Eddy Dissipation Model

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Shuichi Torii - One of the best experts on this subject based on the ideXlab platform.

  • Numerical simulation of turbulent jet diffusion flames by means of two-equation heat transfer Model
    Energy Conversion and Management, 2001
    Co-Authors: Shuichi Torii
    Abstract:

    Abstract The present study deals with a numerical analysis of thermal transport phenomena in a turbulent jet diffusion flame of hydrogen spouting from a vertical circular nozzle. The k – e turbulence and t 2 –e t heat transfer Models, and the Eddy-Dissipation Model are employed to simulate thermal-fluid flow fields and combustion phenomena, respectively. The governing boundary-layer equations are discretized by means of a control volume finite-difference technique and are numerically solved. It is found that (i) the Model employed here can be applied to combustion phenomena, and (ii) the presence of flame causes a substantial attenuation in the turbulent kinetic energy, resulting in the occurrence of laminarization.

  • Thermal transport phenomena of turbulent jet diffusion flames by means of anisotropic k-ε-t2-εt Model
    International Journal of Energy Research, 1999
    Co-Authors: Shuichi Torii
    Abstract:

    A numerical study is performed on transport phenomena in a turbulent jet diffusion flame of hydrogen from a vertical circular nozzle. An anisotropic k-e-t 2 -e t Model and the Eddy-Dissipation Model are employed to simulate thermal fluid flow and combustion phenomena, respectively. The governing boundary-layer equations are discretized by means of a control volume finite-difference technique and are numerically solved. The Model predicts the experimental data in the existing literature. It is found from the study that (i) the Model employed here can be applied to combustion phenomenon, and (ii) the presence of flame enhances the anisotropy of turbulence and causes a substantial attenuation in the turbulent kinetic energy, that is, most turbulent kinetic energy in the flame in the downstream part is laden exclusively in the streamwise fluctuation.

Xianzhi Song - One of the best experts on this subject based on the ideXlab platform.

  • Model evaluation and experimental validation of thermal jet drilling for geothermal energy
    Geothermics, 2019
    Co-Authors: Xianzhi Song, Zehao Lyu, Baojiang Sun
    Abstract:

    Abstract Thermal jet drilling is a technology, which has the potential to be suitable for the exploitation of geothermal energy in relatively deep formations with low costs. Several investigations on this drilling method have been carried out for the depths of less than 1 km or deeper than 2 km. To the best of our knowledge, there is almost no specific study on simulation for thermal jet drilling at the depths between 1 km and 2 km. This paper focuses on investigating applications of different reaction (i.e., laminar, non-premixed, Eddy Dissipation concept, Eddy Dissipation Model and finite rate), turbulence (i.e., standard k-epsilon, realizable k-epsilon, renormalization group k-epsilon and scale-adaptive simulation) and radiation (i.e., P1, discrete ordinate, discrete transfer radiation Model and surface-to-surface) Models to downhole reaction of thermal jet drilling. The objective is to identify the pros and cons of each Model and determine a set of Models that are the most appropriate for the reaction. Experiments are also carried out and data are collected as the benchmark for comparison. Relative errors and iteration for convergence are analyzed for each simulation Model. Results show that the modified simulation temperature by considering the environmental temperature becomes more accurate compared with the experimental data. The laminar Model over-predicts the temperature and yields unreasonable results. Finite rate and Eddy Dissipation Model are the candidates with highest accuracy and acceptable computational time within selected Model settings and boundary conditions. In addition, compared with renormalization group, realizable and scale-adaptive simulation turbulence Models, the standard k-epsilon Model is the most appropriate Model under the conditions selected for this investigation. The discrete ordinate Model can be applicable for the simulation if the error tolerance is 10%. The P1 Model is the most suitable radiation Model. Results in this paper can provide implications for the reaction simulation of thermal jet drilling.

