Concentrating solar thermal power system can provide low carbon,renewable energy resources in countries or regions with strong solar irradiation.For this kind of power plant which is likely to be located in the arid a...Concentrating solar thermal power system can provide low carbon,renewable energy resources in countries or regions with strong solar irradiation.For this kind of power plant which is likely to be located in the arid area,natural draft dry cooling tower is a promising choice.To develop the experimental studies on small cooling tower,a 20 m high natural draft dry cooling tower with fully instrumented measurement system was established by the Queensland Geothermal Energy Centre of Excellence.The performance of this cooling tower was measured with the constant heat input of 600 kW and 840 kW and with ambient temperature ranging from 20 ℃ to 32 ℃.The cooling tower numerical model was refined and validated with the experimental data.The model of 1 MW concentrating solar thermal supercritical CO2 power cycle was developed and integrated with the cooling tower model.The influences of changing ambient temperature and the performance of the cooling tower on efficiency of the power system were simulated.The differences of the mechanism of the ambient temperature effect on Rankine cycle and supercritical CO2 Brayton cycle were analysed and discussed.展开更多
Electro hydrodynamic analogue (EHA) method is applied to study the flow fields in the West Lake. It gives out a satisfactory result on water velocities and discharges of the bridge openings.
Owing to its merits in energy savings, environmental protection and coke quality improvement, the Coke Dry Quenching (CDQ) technology is favorite in coke making industry today. In order to validate the mathematical mo...Owing to its merits in energy savings, environmental protection and coke quality improvement, the Coke Dry Quenching (CDQ) technology is favorite in coke making industry today. In order to validate the mathematical model developed for the cooling process of real CDQ shaft, the one-seventh scale experimental setup was established. With the air as the working fluid and the coke as the packed bed, the coke and gas temperatures and the pressure drop in the cooling shaft were measured. A mathematical model based on the non-Darcian and non-thermal equilibrium model for the cooling process of the CDQ experimental shaft was presented. The computational results were compared to the experimental data. It was found that most numerical predictions were supported by the measured values.展开更多
In this paper,experimental and numerical studies of heat transfer in a test local of side H=0.8 m heated from below are presented and compared.All the walls,the rest of the floor and the ceiling are made from plywood ...In this paper,experimental and numerical studies of heat transfer in a test local of side H=0.8 m heated from below are presented and compared.All the walls,the rest of the floor and the ceiling are made from plywood and polystyrene in sandwich form(3 mmplywood-3 cm polystyrene-3 mmplywood)just on one of the vertical walls contained a glazed door(2 H/3×0.15 m).This local is heated during two heating cycles by a square plate of iron the width L=0.6 H,which represents the heat source,its temperature T_(h) is controlled.The plate is heated for two cycles by an adjustable set-point heat source placed just down the center of it.For each cycle,the heat source is switched“on”for 6 h and switched“off”for 6 h.The outdoor air temperature is kept constant at a low temperature T_(c)<T_(h).All measurements are carried out with k-type thermocouples and with flux meters.Results will be qualitatively presented for two cycles of heating in terms of temperatures and heat flux densitiesϕfor various positions of the test local.The temperature evolution of the center and the profile of the temperature along the vertical centerline are compared by two dimensions simulation using the lattice Boltzmann method.The comparison shows a good agreement with a difference that does not exceed±1℃.展开更多
A novel cooling system with cooling channels is proposed for the stator of 3MW wind-driven generator.An experimental platform is built to investigate the performance of the cooling system with different loads.At30%,50...A novel cooling system with cooling channels is proposed for the stator of 3MW wind-driven generator.An experimental platform is built to investigate the performance of the cooling system with different loads.At30%,50% or 80% generator loads,the temperatures meet the design requirement.However,it is a little over the requirement at 100%load,duo to experimental errors and some unknown thermal resistances.In the test at 100%load,the developing trends of the parameters of these two generators are similar and only minor differences occurs when they reach steady state our work can be benefit for the design and improvement of MW wind-driven generator cooling solutions.展开更多
Various sources of solid particles might exist in the coolant flow of a liquid metal cooled fast reactor(e.g.,through chemical interaction between the coolant and impurities,air,or water,through corrosion of structura...Various sources of solid particles might exist in the coolant flow of a liquid metal cooled fast reactor(e.g.,through chemical interaction between the coolant and impurities,air,or water,through corrosion of structural materials,or from damaged/molten fuel).Such particles may cause flow blockage accidents in a fuel assembly,resulting in a reduction in coolant flow,which potentially causes a local temperature rise in the fuel cladding,cladding failure,and fuel melt.To understand the blockage formation mechanism,in this study,a series of simulated experiments was conducted by releasing different solid particles from a release device into a reducer pipe using gravity.Through detailed analyses,the influence of various experimental parameters(e.g.,particle diameter,capacity,shape,and static friction coefficient,and the diameter and height of the particle release nozzle)on the blockage characteristics(i.e.,blockage probability and position)was examined.Under the current range of experimental conditions,the blockage was significantly influenced by the aforementioned parameters.The ratio between the particle diameter and outlet size of the reducer pipe might be one of the determining factors governing the occurrence of blockage.Specifically,increasing the ratio enhanced blockage(i.e.,larger probability and higher position within the reducer pipe).Increasing the particle size,particle capacity,particle static friction coefficient,and particle release nozzle diameter led to a rise in the blockage probability;however,increasing the particle release nozzle height had a downward influence on the blockage probability.Finally,blockage was more likely to occur in non-spherical particles case than that of spherical particles.This study provides a large experimental database to promote an understanding of the flow blockage mechanism and improve the validation process of fast reactor safety analysis codes.展开更多
