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
[目的]为Pleurotus eryngii—Co60-7木质素降解酶的分离纯化和综合利用提供试验依据。[方法]采用DEAE—Sepharose^TM Fast Flow离子交换介质，分别考察缓冲液pH值、流速和洗脱方式等对刺芹侧耳木质素降解酶分离纯化的影响，确定了最佳...[目的]为Pleurotus eryngii—Co60-7木质素降解酶的分离纯化和综合利用提供试验依据。[方法]采用DEAE—Sepharose^TM Fast Flow离子交换介质，分别考察缓冲液pH值、流速和洗脱方式等对刺芹侧耳木质素降解酶分离纯化的影响，确定了最佳分离纯化层析条件。[结果]DEAE-Sephalose^TM Fast Flow分离纯化Pleurotus eryngii-Co60-7木质素降解酶的最佳层析条件为：选择20mmol／L，pH值为5．0醋酸钠一醋酸缓冲体系，3ml／min的流速，进行分步洗脱（100、200～300和1000mmoL／L NaCl的三步洗脱），可较好地实现刺芹侧耳发酵液木质素降解酶初分，该纯化操作目标蛋白回收率达85％，纯化分离因素为2．71。[结论]该技术在分离纯化刺芹侧耳木质素降解酶上可行，具有潜在的工业应用价值。展开更多
[Objective] This study aimed to establish an efficient process for separation of phycoerythrin by using Q Sepharose Fast Flow resin and verity its feasibility for scale-up. [Method] Elution gradient, sample volume and...[Objective] This study aimed to establish an efficient process for separation of phycoerythrin by using Q Sepharose Fast Flow resin and verity its feasibility for scale-up. [Method] Elution gradient, sample volume and flow rate were optimized to determine the optimal separation condition, under which the scale-up process was verified. [Result] The optimal condition for separation of phycoerythrin by using Q Sepharose FF resin was investigated： 30 ml of laver extract was loaded to the Q Sepharose FF column with a bed volume of 8 ml; subsequently, the column was stepwise eluted with 0-0.10-0.35-1.00 mol/L NaCI solution （pH 6.0） at a constant flow rate of 1 ml/min; the elution peak under 0.35 mol/L NaCI solution was collected, and the recovery rate and purity coefficient （A565/A280） of phycoerythrin were determined as 44.3 and 1.15, respectively. Based on the established process, 75 ml of phycoerythrin extract was loaded to the Q Sepharose FF column with a bed volume of 20 ml for separation, while no significant variation was observed in the separation result. [Conclusion] Phycoerythrin can be well separated from laver extract by using Q Sepharose FF resin and the process is feasible for scale-up.展开更多
Owing to the inherent instability of the natural circulation system,flow instability can easily occur during the operation of a natural circulation lead-cooled fast reactor,especially during the startup phase.A compre...Owing to the inherent instability of the natural circulation system,flow instability can easily occur during the operation of a natural circulation lead-cooled fast reactor,especially during the startup phase.A comprehensive startup scheme for SNCLFR-100,including primary and secondary circuits,is proposed in this paper.It references existing more mature startup schemes in various reactor types.It additionally considers the restriction conditions on the power increase in other schemes and the characteristics of lead-based coolant.On this basis,the multi-scale coupling code ATHLET-OpenFOAM was used to study the flow instability in the startup phase under different power-step amplitudes and power duration times.The results showed that obvious flow instability phenomena were found in the different startup schemes,such as the short-term backflow phenomenon of the core at the initial time of the startup.Moreover,an obvious increase in the flow rate and temperature to the peak value at the later stage of a continuous power rise was observed,as well as continuous oscillations before reaching a steady state.It was determined that the scheme with smaller power-step amplitude and a longer power duration time requires more time to start the reactor.Nevertheless,it will be more conducive to the safe and stable startup of the reactor.展开更多