  • Numerical study on reaction characteristics under high pressure conditions for thermal spallation drilling
    Applied Thermal Engineering, 2018
    Co-Authors: Xianzhi Song, Zehao Lyu, Yu Liu, Yu Shi
    Abstract:

    Abstract Thermal spallation technology is an alternative drilling method, which has the potential to exploit petroleum and geothermal energy with low costs. In this paper, the influence of the structure of the reactor on the characteristics of the flame jet is analyzed from aspects of outlet velocity, temperature, pressure and mole fraction. The Peng-Robinson equations of state and Eddy Dissipation Model are applied in the simulation. An experimental setup is designed and experiments are performed to validate the simulation results. Results show that the reactor length and nozzle length can be reduced in a proper range to obtain better results. The suitable nozzle diameter may be changed for different types of rock to obtain the best rate of penetration. Also, no cooling water may be injected until the temperature of the reactor wall reaches the limitation of failure. Results could provide guidance for field applications.

  • Comparative numerical analysis and optimization in downhole combustion chamber of thermal spallation drilling
    Applied Thermal Engineering, 2017
    Co-Authors: Zehao Lyu, Xianzhi Song, Liu Cui, Zhaohui Wang
    Abstract:

    Abstract Thermal spallation drilling is a non-contact and efficient technology, which is suitable for hard rock formations. It uses downhole combustion to generate high temperature media to heat the bottom rock, which leads to the spallation of the rock. However, no investigation has been carried out in combustion of thermal spallation drilling. In this paper, three combustion Models (Eddy Dissipation Model, Eddy Dissipation concept Model and non-premixed Model) are applied and compared to simulate the reaction in the combustion chamber. Through modifying Magnussen constants, the Eddy Dissipation Model is optimized and validated. Results show that under high velocity conditions, combustion Models based on infinite fast reaction mechanism may not be accurate. An additional reaction step in Eddy Dissipation Model may significantly improve the accuracy. Besides, there is a linear relationship between the average outlet temperature and Magnussen constant in Eddy Dissipation Model. Moreover, through modifying the Magnussen constants, the accuracy of the results can be significantly improved. The optimized Eddy Dissipation Model with two reaction steps not only has the advantages of small computational cost, but also may reflect the actual situation of the combustion reaction. Results in this paper could provide guidance in the design of combustion chamber in thermal spallation drilling.

Zehao Lyu - One of the best experts on this subject based on the ideXlab platform.

  • Model evaluation and experimental validation of thermal jet drilling for geothermal energy
    Geothermics, 2019
    Co-Authors: Xianzhi Song, Zehao Lyu, Baojiang Sun
    Abstract:

    Abstract Thermal jet drilling is a technology, which has the potential to be suitable for the exploitation of geothermal energy in relatively deep formations with low costs. Several investigations on this drilling method have been carried out for the depths of less than 1 km or deeper than 2 km. To the best of our knowledge, there is almost no specific study on simulation for thermal jet drilling at the depths between 1 km and 2 km. This paper focuses on investigating applications of different reaction (i.e., laminar, non-premixed, Eddy Dissipation concept, Eddy Dissipation Model and finite rate), turbulence (i.e., standard k-epsilon, realizable k-epsilon, renormalization group k-epsilon and scale-adaptive simulation) and radiation (i.e., P1, discrete ordinate, discrete transfer radiation Model and surface-to-surface) Models to downhole reaction of thermal jet drilling. The objective is to identify the pros and cons of each Model and determine a set of Models that are the most appropriate for the reaction. Experiments are also carried out and data are collected as the benchmark for comparison. Relative errors and iteration for convergence are analyzed for each simulation Model. Results show that the modified simulation temperature by considering the environmental temperature becomes more accurate compared with the experimental data. The laminar Model over-predicts the temperature and yields unreasonable results. Finite rate and Eddy Dissipation Model are the candidates with highest accuracy and acceptable computational time within selected Model settings and boundary conditions. In addition, compared with renormalization group, realizable and scale-adaptive simulation turbulence Models, the standard k-epsilon Model is the most appropriate Model under the conditions selected for this investigation. The discrete ordinate Model can be applicable for the simulation if the error tolerance is 10%. The P1 Model is the most suitable radiation Model. Results in this paper can provide implications for the reaction simulation of thermal jet drilling.

