The superconducting magnet system of a fusion reactor plays a vital role in plasma confinement,a process that can be dis-rupted by various operational factors.A critical parameter for evaluating the temperature margin...The superconducting magnet system of a fusion reactor plays a vital role in plasma confinement,a process that can be dis-rupted by various operational factors.A critical parameter for evaluating the temperature margin of superconducting magnets during normal operation is the nuclear heating caused by D-T neutrons.This study investigates the impact of nuclear heat-ing on a superconducting magnet system by employing an improved analysis method that combines neutronics and thermal hydraulics.In the magnet system,toroidal field(TF)magnets are positioned closest to the plasma and bear the highest nuclear-heat load,making them prime candidates for evaluating the influence of nuclear heating on stability.To enhance the modeling accuracy and facilitate design modifications,a parametric TF model that incorporates heterogeneity is established to expedite the optimization design process and enhance the accuracy of the computations.A comparative analysis with a homogeneous TF model reveals that the heterogeneous model improves accuracy by over 12%.Considering factors such as heat load,magnetic-field strength,and cooling conditions,the cooling circuit facing the most severe conditions is selected to calculate the temperature of the superconductor.This selection streamlines the workload associated with thermal-hydraulic analysis.This approach enables a more efficient and precise evaluation of the temperature margin of TF magnets.Moreover,it offers insights that can guide the optimization of both the structure and cooling strategy of superconducting magnet systems.展开更多
During fracturing treatment for low-temperature, shallow and high freezing point oil reservoirs, the first-line problems are to overcome uncompleted breakdown, uncompleted cleanup of fracturing fluids and cold damages...During fracturing treatment for low-temperature, shallow and high freezing point oil reservoirs, the first-line problems are to overcome uncompleted breakdown, uncompleted cleanup of fracturing fluids and cold damages to the formations by injecting cold fluid. To avoid those problems, it is suggested to adopt a new encapsulated heat-generating hydraulic fracturing fluid system as described in this paper.; Firstly, two kinds of chemical heat-generating systems were studied and the NH-4Cl-NaNO-2 system was selected. According to the reaction characteristics of the system, oxalic acid was chosen as a catalyst of reaction and encapsulated using ethyl cellulose and paraffin as coating materials by the phase separation method. Compatibility of NH-4Cl-NaNO-2-encapsulated oxalic acid with hydroxypropyl-guar fracturing fluid was also discussed in the paper. The results showed that the hydraulic fracturing fluid containing encapsulated heat-generating agents hare a good stability and compatibility. When the fracturing fluid contains {2.0} mol·L+{-1} NH-4Cl-NaNO-2, {0.93%} encapsulated oxalic acid and {0.08%} ammonium persulfate, the peak temperature can reach {78.0℃} and the viscosity of residual liquid is {3.12} mPa·s after 4 hours.展开更多
Thermal characteristic of cavitation has great influence on the process of occurrence,development and collapse of bubble in hydraulic system. By choosing the stage of bubble growth as the research object,combining wit...Thermal characteristic of cavitation has great influence on the process of occurrence,development and collapse of bubble in hydraulic system. By choosing the stage of bubble growth as the research object,combining with the characteristic of the process of bubble occurrence and development in hydraulic system, and ignoring the impact of thermal radiation,the heat transfer situation of bubble growth was analyzed under appropriate assumptions of thermodynamic conditions in the bubble generation and development process. The mathematical expression of the temperature change of bubble was deduced using thermodynamic principle. Through combining the expression with classic Rayleigh-Plesset Equation,numerical calculation was carried out and the temperature variation over time( or bubble radius) was obtained. The influences of convective heat transfer coefficient of bubble and polytropic exponent on the thermodynamic process of bubble were analyzed. Finally,the thermal characteristic of bubble growth after cavitation occurrence was summarized.展开更多