针对油浸式电力变压器瞬态温升计算效率过低的问题,该文提出本征正交分解-αATS(proper orthogonal decomposition-adaptive time stepping based onαfactor,POD-αATS)降阶自适应变步长瞬态计算方法。首先,推导变压器绕组瞬态温升计...针对油浸式电力变压器瞬态温升计算效率过低的问题,该文提出本征正交分解-αATS(proper orthogonal decomposition-adaptive time stepping based onαfactor,POD-αATS)降阶自适应变步长瞬态计算方法。首先,推导变压器绕组瞬态温升计算的有限元离散方程;其次,采用POD降阶算法改善传统瞬态计算中存在的条件数过大及方程阶数过高的问题;同时对于瞬态计算中的时间步长选择问题,提出适用于非线性问题的αATS变步长策略;然后,为验证方法的有效性,基于110 kV油浸式电力变压器绕组的基本结构建立二维八分区数值计算模型,同时将计算结果与基于110 kV绕组的温升实验结果进行对比。数值计算及实验结果表明,所提算法与全阶定步长算法在流场和温度场中的精度几乎相同,且流场计算效率提升约45倍,温度场计算效率提升约38倍,计算速度得到显著提高。这一点在温升实验中同样得到验证,说明该文所提算法的准确性、高效性及一定的工程实用性。展开更多
In this paper,we first establish a new fractional magnetohydrodynamic(MHD)coupled flow and heat transfer model for a generalized second-grade fluid.This coupled model consists of a fractional momentum equation and a h...In this paper,we first establish a new fractional magnetohydrodynamic(MHD)coupled flow and heat transfer model for a generalized second-grade fluid.This coupled model consists of a fractional momentum equation and a heat conduction equation with a generalized form of Fourier law.The second-order fractional backward difference formula is applied to the temporal discretization and the Legendre spectral method is used for the spatial discretization.The fully discrete scheme is proved to be stable and convergent with an accuracy of O(τ^(2)+N-r),whereτis the time step-size and N is the polynomial degree.To reduce the memory requirements and computational cost,a fast method is developed,which is based on a globally uniform approximation of the trapezoidal rule for integrals on the real line.The strict convergence of the numerical scheme with this fast method is proved.We present the results of several numerical experiments to verify the effectiveness of the proposed method.Finally,we simulate the unsteady fractional MHD flow and heat transfer of the generalized second-grade fluid through a porous medium.The effects of the relevant parameters on the velocity and temperature are presented and analyzed in detail.展开更多
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.
文摘[目的]为Pleurotus eryngii—Co60-7木质素降解酶的分离纯化和综合利用提供试验依据。[方法]采用DEAE—Sepharose^TM Fast Flow离子交换介质，分别考察缓冲液pH值、流速和洗脱方式等对刺芹侧耳木质素降解酶分离纯化的影响，确定了最佳分离纯化层析条件。[结果]DEAE-Sephalose^TM Fast Flow分离纯化Pleurotus eryngii-Co60-7木质素降解酶的最佳层析条件为：选择20mmol／L，pH值为5．0醋酸钠一醋酸缓冲体系，3ml／min的流速，进行分步洗脱（100、200～300和1000mmoL／L NaCl的三步洗脱），可较好地实现刺芹侧耳发酵液木质素降解酶初分，该纯化操作目标蛋白回收率达85％，纯化分离因素为2．71。[结论]该技术在分离纯化刺芹侧耳木质素降解酶上可行，具有潜在的工业应用价值。
基金Supported by National Natural Science Foundation of China(51143012)Natural Science Foundation of Shandong Province(ZR2009BM006)~~
文摘[Objective] This study aimed to establish an efficient process for separation of phycoerythrin by using Q Sepharose Fast Flow resin and verity its feasibility for scale-up. [Method] Elution gradient, sample volume and flow rate were optimized to determine the optimal separation condition, under which the scale-up process was verified. [Result] The optimal condition for separation of phycoerythrin by using Q Sepharose FF resin was investigated： 30 ml of laver extract was loaded to the Q Sepharose FF column with a bed volume of 8 ml; subsequently, the column was stepwise eluted with 0-0.10-0.35-1.00 mol/L NaCI solution （pH 6.0） at a constant flow rate of 1 ml/min; the elution peak under 0.35 mol/L NaCI solution was collected, and the recovery rate and purity coefficient （A565/A280） of phycoerythrin were determined as 44.3 and 1.15, respectively. Based on the established process, 75 ml of phycoerythrin extract was loaded to the Q Sepharose FF column with a bed volume of 20 ml for separation, while no significant variation was observed in the separation result. [Conclusion] Phycoerythrin can be well separated from laver extract by using Q Sepharose FF resin and the process is feasible for scale-up.
