Steady-State and Transient Analysis in Single-Phase Natural Circulation of ABV-6M

2010 ◽  
Author(s):  
Fangnian Wang ◽  
Zhaofei Tian ◽  
Jiange Liu
Keyword(s):  
Steady State ◽  
Mass Flow Rate ◽  
Mass Flow ◽  
Flow Rate ◽  
Nuclear Power ◽  
Transient Analysis ◽  
Natural Circulation ◽  
Reactor Power ◽  
Secondary Circuit ◽  
Small Perturbations

This paper discusses the results of the thermal-hydraulic investigations of natural circulation. The RELAP5/MOD3.4 computer code has been used to simulate the natural circulation in an ABV-6M Nuclear Power Plant (NPP), and steady-state and transient operational characteristics are researched. Some results can be listed as follows. In the steady-state analysis, the relationship between the reactor power and the mass flow rate of primary loop, and the temperature difference of core inlet and outlet are obtained. The comparisons between the RELAP5 results and the theoretic calculation data indicate good general agreement. Besides, the mass flow rate of natural circulation will increase and the flow will become stable more quickly when the reactor power increases on the condition of the system with a fixed construction. The trends of the thermal parameters are obtained and the temperature envelope curve of secondary circuit fluid is ascertained. In the transient analysis, some perturbations, such as the fluctuations of feedwater temperature and feedwater mass flow rate, have influence on the system performance. Then, the comparisons between taking an action and not taking an action on Nitrogen Pressurizer are obtained when these small perturbations occur. It is turn out that the safety of natural circulation loop is sensitive to some small perturbations.

Research on Natural Circulation Flow Characteristics of Floating Nuclear Power Plant in Heaving Motion

2017 ◽  
Author(s):  
Li Ren ◽  
Peng Minjun ◽  
Xia Genglei ◽  
Zhao Yanan
Keyword(s):  
Power Plant ◽  
Nuclear Power Plant ◽  
Mass Flow Rate ◽  
Mass Flow ◽  
Flow Rate ◽  
Nuclear Power ◽  
Natural Circulation ◽  
Flow Characteristics ◽  
Circulation Flow ◽  
Drift Flux Model

The FNPP (Floating Nuclear Power Plant) expanded the application field of Integrated Pressurized Water Reactor (IPWR) in the movable marine platform, it is necessary to study the natural circulation flow characteristics in heaving motion on the ocean. From the characteristics of FNPP, by means of THEATRe code which was based on the two-phase drift flux model and was modified by adding module calculating the effect of heaving motion, the simulation model in heaving motion was built. Using the models developed, the natural circulation operating characteristics of natural circulation in heaving motion and the transitions between forced circulation and natural circulation are analyzed. In the case of amplitude limited, the periods of mass flow rate are equal to periods of heaving motion. The oscillation amplitude of mass flow rate increases with the heaving amplitude increase. In the case of period limited, the natural circulation flow rate oscillating amplitude increases with the heaving period increases. The result obtained are not only evaluating FNPP design behavior properly but also pointing out the direction to further optimum design to ensure FNPP operating safety in heaving motion.

Steady-State Energetic and Exergetic Performances of Single-Phase Natural Circulation Loop With Hybrid Nanofluids

2019 ◽  
Vol 141 (8) ◽  
Author(s):  
Mayaram Sahu ◽  
Jahar Sarkar
Keyword(s):  
Steady State ◽  
Mass Flow Rate ◽  
Entropy Generation ◽  
Mass Flow ◽  
Flow Rate ◽  
Natural Circulation ◽  
Circulation Loop ◽  
Hybrid Nanofluid ◽  
Natural Circulation Loop ◽  
Hybrid Nanofluids

Energy and exergy performances of natural circulation loop (NCL) with various water-based hybrid nanofluids (Al2O3 + TiO2, Al2O3 + CNT, Al2O3 + Ag, Al2O3 + Cu, Al2O3 + CuO, Al2O3 + graphene) with 1% volumetric concentration are compared in this study. New thermophysical property models have been proposed for hybrid nanofluids with different particle shapes and mixture ratio. Effects of power input, loop diameter, loop height, loop inclination and heater/cooler inclination on steady-state mass flow rate, effectiveness, and entropy generation are discussed as well. Results show that both the steady-state mass flow rate and energy–exergy performance are enhanced by using the hybrid nanofluids, except Al2O3 + graphene, which shows the performance decrement within the studied power range. Al2O3 + Ag hybrid nanofluid shows highest enhancement in mass flow rate of 4.8% compared to water. The shape of nanoparticle has shown a significant effect on steady-state performance; hybrid nanofluid having cylindrical and platelet shape nanoparticles yields lower mass flow rate than that of spherical shape. Mass flow rate increases with the increasing loop diameter and height, whereas decreases with the increasing loop and heater/cooler inclinations. Both effectiveness and entropy generation increase with the decreasing loop diameter and height, whereas increasing the loop and heater/cooler inclinations. This study reveals that the particle shape has a significant effect on the performance of hybrid nanofluids in NCL, and the use of hybrid nanofluid is more effective for higher power.