The technology of passive safety is the current trend among safety systems in nuclear power plant. Pas- sive residual heat removal system (PRHRS), a major part of passive safety systems of Chinese advanced PWR, is a n...The technology of passive safety is the current trend among safety systems in nuclear power plant. Pas- sive residual heat removal system (PRHRS), a major part of passive safety systems of Chinese advanced PWR, is a novel design with three-fold natural circulation. On the basis of reasonable physics and mathematics models, MI- TAP-PRHRS code was developed to analyze steady and transient characteristics of the PRHRS. The calculation and analysis show that the code simulates steady characteristics of the PRHRS very well, and it is able to simulate tran- sient characteristics of all startup modes of the PRHRS. However, the quantitative description is poor during the ini- tial stages of the transition process when water hammer occurs.展开更多
In this work an experimental investigation was carried out in order to explore the possibility of realizing a domestic heating system by throttling hydraulic oil. Considering the continuous increasing price of diesel ...In this work an experimental investigation was carried out in order to explore the possibility of realizing a domestic heating system by throttling hydraulic oil. Considering the continuous increasing price of diesel oil, this work gains unique importance. Generating heat directly by throttling is realized using a simple environment friendly system which does not require oil transportation and storage, and eliminates the need for chimneys and annual preventive maintenance, as it is the case with heating by utilizing oil burners, which is prevailing in Jordan. Experimental results show that it is possible to raise the room temperature up to 70?C during 15 minutes which is not a limit value. Experimental results show that temperature rate could be increased by selecting the appropriate pump power and by connecting a number of throttles in parallel.展开更多
基于无线传输的方式设计了针对供热系统的二次网在小区单元间水力平衡的远程监控系统。该监控系统由可编程逻辑控制器(PLC)、电动调节阀和传感器等设备完成底层采集监控,通过PLC云网关和4G移动通信系统将二次网数据无线传输至云服务器,...基于无线传输的方式设计了针对供热系统的二次网在小区单元间水力平衡的远程监控系统。该监控系统由可编程逻辑控制器(PLC)、电动调节阀和传感器等设备完成底层采集监控,通过PLC云网关和4G移动通信系统将二次网数据无线传输至云服务器,采用OPC通信和SQL Server数据库实现云网关服务器和监控系统间的数据传输和存储;在KingSCADA软件和Visual Studio Code软件中分别设计编写本地监控系统和网页远程监控系统,使单元间水力平衡的调节参数可视化。测试结果表明,该监控系统可实现供热系统二次网单元间水力平衡调节的实时远程监控功能,对提高水力平衡调节效率具有现实意义。展开更多
基金the National Natural Science Foundation of China(Nos.52222701,52077211,and 52307034).
文摘The superconducting magnet system of a fusion reactor plays a vital role in plasma confinement,a process that can be dis-rupted by various operational factors.A critical parameter for evaluating the temperature margin of superconducting magnets during normal operation is the nuclear heating caused by D-T neutrons.This study investigates the impact of nuclear heat-ing on a superconducting magnet system by employing an improved analysis method that combines neutronics and thermal hydraulics.In the magnet system,toroidal field(TF)magnets are positioned closest to the plasma and bear the highest nuclear-heat load,making them prime candidates for evaluating the influence of nuclear heating on stability.To enhance the modeling accuracy and facilitate design modifications,a parametric TF model that incorporates heterogeneity is established to expedite the optimization design process and enhance the accuracy of the computations.A comparative analysis with a homogeneous TF model reveals that the heterogeneous model improves accuracy by over 12%.Considering factors such as heat load,magnetic-field strength,and cooling conditions,the cooling circuit facing the most severe conditions is selected to calculate the temperature of the superconductor.This selection streamlines the workload associated with thermal-hydraulic analysis.This approach enables a more efficient and precise evaluation of the temperature margin of TF magnets.Moreover,it offers insights that can guide the optimization of both the structure and cooling strategy of superconducting magnet systems.
基金This work was supported by CNPC Innovation Foundation ( No.2001CX-19).
