With high resolution （1 kin）, the distribution of wind energy resources in Hainan province and over its offshore waters is numerically simulated by using the Wind Energy Simulation Toolkit （WEST） model developed b...With high resolution （1 kin）, the distribution of wind energy resources in Hainan province and over its offshore waters is numerically simulated by using the Wind Energy Simulation Toolkit （WEST） model developed by Meteorological Research Branch of Environment Canada. Compared with observations from eight coastal anemometric towers and 18 existing stations in the province, the simulations show good reproduction of the real distribution of wind resources in Hainan and over its offshore waters, with the relative error of annual mean wind speed being no more than 9% at the 70-m level. Moreover, based on the simulated results of WEST grids that are closest to where the eight wind towers are located, the annual mean wind speeds are further estimated by using the Danish software Wasp （Wind Atlas Analysis and Application Program）. The estimated results are then compared with the observations from the towers. It shows that the relative error is also less than 9%. Therefore, WEST and WEST＋WAsP will be useful tools for the assessment of wind energy resources in high resolution and selection of wind farm sites in Hainan province and over its offshore waters.展开更多
The present paper analyses a case study of the application of dynamic energy simulation on the energy efficiency improvement process of an existing commercial building,the retrofit of a CHP machine for the combined ge...The present paper analyses a case study of the application of dynamic energy simulation on the energy efficiency improvement process of an existing commercial building,the retrofit of a CHP machine for the combined generation of heat and power is analysed.Great attention is dedicated to the correct sizing of the CHP/CCHP plant both in term of energy efficiency and economic viability.A detailed building model is developed and used,through dynamic building simulation,to identify the potential energy and economic savings achievable with the installation of a CHP/CCHP sized based on the results of the simulation itself.The work proves the usefulness of dynamic energy simulation as an evaluation tool for retrofits of CHP plants and provides suggestions on the correct sizing of CHP equipment.It is also meant to prove what could be achieved if those kinds of analysis were carried out during the design of the building.展开更多
VOF （volume of fluid） method has been used to make the numerical simulation of freak wave come true. The comparisons between the numerical results and linear theoretical results corresponding to Eq.（5） have been c...VOF （volume of fluid） method has been used to make the numerical simulation of freak wave come true. The comparisons between the numerical results and linear theoretical results corresponding to Eq.（5） have been carried out to show that the numerical results have a better exhibition of nonlinear characteristics. Wavelet analysis method has been adopted to investigate the time-frequency energy spectrum of simulation freak waves and the results reveal strong nonlinear interaction enables energy to be transferred to high harmonics during the progress of its formation. Varying water depth can enhance the nonlinear interaction, making much more energy be transferred to high harmonics and freak waves with higher asymmetry be generated.展开更多
This study proposes a combined hybrid energy storage system(HESS) and transmission grid(TG) model, and a corresponding time series operation simulation(TSOS) model is established to relieve the peak-shaving pressure o...This study proposes a combined hybrid energy storage system(HESS) and transmission grid(TG) model, and a corresponding time series operation simulation(TSOS) model is established to relieve the peak-shaving pressure of power systems under the integration of renewable energy. First, a linear model for the optimal operation of the HESS is established, which considers the different power-efficiency characteristics of the pumped storage system, electrochemical storage system, and a new type of liquid compressed air energy storage. Second, a TSOS simulation model for peak shaving is built to maximize the power entering the grid from the wind farms and HESS. Based on the proposed model, this study considers the transmission capacity of a TG. By adding the power-flow constraints of the TG, a TSOS-based HESS and TG combination model for peak shaving is established. Finally, the improved IEEE-39 and IEEE-118 bus systems were considered as examples to verify the effectiveness and feasibility of the proposed model.展开更多
Groundwater provides one option to utilise renewable energy sources. The long-term groundwater energy potential for three building complexes, situated at latitude of 64°, was investigated by combining an energy d...Groundwater provides one option to utilise renewable energy sources. The long-term groundwater energy potential for three building complexes, situated at latitude of 64°, was investigated by combining an energy demand simulation for the buildings with hydrogeological modelling. First, a reference year for the building energy demand was created. Secondly, groundwater flow requirements were calculated. The results of the previous stages were utilised in groundwater heat transport modelling in an environment where the natural temperature of groundwater was 4.9°C. Finally, the long-term (50 years) groundwater energy potential was calculated. The groundwater maintained its heating potential during 50 years of operation. When both heating and cooling power were demanded, the long-term pumping rate of groundwater decreased by 60,000 m<sup>3</sup>/a. Energy utilisation created a cold groundwater plume downstream, in which the temperature decreased by 1 to 2.5°C within a distance of 300 m from the site. Groundwater can provide a long-term energy source for large building complexes in the Nordic climate. Results indicate that groundwater could effectively be utilised until the temperature reaches approximately 4°C. Accurate information on the building energy demand and hydrogeology is essential for successful operation.展开更多