scholarly journals Development of circuit model with natural circulation of coolant under conditions of ship motion

Vestnik IGEU ◽  
2021 ◽  
pp. 19-26
Author(s):  
A.M. Samoilov ◽  
A.A. Sataev ◽  
A.A. Blokhin ◽  
V.V. Ivanov
Keyword(s):  
Experimental Data ◽  
Mathematical Model ◽  
Mass Flow Rate ◽  
Mass Flow ◽  
Flow Rate ◽  
Nuclear Power ◽  
Natural Circulation ◽  
Ship Motion ◽  
Nuclear Power Installation ◽  
Testing Bench

Safety is the key requirement to any nuclear power installation. Various factors affect safety during operation of the nuclear power installation. These factors are difficult to study due to the high economic costs. This problem can be solved by developing prototype models to conduct the research of many complex processes. Dynamic impact on the ship installation is one of these processes. The most significant impact is the impact on the natural circulation of the coolant, that is one of the basic emergency safety systems. Also, it is a promising way to ensure movement in the main circulation circuit. The purpose of this paper is to assess the influence of external dynamic forces on the processes of natural circulation. For the study a testing bench has been developed that simulates one of the circulation loops of the reactor unit. The basic method to obtain experimental data is temperature sounding of the specific sections of the circulation route. A mathematical model has been developed that describes this process. The model is based on the equations of momentum conservation and heat balance. In accordance with the experimental data, the calculation of natural circulation for static and dynamic modes has been carried out. A mathematical model to describe this process has been developed. A comparative analysis of the results of calculating the static and dynamic modes has been carried out. It is founded out that the decrease of mass flow rate is about 10 % as compared with the static regime. It confirms the qualitative effect of ship motion on natural circulation. The practical significance of the research is the development of a model under conditions of ship motion, as well as verification of the model at the testing bench. The results show a significant effect of ship motion on the mass flow rate of the coolant in the case of natural circulation. Thus, to ensure the required safety of ship installations, it is recommended to conduct a study of natural circulation in accordance with the developed model under conditions of maximum possible ship motion.

Experimental Observation of the General Trends of the Steady State and Instability Behavior of Supercritical Water Natural Circulation

2013 ◽  
Author(s):  
Fa Lv ◽  
Yan-ping Huang ◽  
Yan-lin Wang ◽  
Xiao Yan
Keyword(s):  
Steady State ◽  
Water Temperature ◽  
Mass Flow Rate ◽  
Mass Flow ◽  
Flow Rate ◽  
Supercritical Water ◽  
Natural Circulation ◽  
Water Pressure ◽  
Heating Power ◽  
Heated Zone

Experimental study on steady state and instability behavior of subcritical and supercritical water natural circulation was performed in a rectangular loop (NPIC-SCNCL) in NPIC, with the pressure of 10 and 21.1∼24.8MPa. According to the experimental results, in steady state the natural circulation displayed higher mass flow rate, heating power and outlet water temperature of the heated zone under supercritical pressure (22.2∼24.8Mpa) than those under subcritical pressure (10MPa). The effects of heating power and water pressure on the steady state behavior of supercritical water natural circulation were also carried out. In the experiments, natural circulation showed instability both in supercritical and subcritical conditions. The results showed that the natural circulation instability appeared when the outlet water temperature of the heated zone got close to the critical temperature under supercritcial pressure. In comparion, the natural circulation instability appeared when the outlet water temperature of the heated zone got close to the saturated temperature in subcritical condition. The instability behavior of supercritical water natural circulation showed the fluctuations of the mass flow rate, water temperature and pressure et al. In the experiments, we also observed that the fluctuations of the parameters mentioned above for supercritical water natural circulation instability could disappear when the heating power is big enough which seemed that the natural circulation returned to a new steady state.