文摘During fracturing treatment for low-temperature, shallow and high freezing point oil reservoirs, the first-line problems are to overcome uncompleted breakdown, uncompleted cleanup of fracturing fluids and cold damages to the formations by injecting cold fluid. To avoid those problems, it is suggested to adopt a new encapsulated heat-generating hydraulic fracturing fluid system as described in this paper.; Firstly, two kinds of chemical heat-generating systems were studied and the NH-4Cl-NaNO-2 system was selected. According to the reaction characteristics of the system, oxalic acid was chosen as a catalyst of reaction and encapsulated using ethyl cellulose and paraffin as coating materials by the phase separation method. Compatibility of NH-4Cl-NaNO-2-encapsulated oxalic acid with hydroxypropyl-guar fracturing fluid was also discussed in the paper. The results showed that the hydraulic fracturing fluid containing encapsulated heat-generating agents hare a good stability and compatibility. When the fracturing fluid contains {2.0} mol·L+{-1} NH-4Cl-NaNO-2, {0.93%} encapsulated oxalic acid and {0.08%} ammonium persulfate, the peak temperature can reach {78.0℃} and the viscosity of residual liquid is {3.12} mPa·s after 4 hours.
基金National Natural Science Foundation of China(No.51275123)
文摘Thermal characteristic of cavitation has great influence on the process of occurrence,development and collapse of bubble in hydraulic system. By choosing the stage of bubble growth as the research object,combining with the characteristic of the process of bubble occurrence and development in hydraulic system, and ignoring the impact of thermal radiation,the heat transfer situation of bubble growth was analyzed under appropriate assumptions of thermodynamic conditions in the bubble generation and development process. The mathematical expression of the temperature change of bubble was deduced using thermodynamic principle. Through combining the expression with classic Rayleigh-Plesset Equation,numerical calculation was carried out and the temperature variation over time( or bubble radius) was obtained. The influences of convective heat transfer coefficient of bubble and polytropic exponent on the thermodynamic process of bubble were analyzed. Finally,the thermal characteristic of bubble growth after cavitation occurrence was summarized.
文摘The technology of passive safety is the current trend among safety systems in nuclear power plant. Pas- sive residual heat removal system (PRHRS), a major part of passive safety systems of Chinese advanced PWR, is a novel design with three-fold natural circulation. On the basis of reasonable physics and mathematics models, MI- TAP-PRHRS code was developed to analyze steady and transient characteristics of the PRHRS. The calculation and analysis show that the code simulates steady characteristics of the PRHRS very well, and it is able to simulate tran- sient characteristics of all startup modes of the PRHRS. However, the quantitative description is poor during the ini- tial stages of the transition process when water hammer occurs.
文摘In this work an experimental investigation was carried out in order to explore the possibility of realizing a domestic heating system by throttling hydraulic oil. Considering the continuous increasing price of diesel oil, this work gains unique importance. Generating heat directly by throttling is realized using a simple environment friendly system which does not require oil transportation and storage, and eliminates the need for chimneys and annual preventive maintenance, as it is the case with heating by utilizing oil burners, which is prevailing in Jordan. Experimental results show that it is possible to raise the room temperature up to 70?C during 15 minutes which is not a limit value. Experimental results show that temperature rate could be increased by selecting the appropriate pump power and by connecting a number of throttles in parallel.
文摘基于无线传输的方式设计了针对供热系统的二次网在小区单元间水力平衡的远程监控系统。该监控系统由可编程逻辑控制器(PLC)、电动调节阀和传感器等设备完成底层采集监控,通过PLC云网关和4G移动通信系统将二次网数据无线传输至云服务器,采用OPC通信和SQL Server数据库实现云网关服务器和监控系统间的数据传输和存储;在KingSCADA软件和Visual Studio Code软件中分别设计编写本地监控系统和网页远程监控系统,使单元间水力平衡的调节参数可视化。测试结果表明,该监控系统可实现供热系统二次网单元间水力平衡调节的实时远程监控功能,对提高水力平衡调节效率具有现实意义。