Highly energy-efficient buildings have generated remarkable interest over the last few years.There is a need for simulation based effective control systems for efficient usage of electrical and fossil fuel driven devi...Highly energy-efficient buildings have generated remarkable interest over the last few years.There is a need for simulation based effective control systems for efficient usage of electrical and fossil fuel driven devices,as they contribute to energy-efficient buildings and assist in gaining flexibility for the human occupancy-based energy loads.In this context,the integrated energy profile of a building can be ascertained by effective research approaches,as this knowledge would be beneficial to understand the demographics with respect to human occupancy and activities,as well as estimate varying energy consumption over time.Utility data from Smart Meter(SM)readings can reveal detailed information that could be mapped to predict resident occupancy and the usage patterns of specific types of appliances over desired time intervals.This research develops a user-driven simulation tool with realistic data acquisition options and assumptions of potential human behavior to determine energy usage patterns over time without the utility billing information.In this work,factors such as level of human occupancy,the possibility of space being occupied,thermostat settings,building envelope infrastructural aspects,types of appliances used in households,appliance energy related capacities,and the probability of using each appliance is considered,along with variance in weather,and heating-cooling systems specifications.For five specific benchmarked scenarios,the range of the random numbers is specified based on assumed potential human behavior for occupancy and energy-consuming appliances usage probabilities,with respect to the time of the day,weekday,and weekends.The simulation is developed using the Visual Basic Application(VBA)^(R)in Microsoft Excel^(R),based on the discrete-event Monte Carlo Simulation(MCS).The simulated energy usage and the cost are reflected in the sensitivity analysis by comparing factors such as the level of human occupancy,appliance type,and time intervals.展开更多
Thermal comfort and indoor air quality as well as the energy efficiency have been recognized as essential parts of sustainable building assessment. This work aims to analyze the energy conservation of the heat recover...Thermal comfort and indoor air quality as well as the energy efficiency have been recognized as essential parts of sustainable building assessment. This work aims to analyze the energy conservation of the heat recovery ventilator and to investigate the effect of the air supply arrangement. Three types of mixing ventilation are chosen for the analysis of coupling ANSYS/FLUENT （a computational fluid dynamics （CFD） program） with TRNSYS （a building energy simulation （BES） software）. The adoption of mutual complementary boundary conditions for CFD and BES provides more accurate and complete information of indoor air distribution and thermal performance in buildings. A typical office-space situated in a middle storey is chosen for the analysis. The office-space is equipped with air-conditioners on the ceiling. A heat recovery ventilation system directly supplies flesh air to the office space. Its thermal performance and indoor air distribution predicted by the coupled method are compared under three types of ventilation system. When the supply and return openings for ventilation are arranged on the ceiling, there is no critical difference between the predictions of the coupled method and BES on the energy consumption of HVAC because PID control is adopted for the supply air temperature of the occupied zone. On the other hand, approximately 21% discrepancy for the heat recovery estimation in the maximum between the simulated results of coupled method and BES-only can be obviously found in the floor air supply ventilation case. The discrepancy emphasizes the necessity of coupling CFD with BES when vertical air temperature gradient exists. Our future target is to estimate the optimum design of heat recovery ventilation system to control CO2 concentration by adjusting flow rate of flesh air.展开更多
We benchmark and analyze the error of energy conservation （EC） scheme in particle-in-cell/Monte Carlo （PIC/MC） algorithms by simulating the radio frequency discharge. The plasma heating behaviors and electron dist...We benchmark and analyze the error of energy conservation （EC） scheme in particle-in-cell/Monte Carlo （PIC/MC） algorithms by simulating the radio frequency discharge. The plasma heating behaviors and electron distributing functions obtained by one-dimensional （1D） simulation are analyzed. Both explicit and implicit algorithms are checked. The results showed that the EC scheme can eliminated the self-heating with wide grid spacing in both cases with a small reduction of the accuracies. In typical parameters, the EC implicit scheme has higher precision than EC explicit scheme. Some ＂numerical cooling＂ behaviors are observed and analyzed. Some other errors are also analyzed. The analysis showed that the EC implicit scheme can be used to qualitative estimation of some discharge problems with much less computational resource cost without much loss of accuracies.展开更多
Based on the characteristic of high energy milling and the micromechanics of composite material, a plastic constitutive equation is implemented for milled composite powders. To check the equation, the extrusion of Ti/...Based on the characteristic of high energy milling and the micromechanics of composite material, a plastic constitutive equation is implemented for milled composite powders. To check the equation, the extrusion of Ti/Al composite powders prepared by high energy milling was simulated. It was from the numerical analysis that the predicted extrusion pressure mounted up with milling time and extrusion ratio increasing, which was perfect agreement with experimental results.展开更多