In order to obtain satisfactory mechanical properties for the cam used in high-power ship diesel engines, a new quenching technology was proposed by designing a two-stage quenching process with an alkaline bath as the...In order to obtain satisfactory mechanical properties for the cam used in high-power ship diesel engines, a new quenching technology was proposed by designing a two-stage quenching process with an alkaline bath as the quenching medium. To demonstrate the effectiveness of the proposed new quenching technology, both numerical analysis and experimental study were performed. The new quenching technology was analyzed using finite element method. The combined effects of the temperature, stress and microstructure fields were investigated considering nonlinear material properties. Finally, an experimental study was performed to verify the effectiveness of the proposed new quenching technology. The numerical results show that internal stress is affected by both thermal stress and transformation stress. In addition, the direction of the internal stress is changed several times due to thermal interaction and microstructure evolution during the quenching process. The experimental results show that the proposed new quenching technology significantly improves the mechanical properties and microstructures of the cam. The tensile strength, the impact resistance and the hardness value of the cam by the proposed new quenching technology are improved by 4.3%, 8.9% and 3.5% compared with those by the traditional quenching technology. Moreover, the residual stress and cam shape deformation are reduced by 40.0% and 48.9% respectively for the cam manufactured by the new quenching technology.展开更多
This paper studies the excavation collapse at the Xianghu subway station on Hangzhou metro line 1.The objective is to present an overview of this case study and discuss the cause of the failure.Through field investiga...This paper studies the excavation collapse at the Xianghu subway station on Hangzhou metro line 1.The objective is to present an overview of this case study and discuss the cause of the failure.Through field investigation and preliminary analysis,the reasons for the excavation collapse were the misuse of the soil parameters,over excavation,incorrect installation of steel struts,invalid monitoring data,and inadequate ground improvement.Finally,a small strain constitutive model was used for further analysis.In order to estimate damage efficiently,the orthogonal array(OA) was introduced for screening the key factor in the numerical experiments.Six estimated indexes including deformations and internal forces of the excavation were taken,and the effectiveness of four factors which may cause the collapse was evaluated.Through numerical experiments and interaction analysis,it is found that the deformation and internal force can be well controlled by jet grouting of the subsoil under the final cutting surface,but increasing the improvement ratio of the jet grouting cannot help optimize the excavation behavior efficiently,and without jet grouting and the fourth level struts,the deformation and internal force of the excavation in this case will far surpass the allowable value.展开更多
Transcritical film cooling was investigated by numerical study in a methane cooled methane/oxygen rocket engine.The respective time-averaged Navier-Stokes equations have been solved for the compressible steady three-d...Transcritical film cooling was investigated by numerical study in a methane cooled methane/oxygen rocket engine.The respective time-averaged Navier-Stokes equations have been solved for the compressible steady three-dimensional(3-D) flow.The flow field computations were performed using the semi-implicit method for pressure linked equation(SIMPLE) algorithm on several blocks of nonuniform collocated grid.The calculation was conducted over a pressure range of 202 650.0 Pa to 1.2×107 Pa and a temperature range of 120.0 K to 3 568.0 K.Twenty-nine different cases were simulated to calculate the impact of different factors.The results show that mass flow rate,length,diameter,number and diffused or convergence of film jet channel,injection angle and jet array arrangements have great impact on transcritical film cooling effectiveness.Furthermore,shape of the jet holes and jet and crossflow turbulence also affect the wall temperature distribution.Two rows of film arranged in different axial angles and staggered arrangement were proposed as new liquid film arrangement.Different radial angles have impact on the film cooling effectiveness in two row-jets cooled cases.The case of in-line and staggered arrangement are almost the same in the region before the second row of jets,but a staggered arrangement has a higher film cooling effectiveness from the second row of jets.展开更多
文摘Concentrating solar thermal power system can provide low carbon,renewable energy resources in countries or regions with strong solar irradiation.For this kind of power plant which is likely to be located in the arid area,natural draft dry cooling tower is a promising choice.To develop the experimental studies on small cooling tower,a 20 m high natural draft dry cooling tower with fully instrumented measurement system was established by the Queensland Geothermal Energy Centre of Excellence.The performance of this cooling tower was measured with the constant heat input of 600 kW and 840 kW and with ambient temperature ranging from 20 ℃ to 32 ℃.The cooling tower numerical model was refined and validated with the experimental data.The model of 1 MW concentrating solar thermal supercritical CO2 power cycle was developed and integrated with the cooling tower model.The influences of changing ambient temperature and the performance of the cooling tower on efficiency of the power system were simulated.The differences of the mechanism of the ambient temperature effect on Rankine cycle and supercritical CO2 Brayton cycle were analysed and discussed.