Experimental Studies on Nanofluid-Based Rectangular Natural Circulation Loop

2019 ◽  
Vol 11 (4) ◽  
Author(s):  
Ramesh Babu Bejjam ◽  
K. Kiran Kumar ◽  
Karthik Balasubramanian
Keyword(s):  
Nusselt Number ◽  
Steady State ◽  
Rayleigh Number ◽  
Mass Flow Rate ◽  
Mass Flow ◽  
Flow Rate ◽  
Thermal Performance ◽  
Natural Circulation ◽  
Working Fluids ◽  
Natural Circulation Loop

The main objective of the present study is to carry out experimental investigation on thermal performance of the nanofluid-based rectangular natural circulation loop (NCL). For this study, an experimental test rig is fabricated with heater as heat source, and tube in tube heat exchanger as heat sink. For the experimentation, three different nanofluids are used as working fluids. The nanometer-sized particles of silicon dioxide (SiO2), copper oxide (CuO), and alumina (Al2O3) are dispersed in distilled water to produce the nanofluids at different volume concentrations ranging from 0.5% to 1.5%. Experiments are carried out at different power inputs and different cold fluid inlet temperatures. The results indicate that NCL operating with nanofluid reaches steady-state condition quickly, when compared to water due to its increased thermal conductivity. The steady-state reaching time is reduced by 12–27% by using different nanofluids as working fluids in the loop when compared to water. The thermal performance parameters like mass flow rate, Rayleigh number, and average Nusselt number of the nanofluid-based NCL are improved by 10.95%, 16.64%, and 8.10%, respectively, when compared with water-based NCL. At a given power input, CuO–water nanofluid possess higher mass flow rate, Rayleigh number and Nusselt number than SiO2–water and Al2O3–water nanofluids due to better thermo-rheological properties.

Pitfalls for Accurate Steady-State Port Flow Simulations

2012 ◽  
Author(s):  
Xiaofeng Yang ◽  
Zhaohui Chen ◽  
Tang-Wei Kuo
Keyword(s):  
Steady State ◽  
Mass Flow Rate ◽  
Mass Flow ◽  
Flow Rate ◽  
Measured Data ◽  
Steady State Flow ◽  
Bench Tests ◽  
Flow Simulations ◽  
Mesh Topology ◽  
State Flow

Steady-state port flow simulations were carried out with a commercial three dimensional (3D) Computational Fluid Dynamics (CFD) code using Cartesian mesh with cut cells to study the prediction accuracy. The accuracy is assessed by comparing predicted and measured mass-flow rate and swirl and tumble torques at various valve lifts using different boundary condition setup and mesh topology relative to port orientation. The measured data is taken from standard steady-state flow bench tests of a production intake port. The predicted mass-flow rates agree to within 1% with the measured data between the intermediate and high valve lifts. At low valve lifts, slight over prediction in mass-flow rate can be observed. The predicted swirl and tumble torques are within 25% of the flow bench measurements. Several meshing parameters were examined in this study. These include: inlet plenum shape and outlet plenum/extension size, embedded sphere with varying minimum mesh size, finer meshes on port and valve surface, orientation of valve and port centerline relative to the mesh lines. For all model orientations examined, only the mesh topology with the valve axis aligned closely with the mesh lines can capture the mass-flow rate drop for very high valve lifts due to flow separation. This study further demonstrated that it is possible to perform 3D CFD flow analyses to adequately simulate steady-state flow bench tests.

Study of Heat Mass and Mass Transfers in a Spray for Containment Application: Analysis of the Influence of the Spray Mass Flow Rate

2008 ◽  
Author(s):  
Pascal Lemaitre ◽  
Emmanuel Porcheron
Keyword(s):  
Mass Flow Rate ◽  
Mass Flow ◽  
Flow Rate ◽  
Nuclear Power ◽  
Initial Conditions ◽  
Hydraulic Behaviour ◽  
Application Analysis ◽  
Mass Flow Rates ◽  
Hypothetical Accident ◽  
Mass Transfers

During the course of a hypothetical accident in a nuclear power plant, spray might be activated in order to reduce static pressure in the containment. To have a better understanding of the heat and mass transfers between a spray and the surrounding confined gas, the IRSN has developed the TOSQAN experiment. This article is devoted to analyse the influence of the injected spray mass flow rate on the thermal-hydraulic of spray tests. In order to perform this analysis, two other tests are performed with exactly the same boundary and initial conditions, except the spray mass flow rate that ranges from 10 to 50 g.s−1. First, the scenario of these three tests and the associated results used for this analysis are presented. Then, we focus our analysis on the inter-comparison of the thermal-hydraulic behaviour induced by spray mass flow rates variations. This inter-comparison is divided into two parts: a global and a local one.

