According to the characteristics of FCC diesel, a technology of liquid-phase hydrodesulfurization of the diesel in tubular reactors was proposed and lab-scale experiments were carried out. A kinetic model for the hydr...According to the characteristics of FCC diesel, a technology of liquid-phase hydrodesulfurization of the diesel in tubular reactors was proposed and lab-scale experiments were carried out. A kinetic model for the hydrodesulfurization process was developed and verified. The model was utilized to predict the sulfur content of products under different operating conditions. The effects of temperature, space velocity, pressure, and hydrogen concentration on the dcsulfurization rate were investigated.展开更多
In order to deal with modeling problem of a pressure balance system with time-delay, nonlinear, time-varying and uncertain characteristics, an intelligent modeling procedure is proposed, which is based on artificial n...In order to deal with modeling problem of a pressure balance system with time-delay, nonlinear, time-varying and uncertain characteristics, an intelligent modeling procedure is proposed, which is based on artificial neural network(ANN) and input-output data of the system during shield tunneling and can overcome the precision problem in mechanistic modeling(MM) approach. The computational results show that the training algorithm with Gauss-Newton optimization has fast convergent speed. The experimental investigation indicates that, compared with mechanistic modeling approach, intelligent modeling procedure can obviously increase the precision in both soil pressure fitting and forecasting period. The effectiveness and accuracy of proposed intelligent modeling procedure are verified in laboratory tests.展开更多
A finite volume algorithm was established in order to investigate two-dimensional hydrodynamic problems. These include viscous free surface flow interaction with free rigid bodies in the case of large and/or relative ...A finite volume algorithm was established in order to investigate two-dimensional hydrodynamic problems. These include viscous free surface flow interaction with free rigid bodies in the case of large and/or relative motions. Two-phase flow with complex deformations at the interface was simulated using a fractional step-volume of fluid algorithm. In addition, body motions were captured by an overlapping mesh system. Here, flow variables are transferred using a simple fully implicit non-conservative interpolation scheme which maintains the second-order accuracy of implemented spatial discretisation. Code was developed and an appropriate set of problems investigated. Results show good potential for development of a virtual hydrodynamics laboratory.展开更多
The purpose of this paper is to show a laboratory scale implementation of a Thyristor Switched Capacitors （TSC） as an alternative for voltage regulation during a direct on line three-phase induction motor starting o...The purpose of this paper is to show a laboratory scale implementation of a Thyristor Switched Capacitors （TSC） as an alternative for voltage regulation during a direct on line three-phase induction motor starting on an emulated weak transmission line. Thyristor switched capacitor bank was chosen because it is a well known topology, considering the very nature of the direct starting induction motors, which represents a highly inductive load, the use of switched reactors becomes unnecessary. Such fact minimizes the introduction of harmonics components, and also reduces the cost of the implementation. The binary disposition of the banks allows a variable Var compensation with sixteen steps, in this case. The solution makes use of low cost devices combined with sliding window voltage and current measurement algorithm and a PI control with dead band control for achieve the shown experimental results, where the system is able to manage a typically 20% voltage drop, reducing it to less than 4%. The schematic of the developed circuit, the control technique and a quite simple method to calculate the binary weight capacitors banks are also presented.展开更多
The modeling of inlet and exhaust systems of internal combustion engine is very important in order to evaluate the engine performance.This paper presents new pressure losses models which can be included in a one dimen...The modeling of inlet and exhaust systems of internal combustion engine is very important in order to evaluate the engine performance.This paper presents new pressure losses models which can be included in a one dimensional engine simulation code.In a first part,a CFD analysis is made in order to show the importance of the density in the modeling approach.Then,the CFD code is used,as a numerical test bench,for the pressure losses models development.These coefficients depend on the geometrical characteristics of the junction and an experimental validation is made with the use of a shock tube test bench.All the models are then included in the engine simulation code of the laboratory.The numerical calculation of unsteady compressible flow,in each pipe of the inlet and exhaust systems,is made and the calculated engine torque is compared with experimental measurements.展开更多
This paper focuses on the investigation of an aft mixing chamber diaphragm in a hybrid rocket motor. Both numerical and ex- perimental researches are carried out to study its effects on the motor performances. The hyb...This paper focuses on the investigation of an aft mixing chamber diaphragm in a hybrid rocket motor. Both numerical and ex- perimental researches are carried out to study its effects on the motor performances. The hybrid rocket motor with star fuel grain is utilized. The 90% hydrogen peroxide （HP） oxidizer and hydroxyl terminated polybutadiene （HTPB） based fuel are adopted as propellants. The diaphragm configuration settled in the aft mixing chamber includes four circular-holes with a uni- form circumferential distribution. For both motors with and without the diaphragm, three-dimensional numerical simulations with gaseous combustions considered are carried out to study the flow field characteristics and motor performances. The com- parison results show that the diaphragm can improve the mixing of the oxidizer and fuel. It has evident effect on increasing the motor efflciencies. Two firing experiments are conducted with full scale motors to investigate the effects of the diaphragm. The diaphragm used in the test is composed of a central steel framework and a closed thermal insulation layer. With the dia- phragm employed, the combustion efficiency increases from 93.9% to 97.34% and the specific impulse efficiency increases from 80.77% to 87.28%, which verifies the positive effect of the diaphragm. Both numerical and experimental studies indicate that the scheme of the aft mixing chamber diaphragm proposed in the paper can improve the efficiencies of the hybrid rocket motor obviously.展开更多
基金the financial support from the SINOPEC(No.2014310031600599)
文摘According to the characteristics of FCC diesel, a technology of liquid-phase hydrodesulfurization of the diesel in tubular reactors was proposed and lab-scale experiments were carried out. A kinetic model for the hydrodesulfurization process was developed and verified. The model was utilized to predict the sulfur content of products under different operating conditions. The effects of temperature, space velocity, pressure, and hydrogen concentration on the dcsulfurization rate were investigated.