Small moving vehicles represent an important category of marine engineering tools and devices(equipment)typically used for ocean resource detection and maintenance of marine rights and interests.The lack of efficient ...Small moving vehicles represent an important category of marine engineering tools and devices(equipment)typically used for ocean resource detection and maintenance of marine rights and interests.The lack of efficient power supply modes is one of the technical bottlenecks restricting the effective utilisation of this type of equipment.In this work,the performance characteristics of a new type of elastic-blade/wave-energy converter(EBWEC)and its core energy conversion component(named wave energy absorber)are comprehensively studied.In particular,computational fluid dynamics(CFD)simulations and experiments have been used to analyze the hydrodynamics and performance characteristics of the EBWEC.The pressure cloud diagrams relating to the surface of the elastic blade were obtained through two-way fluid-solid coupling simulations.The influence of blade thickness and relative speed on the performance characteristics of EBWEC was analyzed accordingly.A prototype of the EBWEC and its bucket test platform were also developed.The power characteristics of the EBWEC were analyzed and studied by using the blade thickness and motion cycle as control variables.The present research shows that the EBWEC can effectively overcome the performance disadvantages related to the transmission shaft torque load and power curve fluctuations of rigid blade wave energy converters(RBWEC).展开更多
A phase-field model is modified to investigate the grain growth and texture evolution in AZ31 magnesium alloy during stressing at elevated temperatures. The order parameters are defined to represent a physical variabl...A phase-field model is modified to investigate the grain growth and texture evolution in AZ31 magnesium alloy during stressing at elevated temperatures. The order parameters are defined to represent a physical variable of grain orientation in terms of three angles in spatial coordinates so that the grain volume of different order parameters can be used to indicate the texture of the alloy. The stiffness tensors for different grains are different because of elastic anisotropy of the magnesium lattice. The tensor is defined by transforming the standard stiffness tensor according to the angle between the （0001） plane of a grain and the direction of applied stress. Therefore, different grains contribute to different amounts of work under applied stress. The simulation results are well-explained by using the limited experimental data available, and the texture results are in good agreement with the experimental observations. The simulation results reveal that the applied stress strongly influences AZ31 alloy grain growth and that the grain-growth rate increases with the applied stress increasing, particularly when the stress is less than 400 MPa. A parameter （△d） is introduced to characterize the degree of grain-size variation due to abnormal grain growth; the △d increases with applied stress increasing and becomes considerably large only when the stress is greater than 800 MPa. Moreover, the applied stress also results in an intensive texture of the 〈0001〉 axis parallel to the direction of compressive stress in AZ31 alloy after growing at elevated temperatures, only when the applied stress is greater than 500 MPa.展开更多
A complete thermodynamic model is described for temperature and heat flow distribution simulation for ventilation networks in underground mines.The method is called the Computational Energy Dynamics(CED)model of the h...A complete thermodynamic model is described for temperature and heat flow distribution simulation for ventilation networks in underground mines.The method is called the Computational Energy Dynamics(CED)model of the heat,mass,and energy transport.The Thermal and Humidity(TH)transport elements of the full model are described for advection,convection,and accumulation,encompassing heat capacity,radiation,latent heat for evaporation,and condensation in the airways,as well as variable heat conduction and accumulation in the rock strata.The thermal flywheel effect for time-dependent temperature field applications is included in the model solution.A CED model validation exercise is described,directly evaluating the iterated,minimized energy balance errors for the mechanical and thermal energy components for each network branch after a converged solution is determined.A simulation example relevant to mine safety and health is shown with the CED-TH model,demonstrating its capabilities in efficiency and accuracy in comparison with measurement results.展开更多
At present,as China vigorously develops new energy automobiles,the social demand for related talents has increased significantly,so the relevant institutions need to optimize and adjust the talent training mode to hel...At present,as China vigorously develops new energy automobiles,the social demand for related talents has increased significantly,so the relevant institutions need to optimize and adjust the talent training mode to help the development of new energy automobiles.This paper summarizes the existing problems of China’s new energy automobile talent training mode,and analyzes the significance of the virtual simulation-based dual-creation talent training mode of new energy automobile and its specific implementation strategies,in order to provide references for the relevant personnel.展开更多
The protection based balance of energy is a new technique specially proposed for long transmission lines. This technique depends upon the calculation of net energy into the transmission line by two independent methods...The protection based balance of energy is a new technique specially proposed for long transmission lines. This technique depends upon the calculation of net energy into the transmission line by two independent methods and comparing them to indicate healthy and faulty conditions. In order to study the performance and feasibility of the protection based on balance of energy, the new protection has been extensively tested by using EMTP on a long transmission line with various configurations and operating conditions (including single pole line, double circuit lines and two phase operation). The results calculated by EMTP show that under any condition of a power system, the proposed technique has excellent performance,the viability even for high resistance ground faults and a short operation time.展开更多
