A new one-dimensional system for resistivity measurement for natural gas hydrate(NGH)exploitation is designed,which is used to study the formation and decomposition processes of NGH.The experimental results verify the...A new one-dimensional system for resistivity measurement for natural gas hydrate(NGH)exploitation is designed,which is used to study the formation and decomposition processes of NGH.The experimental results verify the feasibility of the measurement method,especially in monitoring the nucleation and growth of the NGH. Isovolumetric formation experiment of NGH is performed at 2°C and 7.8 MPa.Before the NGH formation,the initial resistivity is measured to be 4-7Ω·m,which declines to the minimum value of 2-3Ω·m when NGH begins to nucleate after the pressure is reduced to 3.3 MPa.As the NGH grows,the resistivity increases to a great extent,and finally it keeps at 11-13Ω·m,indicating the completion of the formation process.The NGH decomposition experiment is then performed.When the outlet pressure decreases,NGH begins to decompose,accordingly,the resistivity declines gradually,and is at 5-9Ω·m when the decomposition process ends,which is slightly higher than the resistivity value before the formation of NGH.The occurrence and distribution uniformity of NGH are determined by the distribution and magnitude of the resistivity measured on an one-dimensional sand-packed model.This study tackles the accurate estimation for the distribution of NGH in porous medium,and provides an experimental basis for further study on NGH exploitation in the future.展开更多
The kinetics of the thermal decomposition for a naturally ageing ammonium perchlorate(AP) and hydroxyl-terminated-polybutadiene(HTPB) base bleed composite propellant were investigated using a differential scanning cal...The kinetics of the thermal decomposition for a naturally ageing ammonium perchlorate(AP) and hydroxyl-terminated-polybutadiene(HTPB) base bleed composite propellant were investigated using a differential scanning calorimetry(DSC). The naturally ageing AP/HTPB base bleed propellant samples have been stored in a sealed plastic bag at room temperature(5-25 ℃) for more than 20 years. The experimental DSC results were obtained by placing samples(each about 1.5 mg) in a sealed pan under non-isothermal condition under different heating rates, 5.0, 10.0, 15.0, 20.0 and 30.0 ℃·min^(-1). The activation energy and pre-exponential factor were estimated based on the relationship between the exothermic peak temperature and the heating rate by Ozawa and Kissinger methods, respectively. The decomposition kinetic parameters is lower the values under laboratorial aging condition.展开更多
This paper addresses the coordinated operation of natural gas and electricity networks considering the line pack flexibility in the natural gas pipelines.The problem is formulated as a mixed integer linear programming...This paper addresses the coordinated operation of natural gas and electricity networks considering the line pack flexibility in the natural gas pipelines.The problem is formulated as a mixed integer linear programming problem.The objective is to minimize the operation cost of natural gas and electricity networks considering the price of the natural gas supply.Benders decomposition is used to solve the formulated problem.The master problem minimizes the startup and shutdown costs as well as the operation cost of the thermal units other than the gasfired generation units in the electricity network.The first subproblem validates the feasibility of the decisions made in the master problem in the electricity network.And if there is any violation,feasibility Benders cut is generated and added to the master problem.The second subproblem ensures the feasibility of the decisions of the master problem in the natural gas transportation network considering the line pack constraints.The last sub-problem ensuresthe optimality of the natural gas network operation problem considering the demand of the gas-fired generation units and line pack.The nonlinear line pack and flow constraints in the feasibility and optimality subproblems of natural gas transportation network are linearized using Newton-Raphson technique.The presented case study shows the effectiveness of the proposed approach.It is shown that leveraging the stored gas in the natural gas pipelines would further reduce the total operation cost.展开更多
基金Supported by the National High Technology Research and Development Program of China(2006AA09A209)
文摘A new one-dimensional system for resistivity measurement for natural gas hydrate(NGH)exploitation is designed,which is used to study the formation and decomposition processes of NGH.The experimental results verify the feasibility of the measurement method,especially in monitoring the nucleation and growth of the NGH. Isovolumetric formation experiment of NGH is performed at 2°C and 7.8 MPa.Before the NGH formation,the initial resistivity is measured to be 4-7Ω·m,which declines to the minimum value of 2-3Ω·m when NGH begins to nucleate after the pressure is reduced to 3.3 MPa.As the NGH grows,the resistivity increases to a great extent,and finally it keeps at 11-13Ω·m,indicating the completion of the formation process.The NGH decomposition experiment is then performed.When the outlet pressure decreases,NGH begins to decompose,accordingly,the resistivity declines gradually,and is at 5-9Ω·m when the decomposition process ends,which is slightly higher than the resistivity value before the formation of NGH.The occurrence and distribution uniformity of NGH are determined by the distribution and magnitude of the resistivity measured on an one-dimensional sand-packed model.This study tackles the accurate estimation for the distribution of NGH in porous medium,and provides an experimental basis for further study on NGH exploitation in the future.
文摘The kinetics of the thermal decomposition for a naturally ageing ammonium perchlorate(AP) and hydroxyl-terminated-polybutadiene(HTPB) base bleed composite propellant were investigated using a differential scanning calorimetry(DSC). The naturally ageing AP/HTPB base bleed propellant samples have been stored in a sealed plastic bag at room temperature(5-25 ℃) for more than 20 years. The experimental DSC results were obtained by placing samples(each about 1.5 mg) in a sealed pan under non-isothermal condition under different heating rates, 5.0, 10.0, 15.0, 20.0 and 30.0 ℃·min^(-1). The activation energy and pre-exponential factor were estimated based on the relationship between the exothermic peak temperature and the heating rate by Ozawa and Kissinger methods, respectively. The decomposition kinetic parameters is lower the values under laboratorial aging condition.
文摘This paper addresses the coordinated operation of natural gas and electricity networks considering the line pack flexibility in the natural gas pipelines.The problem is formulated as a mixed integer linear programming problem.The objective is to minimize the operation cost of natural gas and electricity networks considering the price of the natural gas supply.Benders decomposition is used to solve the formulated problem.The master problem minimizes the startup and shutdown costs as well as the operation cost of the thermal units other than the gasfired generation units in the electricity network.The first subproblem validates the feasibility of the decisions made in the master problem in the electricity network.And if there is any violation,feasibility Benders cut is generated and added to the master problem.The second subproblem ensures the feasibility of the decisions of the master problem in the natural gas transportation network considering the line pack constraints.The last sub-problem ensuresthe optimality of the natural gas network operation problem considering the demand of the gas-fired generation units and line pack.The nonlinear line pack and flow constraints in the feasibility and optimality subproblems of natural gas transportation network are linearized using Newton-Raphson technique.The presented case study shows the effectiveness of the proposed approach.It is shown that leveraging the stored gas in the natural gas pipelines would further reduce the total operation cost.