基金Project(2013CB035402) supported by the National Basic Research Program of ChinaProjects(51105048,51209028) supported by the National Natural Science Foundation of China
文摘In order to deal with modeling problem of a pressure balance system with time-delay, nonlinear, time-varying and uncertain characteristics, an intelligent modeling procedure is proposed, which is based on artificial neural network(ANN) and input-output data of the system during shield tunneling and can overcome the precision problem in mechanistic modeling(MM) approach. The computational results show that the training algorithm with Gauss-Newton optimization has fast convergent speed. The experimental investigation indicates that, compared with mechanistic modeling approach, intelligent modeling procedure can obviously increase the precision in both soil pressure fitting and forecasting period. The effectiveness and accuracy of proposed intelligent modeling procedure are verified in laboratory tests.
文摘A finite volume algorithm was established in order to investigate two-dimensional hydrodynamic problems. These include viscous free surface flow interaction with free rigid bodies in the case of large and/or relative motions. Two-phase flow with complex deformations at the interface was simulated using a fractional step-volume of fluid algorithm. In addition, body motions were captured by an overlapping mesh system. Here, flow variables are transferred using a simple fully implicit non-conservative interpolation scheme which maintains the second-order accuracy of implemented spatial discretisation. Code was developed and an appropriate set of problems investigated. Results show good potential for development of a virtual hydrodynamics laboratory.
文摘The purpose of this paper is to show a laboratory scale implementation of a Thyristor Switched Capacitors （TSC） as an alternative for voltage regulation during a direct on line three-phase induction motor starting on an emulated weak transmission line. Thyristor switched capacitor bank was chosen because it is a well known topology, considering the very nature of the direct starting induction motors, which represents a highly inductive load, the use of switched reactors becomes unnecessary. Such fact minimizes the introduction of harmonics components, and also reduces the cost of the implementation. The binary disposition of the banks allows a variable Var compensation with sixteen steps, in this case. The solution makes use of low cost devices combined with sliding window voltage and current measurement algorithm and a PI control with dead band control for achieve the shown experimental results, where the system is able to manage a typically 20% voltage drop, reducing it to less than 4%. The schematic of the developed circuit, the control technique and a quite simple method to calculate the binary weight capacitors banks are also presented.
文摘The modeling of inlet and exhaust systems of internal combustion engine is very important in order to evaluate the engine performance.This paper presents new pressure losses models which can be included in a one dimensional engine simulation code.In a first part,a CFD analysis is made in order to show the importance of the density in the modeling approach.Then,the CFD code is used,as a numerical test bench,for the pressure losses models development.These coefficients depend on the geometrical characteristics of the junction and an experimental validation is made with the use of a shock tube test bench.All the models are then included in the engine simulation code of the laboratory.The numerical calculation of unsteady compressible flow,in each pipe of the inlet and exhaust systems,is made and the calculated engine torque is compared with experimental measurements.
文摘This paper focuses on the investigation of an aft mixing chamber diaphragm in a hybrid rocket motor. Both numerical and ex- perimental researches are carried out to study its effects on the motor performances. The hybrid rocket motor with star fuel grain is utilized. The 90% hydrogen peroxide （HP） oxidizer and hydroxyl terminated polybutadiene （HTPB） based fuel are adopted as propellants. The diaphragm configuration settled in the aft mixing chamber includes four circular-holes with a uni- form circumferential distribution. For both motors with and without the diaphragm, three-dimensional numerical simulations with gaseous combustions considered are carried out to study the flow field characteristics and motor performances. The com- parison results show that the diaphragm can improve the mixing of the oxidizer and fuel. It has evident effect on increasing the motor efflciencies. Two firing experiments are conducted with full scale motors to investigate the effects of the diaphragm. The diaphragm used in the test is composed of a central steel framework and a closed thermal insulation layer. With the dia- phragm employed, the combustion efficiency increases from 93.9% to 97.34% and the specific impulse efficiency increases from 80.77% to 87.28%, which verifies the positive effect of the diaphragm. Both numerical and experimental studies indicate that the scheme of the aft mixing chamber diaphragm proposed in the paper can improve the efficiencies of the hybrid rocket motor obviously.