The parametric instability related to ion motion and the resulting cross-beam energy transfer are important aspects in the physics of inertial confinement fusion.The numerical simulation of the above physical problems...The parametric instability related to ion motion and the resulting cross-beam energy transfer are important aspects in the physics of inertial confinement fusion.The numerical simulation of the above physical problems still faces great technical challenges.This paper introduces a 2D hybrid-kinetic particle-in-cell(PIC)code,CBETor.In this code,the motion of ions is described by the kinetic method,the motion of electrons is described by the simplified fluid method and the propagation of laser in plasma is described by solving the wave equation.We use CBETor and the popular fully kinetic PIC code EPOCH to simulate the stimulated Brillouin scattering and cross-beam energy transfer process,respectively.The physical images are in good agreement,but CBETor can significantly reduce the amount of calculation.With the premise of correctly simulating the ion dynamics,our hybrid-kinetic code can effectively suppress the noise of numerical simulation and significantly expand the simulation scale of physical problems.CBETor is very suitable for simulating the physical process dominated by ion motion in the interaction of medium intensity laser and underdense plasma.展开更多
Protein-protein interactions are vital for a wide range of biological processes.The interactions between the hypoxia-inducible factor and von Hippel Lindau(VHL)are attractive drug targets for ischemic heart disease.In...Protein-protein interactions are vital for a wide range of biological processes.The interactions between the hypoxia-inducible factor and von Hippel Lindau(VHL)are attractive drug targets for ischemic heart disease.In order to disrupt this interaction,the strategy to target VHL binding site using a hydroxyproline-like(pro-like)small molecule has been reported.In this study,we focused on the inhibition mechanism between the pro-like inhibitors and the VHL protein,which were investigated via molecular dynamics simulations and binding free energy calculations.It was found that pro-like inhibitors showed a strong binding affinity toward VHL.Binding free energy calculations and free energy decompositions suggested that the modification of various regions of pro-like inhibitors may provide useful information for future drug design.展开更多
A non-hydrostatic, Boussinesq, and three-dimensional large eddy simulation(LES) model was used to study the impact of the Earth's rotation on turbulence and the redistribution of energy in turbulence kinetic energ...A non-hydrostatic, Boussinesq, and three-dimensional large eddy simulation(LES) model was used to study the impact of the Earth's rotation on turbulence and the redistribution of energy in turbulence kinetic energy(TKE) budget. A set of numerical simulations was conducted,(1) with and without rotation,(2) at different latitudes(10°N, 30°N, 45°N, 60°N, and 80°N),(3) with wave breaking and with Langmuir circulation, and(4) under different wind speeds(5, 10, 20, and 30 m/s). The results show that eddy viscosity decreases when rotation is included, indicating that rotation weakens the turbulence strength. The TKE budget become tight with rotation and the effects of rotation grow with latitude. However, rotation become less important under Langmuir circulation since the transport term is strong in the vertical direction. Finally, simulations were conducted based on field data from the Boundary Layer and Air-Sea Transfer Low Wind(CBLAST-Low) experiment. The results, although more complex, are consistent with the results obtained from earlier simulations using ideal numerical conditions.展开更多
A modeling method of regional integrated energy system based on bus method and transient simulation is proposed,and the system optimization is based on the dynamic balance of supply and demand in the whole year energy...A modeling method of regional integrated energy system based on bus method and transient simulation is proposed,and the system optimization is based on the dynamic balance of supply and demand in the whole year energy supply cycle.A CCHP systemof gas turbine coupled with ground source heat pump and electric refrigeration unit is constructed.The energy relationship of the systemis described by bus structure,and the transient calculationmodel is built on TRNSYS platform.The weighted sum of annual total cost saving rate,primary energy saving rate and environmental pollutant shadow cost saving rate is taken as the optimized objective function,and on the basis of annual dynamic balance,the Hooke-Jeeves algorithm is used for optimization of the system configuration.A complex commercial area in Beijing is taken as an example,and different weighting coefficients are set for optimization of the system configuration.The results show that,from the perspective of economy,environmental benefit and primary energy consumption,performance of the system increases and then decreases with rise of gas turbine power;under the simulated cooling/heating load,the maximum number of optimum configuration is seen in the combination of 35 kW gas turbine+723 kW GSHP and 1178 kW electric chiller;in comparison with traditional distributed system,the annual cost saving rate,primary energy saving rate and environmental pollutant shadow cost saving rate of the system are 29.4%,49.6%and 58.2%,respectively.展开更多
According to environmental and energy issues,renewable energy has been vigorously promoted.Now solar power is widely used in many areas but it is limited by the weather conditions and cannot work continuously.Heat sto...According to environmental and energy issues,renewable energy has been vigorously promoted.Now solar power is widely used in many areas but it is limited by the weather conditions and cannot work continuously.Heat storage is a considerable solution for this problem and thermochemical energy storage is the most promising way because of its great energy density and stability.However,this technology is not mature enough to be applied to the industry.The reactor is an important component in the thermochemical energy storage system where the charging and discharging process happens.In this paper,a spiral coil is proposed and used as a reactor in the thermochemical energy storage system.The advantages of the spiral coil include simple structure,small volume,and so on.To investigate the flow characteristics,the simulation was carried out based on energy-minimization multi-scale model(EMMS)and Eulerian