Predictions of Flow Separation at the Valve-Seat for Steady-State Port-Flow Simulation

2014 ◽  
Author(s):  
Tao Fang ◽  
Satbir Singh
Keyword(s):  
Steady State ◽  
Mass Flow Rate ◽  
Mass Flow ◽  
Flow Rate ◽  
Flow Separation ◽  
Combustion Engine ◽  
Flow Simulation ◽  
Valve Lift ◽  
Valve Seat ◽  
Mesh Density

Steady-state port-flow simulations with static valve lift are often utilized to optimize the performance of intake system of an internal combustion engine. Generally, increase in valve lift results in higher mass flow rate through the valve. But in certain cases, mass flow rate can actually decrease with increased valve lift, caused by separation of turbulent flow at the valve-seat. Prediction of this phenomenon using computational fluid dynamics (CFD) models is not trivial. It is found that the computational mesh significantly influences the simulation results. A series of steady-state port flow simulation are carried out using a commercial CFD code. Several mesh topologies are applied for the simulations. The predicted results are compared with available experimental data from flow bench measurements. It is found that the flow separation and reduction in mass flow rate with increased valve lift can be predicted when high mesh density is used in the proximity of the valve seat and the walls of the intake port. Higher mesh density also gives better predictions of mass flow rate compared to the experiments, but only for high valve lifts. For low valve lifts, the error in predicted flow rate is close to 13%.

MHD Transient Free Convection Flow in Vertical Concentric Annulus with Isothermal and Adiabatic Boundaries

2017 ◽  
Vol 11 ◽  
pp. 40-52 ◽  
Author(s):  
Basant K. Jha ◽  
Taiwo S. Yusuf
Keyword(s):  
Steady State ◽  
Free Convection ◽  
Skin Friction ◽  
Mass Flow Rate ◽  
Mass Flow ◽  
Flow Rate ◽  
Steady State Solution ◽  
State Solution ◽  
Concentric Annulus ◽  
Riemann Sum

This paper presents MHD transient flow in an infinite vertical concentric annulus when the fluid is set in motion by free convection current occurring in the annulus as a result of application of isothermal heating on the inner surface of the outer cylinder while the outer surface of the inner cylinder is thermally insulated. The solution of the governing equations are obtained using the well-known Laplace transform technique while the Riemann-sum approximation method has been used to invert the solution from Laplace domain to time domain. The numerical values obtained using Riemann-sum approximation approach is validated by presenting a comparison with the values obtained using the implicit finite difference method as well as the steady-state solution. These comparisons with the steady state solution shows a remarkable agreement at large value of time. The effect of the governing parameters on the velocity field, temperature field, mass flow rate as well as the skin-friction on both surfaces of the annulus have been analysed and presented with the aid of line graph. Generally, we observed that the mass flow rate and skin friction at the isothermally heated surface increases with increase in radius ratio. However, the reverse is seen at the thermally insulated surface as the skin-friction decreases with increase in radius ratio.

Study on Factors Affecting CHF Based on Factorial Analysis in Narrow Rectangular Channel Under Natural Circulation

2018 ◽  
Author(s):  
Li Zichao ◽  
Zhou Tao ◽  
Shi Shun ◽  
Amir Haider ◽  
Li Bing ◽  
...  
Keyword(s):  
Mass Flow Rate ◽  
Influencing Factors ◽  
Mass Flow ◽  
Flow Rate ◽  
Natural Circulation ◽  
Rectangular Channel ◽  
Factorial Analysis ◽  
Contribution Rate ◽  
Factors Affecting ◽  
System Pressure

Research on influencing factors of CHF in narrow rectangular channel under natural circulation is of great significance to the safety of reactors. Taking the narrow rectangular experimental device as the research object, influencing factors of CHF in narrow rectangular channel were experimentally studied under natural circulation. With factorial analysis, effects of different factors and their interactions on CHF were analyzed. It is found that the contribution rate of mass flow rate is the largest, followed by the effect of outlet dryness, followed by the effect of system pressure. Their interactions between different factors have little effects on CHF in narrow rectangular channel under natural circulation.

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