-hang Peng ◽  
Yi Wang
Keyword(s):  
High Temperature ◽  
Degradation Behavior ◽  
Temperature Environment ◽  
High Temperature Environment

Numerical Study of Droplet Evaporation in a High-Temperature Stream

1983 ◽  
Vol 105 (2) ◽  
pp. 389-397 ◽  
Author(s):  
M. Renksizbulut ◽  
M. C. Yuen
Keyword(s):  
Heat Transfer ◽  
High Temperature ◽  
Numerical Solutions ◽  
Numerical Study ◽  
Number Range ◽  
Transfer Rates ◽  
Pressure Drag ◽  
Continuity Equations ◽  
Stream Density ◽  
Solid Spheres

Numerical solutions for high-temperature air flowing past water and methanol droplets and solid spheres, and superheated steam flowing past water droplets were obtained in the Reynolds number range of 10 to 100. The coupled momentum, energy, and specie continuity equations of variable thermophysical properties were solved using finite difference techniques. The numerical results of heat transfer and total drag agree well with existing experimental data. Mass transfer decreases friction drag significantly but at the same time increases pressure drag by almost an equal amount. The net effect is that the standard drag curve for solid spheres can be used for evaporating droplets provided the density is the free stream density and the viscosity of the vapor mixture is evaluated at an appropriate reference temperature and concentration. Both the mass efflux and variable properties decrease heat transfer rates to the droplets.

Development of High Speed and High Temperature Atomic Layer Thermopiles

2019 ◽  
Author(s):  
Lakshya Bhatnagar ◽  
Guillermo Paniagua
Keyword(s):  
Heat Flux ◽  
High Temperature ◽  
High Speed ◽  
Cooling System ◽  
Numerical Study ◽  
Measurement Data ◽  
Atomic Layer ◽  
Heat Fluxes ◽  
Heat Transfer Analysis ◽  
Uncertainty Estimates

Abstract This work aims to provide a technique with which high frequency heat flux measurement data can be acquired in systems with high operational temperatures and high-speed flows with quantifiable and accurate uncertainty estimates. This manuscript presents the detailed calibration and application of an atomic layer thermopile, for heat fluxes with a frequency bandwidth of 0 to 1MHz. Two calibration procedures with a detailed uncertainty analysis. The first procedure consists using a laser to deliver radiation heat flux, while the second consists of a convective heat blowdown experiment. The use of this probe is demonstrated in a high-speed environment at Mach 2. The sensor effectively captures the passage of the normal shock wave and the values are compared with those computed using surface temperature measurement. Finally, a numerical study is carried out to design a cooling system that will allow the sensor to survive in high temperature conditions of 1273K while the sensor film is maintained at 323K. A two-dimensional axisymmetric conjugate heat transfer analysis is carried out to obtain the desired geometry.

Numerical Analysis of Heated Soil Vapor Extraction System

2002 ◽  
Author(s):  
R. S. Jadhav ◽  
R. S. Amano ◽  
J. Jatkar ◽  
R. J. Lind
Keyword(s):  
High Temperature ◽  
Organic Compounds ◽  
Environmental Science ◽  
Numerical Study ◽  
Soil Vapor Extraction ◽  
Vapor Extraction ◽  
Element Analysis ◽  
Volatile Organic ◽  
Heated Soil ◽  
And Diffusion

An innovative and highly effective technique for remediation of soil has been developed—Heated Soil Vapor Extraction (HSVE), which is one of essential technologies that quickly and effectively remediates soil that is contaminated with organic compounds. The system efficiently uses the principles of heat transfer and diffusion to eliminate organic compounds from the soil. It basically consists of a high temperature heat source and a sink to take away the vaporized compounds in the presence of high temperature in the soil. A numerical study has been conducted to further strengthen the fact that the system is very effective, by actually modeling soil with system. Finite Element Analysis software ANSYS® has been used for the purpose of analysis. Such analysis will help environmental science and give new dimensions to soil remediation processes to clean soil off volatile organic compounds so that they can be carried out quickly, efficiently and economically.

Numerical Study on the Interfacial Modification Effects of Soy Protein on Poly(Vinylidene Fluoride)

2019 ◽  
Author(s):  
Zhuoyuan Zheng ◽  
Chen Xin ◽  
Yumeng Li
Keyword(s):  
High Temperature ◽  
Soy Protein ◽  
Disulfide Bonds ◽  
Vinylidene Fluoride ◽  
Numerical Study ◽  
Protein Molecule ◽  
Heat Denaturation ◽  
Β Phase ◽  
Poly Vinylidene Fluoride ◽  
Underlying Mechanisms

Abstract The application of bio-degradable green materials is a rising global trend during the past decades for the sake of environment protection and sustainable development. Soy protein-based biomaterial is a promising candidate to replace the petroleum-based synthetic materials and was proved to be an effective functional modifier for polymers from our previous studies. Molecular dynamic (MD) simulation is implemented in this study to provide insights in understanding the underlying mechanisms. 11S molecule is chosen as a representative of soy protein, and three different denaturation processes are applied, including heat denaturation at two temperatures and the breaking of disulfide bonds. It is observed that by controlling the denaturation conditions, the hydrophobicity of the protein molecule is manipulated: high temperature denaturation can increase the exposed area of hydrophilic residues; whereas, by breaking the disulfide bonds, the hydrophobic residues of the molecules can be largely exposed. Besides, the mechanisms of using protein as functional modifier to tune the structures of the hydrophobic Poly(vinylidene fluoride) (PVDF) polymer (amorphous and β-crystal phases) are studied. S-S debond protein is found to favor the formation of amorphous PVDF; whereas, high temperature denatured one has stronger interactions with β phase.

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