two-phase model.CaCO_(3) particles were chosen as the reactants.Particle distribution was shown in the results.The gas initial velocity was set to 2 m·s^(-1),3 m·s^(-1),and 4 m·s^(-1).When the particles flowed in the coil,gravity,centrifugal force and drag force influenced their flow.With the Reynold numbers increasing,centrifugal and drag force got larger.Accumulation phenomenon existed in the coil and results showed with the gas velocity increasing,accumulation moved from the bottom to the outer wall of the coil.Besides,the accumulation phenomenon was stabilized whenφ>720°.Also due to the centrifugal force,a secondary flow formed,which means solid particles moved from the inside wall to the outside wall.This secondary flow could promote turbulence and mixing of particles and gas.In addition,when the particle volume fraction is reduced from 0.2 to 0.1,the accumulation at the bottom of the coil decreases,and the unevenness of the velocity distribution becomes larger.展开更多
基金Project for Popularization of Advanced Meteorological Technology for 2006, China Meteorological Administration (CMATG2006M41)
文摘With high resolution （1 kin）, the distribution of wind energy resources in Hainan province and over its offshore waters is numerically simulated by using the Wind Energy Simulation Toolkit （WEST） model developed by Meteorological Research Branch of Environment Canada. Compared with observations from eight coastal anemometric towers and 18 existing stations in the province, the simulations show good reproduction of the real distribution of wind resources in Hainan and over its offshore waters, with the relative error of annual mean wind speed being no more than 9% at the 70-m level. Moreover, based on the simulated results of WEST grids that are closest to where the eight wind towers are located, the annual mean wind speeds are further estimated by using the Danish software Wasp （Wind Atlas Analysis and Application Program）. The estimated results are then compared with the observations from the towers. It shows that the relative error is also less than 9%. Therefore, WEST and WEST＋WAsP will be useful tools for the assessment of wind energy resources in high resolution and selection of wind farm sites in Hainan province and over its offshore waters.
文摘The present paper analyses a case study of the application of dynamic energy simulation on the energy efficiency improvement process of an existing commercial building,the retrofit of a CHP machine for the combined generation of heat and power is analysed.Great attention is dedicated to the correct sizing of the CHP/CCHP plant both in term of energy efficiency and economic viability.A detailed building model is developed and used,through dynamic building simulation,to identify the potential energy and economic savings achievable with the installation of a CHP/CCHP sized based on the results of the simulation itself.The work proves the usefulness of dynamic energy simulation as an evaluation tool for retrofits of CHP plants and provides suggestions on the correct sizing of CHP equipment.It is also meant to prove what could be achieved if those kinds of analysis were carried out during the design of the building.
文摘VOF （volume of fluid） method has been used to make the numerical simulation of freak wave come true. The comparisons between the numerical results and linear theoretical results corresponding to Eq.（5） have been carried out to show that the numerical results have a better exhibition of nonlinear characteristics. Wavelet analysis method has been adopted to investigate the time-frequency energy spectrum of simulation freak waves and the results reveal strong nonlinear interaction enables energy to be transferred to high harmonics during the progress of its formation. Varying water depth can enhance the nonlinear interaction, making much more energy be transferred to high harmonics and freak waves with higher asymmetry be generated.
基金supported by the State Grid Science and Technology Project (No.52999821N004)。
文摘This study proposes a combined hybrid energy storage system(HESS) and transmission grid(TG) model, and a corresponding time series operation simulation(TSOS) model is established to relieve the peak-shaving pressure of power systems under the integration of renewable energy. First, a linear model for the optimal operation of the HESS is established, which considers the different power-efficiency characteristics of the pumped storage system, electrochemical storage system, and a new type of liquid compressed air energy storage. Second, a TSOS simulation model for peak shaving is built to maximize the power entering the grid from the wind farms and HESS. Based on the proposed model, this study considers the transmission capacity of a TG. By adding the power-flow constraints of the TG, a TSOS-based HESS and TG combination model for peak shaving is established. Finally, the improved IEEE-39 and IEEE-118 bus systems were considered as examples to verify the effectiveness and feasibility of the proposed model.
文摘Groundwater provides one option to utilise renewable energy sources. The long-term groundwater energy potential for three building complexes, situated at latitude of 64°, was investigated by combining an energy demand simulation for the buildings with hydrogeological modelling. First, a reference year for the building energy demand was created. Secondly, groundwater flow requirements were calculated. The results of the previous stages were utilised in groundwater heat transport modelling in an environment where the natural temperature of groundwater was 4.9°C. Finally, the long-term (50 years) groundwater energy potential was calculated. The groundwater maintained its heating potential during 50 years of operation. When both heating and cooling power were demanded, the long-term pumping rate of groundwater decreased by 60,000 m<sup>3</sup>/a. Energy utilisation created a cold groundwater plume downstream, in which the temperature decreased by 1 to 2.5°C within a distance of 300 m from the site. Groundwater can provide a long-term energy source for large building complexes in the Nordic climate. Results indicate that groundwater could effectively be utilised until the temperature reaches approximately 4°C. Accurate information on the building energy demand and hydrogeology is essential for successful operation.