文摘Electro hydrodynamic analogue (EHA) method is applied to study the flow fields in the West Lake. It gives out a satisfactory result on water velocities and discharges of the bridge openings.
基金This work has been supported by Cross-Century Talents Projects of Educational Ministry of China.
文摘Owing to its merits in energy savings, environmental protection and coke quality improvement, the Coke Dry Quenching (CDQ) technology is favorite in coke making industry today. In order to validate the mathematical model developed for the cooling process of real CDQ shaft, the one-seventh scale experimental setup was established. With the air as the working fluid and the coke as the packed bed, the coke and gas temperatures and the pressure drop in the cooling shaft were measured. A mathematical model based on the non-Darcian and non-thermal equilibrium model for the cooling process of the CDQ experimental shaft was presented. The computational results were compared to the experimental data. It was found that most numerical predictions were supported by the measured values.
文摘In this paper,experimental and numerical studies of heat transfer in a test local of side H=0.8 m heated from below are presented and compared.All the walls,the rest of the floor and the ceiling are made from plywood and polystyrene in sandwich form(3 mmplywood-3 cm polystyrene-3 mmplywood)just on one of the vertical walls contained a glazed door(2 H/3×0.15 m).This local is heated during two heating cycles by a square plate of iron the width L=0.6 H,which represents the heat source,its temperature T_(h) is controlled.The plate is heated for two cycles by an adjustable set-point heat source placed just down the center of it.For each cycle,the heat source is switched“on”for 6 h and switched“off”for 6 h.The outdoor air temperature is kept constant at a low temperature T_(c)<T_(h).All measurements are carried out with k-type thermocouples and with flux meters.Results will be qualitatively presented for two cycles of heating in terms of temperatures and heat flux densitiesϕfor various positions of the test local.The temperature evolution of the center and the profile of the temperature along the vertical centerline are compared by two dimensions simulation using the lattice Boltzmann method.The comparison shows a good agreement with a difference that does not exceed±1℃.
文摘A novel cooling system with cooling channels is proposed for the stator of 3MW wind-driven generator.An experimental platform is built to investigate the performance of the cooling system with different loads.At30%,50% or 80% generator loads,the temperatures meet the design requirement.However,it is a little over the requirement at 100%load,duo to experimental errors and some unknown thermal resistances.In the test at 100%load,the developing trends of the parameters of these two generators are similar and only minor differences occurs when they reach steady state our work can be benefit for the design and improvement of MW wind-driven generator cooling solutions.
基金supported by the Basic and Applied Basic Research Foundation of Guangdong Province(Nos.2021A1515010343,2022A1515011582)the Science and Technology Program of Guangdong Province(Nos.2021A0505030026,2022A0505050029).