  • Numerical study on reaction characteristics under high pressure conditions for thermal spallation drilling
    Applied Thermal Engineering, 2018
    Co-Authors: Xianzhi Song, Zehao Lyu, Yu Liu, Yu Shi
    Abstract:

    Abstract Thermal spallation technology is an alternative drilling method, which has the potential to exploit petroleum and geothermal energy with low costs. In this paper, the influence of the structure of the reactor on the characteristics of the flame jet is analyzed from aspects of outlet velocity, temperature, pressure and mole fraction. The Peng-Robinson equations of state and Eddy Dissipation Model are applied in the simulation. An experimental setup is designed and experiments are performed to validate the simulation results. Results show that the reactor length and nozzle length can be reduced in a proper range to obtain better results. The suitable nozzle diameter may be changed for different types of rock to obtain the best rate of penetration. Also, no cooling water may be injected until the temperature of the reactor wall reaches the limitation of failure. Results could provide guidance for field applications.

  • Comparative numerical analysis and optimization in downhole combustion chamber of thermal spallation drilling
    Applied Thermal Engineering, 2017
    Co-Authors: Zehao Lyu, Xianzhi Song, Liu Cui, Zhaohui Wang
    Abstract:

    Abstract Thermal spallation drilling is a non-contact and efficient technology, which is suitable for hard rock formations. It uses downhole combustion to generate high temperature media to heat the bottom rock, which leads to the spallation of the rock. However, no investigation has been carried out in combustion of thermal spallation drilling. In this paper, three combustion Models (Eddy Dissipation Model, Eddy Dissipation concept Model and non-premixed Model) are applied and compared to simulate the reaction in the combustion chamber. Through modifying Magnussen constants, the Eddy Dissipation Model is optimized and validated. Results show that under high velocity conditions, combustion Models based on infinite fast reaction mechanism may not be accurate. An additional reaction step in Eddy Dissipation Model may significantly improve the accuracy. Besides, there is a linear relationship between the average outlet temperature and Magnussen constant in Eddy Dissipation Model. Moreover, through modifying the Magnussen constants, the accuracy of the results can be significantly improved. The optimized Eddy Dissipation Model with two reaction steps not only has the advantages of small computational cost, but also may reflect the actual situation of the combustion reaction. Results in this paper could provide guidance in the design of combustion chamber in thermal spallation drilling.

Zhaohui Wang - One of the best experts on this subject based on the ideXlab platform.

  • Comparative numerical analysis and optimization in downhole combustion chamber of thermal spallation drilling
    Applied Thermal Engineering, 2017
    Co-Authors: Zehao Lyu, Xianzhi Song, Liu Cui, Zhaohui Wang
    Abstract:

    Abstract Thermal spallation drilling is a non-contact and efficient technology, which is suitable for hard rock formations. It uses downhole combustion to generate high temperature media to heat the bottom rock, which leads to the spallation of the rock. However, no investigation has been carried out in combustion of thermal spallation drilling. In this paper, three combustion Models (Eddy Dissipation Model, Eddy Dissipation concept Model and non-premixed Model) are applied and compared to simulate the reaction in the combustion chamber. Through modifying Magnussen constants, the Eddy Dissipation Model is optimized and validated. Results show that under high velocity conditions, combustion Models based on infinite fast reaction mechanism may not be accurate. An additional reaction step in Eddy Dissipation Model may significantly improve the accuracy. Besides, there is a linear relationship between the average outlet temperature and Magnussen constant in Eddy Dissipation Model. Moreover, through modifying the Magnussen constants, the accuracy of the results can be significantly improved. The optimized Eddy Dissipation Model with two reaction steps not only has the advantages of small computational cost, but also may reflect the actual situation of the combustion reaction. Results in this paper could provide guidance in the design of combustion chamber in thermal spallation drilling.

A. Bounif - One of the best experts on this subject based on the ideXlab platform.

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