文摘Highly energy-efficient buildings have generated remarkable interest over the last few years.There is a need for simulation based effective control systems for efficient usage of electrical and fossil fuel driven devices,as they contribute to energy-efficient buildings and assist in gaining flexibility for the human occupancy-based energy loads.In this context,the integrated energy profile of a building can be ascertained by effective research approaches,as this knowledge would be beneficial to understand the demographics with respect to human occupancy and activities,as well as estimate varying energy consumption over time.Utility data from Smart Meter(SM)readings can reveal detailed information that could be mapped to predict resident occupancy and the usage patterns of specific types of appliances over desired time intervals.This research develops a user-driven simulation tool with realistic data acquisition options and assumptions of potential human behavior to determine energy usage patterns over time without the utility billing information.In this work,factors such as level of human occupancy,the possibility of space being occupied,thermostat settings,building envelope infrastructural aspects,types of appliances used in households,appliance energy related capacities,and the probability of using each appliance is considered,along with variance in weather,and heating-cooling systems specifications.For five specific benchmarked scenarios,the range of the random numbers is specified based on assumed potential human behavior for occupancy and energy-consuming appliances usage probabilities,with respect to the time of the day,weekday,and weekends.The simulation is developed using the Visual Basic Application(VBA)^(R)in Microsoft Excel^(R),based on the discrete-event Monte Carlo Simulation(MCS).The simulated energy usage and the cost are reflected in the sensitivity analysis by comparing factors such as the level of human occupancy,appliance type,and time intervals.
基金Project supported by Grant-in-Aid for Scientific Research (JSPS KAKENHI for Young Scientists (S), 21676005)
文摘Thermal comfort and indoor air quality as well as the energy efficiency have been recognized as essential parts of sustainable building assessment. This work aims to analyze the energy conservation of the heat recovery ventilator and to investigate the effect of the air supply arrangement. Three types of mixing ventilation are chosen for the analysis of coupling ANSYS/FLUENT （a computational fluid dynamics （CFD） program） with TRNSYS （a building energy simulation （BES） software）. The adoption of mutual complementary boundary conditions for CFD and BES provides more accurate and complete information of indoor air distribution and thermal performance in buildings. A typical office-space situated in a middle storey is chosen for the analysis. The office-space is equipped with air-conditioners on the ceiling. A heat recovery ventilation system directly supplies flesh air to the office space. Its thermal performance and indoor air distribution predicted by the coupled method are compared under three types of ventilation system. When the supply and return openings for ventilation are arranged on the ceiling, there is no critical difference between the predictions of the coupled method and BES on the energy consumption of HVAC because PID control is adopted for the supply air temperature of the occupied zone. On the other hand, approximately 21% discrepancy for the heat recovery estimation in the maximum between the simulated results of coupled method and BES-only can be obviously found in the floor air supply ventilation case. The discrepancy emphasizes the necessity of coupling CFD with BES when vertical air temperature gradient exists. Our future target is to estimate the optimum design of heat recovery ventilation system to control CO2 concentration by adjusting flow rate of flesh air.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.11275007,11105057,11175023,and 11275039)the Program for Liaoning Excellent Talents in University,China(Grant No.LJQ2012098)
文摘We benchmark and analyze the error of energy conservation （EC） scheme in particle-in-cell/Monte Carlo （PIC/MC） algorithms by simulating the radio frequency discharge. The plasma heating behaviors and electron distributing functions obtained by one-dimensional （1D） simulation are analyzed. Both explicit and implicit algorithms are checked. The results showed that the EC scheme can eliminated the self-heating with wide grid spacing in both cases with a small reduction of the accuracies. In typical parameters, the EC implicit scheme has higher precision than EC explicit scheme. Some ＂numerical cooling＂ behaviors are observed and analyzed. Some other errors are also analyzed. The analysis showed that the EC implicit scheme can be used to qualitative estimation of some discharge problems with much less computational resource cost without much loss of accuracies.
文摘Based on the characteristic of high energy milling and the micromechanics of composite material, a plastic constitutive equation is implemented for milled composite powders. To check the equation, the extrusion of Ti/Al composite powders prepared by high energy milling was simulated. It was from the numerical analysis that the predicted extrusion pressure mounted up with milling time and extrusion ratio increasing, which was perfect agreement with experimental results.
基金financially supported by the National Natural Science Foundation of China(Grant Number 51475465)the Hunan Provincial Innovation Foundation for Postgraduate(Grant Number CX2015B014).
文摘Small moving vehicles represent an important category of marine engineering tools and devices(equipment)typically used for ocean resource detection and maintenance of marine rights and interests.The lack of efficient power supply modes is one of the technical bottlenecks restricting the effective utilisation of this type of equipment.In this work,the performance characteristics of a new type of elastic-blade/wave-energy converter(EBWEC)and its core energy conversion component(named wave energy absorber)are comprehensively studied.In particular,computational fluid dynamics(CFD)simulations and experiments have been used to analyze the hydrodynamics and performance characteristics of the EBWEC.The pressure cloud diagrams relating to the surface of the elastic blade were obtained through two-way fluid-solid coupling simulations.The influence of blade thickness and relative speed on the performance characteristics of EBWEC was analyzed accordingly.A prototype of the EBWEC and its bucket test platform were also developed.The power characteristics of the EBWEC were analyzed and studied by using the blade thickness and motion cycle as control variables.The present research shows that the EBWEC can effectively overcome the performance disadvantages related to the transmission shaft torque load and power curve fluctuations of rigid blade wave energy converters(RBWEC).