文摘Various sources of solid particles might exist in the coolant flow of a liquid metal cooled fast reactor(e.g.,through chemical interaction between the coolant and impurities,air,or water,through corrosion of structural materials,or from damaged/molten fuel).Such particles may cause flow blockage accidents in a fuel assembly,resulting in a reduction in coolant flow,which potentially causes a local temperature rise in the fuel cladding,cladding failure,and fuel melt.To understand the blockage formation mechanism,in this study,a series of simulated experiments was conducted by releasing different solid particles from a release device into a reducer pipe using gravity.Through detailed analyses,the influence of various experimental parameters(e.g.,particle diameter,capacity,shape,and static friction coefficient,and the diameter and height of the particle release nozzle)on the blockage characteristics(i.e.,blockage probability and position)was examined.Under the current range of experimental conditions,the blockage was significantly influenced by the aforementioned parameters.The ratio between the particle diameter and outlet size of the reducer pipe might be one of the determining factors governing the occurrence of blockage.Specifically,increasing the ratio enhanced blockage(i.e.,larger probability and higher position within the reducer pipe).Increasing the particle size,particle capacity,particle static friction coefficient,and particle release nozzle diameter led to a rise in the blockage probability;however,increasing the particle release nozzle height had a downward influence on the blockage probability.Finally,blockage was more likely to occur in non-spherical particles case than that of spherical particles.This study provides a large experimental database to promote an understanding of the flow blockage mechanism and improve the validation process of fast reactor safety analysis codes.
基金Project(50875268) supported by the National Natural Science Foundation of China Project(CSTC2008AB3057) supported by Foundation of Chongqing Science and Technology Commission, China+1 种基金 Project(108107) supported by the Key Project of Ministry of Education of China Project(50925518) supported by the National Science Fund for Distinguished Young Scholars
文摘In order to obtain satisfactory mechanical properties for the cam used in high-power ship diesel engines, a new quenching technology was proposed by designing a two-stage quenching process with an alkaline bath as the quenching medium. To demonstrate the effectiveness of the proposed new quenching technology, both numerical analysis and experimental study were performed. The new quenching technology was analyzed using finite element method. The combined effects of the temperature, stress and microstructure fields were investigated considering nonlinear material properties. Finally, an experimental study was performed to verify the effectiveness of the proposed new quenching technology. The numerical results show that internal stress is affected by both thermal stress and transformation stress. In addition, the direction of the internal stress is changed several times due to thermal interaction and microstructure evolution during the quenching process. The experimental results show that the proposed new quenching technology significantly improves the mechanical properties and microstructures of the cam. The tensile strength, the impact resistance and the hardness value of the cam by the proposed new quenching technology are improved by 4.3%, 8.9% and 3.5% compared with those by the traditional quenching technology. Moreover, the residual stress and cam shape deformation are reduced by 40.0% and 48.9% respectively for the cam manufactured by the new quenching technology.
基金Project (No. 51078377) supported by the National Natural Science Foundation of China
文摘This paper studies the excavation collapse at the Xianghu subway station on Hangzhou metro line 1.The objective is to present an overview of this case study and discuss the cause of the failure.Through field investigation and preliminary analysis,the reasons for the excavation collapse were the misuse of the soil parameters,over excavation,incorrect installation of steel struts,invalid monitoring data,and inadequate ground improvement.Finally,a small strain constitutive model was used for further analysis.In order to estimate damage efficiently,the orthogonal array(OA) was introduced for screening the key factor in the numerical experiments.Six estimated indexes including deformations and internal forces of the excavation were taken,and the effectiveness of four factors which may cause the collapse was evaluated.Through numerical experiments and interaction analysis,it is found that the deformation and internal force can be well controlled by jet grouting of the subsoil under the final cutting surface,but increasing the improvement ratio of the jet grouting cannot help optimize the excavation behavior efficiently,and without jet grouting and the fourth level struts,the deformation and internal force of the excavation in this case will far surpass the allowable value.
文摘Transcritical film cooling was investigated by numerical study in a methane cooled methane/oxygen rocket engine.The respective time-averaged Navier-Stokes equations have been solved for the compressible steady three-dimensional(3-D) flow.The flow field computations were performed using the semi-implicit method for pressure linked equation(SIMPLE) algorithm on several blocks of nonuniform collocated grid.The calculation was conducted over a pressure range of 202 650.0 Pa to 1.2×107 Pa and a temperature range of 120.0 K to 3 568.0 K.Twenty-nine different cases were simulated to calculate the impact of different factors.The results show that mass flow rate,length,diameter,number and diffused or convergence of film jet channel,injection angle and jet array arrangements have great impact on transcritical film cooling effectiveness.Furthermore,shape of the jet holes and jet and crossflow turbulence also affect the wall temperature distribution.Two rows of film arranged in different axial angles and staggered arrangement were proposed as new liquid film arrangement.Different radial angles have impact on the film cooling effectiveness in two row-jets cooled cases.The case of in-line and staggered arrangement are almost the same in the region before the second row of jets,but a staggered arrangement has a higher film cooling effectiveness from the second row of jets.