文摘Owing to the inherent instability of the natural circulation system,flow instability can easily occur during the operation of a natural circulation lead-cooled fast reactor,especially during the startup phase.A comprehensive startup scheme for SNCLFR-100,including primary and secondary circuits,is proposed in this paper.It references existing more mature startup schemes in various reactor types.It additionally considers the restriction conditions on the power increase in other schemes and the characteristics of lead-based coolant.On this basis,the multi-scale coupling code ATHLET-OpenFOAM was used to study the flow instability in the startup phase under different power-step amplitudes and power duration times.The results showed that obvious flow instability phenomena were found in the different startup schemes,such as the short-term backflow phenomenon of the core at the initial time of the startup.Moreover,an obvious increase in the flow rate and temperature to the peak value at the later stage of a continuous power rise was observed,as well as continuous oscillations before reaching a steady state.It was determined that the scheme with smaller power-step amplitude and a longer power duration time requires more time to start the reactor.Nevertheless,it will be more conducive to the safe and stable startup of the reactor.
文摘针对油浸式电力变压器瞬态温升计算效率过低的问题,该文提出本征正交分解-αATS(proper orthogonal decomposition-adaptive time stepping based onαfactor,POD-αATS)降阶自适应变步长瞬态计算方法。首先,推导变压器绕组瞬态温升计算的有限元离散方程;其次,采用POD降阶算法改善传统瞬态计算中存在的条件数过大及方程阶数过高的问题;同时对于瞬态计算中的时间步长选择问题,提出适用于非线性问题的αATS变步长策略;然后,为验证方法的有效性,基于110 kV油浸式电力变压器绕组的基本结构建立二维八分区数值计算模型,同时将计算结果与基于110 kV绕组的温升实验结果进行对比。数值计算及实验结果表明,所提算法与全阶定步长算法在流场和温度场中的精度几乎相同,且流场计算效率提升约45倍,温度场计算效率提升约38倍,计算速度得到显著提高。这一点在温升实验中同样得到验证,说明该文所提算法的准确性、高效性及一定的工程实用性。
基金supported by the Project of the National Key R&D Program(Grant No.2021YFA1000202)National Natural Science Foundation of China(Grant Nos.12120101001,12001326 and 12171283)+2 种基金Natural Science Foundation of Shandong Province(Grant Nos.ZR2021ZD03,ZR2020QA032 and ZR2019ZD42)China Postdoctoral Science Foundation(Grant Nos.BX20190191 and 2020M672038)the Startup Fund from Shandong University(Grant No.11140082063130)。
文摘In this paper,we first establish a new fractional magnetohydrodynamic(MHD)coupled flow and heat transfer model for a generalized second-grade fluid.This coupled model consists of a fractional momentum equation and a heat conduction equation with a generalized form of Fourier law.The second-order fractional backward difference formula is applied to the temporal discretization and the Legendre spectral method is used for the spatial discretization.The fully discrete scheme is proved to be stable and convergent with an accuracy of O(τ^(2)+N-r),whereτis the time step-size and N is the polynomial degree.To reduce the memory requirements and computational cost,a fast method is developed,which is based on a globally uniform approximation of the trapezoidal rule for integrals on the real line.The strict convergence of the numerical scheme with this fast method is proved.We present the results of several numerical experiments to verify the effectiveness of the proposed method.Finally,we simulate the unsteady fractional MHD flow and heat transfer of the generalized second-grade fluid through a porous medium.The effects of the relevant parameters on the velocity and temperature are presented and analyzed in detail.