基金Project supported by the National Key Research Development Program of China(Grant No.2016YFB0701204)the National Natural Science Foundation of China(Grant Nos.U1302272 and 51571055)
文摘A phase-field model is modified to investigate the grain growth and texture evolution in AZ31 magnesium alloy during stressing at elevated temperatures. The order parameters are defined to represent a physical variable of grain orientation in terms of three angles in spatial coordinates so that the grain volume of different order parameters can be used to indicate the texture of the alloy. The stiffness tensors for different grains are different because of elastic anisotropy of the magnesium lattice. The tensor is defined by transforming the standard stiffness tensor according to the angle between the （0001） plane of a grain and the direction of applied stress. Therefore, different grains contribute to different amounts of work under applied stress. The simulation results are well-explained by using the limited experimental data available, and the texture results are in good agreement with the experimental observations. The simulation results reveal that the applied stress strongly influences AZ31 alloy grain growth and that the grain-growth rate increases with the applied stress increasing, particularly when the stress is less than 400 MPa. A parameter （△d） is introduced to characterize the degree of grain-size variation due to abnormal grain growth; the △d increases with applied stress increasing and becomes considerably large only when the stress is greater than 800 MPa. Moreover, the applied stress also results in an intensive texture of the 〈0001〉 axis parallel to the direction of compressive stress in AZ31 alloy after growing at elevated temperatures, only when the applied stress is greater than 500 MPa.
基金the Alpha Foundation for the Improvement of Mine Safety and Health,Inc.National Institute of Occupational Safety and Health(NIOSH)
文摘A complete thermodynamic model is described for temperature and heat flow distribution simulation for ventilation networks in underground mines.The method is called the Computational Energy Dynamics(CED)model of the heat,mass,and energy transport.The Thermal and Humidity(TH)transport elements of the full model are described for advection,convection,and accumulation,encompassing heat capacity,radiation,latent heat for evaporation,and condensation in the airways,as well as variable heat conduction and accumulation in the rock strata.The thermal flywheel effect for time-dependent temperature field applications is included in the model solution.A CED model validation exercise is described,directly evaluating the iterated,minimized energy balance errors for the mechanical and thermal energy components for each network branch after a converged solution is determined.A simulation example relevant to mine safety and health is shown with the CED-TH model,demonstrating its capabilities in efficiency and accuracy in comparison with measurement results.
文摘At present,as China vigorously develops new energy automobiles,the social demand for related talents has increased significantly,so the relevant institutions need to optimize and adjust the talent training mode to help the development of new energy automobiles.This paper summarizes the existing problems of China’s new energy automobile talent training mode,and analyzes the significance of the virtual simulation-based dual-creation talent training mode of new energy automobile and its specific implementation strategies,in order to provide references for the relevant personnel.
文摘The protection based balance of energy is a new technique specially proposed for long transmission lines. This technique depends upon the calculation of net energy into the transmission line by two independent methods and comparing them to indicate healthy and faulty conditions. In order to study the performance and feasibility of the protection based on balance of energy, the new protection has been extensively tested by using EMTP on a long transmission line with various configurations and operating conditions (including single pole line, double circuit lines and two phase operation). The results calculated by EMTP show that under any condition of a power system, the proposed technique has excellent performance,the viability even for high resistance ground faults and a short operation time.
基金supported by National Natural Science Foundation of China (Nos. 11774430, 11875091, 12075157 and 11975062)
文摘The parametric instability related to ion motion and the resulting cross-beam energy transfer are important aspects in the physics of inertial confinement fusion.The numerical simulation of the above physical problems still faces great technical challenges.This paper introduces a 2D hybrid-kinetic particle-in-cell(PIC)code,CBETor.In this code,the motion of ions is described by the kinetic method,the motion of electrons is described by the simplified fluid method and the propagation of laser in plasma is described by solving the wave equation.We use CBETor and the popular fully kinetic PIC code EPOCH to simulate the stimulated Brillouin scattering and cross-beam energy transfer process,respectively.The physical images are in good agreement,but CBETor can significantly reduce the amount of calculation.With the premise of correctly simulating the ion dynamics,our hybrid-kinetic code can effectively suppress the noise of numerical simulation and significantly expand the simulation scale of physical problems.CBETor is very suitable for simulating the physical process dominated by ion motion in the interaction of medium intensity laser and underdense plasma.
基金supported by the National Natural Science Foundation of China(No.21973064)the Post-Doctor Research Project,West China Hospital,Sichuan University(No.2021HXBH017)。
文摘Protein-protein interactions are vital for a wide range of biological processes.The interactions between the hypoxia-inducible factor and von Hippel Lindau(VHL)are attractive drug targets for ischemic heart disease.In order to disrupt this interaction,the strategy to target VHL binding site using a hydroxyproline-like(pro-like)small molecule has been reported.In this study,we focused on the inhibition mechanism between the pro-like inhibitors and the VHL protein,which were investigated via molecular dynamics simulations and binding free energy calculations.It was found that pro-like inhibitors showed a strong binding affinity toward VHL.Binding free energy calculations and free energy decompositions suggested that the modification of various regions of pro-like inhibitors may provide useful information for future drug design.
基金Supported by the National Natural Science Foundation of China(Nos.41206015,41106019)the National Basic Research Program of China(973 Program)(Nos.2011CB403501,2012CB417402)the Fund for Creative Research Groups by NSFC(No.41121064)
文摘A non-hydrostatic, Boussinesq, and three-dimensional large eddy simulation(LES) model was used to study the impact of the Earth's rotation on turbulence and the redistribution of energy in turbulence kinetic energy(TKE) budget. A set of numerical simulations was conducted,(1) with and without rotation,(2) at different latitudes(10°N, 30°N, 45°N, 60°N, and 80°N),(3) with wave breaking and with Langmuir circulation, and(4) under different wind speeds(5, 10, 20, and 30 m/s). The results show that eddy viscosity decreases when rotation is included, indicating that rotation weakens the turbulence strength. The TKE budget become tight with rotation and the effects of rotation grow with latitude. However, rotation become less important under Langmuir circulation since the transport term is strong in the vertical direction. Finally, simulations were conducted based on field data from the Boundary Layer and Air-Sea Transfer Low Wind(CBLAST-Low) experiment. The results, although more complex, are consistent with the results obtained from earlier simulations using ideal numerical conditions.
基金This research was funded by the Research on Rapid Modeling Methods for Integrated Energy Systems,Grant No.SGTYHT/17-JS-204.
文摘A modeling method of regional integrated energy system based on bus method and transient simulation is proposed,and the system optimization is based on the dynamic balance of supply and demand in the whole year energy supply cycle.A CCHP systemof gas turbine coupled with ground source heat pump and electric refrigeration unit is constructed.The energy relationship of the systemis described by bus structure,and the transient calculationmodel is built on TRNSYS platform.The weighted sum of annual total cost saving rate,primary energy saving rate and environmental pollutant shadow cost saving rate is taken as the optimized objective function,and on the basis of annual dynamic balance,the Hooke-Jeeves algorithm is used for optimization of the system configuration.A complex commercial area in Beijing is taken as an example,and different weighting coefficients are set for optimization of the system configuration.The results show that,from the perspective of economy,environmental benefit and primary energy consumption,performance of the system increases and then decreases with rise of gas turbine power;under the simulated cooling/heating load,the maximum number of optimum configuration is seen in the combination of 35 kW gas turbine+723 kW GSHP and 1178 kW electric chiller;in comparison with traditional distributed system,the annual cost saving rate,primary energy saving rate and environmental pollutant shadow cost saving rate of the system are 29.4%,49.6%and 58.2%,respectively.
基金the financial support provided by Natural Science Foundation of Jiangsu Province (BK20180936)the Initial Funding of Scientific Research for the Introduction of Talents (YJ2021-41)
文摘According to environmental and energy issues,renewable energy has been vigorously promoted.Now solar power is widely used in many areas but it is limited by the weather conditions and cannot work continuously.Heat storage is a considerable solution for this problem and thermochemical energy storage is the most promising way because of its great energy density and stability.However,this technology is not mature enough to be applied to the industry.The reactor is an important component in the thermochemical energy storage system where the charging and discharging process happens.In this paper,a spiral coil is proposed and used as a reactor in the thermochemical energy storage system.The advantages of the spiral coil include simple structure,small volume,and so on.To investigate the flow characteristics,the simulation was carried out based on energy-minimization multi-scale model(EMMS)and Eulerian two-phase model.CaCO_(3) particles were chosen as the reactants.Particle distribution was shown in the results.The gas initial velocity was set to 2 m·s^(-1),3 m·s^(-1),and 4 m·s^(-1).When the particles flowed in the coil,gravity,centrifugal force and drag force influenced their flow.With the Reynold numbers increasing,centrifugal and drag force got larger.Accumulation phenomenon existed in the coil and results showed with the gas velocity increasing,accumulation moved from the bottom to the outer wall of the coil.Besides,the accumulation phenomenon was stabilized whenφ>720°.Also due to the centrifugal force,a secondary flow formed,which means solid particles moved from the inside wall to the outside wall.This secondary flow could promote turbulence and mixing of particles and gas.In addition,when the particle volume fraction is reduced from 0.2 to 0.1,the accumulation at the bottom of the coil decreases,and the unevenness of the velocity distribution becomes larger.
